├── LICENSE ├── README.md ├── _01_basics ├── Datatypes.java ├── Main.java ├── Operators.java ├── StringMethods.java ├── Typecasting.java └── Variables.java ├── _02_control_statements ├── BreakAndContinue.java ├── Enhanced_Switch.java ├── For.java ├── IfElse.java ├── Nested_Switch.java ├── Switch.java ├── WhileLoop.java └── important.txt ├── _03_methods ├── MethodOverloading.java ├── MethodWithParameters.java ├── Methods.java ├── Recursion.java ├── ReturnValues.java ├── Scope.java └── Variable_Length_Arguments.java ├── _04_Class_and_Objects └── RectArea.java ├── _05_Constructor ├── RectArea.java └── default_c.java ├── _06_StaticMembers └── MathApplication.java ├── _07_NestingofMethods └── Nesting.java ├── _08_Inheritance ├── _01_Single_Inheritance │ └── SingleInheritance.java ├── _02_Multilevel_Inheritance │ └── MultilevelInheritance.java └── _03_Hierarchical_Inheritance │ └── HierarchicalInheritance.java ├── _09_Polymorphism ├── MethodOverloading.java ├── MethodOverriding.java └── PolymorphismProgram.java ├── _10_Abstraction └── Abstraction.java ├── _11_Arrays ├── Array.java ├── Array_Matrix.java ├── Array_Sorting.java ├── Enum.java ├── TwoDArray.java └── VectorProgram.java ├── _12_Strings ├── String_Functions.java ├── String_Ordering.java └── String_Program.java ├── _13_Interfaces ├── InterfaceTestImplement.java └── MultipleOrHybridInheritance.java ├── _14_Making_Package └── ClassA.java ├── _15_Importing_Package └── Package_Test.java ├── _16_Thread ├── RunnableInterfaceThread.java ├── ThreadMethods.java ├── ThreadPriority.java ├── ThreadTest.java └── eg_SRS.java ├── _17_Exception_Handling ├── CmdLineInputException.class ├── CmdLineInputException.java ├── DivideByZeroError.java ├── ErrorTest.java ├── ExceptionHandling.java ├── Multiple_catch_Blocks.java ├── Nested_Try.java ├── Throw_Exception.java └── Using_Finally_Block.java ├── _18_Applets ├── HelloJavaApplet.class ├── HelloJavaApplet.html └── HelloJavaApplet.java ├── _19_File_Handling ├── CopyCharactersInFile.java ├── ReadBytesFromFile.java └── WriteBytesToFile.java └── _20_Database_Connectivity └── OracleConnect.java /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Learn Java Programming Java 2 | 3 | - In this repository you will find topic wise programs of java from basics to intermediate. 4 | 5 | - This follows topic wise approach that will also help you to cover your college syllabus. 6 | 7 | - You can send a pull request if you think that you have more programs for a topic. 8 | 9 | - **Fork** this **Repository** and mark a **Star** 10 | 11 | - So lets learn Java together. 12 | 13 | IntelliJIDEA 14 | -------------------------------------------------------------------------------- /_01_basics/Datatypes.java: -------------------------------------------------------------------------------- 1 | public class Datatypes { 2 | public static void main (String[] args) { 3 | int myNum = 5; // Integer (whole number) 4 | float myFloatNum = 5.99f; // Floating point number 5 | char myLetter = 'D'; // Character 6 | boolean myBool = true; // Boolean 7 | String myText = "Hello"; // String 8 | 9 | 10 | System.out.println("These below are the datatypes : "); 11 | System.out.println("Integer Value = "+myNum); 12 | System.out.println("Integer Value = "+myFloatNum); 13 | System.out.println("Integer Value = "+myLetter); 14 | System.out.println("Integer Value = "+myBool); 15 | System.out.println("Integer Value = "+myText); 16 | 17 | } 18 | } 19 | 20 | //Primitive Datatypes in Java 21 | 22 | /* 23 | 24 | 25 | Data Type Size Description 26 | byte 1 byte Stores whole numbers from -128 to 127 27 | short 2 bytes Stores whole numbers from -32,768 to 32,767 28 | int 4 bytes Stores whole numbers from -2,147,483,648 to 2,147,483,647 29 | long 8 bytes Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 30 | float 4 bytes Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits 31 | double 8 bytes Stores fractional numbers. Sufficient for storing 15 decimal digits 32 | boolean 1 bit Stores true or false values 33 | char 2 bytes Stores a single character/letter or ASCII values 34 | 35 | */ 36 | -------------------------------------------------------------------------------- /_01_basics/Main.java: -------------------------------------------------------------------------------- 1 | public class Main { 2 | 3 | public static void main(String[] args) { 4 | System.out.println("Hello World"); 5 | } 6 | } 7 | // This is a single line comment in java 8 | 9 | /* 10 | This is 11 | a multiline comment 12 | in java 13 | */ 14 | -------------------------------------------------------------------------------- /_01_basics/Operators.java: -------------------------------------------------------------------------------- 1 | import java.util.Scanner; 2 | public class Operators { 3 | public static void main (String[] args) { 4 | int x,y,sum,sub,mul,div,mod; 5 | Scanner inp = new Scanner(System.in); 6 | System.out.println("Enter value of x"); 7 | x = inp.nextInt(); 8 | System.out.println("Enter value of y"); 9 | y = inp.nextInt(); 10 | sum = x + y; 11 | sub = x - y; 12 | mul = x * y; 13 | div = x / y; 14 | mod = x % y; 15 | System.out.println("Sum = "+sum); 16 | System.out.println("Sum = "+sub); 17 | System.out.println("Sum = "+mul); 18 | System.out.println("Sum = "+div); 19 | System.out.println("Sum = "+mod); 20 | } 21 | } 22 | -------------------------------------------------------------------------------- /_01_basics/StringMethods.java: -------------------------------------------------------------------------------- 1 | public class StringMethods { 2 | public static void main (String[] args) { 3 | String greeting = "Hello"; 4 | System.out.println(greeting+" Sahil"); 5 | 6 | //Function to get string length 7 | String txt = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 8 | System.out.println("The length of the txt string is: " + txt.length()); 9 | 10 | //String to UPPERCASE 11 | String words = "Hello World"; 12 | System.out.println(words.toUpperCase()); 13 | //String to lowercase 14 | System.out.println(words.toLowerCase()); 15 | 16 | //Finding a Character in a String 17 | String text = "Please locate where 'sb' occurs"; 18 | System.out.println("sb is at "+text.indexOf("sb")+"th location"); 19 | 20 | //String Concatenation + 21 | String firstName = "Sahil"; 22 | String lastName = "Batra"; 23 | System.out.println("My name is "+firstName+" "+lastName); 24 | 25 | //String Concatenation using concat() method 26 | System.out.println(firstName.concat(lastName)+" is my name."); 27 | 28 | //Special Characters 29 | /* 30 | Escape character Result Description 31 | \' ' Single quote 32 | \" " Double quote 33 | \\ \ Backslash 34 | */ 35 | String desc = "We are the so-called \"Punjabi\" from the north."; 36 | System.out.println(desc); 37 | String text1 = "It\'s alright"; 38 | System.out.println("Dont worry "+text1); 39 | 40 | //Six other escape sequences are valid in Java: 41 | /* 42 | Code Result 43 | \n New Line 44 | \r Carriage Return 45 | \t Tab 46 | \b Backspace 47 | \f Form Feed 48 | Try above yourself 49 | */ 50 | 51 | //WARNING! 52 | //Java uses the + operator for both addition and concatenation. 53 | //Numbers are added. Strings are concatenated. 54 | } 55 | } 56 | -------------------------------------------------------------------------------- /_01_basics/Typecasting.java: -------------------------------------------------------------------------------- 1 | public class Typecasting { 2 | public static void main(String[] args) { 3 | 4 | //Widening Casting 5 | 6 | int myInt = 9; 7 | double myDouble = myInt; // Automatic casting: int to double 8 | 9 | System.out.println(myInt); // Outputs 9 10 | System.out.println(myDouble); // Outputs 9.0 11 | 12 | //Narrowing Casting 13 | 14 | double myDoublen = 9.78d; 15 | int myIntn = (int) myDouble; // Manual casting: double to int 16 | 17 | System.out.println(myDouble); // Outputs 9.78 18 | System.out.println(myInt); // Outputs 9 but still its a wrong practise 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /_01_basics/Variables.java: -------------------------------------------------------------------------------- 1 | public class Variables { 2 | public static void main (String[] args) { 3 | String myName = "Sahil"; 4 | int Num = 15; // declaration with initialization 5 | Num = 20; // initialization afterwards 6 | System.out.println(Num); 7 | final int myConst = 30; 8 | System.out.println(myConst); 9 | //myNum = 25; // will generate an error: cannot assign a value to a final variable 10 | 11 | // other data types 12 | 13 | int myNum = 5; 14 | float myFloatNum = 5.99f; 15 | char myLetter = 'D'; 16 | boolean myBool = true; 17 | String myText = "Hello"; 18 | 19 | System.out.println("Integer Value = "+myNum); 20 | System.out.println("Integer Value = "+myFloatNum); 21 | System.out.println("Integer Value = "+myLetter); 22 | System.out.println("Integer Value = "+myBool); 23 | System.out.println("Integer Value = "+myText); 24 | 25 | // For numeric values, the + character works as a mathematical operator 26 | int x = 5; 27 | int y = 6; 28 | System.out.println(x + y); // Print the value of x + y 29 | 30 | // Declare Many Variables 31 | int a = 5, b = 6, c = 50; 32 | System.out.println(a + b + c); 33 | System.out.println(a+ "" +b+ "" +c); 34 | } 35 | } 36 | 37 | // variable declaration : 38 | // data type variable_name = value; 39 | /* you can add the final keyword if you don't want others 40 | (or yourself) to overwrite existing values 41 | (this will declare the variable as "final" or "constant", 42 | which means unchangeable and read-only */ 43 | // Here x. y , a,b myNum and more of these are called java identifiers 44 | -------------------------------------------------------------------------------- /_02_control_statements/BreakAndContinue.java: -------------------------------------------------------------------------------- 1 | public class BreakAndContinue { 2 | public static void main(String[] args) { 3 | System.out.println("Breaking at 4 but loop is till 10"); 4 | for (int i = 0; i <= 10; i++) { 5 | if (i == 4) { 6 | break; 7 | } 8 | System.out.println(i); 9 | } 10 | System.out.println("\nContinuing at 4 but loop is till 10"); 11 | for (int j = 0; j < 