├── ALPR
    ├── ALPR.java
    ├── License Plate Photos
    │   ├── ca2004.jpg
    │   ├── ca2005.jpg
    │   ├── ca2006.jpg
    │   ├── ca_10.jpeg
    │   ├── ca_12.jpeg
    │   ├── ca_aug2012.png
    │   ├── fl_1.jpeg
    │   ├── ny_1.jpeg
    │   └── tx_4.jpeg
    └── Training Data
    │   ├── letters-1 image.png
    │   ├── letters-2 image.png
    │   ├── letters-3 image.png
    │   └── numbers image.png
├── EscapeNestedLoops.java
├── Factorial.java
├── Image Filters
    └── ImageFilter.java
├── Java 8 Streams
    ├── JavaStreams.java
    ├── bands.txt
    └── data.txt
├── LICENSE
├── LinkedList.java
├── ListToArray.java
├── MapFunctions.java
├── MyIterator.java
├── Primes.java
├── QuickSort.java
├── README.md
├── SplitString.java
├── StringToInt.java
├── Temperature.java
├── Tree.java
├── bubbleSort.java
├── insertionSort.java
├── mergeSort.java
├── primes.txt
└── selectionSort.java


/ALPR/ALPR.java:
--------------------------------------------------------------------------------
  1 | // Automatic License Plate Recognition (ALPR)
  2 | // (c) 2023, Joe James
  3 | 
  4 | /*******************************************************************************
  5 |  * This Automatic License Plate Reader program is mainly intended to 
  6 |  * accompany my series of YouTube tutorial videos here, 
  7 |  * https://www.youtube.com/user/joejamesusa and is mainly 
  8 |  * intended for educational purposes. You are invited to subscribe to my 
  9 |  * video channel, and to download and use any code in this Java 
 10 |  * repository, according to the MIT License. Feel free to post any comments 
 11 |  * on my YouTube channel. 
 12 |  * 
 13 |  * ****************************************************************************/
 14 | 
 15 | import java.util.*;
 16 | import java.awt.*;
 17 | import java.awt.image.*;
 18 | import java.awt.geom.AffineTransform;
 19 | import java.io.*;
 20 | import javax.imageio.ImageIO;
 21 | import javax.swing.*;
 22 | import java.util.stream.*;
 23 | import java.lang.Math;
 24 | 
 25 | public class ALPR {
 26 | 	// Penitentiary Gothic font, 20x43 pix = 860 pixels
 27 | 	int[] CHARSIZE = {20, 43};
 28 | 	int NUMPIXELS = CHARSIZE[0] * CHARSIZE[1];
 29 | 	ArrayList<String> trainLabels = new ArrayList<>(Arrays.asList("A","B","C","D","E","F","G","H","I","J","K","L","M",
 30 | 		"N","O","P","Q","R","S","T","U","V","W","X","Y","Z","0","1","2","3","4","5","6","7","8","9"));
 31 | 	ArrayList<Integer[]> trainData = new ArrayList<>(trainLabels.size());
 32 | 
 33 | 	public static void main(String[] args) {
 34 | 		ALPR alpr = new ALPR();
 35 | 		File[] files = new File[4];
 36 | 		files[0] = new File("Training Data/letters-1 image.png");
 37 | 		files[1] = new File("Training Data/letters-2 image.png");
 38 | 		files[2] = new File("Training Data/letters-3 image.png");
 39 | 		files[3] = new File("Training Data/numbers image.png");
 40 | 		alpr.train(files);
 41 | 
 42 | 		//File file = new File("License Plate Photos/ca_aug2012.png");
 43 | 		//File file = new File("License Plate Photos/ca_12.jpeg");
 44 | 		File file = new File("License Plate Photos/ca_10.jpeg");
 45 | 		//File file = new File("License Plate Photos/ca2004.jpg");
 46 | 		//File file = new File("License Plate Photos/ca2005.jpg");
 47 | 		//File file = new File("License Plate Photos/ca2006.jpg");
 48 | 		//File file = new File("License Plate Photos/ca_blue_1.jpeg");
 49 | 		//File file = new File("License Plate Photos/tx_4.jpeg");
 50 | 		//File file = new File("License Plate Photos/ny_1.jpeg");
 51 | 		//File file = new File("License Plate Photos/fl_1.jpeg");
 52 | 		alpr.readPlate(file);
 53 | 	}
 54 | 
 55 | 	public void readPlate(File file) {
 56 | 		System.out.println("Loading file.");
 57 | 		BufferedImage img = null;
 58 | 		int height1 = 200;
 59 | 		ArrayList<Integer[]> testData = new ArrayList<>();
 60 | 		try { img = ImageIO.read(file); } 
 61 | 		catch (IOException e) { e.printStackTrace(System.out); }
 62 | 
 63 | 		if (img != null) {
 64 | 			display(img);
 65 | 			img = toGrayScale(img);
 66 | 			display(img);
 67 | 			img = getScaledImage(img, height1);
 68 | 
 69 | 			// Crop out top and bottom margins
 70 | 			int[] vertBounds = getTopBottom(img);
 71 | 			img = img.getSubimage(0, vertBounds[0], img.getWidth(), vertBounds[1]-vertBounds[0]);
 72 | 
 73 | 			// Scale image to CHARSIZE height
 74 | 			img = getScaledImage(img, CHARSIZE[1]);
 75 | 			System.out.println("  Scaled image: " + img.getHeight() + "x" + img.getWidth());
 76 | 			display(img);
 77 | 
 78 | 			// boost contrast
 79 | 			img = boostContrast(img);
 80 | 
 81 | 			ArrayList<Integer> edges = getEdges(img);
 82 | 			System.out.println(" Found edges: " + edges);
 83 | 			/*display(img.getSubimage(edges.get(0)+2, 0, CHARSIZE[0], img.getHeight()));
 84 | 			display(img.getSubimage(edges.get(1)+2, 0, CHARSIZE[0], img.getHeight()));
 85 | 			display(img.getSubimage(edges.get(2)+2, 0, CHARSIZE[0], img.getHeight()));
 86 | 			display(img.getSubimage(edges.get(3)+2, 0, CHARSIZE[0], img.getHeight()));
 87 | 			display(img.getSubimage(edges.get(4)+2, 0, CHARSIZE[0], img.getHeight()));
 88 | 			display(img.getSubimage(edges.get(5)+2, 0, CHARSIZE[0], img.getHeight()));
 89 | 			display(img.getSubimage(edges.get(6)+2, 0, CHARSIZE[0], img.getHeight()));*/
 90 | 
 91 | 			// add character data to ArrayList for comparisons to trainData
 92 | 			testData = imgToArray(img, testData, edges);
 93 | 
 94 | 			// identify characters in testData
 95 | 			String plateNum = identify(testData);
 96 | 			System.out.println(plateNum);
 97 | 		}
 98 | 	}
 99 | 
100 | 	// receives an image of a plate, splits it into digits
101 | 	public void train(File[] files) {
102 | 		BufferedImage img = null;
103 | 		
104 | 		for (int i=0; i<files.length; i++) {
105 | 		try {
106 | 			img = ImageIO.read(files[i]);
107 | 		} catch (IOException e) { }
108 | 
109 | 		if (img != null) {
110 | 			//System.out.println("  Training Image Loaded " + img.getHeight() + "x" + img.getWidth());
111 | 			// convert to grayscale img
112 | 			img = toGrayScale(img);
113 | 
114 | 			// find top and bottom edges of characters to trim whitespace
115 | 			int[] rowSums = new int[img.getHeight()];
116 | 			for (int y=0; y<img.getHeight(); y++) {
117 | 				for (int x=0; x<img.getWidth(); x++) {
118 | 					rowSums[y] += img.getRGB(x, y)& 0xFF;
119 | 				}
120 | 			}
121 | 
122 | 			int[] vertBounds = new int[2];
123 | 			vertBounds = getBounds(vertBounds, rowSums);
124 | 			System.out.println("  Top row = " + ++vertBounds[0] + ".  Bottom row = " + vertBounds[1] + ".");
125 | 			
126 | 			// Crop out top and bottom white margins
127 | 			img = img.getSubimage(0, vertBounds[0], img.getWidth(), vertBounds[1]-vertBounds[0]);
128 | 
129 | 			// Scale image to CHARSIZE height
130 | 			img = getScaledImage(img, CHARSIZE[1]);
131 | 			//System.out.println("  Height = " + img.getHeight() + ".  Width = " + img.getWidth() + ".");
132 | 			//display(img);
133 | 
134 | 			// get edges between characters (find left edge of each character)
135 | 			ArrayList<Integer> edges = getEdges(img);
136 | 			
137 | 			// add grayscale data for each character to training data set
138 | 			trainData = imgToArray(img, trainData, edges);
139 | 			
140 | 			//int[] intArray = Arrays.stream(trainData.get(trainData.size()-1)).mapToInt(Integer::intValue).toArray();
141 | 			//display(intArray, CHARSIZE[0], CHARSIZE[1]);
142 | 		}
143 | 		}
144 | 		// add a few hard-coded chars to training data 
145 | 		addMoreTrainingData();
146 | 
147 | 		System.out.println(trainData.size() + " characters loaded.");
148 | 	}
149 | 
150 | 	// convert imageto grayscale 
151 | 	public BufferedImage toGrayScale(BufferedImage img) {
152 | 		System.out.println("  Converting to GrayScale.");
153 | 		BufferedImage grayImage = new BufferedImage(
154 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
155 | 		Graphics g = grayImage.getGraphics();
156 | 		g.drawImage(img, 0, 0, null);
157 | 		g.dispose();
158 | 		return grayImage;
159 | 	}
160 | 
161 | 	// display image in a JPanel popup
162 | 	public void display (BufferedImage img) {
163 | 		//System.out.println("  Displaying image.");
164 | 		JFrame frame = new JFrame();
165 | 	    JLabel label = new JLabel();
166 | 		frame = new JFrame();
167 | 		frame.setSize(img.getWidth(), img.getHeight());
168 | 		label.setIcon(new ImageIcon(img));
169 | 		frame.getContentPane().add(label, BorderLayout.CENTER);
170 | 		frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
171 | 		frame.pack();
172 | 		frame.setVisible(true);
173 | 	}
174 | 
175 | 	// display image in a JPanel popup, from int array
176 | 	private void display(int[] pixels, int width, int height) {
