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Data Types and Operators
(Non-Primitive Data Types)
Strings, Arrays
Control Flow Statements
Conditional Statements
if, if-else, nested if, switch
Looping Statements
for, while, do-while
Branching Statements
break, continue, return
Object-Oriented Programming (OOP)
Exception Handling
Collections Framework
Overview of Collections
List, Set, Map
Java I/O
Multithreading
GUI Programming with Swing
Advanced Topics
JAVA CODE
java introduction
JAVA PROGRAMME
Object-Oriented Programming and Java
Java Basics
Working with Objects
Arrays, Conditionals, and Loops
Creating Classes and Applications in Java
More About Methods
Java Applet Basics
Graphics, Fonts, and Color
Simple Animation and Threads
More Animation, Images, and Sound
Managing Simple Events and Interactivity
Creating User Interfaces with the awt
Windows, Networking, and Other Tidbits
Modifiers, Access Control, and Class Design
Packages and Interfaces
Exceptions
Multithreading
Streams and I/O
Using Native Methods and Libraries
Under the Hood
Java Programming Tools
Working with Data Structures in Java
Advanced Animation and Media
Fun with Image Filters
Client/Server Networking in Java
Emerging Technologies
appendix A :- Language Summary
appendix B :- Class Hierarchy Diagrams
appendix C The Java Class Library
appendix D Bytecodes Reference
appendix E java.applet Package Reference
appendix F java.awt Package Reference
appendix G java.awt.image Package Reference
appendix H java.awt.peer Package Reference
appendix I java.io Package Reference
appendix J java.lang Package Reference
appendix K java.net Package Reference
appendix L java.util Package Reference

Java Tutorial

Introduction Java Programming language

What is Java?

Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It was developed by Sun Microsystems in 1995, and later acquired by Oracle Corporation. Java is known for its portability, performance, and robustness, making it a popular choice for a wide range of applications from web development to mobile apps and large-scale enterprise systems.

Key Features of Java

  1. Object-Oriented: Everything in Java is an object which simplifies software development and maintenance.
  2. Platform-Independent: Java code is compiled into bytecode which can be run on any system that has a Java Virtual Machine (JVM).
  3. Simple: Java is designed to be easy to learn and use, with a clean syntax.
  4. Secure: Java has strong security features that enable the development of virus-free, tamper-free systems.
  5. Robust: Java has strong memory management and exception handling features.
  6. Multithreaded: Java supports multithreading, which allows the performance of multiple tasks simultaneously.
  7. High Performance: Java’s performance is enhanced with Just-In-Time compilers.
  8. Distributed: Java facilitates distributed computing with its network-centric design.

Java Development Kit (JDK)

The JDK is a software development kit used to develop Java applications. It includes:

  • JRE (Java Runtime Environment): Contains the JVM and standard libraries for running Java applications.
  • Java Compiler: Converts Java source code into bytecode.
  • Java Debugger: A tool for debugging Java applications.
  • JavaDoc: A tool for generating API documentation in HTML format from Java source code.

Basic Structure of a Java Program

A basic Java program consists of classes and methods. The entry point of any Java program is the main method. Here is a simple example:

				
					public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
  • Class Definition: The program defines a class named HelloWorld.
  • Main Method: The main method is the entry point of the program. The String[] args parameter is used for command-line arguments.
  • System.out.println: This statement prints text to the console.

Setting Up Java Development Environment

  1. Install JDK: Download and install the JDK from the Oracle website or any other source.
  2. Set Up Environment Variables:
    • JAVA_HOME: Points to the directory where the JDK is installed.
    • PATH: Includes the bin directory of the JDK to run Java commands from the command line.
  3. Install an IDE: Use an Integrated Development Environment (IDE) like IntelliJ IDEA, Eclipse, or NetBeans for easier development and debugging.

Compiling and Running a Java Program

  1. Write the Code: Create a Java source file with a .java extension.

  2. Compile the Code: Use the javac command to compile the source file into bytecode.

				
					javac HelloWorld.java

This generates a HelloWorld.class file containing the bytecode.