10; j++) { 12 | if (j== 4) { 13 | continue; 14 | } 15 | System.out.println(j); 16 | } 17 | } 18 | } 19 | -------------------------------------------------------------------------------- /_02_control_statements/Enhanced_Switch.java: -------------------------------------------------------------------------------- 1 | import java.util.Scanner; 2 | // Shorthand Switch Statement 3 | public class Enhanced_Switch { 4 | public static void main(String[] args) { 5 | Scanner inp = new Scanner(System.in); 6 | String fruit = inp.next(); 7 | 8 | switch (fruit) { 9 | case "Mango" -> System.out.println("King of fruit"); 10 | case "Apple" -> System.out.println("A sweet red fruit"); 11 | case "Orange" -> System.out.println("A round fruit"); 12 | case "Grapes" -> System.out.println("Small green fruit"); 13 | default -> System.out.println("Please enter a valid food"); 14 | } 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /_02_control_statements/For.java: -------------------------------------------------------------------------------- 1 | public class For { 2 | public static void main(String[] args) { 3 | System.out.println("Loop from 0 to 5"); 4 | for (int i = 0; i <= 5; i++) { 5 | System.out.println(i); 6 | } 7 | System.out.println("Loop for even numbers 0 to 10"); 8 | for (int j = 0; j <= 10; j = j + 2) { 9 | System.out.println(j); 10 | } 11 | //Using for loop with array 12 | String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; 13 | for (String k : cars) { 14 | System.out.println(k); 15 | } 16 | } 17 | } 18 | -------------------------------------------------------------------------------- /_02_control_statements/IfElse.java: -------------------------------------------------------------------------------- 1 | public class IfElse { 2 | public static void main (String[] args) { 3 | //if statement 4 | if (20 > 18) { 5 | System.out.println("20 is greater than 18"); 6 | } 7 | int x = 20; 8 | int y = 18; 9 | if (x > y) { 10 | System.out.println("x is greater than y"); 11 | } 12 | //if else statement 13 | int time = 20; 14 | if (time < 18) { 15 | System.out.println("Good day."); 16 | } else { 17 | System.out.println("Good evening."); 18 | } 19 | //else if statement 20 | int t = 22; 21 | if (t < 10) { 22 | System.out.println("Good morning."); 23 | } else if (t < 20) { 24 | System.out.println("Good day."); 25 | } else { 26 | System.out.println("Good evening."); 27 | } 28 | //Short Hand if..else (Ternary Operator) 29 | int timezone = 20; 30 | String result = (timezone < 18) ? "Good day." : "Good evening."; 31 | System.out.println(result); 32 | } 33 | } 34 | -------------------------------------------------------------------------------- /_02_control_statements/Nested_Switch.java: -------------------------------------------------------------------------------- 1 | import java.util.Scanner; 2 | 3 | public class Nested_Switch { 4 | public static void main(String[] args) { 5 | Scanner inp = new Scanner(System.in); 6 | int empID = inp.nextInt(); 7 | String department = inp.next(); 8 | 9 | //ENHANCED SWTICH STATEMENT 10 | 11 | switch (empID) { 12 | case 1 -> System.out.println("Sahil Batra"); 13 | case 2 -> System.out.println("Kabir Jangra"); 14 | case 3 -> { 15 | System.out.println("Employee Number 3"); 16 | switch (department) { 17 | case "IT" -> System.out.println("IT Department"); 18 | case "Management" -> System.out.println("Management Department"); 19 | default -> System.out.println("No department entered"); 20 | } 21 | } 22 | default -> System.out.println("Enter correct Emp ID"); 23 | } 24 | } 25 | } 26 | // OR NORMAL SWITCH STATEMENT 27 | 28 | // switch (empID) { 29 | // case 1: 30 | // System.out.println("Sahil Batra"); 31 | // break; 32 | // case 2: 33 | // System.out.println("Kabir Jangra"); 34 | // break; 35 | // case 3: 36 | // System.out.println("Employee Number 3"); 37 | // switch (department) { 38 | // case "IT": 39 | // System.out.println("IT Department"); 40 | // break; 41 | // case "Management": 42 | // System.out.println("Management Department"); 43 | // break; 44 | // default: 45 | // System.out.println("No department entered"); 46 | // } 47 | // break; 48 | // default: 49 | // System.out.println("Enter correct Emp ID"); 50 | // } 51 | 52 | -------------------------------------------------------------------------------- /_02_control_statements/Switch.java: -------------------------------------------------------------------------------- 1 | import java.util.Scanner; 2 | public class Switch { 3 | public static void main(String[] args) { 4 | Scanner inp = new Scanner(System.in); 5 | System.out.println("Enter the number of the day"); 6 | int day = inp.nextInt(); 7 | switch (day) { 8 | case 1: 9 | System.out.println("Monday"); 10 | break; 11 | case 2: 12 | System.out.println("Tuesday"); 13 | break; 14 | case 3: 15 | System.out.println("Wednesday"); 16 | break; 17 | case 4: 18 | System.out.println("Thursday"); 19 | break; 20 | case 5: 21 | System.out.println("Friday"); 22 | break; 23 | case 6: 24 | System.out.println("Saturday"); 25 | break; 26 | case 7: 27 | System.out.println("Sunday"); 28 | break; 29 | default: 