177 | 		System.out.println("  Printing image for array length: " + pixels.length + ", " + width + "x" + height);
178 | 		BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
179 | 		WritableRaster raster = img.getRaster();
180 | 		raster.setPixels(0, 0, width, height, pixels);
181 | 		display(img);
182 | 	}
183 | 
184 | 	// scale image
185 | 	private BufferedImage getScaledImage (BufferedImage img, int newHeight) {
186 | 		System.out.println("  Scaling image.");
187 | 		double scaleFactor = (double) newHeight/img.getHeight();
188 | 		BufferedImage scaledImg = new BufferedImage(
189 | 			(int)(scaleFactor*img.getWidth()), newHeight, BufferedImage.TYPE_BYTE_GRAY);
190 | 		AffineTransform at = new AffineTransform();
191 | 		at.scale(scaleFactor, scaleFactor);
192 | 		AffineTransformOp scaleOp = new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
193 | 		return scaleOp.filter(img, scaledImg);
194 | 	}
195 | 
196 | 	// convert grayscale image to BW
197 | 	private BufferedImage boostContrast(BufferedImage img) {
198 | 		// compute average pixel darkness
199 | 		int avg = 0;
200 | 		for (int y=0; y<img.getHeight(); y++) {
201 | 				for (int x=0; x<img.getWidth(); x++) {
202 | 					avg += img.getRGB(x, y)& 0xFF;
203 | 				}
204 | 			}
205 | 		avg /= img.getHeight() * img.getWidth();
206 | 
207 | 		// convert grayscale pixels in img to BW
208 | 		for (int y=0; y<img.getHeight(); y++) {
209 | 			for (int x=0; x<img.getWidth(); x++) {
210 | 				int p = img.getRGB(x, y)& 0xFF;
211 | 				if (p>avg)
212 | 					p = (255<<24) | (255<<16) | (255<<8) | 255;
213 | 				else
214 | 					p = (255<<24) | (0<<16) | (0<<8) | 0;
215 | 				img.setRGB(x, y, p);
216 | 			}
217 | 		}
218 | 		return img;
219 | 	}
220 | 
221 | 	private Integer[] boostContrast(Integer[] data) { 
222 | 		// compute average pixel darkness
223 | 		int avg = 0;
224 | 		for (int i=0; i<data.length; i++) {
225 | 			avg += data[i];
226 | 		}
227 | 		avg /= data.length;
228 | 
229 | 		// convert grayscale to BW
230 | 		for (int i=0; i<data.length; i++) {
231 | 			if (data[i]>avg)
232 | 				data[i] = 255;
233 | 			else
234 | 				data[i] = 0;
235 | 		}
236 | 		//int[] bwChar = Arrays.stream(data).mapToInt(Integer::intValue).toArray();
237 | 		//display(bwChar, CHARSIZE[0], CHARSIZE[1]);
238 | 		return data;
239 | 	}
240 | 
241 | 	// use trainData to identify each character in testData
242 | 	private String identify(ArrayList<Integer[]> testData) { 
243 | 		System.out.println("  Identifying characters in plate.");
244 | 		String plateNum = "";
245 | 		for (Integer[] testChar : testData) {
246 | 			int[] distances = new int[trainData.size()];
247 | 			for (int t=0; t<trainData.size(); t++) {
248 | 				for (int p=0; p<NUMPIXELS; p++) {
249 | 					distances[t] += Math.abs(trainData.get(t)[p] - testChar[p]);
250 | 				}
251 | 			}
252 | 
253 | 			//pick shortest distance in distances
254 | 			//for (int d : distances)
255 | 				//System.out.print(d + " ");
256 | 			int minVal=distances[0], minIndex=0;
257 | 			for (int i=0; i<distances.length; i++) {
258 | 				//System.out.println(trainLabels.get(i) + " " + distances[i]);
259 | 				if (distances[i] < minVal) {
260 | 					minVal = distances[i];
261 | 					minIndex = i;
262 | 				}
263 | 			}
264 | 			plateNum += trainLabels.get(minIndex);
265 | 		/*	int[] trainCharArray = Arrays.stream(trainData.get(minIndex)).mapToInt(Integer::intValue).toArray();
266 | 			display(trainCharArray, CHARSIZE[0], CHARSIZE[1]);
267 | 			int[] testCharArray = Arrays.stream(testChar).mapToInt(Integer::intValue).toArray();
268 | 			display(testCharArray, CHARSIZE[0], CHARSIZE[1]); */
269 | 		} /*
270 | 		for (Integer[] testChar : testData) {
271 | 			for (Integer i : testChar)
272 | 				System.out.print(i + ",");
273 | 			System.out.println();
274 | 		}*/
275 | 		return plateNum;
276 | 	}
277 | 
278 | 	// append hard-coded character data to trainingData to improve accuracy
279 | 	private void addMoreTrainingData() { 
280 | 		// Need to hard code in training data for 7, T, Y, V, 8, 5, B, 2, Z, E, F using int[] from a test image to improve accuracy
281 | 		Integer[] seven = {255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255};
282 | 		trainData.add(seven);
283 | 		trainLabels.add("7");
284 | 		Integer[] why = {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,0,0,0,0,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,0,0,0,0,0,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,0,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255};
285 | 		trainData.add(why);
286 | 		trainLabels.add("Y");
287 | 		Integer[] eff = {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255};
288 | 		trainData.add(eff);
289 | 		trainLabels.add("F");
290 | 		Integer[] two = {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,0,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
291 | 		trainData.add(two);
292 | 		trainLabels.add("2"); 
293 | 		Integer[] bee = {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,255,255,255,255,255};
294 | 		trainData.add(bee);
295 | 		trainLabels.add("B"); /*
296 | 		Integer[] two = {};
297 | 		trainData.add(two);
298 | 		trainLabels.add("2");
299 | 		Integer[] two = {};
300 | 		trainData.add(two);
301 | 		trainLabels.add("2");
302 | 		Integer[] two = {};
303 | 		trainData.add(two);
304 | 		trainLabels.add("2");
305 | 		Integer[] two = {};
306 | 		trainData.add(two);
307 | 		trainLabels.add("2");*/
308 | 		return;
309 | 	}
310 | 
311 | 	// find top and bottom edges of characters on plate
312 | 	private int[] getTopBottom(BufferedImage img) {
313 | 		// calculate row sums to find top and bottom edges of characters
314 | 		int[] rowSums = new int[img.getHeight()];
315 | 		for (int y=0; y<img.getHeight(); y++) {
316 | 			for (int x=0; x<img.getWidth(); x++) {
317 | 				rowSums[y] += img.getRGB(x, y)& 0xFF;
318 | 			}
319 | 		}
320 | 
321 | 		// find top and bottom bounds of plate numbers
322 | 		int[] deltaGray = new int[200];
323 | 		for (int i=0; i<img.getHeight()-2; i++) {
324 | 			deltaGray[i] = (rowSums[i] - rowSums[i+2])/1000;
325 | 		}
326 | 		int[] vertBounds = new int[2];
327 | 		for (int i=120; i>50; i--) {
328 | 			if (deltaGray[i] > 5) {
329 | 				vertBounds[0] = i-2;
330 | 				break;
331 | 			}
332 | 		}
333 | 		for (int i=120; i<180; i++) {
334 | 			if (deltaGray[i] < -5) {
335 | 				vertBounds[1] = i+2;
336 | 				break;
337 | 			}
338 | 		}
339 | 		System.out.println("Vert bounds: " + vertBounds[0] + " " + vertBounds[1]);
340 | 		return vertBounds;
341 | 	}
342 | 
343 | 	// add grayscale data for each character to ArrayList
344 | 	private ArrayList<Integer[]> imgToArray (BufferedImage img, ArrayList<Integer[]> data, ArrayList<Integer> edges) {
345 | 		for (Integer e : edges) {
346 | 			data.add(new Integer[NUMPIXELS]);
347 | 			for (int j=0; j<img.getHeight(); j++) {
348 | 				for (int i=0; i<CHARSIZE[0]; i++) {
349 | 					data.get(data.size() - 1)[j*CHARSIZE[0] + i] = img.getRGB(e + i, j)& 0xFF;
350 | 				}
351 | 			}
352 | 		}
353 | 		return data;
354 | 	}
355 | 
356 | 	// find upper and lower whitespace bounds given a grayscale sums array
357 | 	private int[] getBounds (int[] bounds, int[] sums) {
358 | 		int upper = 0, lower = 0;
359 | 		boolean upperFound = false;
360 | 		for (int i=bounds[0]; i<sums.length; i++) {
361 | 			if ((upper <= sums[i]) && !(upperFound)) {
362 | 				upper = sums[i];
363 | 				bounds[0] = i;
364 | 			}
365 | 			else {
366 | 				upperFound = true;
367 | 				if (lower < sums[i]) {
368 | 					lower = sums[i];
369 | 					bounds[1] = i;
370 | 				}
371 | 			}
372 | 		}
373 | 		return bounds;
374 | 	}
375 | 
376 | 	// find gaps between characters
377 | 	private ArrayList<Integer> getEdges(BufferedImage img) {
378 | 		System.out.println("  Getting edges between characters.");
379 | 		// Locate whitespace delimiters between characters (left & rt bounds for each character)
380 | 		int[] colSums = new int[img.getWidth()];
381 | 		for (int y=0; y<img.getHeight(); y++) {
382 | 			for (int x=0; x<img.getWidth(); x++) {
383 | 				colSums[x] += (img.getRGB(x, y)& 0xFF);
384 | 			}
385 | 		}
386 | 
387 | 		//for (int i=0; i<colSums.length-1; i++)
388 | 		//	System.out.print(colSums[i] + " ");
389 | 
390 | 		// find gaps and locate center of gaps
391 | 		ArrayList<Integer> edges = new ArrayList<>();
392 | 		int col = 0; 
393 | 		while (col<colSums.length-1) {
394 | 			int whiteCols = 0;
395 | 			while ((col+whiteCols<colSums.length-1) & (colSums[col+whiteCols] > 250*CHARSIZE[1])) {
396 | 				whiteCols += 1;
397 | 			}
398 | 			if ((whiteCols > 1) & (col+whiteCols+CHARSIZE[0] < img.getWidth()))
399 | 				edges.add((int)(col + whiteCols -1));
400 | 			col += whiteCols + 1;
401 | 		}
402 | 		//System.out.println(edges);
403 | 
404 | 		return edges; 
405 | 	}
406 | 
407 | }
408 | 
409 | 


