├── README.md
└── project
    ├── project.iml
    └── src
        ├── Main.java
        └── lk
            └── himash
                ├── Illustration_01.java
                ├── Illustration_02.java
                ├── Illustration_03.java
                ├── Illustration_04.java
                ├── model
                    └── Car.java
                └── util
                    └── DB.java


/README.md:
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 1 | # Core-Java-Patterns
 2 | 
 3 | Includes Java related questions and answer.
 4 | 
 5 | ## Requirements
 6 | 
 7 | 01) Java 17
 8 | 
 9 | ## Project setup
10 | 
11 | 01) Clone the project
12 | 
13 | 	https://github.com/himash79/Core-Java-patterns.git
14 | 
15 | 02) Figure out the features
16 | 


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/project/project.iml:
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 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <module type="JAVA_MODULE" version="4">
 3 |   <component name="NewModuleRootManager" inherit-compiler-output="true">
 4 |     <exclude-output />
 5 |     <content url="file://$MODULE_DIR$">
 6 |       <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
 7 |     </content>
 8 |     <orderEntry type="inheritedJdk" />
 9 |     <orderEntry type="sourceFolder" forTests="false" />
10 |   </component>
11 | </module>


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/project/src/Main.java:
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 1 | // Press Shift twice to open the Search Everywhere dialog and type `show whitespaces`,
 2 | // then press Enter. You can now see whitespace characters in your code.
 3 | public class Main {
 4 |     public static void main(String[] args) {
 5 |         // Press Alt+Enter with your caret at the highlighted text to see how
 6 |         // IntelliJ IDEA suggests fixing it.
 7 |         System.out.printf("Hello and welcome!");
 8 | 
 9 |         // Press Shift+F10 or click the green arrow button in the gutter to run the code.
10 |         for (int i = 1; i <= 5; i++) {
11 | 
12 |             // Press Shift+F9 to start debugging your code. We have set one breakpoint
13 |             // for you, but you can always add more by pressing Ctrl+F8.
14 |             System.out.println("i = " + i);
15 |         }
16 |     }
17 | }


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/project/src/lk/himash/Illustration_01.java:
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 1 | package lk.himash;
 2 | 
 3 | import java.util.*;
 4 | 
 5 | public class Illustration_01 {
 6 |     public static void main(String[] args) {
 7 | 
 8 | //      Write a program to find the first non-repeating number in the following array
 9 |         int [] arr = new int [] {5, 4, 2, 5, 3, 8, 5, 2, 1, 8};
10 |         HashSet<Integer> uniqueValues = new HashSet<>();
11 |         List<Integer> duplicates = new ArrayList<>();
12 |         List<Integer> list = new ArrayList<>();
13 | 
14 |         for (int j : arr) {
15 |             list.add(j);
16 |             if (!uniqueValues.add(j)) { // If the value added success true otherwise false
17 |                 duplicates.add(j);
18 |             }
19 |         }
20 | 
21 |         list.removeAll(duplicates);
22 | 
23 |         System.out.println("Initial non-duplicate value is : " + list.get(0));
24 | 
25 |     }
26 | 
27 | }
28 | 


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/project/src/lk/himash/Illustration_02.java:
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 1 | package lk.himash;
 2 | 
 3 | import java.util.ArrayList;
 4 | import java.util.HashSet;
 5 | import java.util.List;
 6 | import java.util.Set;
 7 | 
 8 | public class Illustration_02 {
 9 |     public static void main(String[] args) {
10 | 
11 | //      Write a program to find the all repeating numbers & non-repeating numbers & remove duplicates in the following array
12 |         int [] arr = new int [] {5, 4, 2, 5, 3, 8, 5, 2, 1, 8};
13 |         List<Integer> list = new ArrayList<>();
14 |         Set<Integer> nonRepeatNo = new HashSet<>();
15 |         List<Integer> repeatNo = new ArrayList<>();
16 | 
17 |         for(int i=0; i<arr.length; i++){
18 |             list.add(arr[i]);
19 |             if(!nonRepeatNo.add(arr[i])) {
20 |                 repeatNo.add(arr[i]);
21 |             }
22 |         }
23 | 
24 |         list.removeAll(repeatNo);
25 | 
26 |         System.out.println("without duplicates : " + list);
27 |         System.out.println("duplicates : " + repeatNo);
28 |         System.out.println("non duplicates : " + nonRepeatNo);
29 | 
30 |     }
31 | }
32 | 


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/project/src/lk/himash/Illustration_03.java:
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 1 | package lk.himash;
 2 | 
 3 | public class Illustration_03 {
 4 |     public static void main(String[] args) {
 5 | 
 6 | //       Write a program to reverse the below paragraph
 7 | 
 8 |         String word = "Hello My World";
 9 | 
10 |         StringBuilder out = new StringBuilder(); // method 01
11 |         char[] charArr = word.toCharArray();
12 |         for(int i = charArr.length - 1; i >= 0; i--) {
13 |             out.append(charArr[i]);
14 |         }
15 |         System.out.println(out);
16 | 
17 |         StringBuilder strBuilder = new StringBuilder(word);// method 02
18 |         System.out.println(strBuilder.reverse());
19 | 
20 |         StringBuffer strBuffer = new StringBuffer(word);// method 03
21 |         System.out.println(strBuffer.reverse());
22 |     }
23 | }
24 | 