30 | System.out.println("Wrong Input"); 31 | } 32 | } 33 | } 34 | -------------------------------------------------------------------------------- /_02_control_statements/WhileLoop.java: -------------------------------------------------------------------------------- 1 | public class WhileLoop { 2 | public static void main(String[] args) { 3 | System.out.println("Loop from 0 to 5"); 4 | int i = 0; 5 | while (i <= 5) { 6 | System.out.println(i); 7 | i++; 8 | } 9 | System.out.println("\nLoop from 5 to 0"); 10 | int j = 5; 11 | while (j >= 0) { 12 | System.out.println(j); 13 | j--; 14 | } 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /_02_control_statements/important.txt: -------------------------------------------------------------------------------- 1 | Must check Condition_and_Looping_Problems (folder) 2 | In that folder you will find all problems/programs 3 | of conditionals/control statements (Basic and Intermediate) -------------------------------------------------------------------------------- /_03_methods/MethodOverloading.java: -------------------------------------------------------------------------------- 1 | public class MethodOverloading { 2 | static int plusMethodInt(int x, int y) { 3 | return x + y; 4 | } 5 | 6 | static double plusMethodDouble(double x, double y) { 7 | return x + y; 8 | } 9 | 10 | public static void main(String[] args) { 11 | int myNum1 = plusMethodInt(8, 5); 12 | double myNum2 = plusMethodDouble(4.3, 6.26); 13 | System.out.println("int: " + myNum1); 14 | System.out.println("double: " + myNum2); 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /_03_methods/MethodWithParameters.java: -------------------------------------------------------------------------------- 1 | public class MethodWithParameters { 2 | static void myMethod(String fname, int age) { 3 | System.out.println(fname+" Batra is of age "+age); 4 | } 5 | public static void main(String[] args) { 6 | myMethod("Sahil",21); 7 | myMethod("Shvivam",11); 8 | } 9 | } 10 | -------------------------------------------------------------------------------- /_03_methods/Methods.java: -------------------------------------------------------------------------------- 1 | public class Methods { 2 | static void mtMethod() { 3 | System.out.println("I just got executed"); 4 | } 5 | public static void main(String[] args) { 6 | mtMethod(); 7 | mtMethod(); 8 | } 9 | } 10 | -------------------------------------------------------------------------------- /_03_methods/Recursion.java: -------------------------------------------------------------------------------- 1 | //Adding two numbers together is easy to do, but adding a range of numbers is more complicated. In the following example, recursion is used to add a range of numbers together by breaking it down into the simple task of adding two numbers: 2 | public class Recursion { 3 | public static void main(String[] args) { 4 | int result = sum(10); 5 | System.out.println(result); 6 | int resultn = sumn(5,10); 7 | System.out.println(resultn); 8 | } 9 | //Use recursion to add all numbers up to 10 10 | public static int sum(int k) { 11 | if(k>0) { 12 | return k + sum(k-1); 13 | } else { 14 | return 0; 15 | } 16 | } 17 | //Use recursion to add all numbers between start to end 18 | public static int sumn(int start, int end) { 19 | if(end > start) { 20 | return end + sumn(start, end - 1); 21 | } else { 22 | return end; 23 | } 24 | } 25 | } 26 | -------------------------------------------------------------------------------- /_03_methods/ReturnValues.java: -------------------------------------------------------------------------------- 1 | public class ReturnValues { 2 | static int myMethod(int x, int y) { 3 | return x + y; 4 | } 5 | // Create a checkAge() method with an integer variable called age 6 | static void checkAge(int age) { 7 | 8 | // If age is less than 18, print "access denied" 9 | if (age < 18) { 10 | System.out.println("Access denied - You are not old enough!"); 11 | 12 | // If age is greater than, or equal to, 18, print "access granted" 13 | } else { 14 | System.out.println("Access granted - You are old enough!"); 15 | } 16 | 17 | } 18 | 19 | 20 | public static void main(String[] args) { 21 | System.out.println("Sum = "+myMethod(5,10)); 22 | int z = myMethod(11,18); 23 | System.out.println("Z = "+z+"\n"); 24 | 25 | checkAge(2); // Call the checkAge method and pass along an age of 20 26 | checkAge(20); 27 | } 28 | } 29 | -------------------------------------------------------------------------------- /_03_methods/Scope.java: -------------------------------------------------------------------------------- 1 | public class Scope { 2 | public static void main(String[] args) { 3 | 4 | // Code here CANNOT use x 5 | 6 | int x = 1000; 7 | 8 | // Code here can use x 9 | System.out.println(x); 10 | 11 | { // This is a block 12 | 13 | // Code here CANNOT use y 14 | 15 | int y = 100; 16 | 17 | // Code here CAN use x 18 | System.out.println(y); 19 | 20 | } // The block ends here 21 | 22 | // Code here CANNOT use y 23 | 24 | } 25 | } 26 | -------------------------------------------------------------------------------- /_03_methods/Variable_Length_Arguments.java: -------------------------------------------------------------------------------- 1 | import java.util.Arrays; 2 | 3 | public class Variable_Length_Arguments { 4 | public static void main(String[] args) { 5 | 6 | mix_vargs(10,20,"Hello","Bye"); 7 | vargs(100,20,25,26,28); 8 | } 9 | static void vargs(int ...v) { 10 | System.out.println("Variable Arguments of Int below:"); 11 | System.out.println(Arrays.toString(v)); 12 | } 13 | static void mix_vargs(int a, int b, String ...v) { 14 | int sum = a+ b; 15 | System.out.println("Sum is ="+sum); 16 | System.out.println("Variable Arguments of String below:"); 17 | System.out.println(Arrays.toString(v)); 18 | } 19 | } 20 | -------------------------------------------------------------------------------- /_04_Class_and_Objects/RectArea.java: -------------------------------------------------------------------------------- 1 | class Rectangle { 2 | int length, width; // Declaration of variables 3 | void getData(int x, int y) { // Definition of method 4 | length = x; 5 | width = y; 6 | } 7 | int rectArea() { // Definition of another method 8 | int area = length * width; 9 | return (area); 10 | } 11 | } //End of class 12 | 13 | class RectArea { //Main class 14 | public static void main(String args[]) { 15 | int area1, area2; 16 | Rectangle rect1 = new Rectangle(); // Creating object rect1 17 | Rectangle rect2 = new Rectangle(); // Creating object rect2 18 | rect1.length = 15; // Accessing variable 19 | rect1.width = 20; // Accessing variable 20 | area1 = rect1.length * rect1.width; 21 | rect2.getData(20,10); // Accessing Method 22 | area2 = rect2.rectArea(); // Accessing Method 23 | System.out.println("Area1 = "+area1); 24 | System.out.println("Area2 = "+area2); 25 | } 26 | } 27 | -------------------------------------------------------------------------------- /_05_Constructor/RectArea.java: -------------------------------------------------------------------------------- 1 | class Rectangle { 2 | int length, width; // Declaration of variables 3 | Rectangle(int x, int y) { // Definition Constructor 4 | length = x; 5 | width = y; 6 | } 7 | int rectArea() { // Definition of another method 8 | return (length * width); 9 | 10 | } 11 | } 12 | 13 | class RectArea { 14 | public static void main(String args[]) { 15 | Rectangle rect1 = new Rectangle(15,10); // Calling Constructor 16 | int area1 = rect1.rectArea(); 17 | System.out.println("Area1 = "+area1); 18 | } 19 | } 20 | -------------------------------------------------------------------------------- /_05_Constructor/default_c.java: -------------------------------------------------------------------------------- 1 | // Program to see concept of default and parameterized constructor 2 | 3 | class perimeter { 4 | int length; 5 | int breadth; 6 | perimeter() { 7 | length = 0; 8 | breadth = 0; 9 | } 10 | perimeter(int x, int y) { 11 | length = x; 12 | breadth = y; 13 | } 14 | void cal_perimeter() { 15 | int peri; 16 | peri = 2* (length + breadth); 17 | System.out.println("\nPerimeter of Rectangle is: "+peri); 18 | } 19 | } 20 | 21 | class default_c { 22 | public static void main(String args[]) { 23 | perimeter p1 = new perimeter(); 24 | perimeter p2 = new perimeter(5,10); 25 | p1.cal_perimeter(); 26 | p2.cal_perimeter(); 27 | } 28 | } 29 | -------------------------------------------------------------------------------- /_06_StaticMembers/MathApplication.java: -------------------------------------------------------------------------------- 1 | class MathOperation { 2 | static float mul(float x, float y) { 3 | return x*y; 4 | } 5 | static float divide(float x, float y) { 6 | return x/y; 7 | } 8 | } 9 | 10 | class MathApplication { 11 | public static void main(String args[]) { 12 | float a = MathOperation.mul(4.0f,5.0f); 13 | float b = MathOperation.divide(a,2.0f); 14 | System.out.println("B = "+b); 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /_07_NestingofMethods/Nesting.java: -------------------------------------------------------------------------------- 1 | class Nesting { 2 | int m,n; 3 | Nesting(int x, int y) { 4 | m = x; 5 | n = y; 6 | } 7 | int largest() { 8 | if(m >= n) { 9 | return (m); 10 | } else { 11 | return (n); 12 | } 13 | } 14 | void display () { 15 | int large = largest(); // Nesting of method in this another display method 16 | System.out.println("Largest Value = "+large); 17 | } 18 | } 19 | class NestingClassMain { 20 | public static void main(String args[]) { 21 | Nesting nest = new Nesting(50,40); 22 | nest.display(); 23 | } 24 | } 25 | -------------------------------------------------------------------------------- /_08_Inheritance/_01_Single_Inheritance/SingleInheritance.java: -------------------------------------------------------------------------------- 1 | class Room { 2 | int length; 3 | int breadth; 4 | Room(int x, int y) { 5 | length = x; 6 | breadth = y; 7 | } 8 | int area() { 9 | return (length * breadth); 10 | } 11 | } 12 | 13 | class BedRoom extends Room { 14 | int height; 15 | BedRoom(int x, int y, int