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/ALPR/License Plate Photos/ca2004.jpg:
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/ALPR/License Plate Photos/ca_12.jpeg:
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/ALPR/License Plate Photos/ca_aug2012.png:
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/ALPR/License Plate Photos/fl_1.jpeg:
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/EscapeNestedLoops.java:
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 1 | // Java - How to Break out of Nested For Loops
 2 | 
 3 | class EscapeNestedLoops {
 4 | 	public static void main(String[] args) {
 5 | 
 6 | 		for(int x=0; x<8; x++) {
 7 | 			for(int y=1; y<4; y++) {
 8 | 				System.out.println(x + " " + y + " " + x*y);
 9 | 				if(x * y > 5)
10 | 					break;
11 | 			}
12 | 		}
13 | 
14 | 		System.out.println(" ");
15 | 		
16 | 		xLoop:
17 | 		for(int x=0; x<8; x++) {
18 | 			for(int y=1; y<4; y++) {
19 | 				System.out.println(x + " " + y + " " + x*y);
20 | 				if(x * y > 5)
21 | 					break xLoop;
22 | 			}
23 | 		}
24 | 
25 | 	}
26 | }


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/Factorial.java:
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 1 | public class Factorial {
 2 | 	public static void main(String[] args) {
 3 | 		Factorial factorial = new Factorial();
 4 | 		System.out.println(factorial.getRecursiveFactorial(6));
 5 | 		System.out.println(factorial.getIterativeFactorial(6));
 6 | 	}
 7 | 	
 8 | 	public int getRecursiveFactorial(int n) {
 9 | 		if (n < 0) return -1;
10 | 		else if (n < 2) return 1;
11 | 		else return (n * getRecursiveFactorial(n-1));		
12 | 	}
13 | 	
14 | 	public int getIterativeFactorial(int n) {
15 | 		if (n < 0) return -1;
16 | 		int fact = 1;
17 | 		for (int i = 1; i <= n; i++)
18 | 			fact *= i;
19 | 		return fact;
20 | 	}
21 | }