3. Run the Program: Use the java command to run the compiled bytecode.

				
					java HelloWorld

Object-Oriented Concepts in Java

  1. Classes and Objects:
  • Class: A blueprint for objects. It defines properties and behaviors.
  • Object: An instance of a class.
  •  

Example:

				
					class Dog {
    String name;
    int age;

    void bark() {
        System.out.println("Woof!");
    }
}

public class Main {
    public static void main(String[] args) {
        Dog myDog = new Dog();
        myDog.name = "Buddy";
        myDog.age = 3;
        myDog.bark();
    }
}

2. Inheritance: Allows a new class to inherit properties and methods from an existing class.

				
					class Animal {
    void eat() {
        System.out.println("This animal eats.");
    }
}

class Dog extends Animal {
    void bark() {
        System.out.println("Woof!");
    }
}

public class Main {
    public static void main(String[] args) {
        Dog myDog = new Dog();
        myDog.eat();
        myDog.bark();
    }
}

3. Polymorphism: Allows methods to do different things based on the object it is acting upon.

				
					class Animal {
    void makeSound() {
        System.out.println("Some sound");
    }
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Woof!");
    }
}

class Cat extends Animal {
    void makeSound() {
        System.out.println("Meow!");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal myAnimal = new Dog();
        myAnimal.makeSound();  // Outputs "Woof!"

        myAnimal = new Cat();
        myAnimal.makeSound();  // Outputs "Meow!"
    }
}

4. Encapsulation: Restricts direct access to some of an object’s components, which can be accessed through methods.

				
					class Person {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

public class Main {
    public static void main(String[] args) {
        Person person = new Person();
        person.setName("John");
        System.out.println(person.getName());
    }
}

5. Abstraction: Hides the complex implementation details and shows only the essential features of the object.

				
					abstract class Animal {
    abstract void makeSound();

    void sleep() {
        System.out.println("Sleeping...");
    }
}

class Dog extends Animal {
    void makeSound() {
        System.out.println("Woof!");
    }
}

public class Main {
    public static void main(String[] args) {
        Animal myDog = new Dog();
        myDog.makeSound();  // Outputs "Woof!"
        myDog.sleep();      // Outputs "Sleeping..."
    }
}
prime number

Basic Java Syntax

  • Variables: Store data values.
				
					int myNumber = 5;
String myText = "Hello";
  • Data Types: Define the type of data that can be stored.
				
					int num = 10;
float rate = 3.14f;
char grade = 'A';
boolean isValid = true;
  • Operators: Perform operations on variables and values.
				
					int sum = 10 + 5;  // Addition
int diff = 10 - 5; // Subtraction
int product = 10 * 5; // Multiplication
int quotient = 10 / 5; // Division
  • Control Flow Statements: Direct the flow of execution.
  • If-else statement:
				
					if (num > 0) {
    System.out.println("Positive");
} else {
    System.out.println("Negative");
}
  • Switch statement:
				
					switch (grade) {
    case 'A':
        System.out.println("Excellent");
        break;
    case 'B':
        System.out.println("Good");
        break;
    default:
        System.out.println("Needs Improvement");
}
  • Loops: Execute a block of code multiple times.
  • For loop:
				
					for (int i = 0; i < 5; i++) {
    System.out.println(i);
}
  • While loop:
				
					int i = 0;
while (i < 5) {
    System.out.println(i);
    i++;
}
  • Do-while loop:
				
					int i = 0;
do {
    System.out.println(i);
    i++;
} while (i < 5);

Java is a versatile and widely-used programming language that provides a strong foundation for developing a wide range of applications. Its simplicity, portability, and robustness make it an ideal choice for beginners and experienced developers alike. By understanding the basics of Java, including its syntax, object-oriented principles, and core features, you can start building your own Java applications and explore more advanced topics as you progress.

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