z) { 16 | super(x, y); // Pass values to super class 17 | height = z; 18 | } 19 | int volume() { 20 | return (length * breadth * height); 21 | } 22 | } 23 | 24 | public class SingleInheritance { 25 | public static void main(String args[]) { 26 | BedRoom room1 = new BedRoom(14, 12, 10); 27 | int area1 = room1.area(); 28 | int volume1 = room1.volume(); 29 | System.out.println("Area = "+area1); 30 | System.out.println("Volume = "+volume1); 31 | } 32 | } 33 | -------------------------------------------------------------------------------- /_08_Inheritance/_02_Multilevel_Inheritance/MultilevelInheritance.java: -------------------------------------------------------------------------------- 1 | class Animal { 2 | void eat() { 3 | System.out.println("eating..."); 4 | } 5 | } 6 | 7 | class Dog extends Animal { 8 | void bark() { 9 | System.out.println("barking..."); 10 | } 11 | } 12 | 13 | class BabyDog extends Dog { 14 | void weep() { 15 | System.out.println("weeping..."); 16 | } 17 | } 18 | 19 | class MultilevelInheritance { 20 | public static void main (String args[]) { 21 | BabyDog d = new BabyDog(); 22 | d.weep(); 23 | d.bark(); 24 | d.eat(); 25 | } 26 | } 27 | -------------------------------------------------------------------------------- /_08_Inheritance/_03_Hierarchical_Inheritance/HierarchicalInheritance.java: -------------------------------------------------------------------------------- 1 | class Animal { 2 | void eat() { 3 | System.out.println("eating..."); 4 | } 5 | } 6 | 7 | class Dog extends Animal { 8 | void bark() { 9 | System.out.println("barking..."); 10 | } 11 | } 12 | class Cat extends Animal { 13 | void meow() { 14 | System.out.println("meowing..."); 15 | } 16 | } 17 | 18 | public class HierarchicalInheritance { 19 | public static void main (String args[]) { 20 | Cat c = new Cat(); 21 | c.meow(); 22 | c.eat(); 23 | //c.bark(); //it will give error 24 | Dog d = new Dog(); 25 | d.bark(); 26 | d.eat(); 27 | } 28 | } 29 | -------------------------------------------------------------------------------- /_09_Polymorphism/MethodOverloading.java: -------------------------------------------------------------------------------- 1 | class Vehicle { 2 | void speed() { 3 | System.out.println("Vehicle Speeds :"); 4 | } 5 | } 6 | 7 | class Bike extends Vehicle { 8 | int x; 9 | void speed(int a) { 10 | x = a; 11 | System.out.println("Bike Speed = "+x+"km/h"); 12 | } 13 | } 14 | 15 | class Car extends Bike { 16 | int x,y; 17 | void speed(int a, int b) { 18 | x = a; 19 | y = b; 20 | System.out.println("Normal Car Speed = "+x+"km/h"); 21 | System.out.println("Sports Car Speed = "+y+"km/h"); 22 | } 23 | } 24 | 25 | public class MethodOverloading { 26 | public static void main(String args[]) { 27 | Car obj = new Car(); 28 | obj.speed(); 29 | obj.speed(90); 30 | obj.speed(120,190); 31 | } 32 | } 33 | -------------------------------------------------------------------------------- /_09_Polymorphism/MethodOverriding.java: -------------------------------------------------------------------------------- 1 | class Super { 2 | int x; 3 | Super(int x) { 4 | this.x = x; 5 | } 6 | void display() { // Method defined once 7 | System.out.println("Super x = "+x); 8 | } 9 | } 10 | 11 | class Sub extends Super { 12 | int y; 13 | Sub(int x, int y) { 14 | super(x); 15 | this.y = y; 16 | } 17 | void display() { // method defined again (Method Overriding) 18 | System.out.println("Super x = "+x); 19 | System.out.println("Super y = "+y); 20 | } 21 | } 22 | 23 | public class MethodOverriding { 24 | public static void main(String args[]) { 25 | Sub s1 = new Sub(100,200); 26 | s1.display(); 27 | } 28 | } 29 | -------------------------------------------------------------------------------- /_09_Polymorphism/PolymorphismProgram.java: -------------------------------------------------------------------------------- 1 | // Here same name of method is used in different classes but having different functionalities 2 | 3 | class Animal { 4 | public void animalSound() { 5 | System.out.println("The animal makes a sound"); 6 | } 7 | } 8 | 9 | class Pig extends Animal { 10 | public void animalSound() { 11 | System.out.println("The pig says: wee wee"); 12 | } 13 | } 14 | 15 | class Dog extends Animal { 16 | public void animalSound() { 17 | System.out.println("The dog says: bow wow"); 18 | } 19 | } 20 | 21 | public class PolymorphismProgram { 22 | public static void main(String args[]) { 23 | Animal myAnimal = new Animal(); // Create an Animal object 24 | Animal myPig = new Pig(); // Create a Pig object 25 | Animal myDog = new Dog(); // Create a Dog object 26 | myAnimal.animalSound(); 27 | myPig.animalSound(); 28 | myDog.animalSound(); 29 | } 30 | } 31 | -------------------------------------------------------------------------------- /_10_Abstraction/Abstraction.java: -------------------------------------------------------------------------------- 1 | abstract class Shape { 2 | abstract void draw(); 3 | } 4 | 5 | class Rectangle extends Shape { 6 | void draw() { 7 | System.out.println("Draw Rectangle"); 8 | } 9 | } 10 | 11 | class Circle extends