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/Image Filters/ImageFilter.java:
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  1 | /*******************************************************************************
  2 |  * Filter Algorithms for Java BufferedImage
  3 |  * (c) 2023, Joe James
  4 |  * 
  5 |  * This program loads an image file. It has methods to:  
  6 |  *  - display the image in a JPanel popup window; 
  7 |  *  - convert the image to grayscale;
  8 |  *  - scale a grayscale image to a different size;
  9 |  *  - pixelate a grayscale image;
 10 |  *  - apply a Gaussian blur to a grayscale image;
 11 |  *  - detect edges of a grayscale image;
 12 |  *  - brighten a color image.
 13 |  * 
 14 |  * These files are mainly intended to accompany my series of YouTube tutorial 
 15 |  * videos here, https://www.youtube.com/user/joejamesusa and are mainly 
 16 |  * intended for educational purposes. You are invited to subscribe to my 
 17 |  * video channel, and to download and use any code in this Java 
 18 |  * repository, according to the MIT License. Feel free to post any comments 
 19 |  * on my YouTube channel. 
 20 |  * 
 21 |  * ****************************************************************************/
 22 | 
 23 | import java.util.*;
 24 | import java.awt.*;
 25 | import java.awt.image.*;
 26 | import java.io.*;
 27 | import javax.imageio.ImageIO;
 28 | import javax.swing.*;
 29 | import java.awt.geom.AffineTransform;
 30 | 
 31 | public class ImageFilter {
 32 | 
 33 | 	public static void main(String[] args) {
 34 | 		File file = new File("photo.png");
 35 | 		//File file = new File("License Plate Photos/ca_10.jpeg");
 36 | 		BufferedImage img = null;
 37 | 
 38 | 		try { img = ImageIO.read(file); } 
 39 | 		catch (IOException e) { e.printStackTrace(System.out); }
 40 | 
 41 | 		if (img != null) {
 42 | 			display(img);
 43 | 			//img = brighten(img);
 44 | 			img = toGrayScale(img);
 45 | 			//img = toGrayScale2(img);
 46 | 			//display(img);
 47 | 			//img = pixelate(img);
 48 | 			//img = pixelate2(img, 3);
 49 | 			//img = resize(img, 150);
 50 | 			//img = blur(img);
 51 | 			img = blur(blur(img));
 52 | 			img = heavyblur(img);
 53 | 			img = detectEdges(img);
 54 | 			display(img);
 55 | 		}
 56 | 	}
 57 | 
 58 | 	// display image in a JPanel popup
 59 | 	public static void display (BufferedImage img) {
 60 | 		System.out.println("  Displaying image.");
 61 | 		JFrame frame = new JFrame();
 62 | 	    JLabel label = new JLabel();
 63 | 		frame.setSize(img.getWidth(), img.getHeight());
 64 | 		label.setIcon(new ImageIcon(img));
 65 | 		frame.getContentPane().add(label, BorderLayout.CENTER);
 66 | 		frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
 67 | 		frame.pack();
 68 | 		frame.setVisible(true);
 69 | 	}
 70 | 
 71 | 	// convert image to grayscale
 72 | 	public static BufferedImage toGrayScale (BufferedImage img) {
 73 | 		System.out.println("  Converting to GrayScale.");
 74 | 		BufferedImage grayImage = new BufferedImage(
 75 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
 76 | 		Graphics g = grayImage.getGraphics();
 77 | 		g.drawImage(img, 0, 0, null);
 78 | 		g.dispose();
 79 | 		return grayImage;
 80 | 	}
 81 | 
 82 | 	public static BufferedImage toGrayScale2 (BufferedImage img) {
 83 | 		System.out.println("  Converting to GrayScale2.");
 84 | 		BufferedImage grayImage = new BufferedImage(
 85 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
 86 | 		int rgb=0, r=0, g=0, b=0;
 87 | 		for (int y=0; y<img.getHeight(); y++) {
 88 | 			for (int x=0; x<img.getWidth(); x++) {
 89 | 				rgb = (int)(img.getRGB(x, y));
 90 | 				r = ((rgb >> 16) & 0xFF);
 91 | 				g = ((rgb >> 8) & 0xFF);
 92 | 				b = (rgb & 0xFF);
 93 | 				rgb = (int)((r+g+b)/3);
 94 | 				//rgb = (int)(0.299 * r + 0.587 * g + 0.114 * b);
 95 | 				rgb = (255<<24) | (rgb<<16) | (rgb<<8) | rgb;
 96 | 				grayImage.setRGB(x,y,rgb);
 97 | 			}
 98 | 		}
 99 | 		return grayImage;
100 | 	}
101 | 
102 | 	// apply 2x2 pixelation to a grayscale image
103 | 	public static BufferedImage pixelate (BufferedImage img) {
104 | 		BufferedImage pixImg = new BufferedImage(
105 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
106 | 		int pix = 0, p=0;
107 | 		for (int y=0; y<img.getHeight()-2; y+=2) {
108 | 			for (int x=0; x<img.getWidth()-2; x+=2) {
109 | 				pix = (int)((img.getRGB(x, y)& 0xFF)
110 | 				+ (img.getRGB(x+1, y)& 0xFF)
111 | 				+ (img.getRGB(x, y+1)& 0xFF)
112 | 				+ (img.getRGB(x+1, y+1)& 0xFF))/4;
113 | 				p = (255<<24) | (pix<<16) | (pix<<8) | pix; 
114 | 				pixImg.setRGB(x,y,p);
115 | 				pixImg.setRGB(x+1,y,p);
116 | 				pixImg.setRGB(x,y+1,p);
117 | 				pixImg.setRGB(x+1,y+1,p);
118 | 			}
119 | 		}
120 | 		return pixImg;
121 | 	}
122 | 
123 | 	// apply nxn pixelation to a grayscale image
124 | 	public static BufferedImage pixelate2 (BufferedImage img, int n) {
125 | 		BufferedImage pixImg = new BufferedImage(
126 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
127 | 		int pix = 0, p=0;
128 | 		for (int y=0; y<img.getHeight()-n; y+=n) {
129 | 			for (int x=0; x<img.getWidth()-n; x+=n) {
130 | 				for (int a=0; a<n; a++) {
131 | 					for (int b=0; b<n; b++) {
132 | 						pix += (img.getRGB(x+a, y+b)& 0xFF);
133 | 					}
134 | 				}
135 | 				pix = (int)(pix/n/n);
136 | 				for (int a=0; a<n; a++) {
137 | 					for (int b=0; b<n; b++) {
138 | 						p = (255<<24) | (pix<<16) | (pix<<8) | pix; 
139 | 						pixImg.setRGB(x+a,y+b,p);
140 | 					}
141 | 				}
142 | 				pix = 0;
143 | 			}
144 | 		}
145 | 		return pixImg;
146 | 	}	
147 | 
148 | 	// scale a grayscale image
149 | 	public static BufferedImage resize (BufferedImage img, int newHeight) {
150 | 		System.out.println("  Scaling image.");
151 | 		double scaleFactor = (double) newHeight/img.getHeight();
152 | 		BufferedImage scaledImg = new BufferedImage(
153 | 			(int)(scaleFactor*img.getWidth()), newHeight, BufferedImage.TYPE_BYTE_GRAY);
154 | 		AffineTransform at = new AffineTransform();
155 | 		at.scale(scaleFactor, scaleFactor);
156 | 		AffineTransformOp scaleOp = new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
157 | 		return scaleOp.filter(img, scaledImg);
158 | 	}
159 | 
160 | 	// apply 3x3 Gaussian blur to a grayscale image
161 | 	public static BufferedImage blur (BufferedImage img) {
162 | 		BufferedImage blurImg = new BufferedImage(
163 | 			img.getWidth()-2, img.getHeight()-2, BufferedImage.TYPE_BYTE_GRAY);
164 | 		int pix = 0;
165 | 		for (int y=0; y<blurImg.getHeight(); y++) {
166 | 			for (int x=0; x<blurImg.getWidth(); x++) {
167 | 				pix = (int)(4*(img.getRGB(x+1, y+1)& 0xFF)
168 | 				+ 2*(img.getRGB(x+1, y)& 0xFF)
169 | 				+ 2*(img.getRGB(x+1, y+2)& 0xFF)
170 | 				+ 2*(img.getRGB(x, y+1)& 0xFF)
171 | 				+ 2*(img.getRGB(x+2, y+1)& 0xFF)
172 | 				+ (img.getRGB(x, y)& 0xFF)
173 | 				+ (img.getRGB(x, y+2)& 0xFF)
174 | 				+ (img.getRGB(x+2, y)& 0xFF)
175 | 				+ (img.getRGB(x+2, y+2)& 0xFF))/16;
176 | 				int p = (255<<24) | (pix<<16) | (pix<<8) | pix; 
177 | 				blurImg.setRGB(x,y,p);
178 | 			}
179 | 		}
180 | 		return blurImg;
181 | 	}
182 | 
183 | 	// apply 5x5 Gaussian blur to a grayscale image
184 | 	public static BufferedImage heavyblur (BufferedImage img) {
185 | 		BufferedImage blurImg = new BufferedImage(
186 | 			img.getWidth()-4, img.getHeight()-4, BufferedImage.TYPE_BYTE_GRAY);
187 | 		int pix = 0;
188 | 		for (int y=0; y<blurImg.getHeight(); y++) {
189 | 			for (int x=0; x<blurImg.getWidth(); x++) {
190 | 				pix = (int)(
191 | 				10*(img.getRGB(x+3, y+3)& 0xFF)
192 | 				+ 6*(img.getRGB(x+2, y+1)& 0xFF)
193 | 				+ 6*(img.getRGB(x+1, y+2)& 0xFF)
194 | 				+ 6*(img.getRGB(x+2, y+3)& 0xFF)
195 | 				+ 6*(img.getRGB(x+3, y+2)& 0xFF)
196 | 				+ 4*(img.getRGB(x+1, y+1)& 0xFF)
197 | 				+ 4*(img.getRGB(x+1, y+3)& 0xFF)
198 | 				+ 4*(img.getRGB(x+3, y+1)& 0xFF)
199 | 				+ 4*(img.getRGB(x+3, y+3)& 0xFF)
200 | 				+ 2*(img.getRGB(x, y+1)& 0xFF)
201 | 				+ 2*(img.getRGB(x, y+2)& 0xFF)
202 | 				+ 2*(img.getRGB(x, y+3)& 0xFF)
203 | 				+ 2*(img.getRGB(x+4, y+1)& 0xFF)
204 | 				+ 2*(img.getRGB(x+4, y+2)& 0xFF)
205 | 				+ 2*(img.getRGB(x+4, y+3)& 0xFF)
206 | 				+ 2*(img.getRGB(x+1, y)& 0xFF)
207 | 				+ 2*(img.getRGB(x+2, y)& 0xFF)
208 | 				+ 2*(img.getRGB(x+3, y)& 0xFF)
209 | 				+ 2*(img.getRGB(x+1, y+4)& 0xFF)
210 | 				+ 2*(img.getRGB(x+2, y+4)& 0xFF)
211 | 				+ 2*(img.getRGB(x+3, y+4)& 0xFF)
212 | 				+ (img.getRGB(x, y)& 0xFF)
213 | 				+ (img.getRGB(x, y+2)& 0xFF)
214 | 				+ (img.getRGB(x+2, y)& 0xFF)
215 | 				+ (img.getRGB(x+2, y+2)& 0xFF))/74;
216 | 				int p = (255<<24) | (pix<<16) | (pix<<8) | pix; 
217 | 				blurImg.setRGB(x,y,p);
218 | 			}
219 | 		}
220 | 		return blurImg;
221 | 	}
222 | 
223 | 	// detect edges of a grayscale image using Sobel algorithm 
224 | 	// (for best results, apply blur before finding edges)
225 | 	public static BufferedImage detectEdges (BufferedImage img) {
226 | 		int h = img.getHeight(), w = img.getWidth(), threshold=30, p = 0;
227 | 		BufferedImage edgeImg = new BufferedImage(w, h, BufferedImage.TYPE_BYTE_GRAY);
228 | 		int[][] vert = new int[w][h];
229 | 		int[][] horiz = new int[w][h];
230 | 		int[][] edgeWeight = new int[w][h];
231 | 		for (int y=1; y<h-1; y++) {
232 | 			for (int x=1; x<w-1; x++) {
233 | 				vert[x][y] = (int)(img.getRGB(x+1, y-1)& 0xFF + 2*(img.getRGB(x+1, y)& 0xFF) + img.getRGB(x+1, y+1)& 0xFF
234 | 					- img.getRGB(x-1, y-1)& 0xFF - 2*(img.getRGB(x-1, y)& 0xFF) - img.getRGB(x-1, y+1)& 0xFF);
235 | 				horiz[x][y] = (int)(img.getRGB(x-1, y+1)& 0xFF + 2*(img.getRGB(x, y+1)& 0xFF) + img.getRGB(x+1, y+1)& 0xFF
236 | 					- img.getRGB(x-1, y-1)& 0xFF - 2*(img.getRGB(x, y-1)& 0xFF) - img.getRGB(x+1, y-1)& 0xFF);
237 | 				edgeWeight[x][y] = (int)(Math.sqrt(vert[x][y] * vert[x][y] + horiz[x][y] * horiz[x][y]));
238 | 				if (edgeWeight[x][y] > threshold)
239 | 					p = (255<<24) | (255<<16) | (255<<8) | 255;
240 | 				else 
241 | 					p = (255<<24) | (0<<16) | (0<<8) | 0; 
242 | 				edgeImg.setRGB(x,y,p);
243 | 			}
244 | 		}
245 | 		return edgeImg;
246 | 	}
247 | 
248 | 	// brighten color image by a percentage 
249 | 	public static BufferedImage brighten (BufferedImage img, int percentage) {
250 | 		int r=0, g=0, b=0, rgb=0, p=0;
251 | 		int amount = (int)(percentage * 255 / 100); // rgb scale is 0-255, so 255 is 100%
252 | 		BufferedImage newImage = new BufferedImage(
253 | 			img.getWidth(), img.getHeight(), BufferedImage.TYPE_INT_ARGB);
254 | 		for (int y=0; y<img.getHeight(); y+=1) {
255 | 			for (int x=0; x<img.getWidth(); x+=1) {
256 | 				rgb = img.getRGB(x, y);
257 | 				r = ((rgb >> 16) & 0xFF) + amount;
258 | 				g = ((rgb >> 8) & 0xFF) + amount;
259 | 				b = (rgb & 0xFF) + amount;
260 | 				if (r>255) r=255;
261 | 				if (g>255) g=255;
262 | 				if (b>255) b=255;
263 | 				p = (255<<24) | (r<<16) | (g<<8) | b;
264 | 				newImage.setRGB(x,y,p);
265 | 			}
266 | 		}
267 | 		return newImage;
268 | 	}
269 | 
270 | }
271 | 
272 | 
273 | 
274 | 
275 | 
276 | 
277 | 
278 | 
279 | 
280 | 
281 | 
282 | 