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/project/src/lk/himash/Illustration_04.java:
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 1 | package lk.himash;
 2 | 
 3 | import lk.himash.model.Car;
 4 | import lk.himash.util.DB;
 5 | 
 6 | import java.util.ArrayList;
 7 | import java.util.List;
 8 | 
 9 | public class Illustration_04 {
10 |     public static void main(String[] args) {
11 | 
12 |         List<Car> initDetails = DB.fetchCarsIniDetails();
13 |         List<Car> otherDetails = DB.fetchCarsOtherDetails();
14 |         List<Car> totalDetails = new ArrayList<>();
15 | 
16 |         // If the both list contains same count of records
17 |         for (int i = 0; i < initDetails.size(); i++) {
18 |             Car c = new Car();
19 |             c.setId(initDetails.get(i).getId());
20 |             c.setManufacture(initDetails.get(i).getManufacture());
21 |             c.setModel(initDetails.get(i).getModel());
22 |             if(i != otherDetails.size()) {
23 |                 c.setCost(otherDetails.get(i).getCost());
24 |                 c.setStatus(otherDetails.get(i).isStatus());
25 |             }
26 |             totalDetails.add(c);
27 |         }
28 | 
29 |         // If the both list contains different count of records
30 |         for (int i = 0; i < initDetails.size(); i++) {
31 |             Car c = new Car();
32 |             c.setId(initDetails.get(i).getId());
33 |             c.setManufacture(initDetails.get(i).getManufacture());
34 |             c.setModel(initDetails.get(i).getModel());
35 |             totalDetails.add(c);
36 |         }
37 |         for (int j = 0; j < otherDetails.size(); j++) {
38 |             if (j == totalDetails.size()) {
39 |                 Car car = new Car(otherDetails.get(j).getCost(), otherDetails.get(j).isStatus());
40 |                 totalDetails.add(car);
41 |             } else {
42 |                 totalDetails.get(j).setCost(otherDetails.get(j).getCost());
43 |                 totalDetails.get(j).setStatus(otherDetails.get(j).isStatus());
44 |             }
45 |         }
46 |         System.out.println(totalDetails);
47 |     }
48 | 
49 | }
50 | 


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/project/src/lk/himash/model/Car.java:
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 1 | package lk.himash.model;
 2 | 
 3 | public class Car {
 4 | 
 5 |     private int id;
 6 |     private String manufacture;
 7 |     private String model;
 8 |     private double cost;
 9 |     private boolean status;
10 | 
11 |     @Override
12 |     public String toString() {
13 |         return "Car{" +
14 |                 "id=" + id +
15 |                 ", manufacture='" + manufacture + '\'' +
16 |                 ", model='" + model + '\'' +
17 |                 ", cost=" + cost +
18 |                 ", status=" + status +
19 |                 '}';
20 |     }
21 | 
22 |     public Car(int id, String manufacture, String model, double cost, boolean status) {
23 |         this.id = id;
24 |         this.manufacture = manufacture;
25 |         this.model = model;
26 |         this.cost = cost;
27 |         this.status = status;
28 |     }
29 | 
30 |     public Car() {
31 |     }
32 | 
33 |     public Car(int id, String manufacture, String model) {
34 |         this.id = id;
35 |         this.manufacture = manufacture;
36 |         this.model = model;
37 |     }
38 | 
39 |     public Car(double cost, boolean status) {
40 |         this.cost = cost;
41 |         this.status = status;
42 |     }
43 | 
44 |     public int getId() {
45 |         return id;
46 |     }
47 | 
48 |     public void setId(int id) {
49 |         this.id = id;
50 |     }
51 | 
52 |     public String getManufacture() {
53 |         return manufacture;
54 |     }
55 | 
56 |     public void setManufacture(String manufacture) {
57 |         this.manufacture = manufacture;
58 |     }
59 | 
60 |     public String getModel() {
61 |         return model;
62 |     }
63 | 
64 |     public void setModel(String model) {
65 |         this.model = model;
66 |     }
67 | 
68 |     public double getCost() {
69 |         return cost;
70 |     }
71 | 
72 |     public void setCost(double cost) {
73 |         this.cost = cost;
74 |     }
75 | 
76 |     public boolean isStatus() {
77 |         return status;
78 |     }
79 | 
80 |     public void setStatus(boolean status) {
81 |         this.status = status;
82 |     }
83 | }


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/project/src/lk/himash/util/DB.java:
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 1 | package lk.himash.util;
 2 | 
 3 | import lk.himash.model.Car;
 4 | 
 5 | import java.util.ArrayList;
 6 | import java.util.List;
 7 | 
 8 | public class DB {
 9 | 
10 |     public static List<Car> fetchCarsIniDetails() {
11 |         List<Car> cars = new ArrayList<>();
12 |         Car car1 = new Car(1, "Toyota", "Axio");
13 |         Car car2 = new Car(2, "Honda", "Civic");
14 |         Car car3 = new Car(3, "Audi", "A5");
15 |         Car car4 = new Car(4, "BMW", "320SI");
16 |         cars.add(car1);
17 |         cars.add(car2);
18 |         cars.add(car3);
19 |         cars.add(car4);
20 |         return cars;
21 |     }
22 | 
23 |     public static List<Car> fetchCarsOtherDetails() {
24 |         List<Car> cars = new ArrayList<>();
25 |         Car car1 = new Car(30000.00, false);
26 |         Car car2 = new Car(15000.00, true);
27 |         Car car3 = new Car(80000.00, false);
28 |         cars.add(car1);
29 |         cars.add(car2);
30 |         cars.add(car3);
31 |         return cars;
32 |     }
33 | 
34 | }
35 | 


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