Shape { 12 | void draw() { 13 | System.out.println("Draw Circle"); 14 | } 15 | } 16 | 17 | public class Abstraction { 18 | public static void main(String args[]) { 19 | Shape s1 = new Rectangle(); 20 | Shape s2 = new Circle(); 21 | s1.draw(); 22 | s2.draw(); 23 | } 24 | } 25 | -------------------------------------------------------------------------------- /_11_Arrays/Array.java: -------------------------------------------------------------------------------- 1 | package com._11_Arrays; 2 | 3 | public class Array { 4 | public static void main(String[] args) { 5 | int num[] = {10,20,30,40,50}; 6 | for(int i = 0; i<5 ; i++) { 7 | System.out.println("Array "+i+" = "+num[i]); 8 | } 9 | } 10 | } 11 | -------------------------------------------------------------------------------- /_11_Arrays/Array_Matrix.java: -------------------------------------------------------------------------------- 1 | package com._11_Arrays; 2 | 3 | public class Array_Matrix { 4 | public static void main(String[] args) { 5 | // int[][] arr = new int[3][]; 6 | int[][] arr = { 7 | {1,2,3}, 8 | {4,5,6}, 9 | {7,8,9} 10 | }; 11 | } 12 | } 13 | -------------------------------------------------------------------------------- /_11_Arrays/Array_Sorting.java: -------------------------------------------------------------------------------- 1 | package com._11_Arrays; 2 | 3 | public class Array_Sorting { 4 | public static void main(String[] args) { 5 | int number[] = {56, 48, 88, 60, 72}; 6 | int n = number.length; // Array Length 7 | System.out.println("Given List: "); 8 | for (int i = 0; i < n; i++) { 9 | System.out.print(" " + number[i]); 10 | } 11 | System.out.println("\n"); 12 | //Sorting Begins 13 | for (int i = 0; i < n; i++) { 14 | for (int j = 0; j < i; j++) { 15 | if (number[i] < number[j]) { 16 | int temp = number[i]; 17 | number[i] = number[j]; 18 | number[j] = temp; 19 | } 20 | } // Sorting Ends 21 | } 22 | System.out.println("Sorted List"); 23 | for(int i = 0; i100) 30 | 31 | throw new MarksOutOfBounds(); 32 | 33 | System.out.println("Your Marks:"+marks); 34 | 35 | } 36 | catch(MarksOutOfBounds e) 37 | 38 | { 39 | e.showError(); 40 | } 41 | 42 | 43 | } 44 | 45 | } 46 | -------------------------------------------------------------------------------- /_17_Exception_Handling/ExceptionHandling.java: -------------------------------------------------------------------------------- 1 | public class ExceptionHandling { 2 | public static void main(String[] args) { 3 | int a = 10; 4 | int b = 5; 5 | int c = 5; 6 | try { 7 | int x = a/(b-c); 8 | } 9 | catch (ArithmeticException e) { 10 | System.out.println("Division by zero not allowed"); 11 | } 12 | int y = a/(b+c); 13 | System.out.println("Y = "+y); 14 | } 15 | } 16 | -------------------------------------------------------------------------------- /_17_Exception_Handling/Multiple_catch_Blocks.java: -------------------------------------------------------------------------------- 1 | public class Multiple_catch_Blocks { 2 | public static void main(String[] args) { 3 | int a[] = {5,10}; 4 | int b = 5; 5 | try { 6 | int x = a[2]/b-a[1]; 7 | } 8 | catch (ArrayIndexOutOfBoundsException e) { 9 | System.out.println("Array index error"); 10 | } 11 | catch (ArrayStoreException e){ 12 | System.out.println("Wrong datatype"); 13 | } 14 | int y = a[1]/a[0]; 15 | System.out.println("Y = "+y); 16 | } 17 | } 18 | -------------------------------------------------------------------------------- /_17_Exception_Handling/Nested_Try.java: -------------------------------------------------------------------------------- 1 | public class Nested_Try { 2 | public static void main(String[] args) { 3 | try { 4 | int a = 2, b = 4, c = 2, x = 7, z; 5 | int p[] = {2}; 6 | p[3] = 33; 7 | try{ 8 | z = x/((b*b) - (4*a*c)); 9 | System.out.println("The value of z is = "+z); 10 | } 11 | catch (ArithmeticException e) { 12 | System.out.println("Division by zero not possible"); 13 | } 14 | } 15 | catch (ArrayIndexOutOfBoundsException e) { 16 | System.out.println("Array index is out of bound"); 17 | } 18 | } 19 | } 20 | -------------------------------------------------------------------------------- /_17_Exception_Handling/Throw_Exception.java: -------------------------------------------------------------------------------- 1 | class Throwing_own_exception extends Exception { 2 | Throwing_own_exception(String message) { 3 | super(message); 4 | } 5 | } 6 | 7 | public class Throw_Exception { 8 | public static void main(String[] args) { 9 | int x=5, y=1000; 10 | try { 11 | float z = (float)x / (float)y; 12 | if(z<0.01) { 13 | throw new Throwing_own_exception("Number is too small"); 14 | } 15 | } 16 | catch (Throwing_own_exception e) { 17 | System.out.println("Caught my exception"); 18 | System.out.println(e.getMessage()); 19 | } 20 | finally { 21 | System.out.println("I am always here"); 22 | } 23 | } 24 | } 25 | -------------------------------------------------------------------------------- /_17_Exception_Handling/Using_Finally_Block.java: -------------------------------------------------------------------------------- 1 | public class