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/Java 8 Streams/JavaStreams.java:
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  1 | import java.lang.String;
  2 | import java.util.Arrays;
  3 | import java.util.List;
  4 | import java.util.stream.*;
  5 | import java.util.*;
  6 | import java.nio.file.*;
  7 | import java.io.IOException;
  8 | 
  9 | public class JavaStreams {
 10 | 	public static void main(String[] args) throws IOException {
 11 | 		// 1. Integer Stream
 12 | 		IntStream
 13 | 			.range(1, 10)
 14 | 			.forEach(System.out::print);
 15 | 		System.out.println();
 16 | 		
 17 | 		// 2. Integer Stream with skip
 18 | 		IntStream
 19 | 			.range(1, 10)
 20 | 			.skip(5)
 21 | 			.forEach(x -> System.out.println(x));
 22 | 		System.out.println();
 23 | 		
 24 | 		// 3. Integer Stream with sum
 25 | 		System.out.println(
 26 | 		IntStream
 27 | 			.range(1, 5)
 28 | 			.sum());
 29 | 		System.out.println();
 30 | 			
 31 | 		// 4. Stream.of, sorted and findFirst
 32 | 		Stream.of("Ava", "Aneri", "Alberto")
 33 | 			.sorted()
 34 | 			.findFirst()
 35 | 			.ifPresent(System.out::println);
 36 | 			
 37 | 		// 5. Stream from Array, sort, filter and print
 38 | 		String[] names = {"Al", "Ankit", "Kushal", "Brent", "Sarika", "amanda", "Hans", "Shivika", "Sarah"};
 39 | 		Arrays.stream(names)	// same as Stream.of(names)
 40 | 			.filter(x -> x.startsWith("S"))
 41 | 			.sorted()
 42 | 			.forEach(System.out::println);
 43 | 					
 44 | 		// 6. average of squares of an int array
 45 | 		Arrays.stream(new int[] {2, 4, 6, 8, 10})
 46 | 			.map(x -> x * x)
 47 | 			.average()
 48 | 			.ifPresent(System.out::println);
 49 | 		
 50 | 		// 7. Stream from List, filter and print
 51 | 		List<String> people = Arrays.asList("Al", "Ankit", "Brent", "Sarika", "amanda", "Hans", "Shivika", "Sarah");
 52 | 		people
 53 | 			.stream()
 54 | 			.map(String::toLowerCase)
 55 | 			.filter(x -> x.startsWith("a"))
 56 | 			.forEach(System.out::println);
 57 | 			
 58 | 		// 8. Stream rows from text file, sort, filter, and print
 59 | 		Stream<String> bands = Files.lines(Paths.get("bands.txt"));
 60 | 		bands
 61 | 			.sorted()
 62 | 			.filter(x -> x.length() > 13)
 63 | 			.forEach(System.out::println);
 64 | 		bands.close();
 65 | 		
 66 | 		// 9. Stream rows from text file and save to List
 67 | 		List<String> bands2 = Files.lines(Paths.get("bands.txt"))
 68 | 			.filter(x -> x.contains("jit"))
 69 | 			.collect(Collectors.toList());
 70 | 		bands2.forEach(x -> System.out.println(x));
 71 | 		
 72 | 		// 10. Stream rows from CSV file and count
 73 | 		Stream<String> rows1 = Files.lines(Paths.get("data.txt"));
 74 | 		int rowCount = (int)rows1
 75 | 			.map(x -> x.split(","))
 76 |             .filter(x -> x.length == 3)
 77 | 			.count();
 78 | 		System.out.println(rowCount + " rows.");
 79 | 		rows1.close();
 80 | 		
 81 | 		// 11. Stream rows from CSV file, parse data from rows
 82 | 		Stream<String> rows2 = Files.lines(Paths.get("data.txt"));
 83 | 		rows2
 84 | 			.map(x -> x.split(","))
 85 |             .filter(x -> x.length == 3)
 86 | 			.filter(x -> Integer.parseInt(x[1]) > 15)
 87 | 			.forEach(x -> System.out.println(x[0] + "  " + x[1] + "  " + x[2]));
 88 | 		rows2.close();
 89 | 		
 90 | 		// 12. Stream rows from CSV file, store fields in HashMap
 91 | 		Stream<String> rows3 = Files.lines(Paths.get("data.txt"));
 92 | 		Map<String, Integer> map = new HashMap<>();
 93 | 		map = rows3
 94 | 			.map(x -> x.split(","))
 95 |             .filter(x -> x.length == 3)
 96 | 			.filter(x -> Integer.parseInt(x[1]) > 15)
 97 | 			.collect(Collectors.toMap(
 98 |                 x -> x[0],
 99 |                 x -> Integer.parseInt(x[1])));
100 | 		rows3.close();
101 | 		for (String key : map.keySet()) {
102 | 			System.out.println(key + "  " + map.get(key));
103 | 		}
104 | 			
105 | 		// 13. Reduction - sum
106 | 		double total = Stream.of(7.3, 1.5, 4.8)
107 | 			.reduce(0.0, (Double a, Double b) -> a + b);
108 | 		System.out.println("Total = " + total);
109 | 		
110 | 		// 14. Reduction - summary statistics
111 | 		IntSummaryStatistics summary = IntStream.of(7, 2, 19, 88, 73, 4, 10)
112 | 			.summaryStatistics();
113 | 		System.out.println(summary);
114 | 	}
115 | }


--------------------------------------------------------------------------------
/Java 8 Streams/bands.txt:
--------------------------------------------------------------------------------
 1 | Rolling Stones
 2 | Lady Gaga
 3 | Jackson Browne
 4 | Maroon 5
 5 | Arijit Singh
 6 | Elton John
 7 | John Mayer
 8 | CCR
 9 | Eagles
10 | Pink
11 | Aerosmith
12 | Adele
13 | Taylor Swift
14 | Faye Wong
15 | Bob Seger
16 | ColdPlay
17 | Boston
18 | The Cars
19 | Cheap Trick
20 | Def Leppard
21 | Ed Sheeran
22 | Dire Straits
23 | Train
24 | Tom Petty
25 | Jack Johnson
26 | Jimmy Buffett
27 | Mumford and Sons
28 | Phil Collins
29 | Rod Stewart
30 | The Script
31 | Elvis
32 | Michael Buble


--------------------------------------------------------------------------------
/Java 8 Streams/data.txt:
--------------------------------------------------------------------------------
1 | A,12,3.7
2 | B,17,2.8
3 | C,14,1.9
4 | D,23,2.7
5 | E
6 | F,18,3.4
7 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2017 Joe James
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


--------------------------------------------------------------------------------
/LinkedList.java:
--------------------------------------------------------------------------------
  1 | // Linked List in Java. Written by Joe James.
  2 | public class LinkedList {
  3 | 	Node root;
  4 | 	int size;
  5 | 	
  6 | 	public LinkedList() {
  7 | 		root = new Node();
  8 | 		size = 0;
  9 | 	}
 10 | 	
 11 | 	// Test code - main function
 12 | 	public static void main(String[] args) {
 13 | 		LinkedList ll = new LinkedList();
 14 | 		System.out.println(ll.getSize());
 15 | 		ll.add(8);
 16 | 		System.out.println(ll.getSize());
 17 | 		ll.add(17);
 18 | 		ll.add(5);
 19 | 		ll.add(10);
 20 | 		System.out.println(ll.find(17).getData());
 21 | 		ll.remove(5);
 22 | 		System.out.println(ll.getSize());
 23 | 		System.out.println(ll.find(5));
 24 | 	}
 25 | 	
 26 | 	public void setSize(int s) {
 27 | 		this.size = s;
 28 | 	}
 29 | 	
 30 | 	public int getSize() {
 31 | 		return this.size;
 32 | 	}
 33 | 	
 34 | 	public Node add(int data) {
 35 | 		Node newNode = new Node(data, root);
 36 | 		this.root = newNode;
 37 | 		this.size++;
 38 | 		return newNode;
 39 | 	}
 40 | 	
 41 | 	public Node find(int data) {
 42 | 		Node thisNode = this.root;
 43 | 		
 44 | 		while (thisNode != null) {
 45 | 			if (thisNode.getData() == data)
 46 | 				return thisNode;
 47 | 			thisNode = thisNode.getNextNode();
 48 | 		}
 49 | 		return null;
 50 | 	}
 51 | 	
 52 | 	public boolean remove(int data) {
 53 | 		Node thisNode = this.root;
 54 | 		Node prevNode = null;
 55 | 		
 56 | 		while (thisNode != null) {
 57 | 			if (thisNode.getData() == data) {
 58 | 				if (prevNode != null)
 59 | 					prevNode.setNextNode(thisNode.getNextNode());
 60 | 				else
 61 | 					this.root = null;
 62 | 				this.setSize(this.getSize()-1);
 63 | 				return true;
 64 | 			}
 65 | 			prevNode = thisNode;
 66 | 			thisNode = thisNode.getNextNode();
 67 | 		}
 68 | 		return false;
 69 | 	}
 70 | 	
 71 | 	// Node class
 72 | 	private class Node {
 73 | 		private Node nextNode;
 74 | 		private int data;
 75 | 
 76 | 		// 0-arg constructor, 1-arg constructor, 2-arg constructor
 77 | 		private Node() { }
 78 | 		
 79 | 		private Node(int val) {
 80 | 			data = val;
 81 | 		}
 82 | 		
 83 | 		private Node(int val, Node next) {
 84 | 			data = val;
 85 | 			nextNode = next;
 86 | 		}
 87 | 		
 88 | 		private void setData(int val) {
 89 | 			this.data = val;
 90 | 		}
 91 | 		
 92 | 		private int getData() {
 93 | 			return this.data;
 94 | 		}
 95 | 		
 96 | 		private void setNextNode(Node n) {
 97 | 			this.nextNode = n;
 98 | 		}
 99 | 		
100 | 		private Node getNextNode() {
101 | 			return this.nextNode;
102 | 		}
103 | 	}
104 | }


--------------------------------------------------------------------------------
/ListToArray.java:
--------------------------------------------------------------------------------
 1 | // Java: convert ArrayList<String> to String[]
 2 | import java.util.ArrayList;
 3 | import java.util.Arrays;
 4 | import java.util.List;
 5 | import java.util.stream.*;
 6 | 
 7 | class ListToArray {
 8 | 	public static void main(String[] args) {
 9 | 		// create Array
10 | 		String[] array = {"Bugatti", "Ferarri", "Lamborghini", "Rolls Royce"};
11 | 		
12 | 		// 3 ways to print Array
13 | 		System.out.println(Arrays.toString(array));
14 | 
15 | 		for(String s : array) {
16 | 			System.out.print(s + ", ");
17 | 		}
18 | 		System.out.println();
19 | 
20 | 		Stream.of(array) 
21 | 			.forEach(System.out::println);
22 | 		
23 | 		// 2 ways to convert Array to ArrayList
24 | 		List<String> arrayList = new ArrayList<>(Arrays.asList(array));
25 | 		System.out.println("arrayList: " + arrayList);
26 | 		
27 | 		List<String> arrayList2 = new ArrayList<>(List.of(array));
28 | 		System.out.println("arrayList2: " + arrayList2);
29 | 		
30 | 		// convert ArrayList to Array
31 | 		String[] array2 = arrayList.toArray(new String[0]);
32 | 
33 | 		// print Array
34 | 		Stream.of(array2) 
35 | 			.forEach(System.out::println);
36 | 
37 | 	}
38 | }
39 | 
40 | 
41 | 
42 | 
43 | 
44 | 
45 | 
46 | 


--------------------------------------------------------------------------------
/MapFunctions.java:
--------------------------------------------------------------------------------
 1 | // Java HashMap
 2 | // Joe James 2023
 3 | 
 4 | import java.util.Map;
 5 | import java.util.HashMap;
 6 | import java.util.Map.Entry;
 7 | import java.util.stream.*;
 8 | 
 9 | class MapFunctions {
10 | 	public static void main (String[] args) {
11 | 		// 1. Create a HashMap, add kv pairs
12 | 		Map<String, Integer> ages = new HashMap<String, Integer>();
13 | 		// OR, to initialize capaacity,
14 | 		// Map<String, Integer> ages = new HashMap<String, Integer>(100);
15 | 		ages.put("Avni",11);
16 | 		ages.put("Bing", 12);
17 | 		ages.put("Cassie", 13);
18 | 		ages.put("Devarshi", 14);
19 | 		System.out.println(ages);
20 | 
21 | 		// 2. Get an item from the map
22 | 		String person = "Cassie";
23 | 		System.out.println(person + " : " + ages.get(person));
24 | 		System.out.println("Frank" + " : " + ages.getOrDefault("Frank", 0));
25 | 
26 | 		// 3. Check for membership
27 | 		System.out.println("Contains key Avni?: " + ages.containsKey("Avni"));
28 | 		System.out.println("Contains value 23?: " + ages.containsValue(23));
29 | 
30 | 		// 4. Remove an item from the map
31 | 		ages.remove("Bing");
32 | 		System.out.println(ages);
33 | 		ages.remove("Devarshi", 41);
34 | 		System.out.println(ages);
35 | 
36 | 		// 5. Get count of items in map
37 | 		System.out.println("Num Items = " + ages.size());
38 | 
39 | 		// 6. Remove all items from map
40 | 		ages.clear();
41 | 		System.out.println("Empty map? " + ages.isEmpty());
42 | 		ages.put("Elena", 15);
43 | 		ages.put("Frank", 16);
44 | 		System.out.println(ages);
45 | 
46 | 		// 7. Conditional add & replace
47 | 		ages.putIfAbsent("George", 23); 
48 | 		ages.putIfAbsent("Elena", 5);
49 | 		System.out.println(ages);
50 | 		ages.replace("George", 23, 17);
51 | 		ages.replace("George", 44, 55);
52 | 		System.out.println(ages);
53 | 
54 | 		// 8. Get collection of Values
55 | 		System.out.println(ages.values());
56 | 
57 | 		// 9. Iterate keys using enhanced for loop
58 | 		for (String key : ages.keySet()) {
59 | 			System.out.println(key +  " : " + ages.get(key));
60 | 		}
61 | 
62 | 		// 10. Iterate KV pairs using enhanced for loop
63 | 		for (Map.Entry<String, Integer> pair : ages.entrySet()) {
64 | 			System.out.println(pair.getKey() + " : " + pair.getValue());
65 | 		}
66 | 
67 | 		// 11. Iterate KV pairs using Java 8 Stream API
68 | 		ages.entrySet().stream().forEach(pair ->  System.out.println(pair.getKey() + " : " + pair.getValue()));
69 | 
70 | 	}
71 | }


--------------------------------------------------------------------------------
/MyIterator.java:
--------------------------------------------------------------------------------
 1 | import java.util.ArrayList;
 2 | import java.util.Iterator;
 3 | import java.util.ListIterator;
 4 | 
 5 | public class MyIterator {
 6 | 		
 7 | 	public static void main(String[] args) {
 8 | 		ArrayList<String> cars = new ArrayList<>();
 9 | 		cars.add("Chevy");
10 | 		cars.add("Ford");
11 | 		cars.add("Honda");
12 | 		cars.add("Mercedes");
13 | 		cars.add("Toyota");
14 | 		
15 | 		// for loop
16 | 		System.out.println("For Loop:");
17 | 		for (int i = 0; i < cars.size(); i++) {
18 | 			System.out.print(cars.get(i) + " ");
19 | 		}
20 | 		
21 | 		// advanced for loop
22 | 		System.out.println("\n\nAdvanced For Loop:");
23 | 		for (String car : cars) {
24 | 			System.out.print(car + " ");
25 | 		}
26 | 		
27 | 		// while loop
28 | 		System.out.println("\n\nWhile Loop:");
29 | 		int i = 0;
30 | 		while (i < cars.size()) {
31 | 			System.out.print(cars.get(i++) + " ");
32 | 		}
33 | 		
34 | 		// Iterator (supports hasNext, next, remove)
35 | 		System.out.println("\n\nIterator:");
36 | 		Iterator<String> iterator = cars.iterator();
37 | 		while (iterator.hasNext()) {
38 | 			System.out.print(iterator.next() + " ");
39 | 		}
40 | 		
41 | 		// ListIterator (supports hasNext, next, remove, hasPrevious, previous, add)
42 | 		System.out.println("\n\nListIterator:");
43 | 		ListIterator<String> li = cars.listIterator();
44 | 		while (li.hasNext()) {
45 | 			System.out.print(li.next() + " ");
46 | 		}
47 | 		
48 | 		// Java 8 Stream
49 | 		System.out.println("\n\nJava 8 Stream:");
50 | 		cars.forEach((car) -> {
51 | 			System.out.print(car + " ");
52 | 		});
53 | 	}
54 | }
55 | 
56 | 
57 | 
58 | 
59 | 
60 | 
61 | 


--------------------------------------------------------------------------------
/Primes.java:
--------------------------------------------------------------------------------
 1 | // version 1
 2 | public class Primes {
 3 | 
 4 |     public static void main(String[] args) {
 5 |         int max = 10;
 6 |         for (int x = 2; x <= max; x++) {
 7 |             boolean isPrime = true;
 8 |             for (int y = 2; y < x; y++)
 9 | 				if (x % y == 0)
10 |                     isPrime = false;
11 |             if (isPrime)
12 |                 System.out.println(x);
13 |         }
14 |     }
15 | }
16 | //--------------------------------------------
17 | // version 2: break
18 | public class Primes {
19 | 
20 |     public static void main(String[] args) {
21 |         int max = 10;
22 |         for (int x = 2; x <= max; x++) {
23 |             boolean isPrime = true;
24 |             for (int y = 2; y < x; y++)
25 | 				if (x % y == 0) {
26 | 					isPrime = false;
27 | 					break;
28 | 				}
29 |             if (isPrime)
30 |                 System.out.println(x);
31 |         }
32 |     }
33 | }
34 | //--------------------------------------------
35 | // version 3: break, add to list
36 | import java.util.ArrayList;
37 | 
38 | public class Primes {
39 | 
40 |     public static void main(String[] args) {
41 |         ArrayList<Integer> primeList  = new ArrayList<>();
42 | 
43 |         int max = 10000;
44 |         for (int x = 2; x <= max; x++) {
45 |             boolean isPrime = true;
46 |             for (int y = 2; y < x; y++)
47 | 				if (x % y == 0) {
48 |                     isPrime = false;
49 |                     break;
50 |                 }
51 |             if (isPrime)
52 |                 primeList.add(x);
53 |         }
54 |         System.out.println(primeList);
55 |     }
56 | }
57 | //--------------------------------------------
58 | // version 4: break, add to list, square root
59 | import java.util.ArrayList;
60 | 
61 | public class Primes {
62 | 
63 |     public static void main(String[] args) {
64 |         ArrayList<Integer> primeList  = new ArrayList<>();
65 | 
66 |         int max = 200000;
67 |         for (int x = 2; x <= max; x++) {
68 |             boolean isPrime = true;
69 |             for (int y = 2; y < Math.sqrt(x); y++)
70 | 				if (x % y == 0) {
71 |                     isPrime = false;
72 |                     break;
73 |                 }
74 |             if (isPrime)
75 |                 primeList.add(x);
76 |         }
77 |         System.out.println(primeList);
78 |     }
79 | }
80 | 