Using_Finally_Block { 2 | public static void main(String[] args) { 3 | int a[] = {5,10}; 4 | int b = 5; 5 | try { 6 | int x = a[2]/b-a[1]; 7 | } 8 | catch (ArrayIndexOutOfBoundsException e) { 9 | System.out.println("Array index error"); 10 | } 11 | catch (ArrayStoreException e){ 12 | System.out.println("Wrong datatype"); 13 | } 14 | finally { 15 | int y = a[1]/a[0]; 16 | System.out.println("Used Finally Block Here"); 17 | System.out.println("Y = "+y); 18 | } 19 | } 20 | } 21 | -------------------------------------------------------------------------------- /_18_Applets/HelloJavaApplet.class: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/infotechprogrammer/learn-java-programming/5e69a644ac63e55cb1af2380160b590327abdba0/_18_Applets/HelloJavaApplet.class -------------------------------------------------------------------------------- /_18_Applets/HelloJavaApplet.html: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | -------------------------------------------------------------------------------- /_18_Applets/HelloJavaApplet.java: -------------------------------------------------------------------------------- 1 | import java.awt.*; 2 | import java.applet.*; 3 | 4 | public class HelloJavaApplet extends Applet { 5 | public void draw(Graphics g) { 6 | g.drawString("Hello Java",10,100); 7 | } 8 | } 9 | -------------------------------------------------------------------------------- /_19_File_Handling/CopyCharactersInFile.java: -------------------------------------------------------------------------------- 1 | import java.io.*; 2 | public class CopyCharactersInFile { 3 | public static void main(String[] args) { 4 | File inFile = new File("input.bat"); 5 | File outFile = new File("output.bat"); 6 | FileReader ins = null; 7 | FileWriter outs = null; 8 | try 9 | { 10 | ins = new FileReader(inFile); 11 | outs = new FileWriter(outFile); 12 | int ch; 13 | while ((ch = ins.read()) != -1) { 14 | outs.write(ch); 15 | } 16 | } 17 | catch(IOException e) { 18 | System.out.println(e); 19 | System.exit(-1); 20 | } 21 | finally { 22 | try { 23 | ins.close(); 24 | outs.close(); 25 | } 26 | catch (IOException e) { 27 | } 28 | } 29 | } 30 | } 31 | -------------------------------------------------------------------------------- /_19_File_Handling/ReadBytesFromFile.java: -------------------------------------------------------------------------------- 1 | import java.io.*; 2 | public class ReadBytesFromFile { 3 | public static void main(String[] args) { 4 | FileInputStream infile; 5 | int b; 6 | try { 7 | infile = new FileInputStream("city.txt"); 8 | while ((b=infile.read()) != -1) { 9 | System.out.println((char)b); 10 | } 11 | infile.close(); 12 | } 13 | catch (IOException e) { 14 | System.out.println(e); 15 | } 16 | } 17 | } 18 | -------------------------------------------------------------------------------- /_19_File_Handling/WriteBytesToFile.java: -------------------------------------------------------------------------------- 1 | import java.io.*; 2 | public class WriteBytesToFile { 3 | public static void main(String[] args) { 4 | byte cities[] = {'D','E','L','H','I','\n','J','A','L','A','N','D','H','A','R','\n','L','O','N','D','O','N','\n'}; 5 | FileOutputStream outfile = null; 6 | try { 7 | outfile = new FileOutputStream("city.txt"); 8 | outfile.write(cities); 9 | outfile.close(); 10 | } 11 | catch (IOException e) { 12 | System.out.println(e); 13 | System.exit(-1); 14 | } 15 | } 16 | } 17 | -------------------------------------------------------------------------------- /_20_Database_Connectivity/OracleConnect.java: -------------------------------------------------------------------------------- 1 | import java.sql.*; 2 | 3 | public class OracleConnect { 4 | // Your information may be different than my database information given here below 5 | static final String DB_URL = "jdbc:oracle:thin:@localhost:1521:orcl"; 6 | static final String USER = "hr"; 7 | static final String PASS = "hr"; 8 | static final String QUERY = "SELECT employee_id, first_name, last_name, salary FROM Employees"; 9 | 10 | public static void main(String[] args) { 11 | // Open a connection 12 | try { 13 | Class.forName("oracle.jdbc.driver.OracleDriver"); 14 | System.out.println("Driver Loaded"); 15 | Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); 16 | System.out.println("Connection Established"); 17 | 18 | Statement stmt = conn.createStatement(); 19 | ResultSet rs = stmt.executeQuery(QUERY); 20 | { 21 | // Extract data from result set 22 | while (rs.next()) { 23 | // Retrieve by column name 24 | System.out.print("ID: " + rs.getInt("employee_id")); 25 | System.out.print(", First_Name: " + rs.getString("first_name")); 26 | System.out.print(", Last_Name: " + rs.getString("last_name")); 27 | System.out.println(", Salary: " + rs.getInt("salary")); 28 | } 29 | conn.close(); 30 | } 31 | } 32 | catch (ClassNotFoundException e) { 33 | System.out.println("Driver not loaded"); 34 | } 35 | catch (SQLException e) { 36 | e.printStackTrace(); 37 | } 38 | } 39 | } 40 | --------------------------------------------------------------------------------