--------------------------------------------------------------------------------
/QuickSort.java:
--------------------------------------------------------------------------------
 1 | import java.util.Arrays;
 2 | import java.util.Random;
 3 | 
 4 | public class QuickSort {
 5 | 	public void quickSort(int[] A) {
 6 | 		quickSort(A, 0, A.length-1);
 7 | 	}
 8 | 	
 9 | 	private void quickSort(int[] A, int low, int high) {
10 | 		if (low < high+1) {
11 | 			int p = partition(A, low, high);
12 | 			quickSort(A, low, p-1);
13 | 			quickSort(A, p+1, high);
14 | 		}
15 | 	}
16 | 
17 | 	private void swap(int[] A, int index1, int index2) {
18 | 		int temp = A[index1];
19 | 		A[index1] = A[index2];
20 | 		A[index2] = temp;		
21 | 	}
22 | 	
23 | 	// returns random pivot index between low and high inclusive.
24 | 	private int getPivot(int low, int high) {
25 | 		Random rand = new Random();
26 | 		return rand.nextInt((high - low) + 1) + low;
27 | 	}
28 | 
29 | 	// moves all n < pivot to left of pivot and all n > pivot 
30 | 	// to right of pivot, then returns pivot index.
31 | 	private int partition(int[] A, int low, int high) {
32 | 		swap(A, low, getPivot(low, high));
33 | 		int border = low + 1;
34 | 		for (int i = border; i <= high; i++) {
35 | 			if (A[i] < A[low]) {
36 | 				swap(A, i, border++);
37 | 			}
38 | 		}
39 | 		swap(A, low, border-1);
40 | 		return border-1;
41 | 	}
42 | 	
43 | 	public static void main(String[] args) {
44 | 		QuickSort qs = new QuickSort();
45 | 		int[] A = {9, 0, 1, 3, 4, 5, 2, 9, 8, 7, 6, 5, 9, 1, 0, 9};
46 | 		System.out.println(Arrays.toString(A));
47 | 		qs.quickSort(A);
48 | 		System.out.println(Arrays.toString(A));
49 | 	}
50 | }
51 | 
52 | 
53 | 
54 | 
55 | 
56 | 
57 | 
58 | 
59 | 
60 | 
61 | 
62 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | # Java
 2 | These files are mainly intended to accompany my series of YouTube tutorial videos here, 
 3 | https://www.youtube.com/user/joejamesusa
 4 | and are mainly intended for educational purposes.
 5 | You are invited to subscribe to my video channel, and to download and use any code in 
 6 | this Java repository, according to the MIT License. 
 7 | Feel free to post any comments on my YouTube channel.
 8 | 
 9 | Joe James.
10 | Fremont, California
11 | Copyright (C) 2015-2018, Joe James
12 | 


--------------------------------------------------------------------------------
/SplitString.java:
--------------------------------------------------------------------------------
 1 | // Java: Split a String at char
 2 | import java.util.Arrays;
 3 | 
 4 | class SplitString {
 5 | 	
 6 | 	public static void main(String[] args) {
 7 | 		String s = "My dog ate my homework; Can I turn it in tomorrow?";
 8 | 
 9 | 		String[] ss = s.split(" ");
10 | 		System.out.println(Arrays.toString(ss));
11 | 
12 | 		ss = s.split(";");
13 | 		System.out.println(Arrays.toString(ss));
14 | 
15 | 		// you must escape special chars because the split parameter is a regex
16 | 		// special chars include \ . + ^ $ | ? * ( ) [ {
17 | 		String t = "54.25-128.17";
18 | 		String[] tt = t.split("\\.");
19 | 		System.out.println(Arrays.toString(tt));
20 | 
21 | 		// include multiple split chars inside brackets
22 | 		tt = t.split("[.-]");
23 | 		System.out.println(Arrays.toString(tt));
24 | 
25 | 	}
26 | }
27 | 
28 | 
29 | 
30 | 
31 | 
32 | 
33 | 
34 | 
35 | 
36 | 


--------------------------------------------------------------------------------
/StringToInt.java:
--------------------------------------------------------------------------------
 1 | // Java - Convert String to an Int
 2 | 
 3 | class StringToInt {
 4 | 	public static void main(String[] args) {
 5 | 		String s = "222";
 6 | 		int i;
 7 | 		Integer integer;
 8 | 		
 9 | 		// returns an int
10 | 		i = Integer.parseInt(s); 
11 | 		System.out.println(i + 1);
12 | 
13 | 		// returns an Integer
14 | 		integer = Integer.valueOf(s); 
15 | 		System.out.println(integer + 2);
16 | 
17 | 		// Best Practice: safely returns an Integer
18 | 		try {
19 | 			integer = Integer.valueOf(s); 
20 | 		} catch (NumberFormatException e) {
21 | 			integer = 0;
22 | 		}
23 | 		System.out.println(integer + 3);
24 | 	}
25 | 
26 | }


--------------------------------------------------------------------------------
/Temperature.java:
--------------------------------------------------------------------------------
 1 | public class Temperature {
 2 | 	public static void main(String[] args) {
 3 | 		Temperature temperature = new Temperature();
 4 | 		
 5 | 		double fTemp = 77.5;
 6 | 		double cTemp = temperature.toCelsius(fTemp);
 7 | 		System.out.printf("%.2f Fahrenheit = %.2f Celsius.\n", fTemp, cTemp);
 8 | 		
 9 | 		cTemp = 37.2;
10 | 		fTemp = temperature.toFahrenheit(cTemp);
11 | 		System.out.printf("%.2f Celsius = %.2f Fahrenheit.\n", cTemp, fTemp);
12 | 	}
13 | 	
14 | 	public double toCelsius(double f) {
15 | 		return (f - 32.0) / 1.8;
16 | 	}
17 | 
18 | 	public double toFahrenheit(double c) {
19 | 		return (c * 1.8) + 32.0;
20 | 	}
21 | }


--------------------------------------------------------------------------------
/Tree.java:
--------------------------------------------------------------------------------
  1 | // Java Binary Search Tree
  2 | 
  3 | public class Tree {
  4 | 	Node root;
  5 | 	
  6 | 	// some basic test code
  7 | 	public static void main(String[] args) {
  8 | 		Tree tree = new Tree();
  9 | 		int[] items = {5, 8, 7, 1, 9, 3, 0, 4, 6, 2};
 10 | 		for (int i : items)
 11 | 			tree.insert(i);
 12 | 		
 13 | 		System.out.println("Tree Height: " + tree.getHeight());
 14 | 		System.out.println("Tree Size: " + tree.getSize());
 15 | 		System.out.println("Find 3: " + tree.find(3));
 16 | 		tree.inorder();
 17 | 	}
 18 | 
 19 | 	public boolean insert(int val) {
 20 | 		if (root == null) {
 21 | 			root = new Node(val);
 22 | 			return true;
 23 | 		}
 24 | 		else 
 25 | 			return root.insert(val);
 26 | 	}
 27 | 	
 28 | 	public boolean find(int val) {
 29 | 		if (root == null) 
 30 | 			return false;
 31 | 		else 
 32 | 			return root.find(val);
 33 | 	}
 34 |   
 35 | 	public int getHeight() {
 36 | 		if (root != null)
 37 | 			return root.getHeight();
 38 | 		else
 39 | 			return 0;
 40 | 	}
 41 | 	
 42 | 	public int getSize() {
 43 | 		if (root != null)
 44 | 			return root.getSize();
 45 | 		else
 46 | 			return 0;
 47 | 	}
 48 | 	
 49 | 	public void preorder() {
 50 | 		if (root != null) {
 51 | 			System.out.println("Preorder:");
 52 | 			root.preorder();
 53 | 		}
 54 | 	}
 55 | 	
 56 | 	public void postorder() {
 57 | 		if (root != null) {
 58 | 			System.out.println("Postorder:");
 59 | 			root.postorder();
 60 | 		}
 61 | 	}
 62 | 	
 63 | 	public void inorder() {
 64 | 		if (root != null) {
 65 | 			System.out.println("Inorder:");
 66 | 			root.inorder();
 67 | 		}
 68 | 	}
 69 | 
 70 | 	private class Node {
 71 | 		private Node leftChild;
 72 | 		private Node rightChild;
 73 | 		private int data;
 74 | 
 75 | 		private Node(int val) {
 76 | 			data = val;
 77 | 			leftChild = null;
 78 | 			rightChild = null;
 79 | 		}
 80 | 
 81 | 		private boolean insert(int val) {
 82 | 			boolean added = false;
 83 | 			if (this == null) {
 84 | 				this.data = val;
 85 | 				return true;
 86 | 			}
 87 | 			else {
 88 | 				if (val < this.data) {
 89 | 					if (this.leftChild == null) {
 90 | 						this.leftChild = new Node(val);
 91 | 						return true;
 92 | 					}
 93 | 					else 
 94 | 						added = this.leftChild.insert(val);
 95 | 				}
 96 | 				else if (val > this.data) {
 97 | 					if (this.rightChild == null) {
 98 | 						this.rightChild = new Node(val);
 99 | 						return true;
100 | 					}
101 | 					else
102 | 						added = this.rightChild.insert(val);
103 | 				}
104 | 			}
105 | 			return added;
106 | 		}
107 | 		
108 | 		private boolean find(int val) {
109 | 			boolean found = false;
110 | 			if (this == null) 
111 | 				return false;
112 | 			else {
113 | 				if (val == this.data)
114 | 					return true;                        
115 | 				else if (val < this.data && this.leftChild != null)
116 | 					found = this.leftChild.find(val);
117 | 				else if (val > this.data && this.rightChild != null)
118 | 					found = this.rightChild.find(val);
119 | 			}
120 | 			return found;
121 | 		}
122 | 		
123 | 		private int getHeight() {
124 | 			int leftHeight = 0, rightHeight = 0;
125 | 			
126 | 			if (this.leftChild != null)
127 | 				leftHeight = this.leftChild.getHeight();
128 | 						
129 | 			if (this.rightChild != null)
130 | 				rightHeight = this.rightChild.getHeight();
131 | 			
132 | 			return 1 + Math.max(leftHeight, rightHeight);
133 | 		}
134 | 		
135 | 		private int getSize() {
136 | 			int leftSize = 0, rightSize = 0;
137 | 			
138 | 			if (this.leftChild != null)
139 | 				leftSize = this.leftChild.getSize();
140 | 						
141 | 			if (this.rightChild != null)
142 | 				rightSize = this.rightChild.getSize();
143 | 			
144 | 			return 1 + leftSize + rightSize;			
145 | 		}
146 | 		
147 | 		private void preorder() {
148 | 			if (this != null) {
149 | 				System.out.println(this.data);
150 | 				if (this.leftChild != null)
151 | 					this.leftChild.preorder();
152 | 				if (this.rightChild != null)
153 | 					this.rightChild.preorder();
154 | 			}
155 | 		}
156 | 		
157 | 		private void postorder() {
158 | 			if (this != null) {
159 | 				if (this.leftChild != null)
160 | 					this.leftChild.postorder();
161 | 				if (this.rightChild != null)
162 | 					this.rightChild.postorder();
163 | 				System.out.println(this.data);
164 | 			}
165 | 		}
166 | 		
167 | 		private void inorder() {
168 | 			if (this != null) {
169 | 				if (this.leftChild != null)
170 | 					this.leftChild.inorder();
171 | 				System.out.println(this.data);
172 | 				if (this.rightChild != null)
173 | 					this.rightChild.inorder();
174 | 			}
175 | 		}
176 | 	}
177 | }


--------------------------------------------------------------------------------
/bubbleSort.java:
--------------------------------------------------------------------------------
 1 | public int[] bubbleSort (int[] list) {
 2 | 	int i, j, temp = 0;
 3 | 	for (i = 0; i < list.length - 1; i++) {
 4 | 		for (j = 0; j < list.length - 1 - i; j++) {
 5 | 			if (list[j] > list[j + 1]) {
 6 | 				temp = list[j];
 7 | 				list[j] = list[j + 1];
 8 | 				list[j + 1] = temp;
 9 | 			}
10 | 		}
11 | 	}
12 | 	return list;
13 | }
14 | 


--------------------------------------------------------------------------------
/insertionSort.java:
--------------------------------------------------------------------------------
 1 | // using Array
 2 | public int[] insertionSort (int[] list) {
 3 | 	int i, j, key, temp;
 4 | 	for (i = 1; i < list.length; i++) {
 5 | 		key = list[i];
 6 | 		j = i - 1;
 7 | 		while (j >= 0 && key < list[j]) {
 8 | 			temp = list[j];
 9 | 			list[j] = list[j + 1];
10 | 			list[j + 1] = temp;
11 | 			j--;
12 | 		}
13 | 	}
14 | 	return list;
15 | }
16 | 
17 | // using ArrayList
18 | public ArrayList<Integer> insertionSort (ArrayList<Integer> list) {
19 | 	int i, j, key, temp;
20 | 	for (i = 1; i < list.size(); i++) {
21 | 		key = list.get(i);
22 | 		j = i - 1;
23 | 		while (j >= 0 && key < list.get(j)) {
24 | 			temp = list.get(j);
25 | 			list.set(j, list.get(j + 1));
26 | 			list.set(j + 1, temp);
27 | 			j--;
28 | 		}
29 | 	}
30 | 	return list;
31 | }


--------------------------------------------------------------------------------
/mergeSort.java:
--------------------------------------------------------------------------------
 1 | public void mergeSort (int[] list, int lowIndex, int highIndex) {
 2 | 	if (lowIndex == highIndex)
 3 | 		return;
 4 | 	else {
 5 | 		int midIndex = (lowIndex + highIndex) / 2;
 6 | 		mergeSort(list, lowIndex, midIndex);
 7 | 		mergeSort(list, midIndex + 1, highIndex);
 8 | 		merge(list, lowIndex, midIndex, highIndex);
 9 | 	} 
10 | }
11 | 
12 | public void merge(int[] list, int lowIndex, int midIndex, int highIndex) {
13 | 	int[] L = new int[midIndex - lowIndex + 2];
14 | 	
15 | 	for (int i = lowIndex; i <= midIndex; i++) {
16 | 		L[i - lowIndex] = list[i];
17 | 	}
18 | 	L[midIndex - lowIndex + 1] = Integer.MAX_VALUE;
19 | 	int[] R = new int[highIndex - midIndex + 1];
20 | 	
21 | 	for (int i = midIndex + 1; i <= highIndex; i++) {
22 | 		R[i - midIndex - 1] = list[i];
23 | 	}
24 | 	R[highIndex - midIndex] = Integer.MAX_VALUE;
25 | 	int i = 0, j = 0;
26 | 	
27 | 	for (int k = lowIndex; k <= highIndex; k++) {
28 | 		if (L[i] <= R[j]) {
29 | 			list[k] = L[i];
30 | 			i++;
31 | 		}
32 | 		else {
33 | 			list[k] = R[j];
34 | 			j++;
35 | 		}
36 | 	} 
37 | }
38 | 


--------------------------------------------------------------------------------
/primes.txt:
--------------------------------------------------------------------------------
 1 | // version 1
 2 | public class Primes {
 3 | 
 4 |     public static void main(String[] args) {
 5 |         int max = 10;
 6 |         for (int x = 2; x <= max; x++) {
 7 |             boolean isPrime = true;
 8 |             for (int y = 2; y < x; y++)
 9 | 				if (x % y == 0)
10 |                     isPrime = false;
11 |             if (isPrime)
12 |                 System.out.println(x);
13 |         }
14 |     }
15 | }
16 | --------------------------------------------
17 | // version 2: break
18 | public class Primes {
19 | 
20 |     public static void main(String[] args) {
21 |         int max = 10;
22 |         for (int x = 2; x <= max; x++) {
23 |             boolean isPrime = true;
24 |             for (int y = 2; y < x; y++)
25 | 				if (x % y == 0) {
26 | 					isPrime = false;
27 | 					break;
28 | 				}
29 |             if (isPrime)
30 |                 System.out.println(x);
31 |         }
32 |     }
33 | }
34 | --------------------------------------------
35 | // version 3: break, add to list
36 | import java.util.ArrayList;
37 | 
38 | public class Primes {
39 | 
40 |     public static void main(String[] args) {
41 |         ArrayList<Integer> primeList  = new ArrayList<>();
42 | 
43 |         int max = 10000;
44 |         for (int x = 2; x <= max; x++) {
45 |             boolean isPrime = true;
46 |             for (int y = 2; y < x; y++)
47 | 				if (x % y == 0) {
48 |                     isPrime = false;
49 |                     break;
50 |                 }
51 |             if (isPrime)
52 |                 primeList.add(x);
53 |         }
54 |         System.out.println(primeList);
55 |     }
56 | }
57 | --------------------------------------------
58 | // version 4: break, add to list, square root
59 | import java.util.ArrayList;
60 | 
61 | public class Primes {
62 | 
63 |     public static void main(String[] args) {
64 |         ArrayList<Integer> primeList  = new ArrayList<>();
65 | 
66 |         int max = 200000;
67 |         for (int x = 2; x <= max; x++) {
68 |             boolean isPrime = true;
69 |             for (int y = 2; y < Math.sqrt(x); y++)
70 | 				if (x % y == 0) {
71 |                     isPrime = false;
72 |                     break;
73 |                 }
74 |             if (isPrime)
75 |                 primeList.add(x);
76 |         }
77 |         System.out.println(primeList);
78 |     }
79 | }
80 | 


--------------------------------------------------------------------------------
/selectionSort.java:
--------------------------------------------------------------------------------
 1 | public int[] selectionSort (int[] list) {
 2 | 	int i, j, minValue, minIndex, temp = 0;
 3 | 	for (i = 0; i < list.length; i++) {
 4 | 		minValue = list[i];
 5 | 		minIndex = i;
 6 | 		for (j = i; j < list.length; j++) {
 7 | 			if (list[j] < minValue) {
 8 | 				minValue = list[j];
 9 | 				minIndex = j;
10 | 			}
11 | 		}
12 | 		if (minValue < list[i]) {
13 | 			temp = list[i];
14 | 			list[i] = list[minIndex];
15 | 			list[minIndex] = temp;
16 | 		}
17 | 	}
18 | 	return list;
19 | }
20 | 


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