Java Programming Basics

Overview

Java is a popular, high-level programming language known for its portability, performance, and robust nature. This README provides a comprehensive guide to the basics of Java programming, including input/output statements and fundamental syntax.

Table of Contents

1. Introduction
2. Basic Syntax
   • Hello World Program
   • Comments
3. Data Types and Variables
4. Input/Output Statements
   • Output Statements
   • Input Statements
5. Control Flow Statements
6. Example Programs
7. Further Reading and Resources
8. Contact Information

Introduction

Java is a versatile and widely-used programming language that follows the object-oriented programming paradigm. It is designed to be platform-independent, allowing code to run on any machine equipped with the Java Virtual Machine (JVM).

Basic Syntax

Hello World Program

The simplest Java program is the "Hello World" program. This program prints "Hello, World!" to the console.

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Comments

Comments are used to explain code and are ignored by the compiler.

• Single-line comments start with //.

// This is a single-line comment

• Multi-line comments are enclosed within /* and */.

/*
 This is a multi-line comment.
 It can span multiple lines.
*/

Data Types and Variables

Java supports various data types, which are categorized into two groups: primitive and reference types.

Primitive Data Types

• int: integer
• float: floating-point number
• double: double-precision floating-point number
• char: single character
• boolean: true or false
• byte, short, long: other integer types

Variables

Variables are used to store data. Here's how to declare and initialize variables:

int number = 5;
float decimal = 3.14f;
char letter = 'A';
boolean flag = true;

Input/Output Statements

Output Statements

To display output to the console, use System.out.print() and System.out.println().

• System.out.print(): Prints text without a newline at the end.

System.out.print("Hello, ");
System.out.print("World!");

• System.out.println(): Prints text with a newline at the end.

System.out.println("Hello, World!");

Input Statements

To take input from the user, use the Scanner class from the java.util package.

1. Import the Scanner class:

import java.util.Scanner;

2. Create a Scanner object:

Scanner scanner = new Scanner(System.in);

3. Use the Scanner methods to read input:

System.out.print("Enter your name: ");
String name = scanner.nextLine();

System.out.print("Enter your age: ");
int age = scanner.nextInt();

Control Flow Statements

Java provides several control flow statements for decision making, looping, and branching.

If-Else Statement

if (age >= 18) {
    System.out.println("You are an adult.");
} else {
    System.out.println("You are a minor.");
}

Switch Statement

int day = 2;
switch (day) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    default:
        System.out.println("Other day");
        break;
}

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++;
}

Example Programs

Program to Add Two Numbers

import java.util.Scanner;

public class AddTwoNumbers {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter first number: ");
        int num1 = scanner.nextInt();

        System.out.print("Enter second number: ");
        int num2 = scanner.nextInt();

        int sum = num1 + num2;
        System.out.println("The sum is: " + sum);
    }
}

Program to Check Even or Odd

import java.util.Scanner;

public class EvenOdd {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter a number: ");
        int num = scanner.nextInt();

        if (num % 2 == 0) {
            System.out.println(num + " is even.");
        } else {
            System.out.println(num + " is odd.");
        }
    }
}

Further Reading and Resources

• Java Documentation
• Oracle Java Tutorials
• GeeksforGeeks Java Tutorials

Contact Information

For questions or support, please contact:

• Email: atharvkote3@gmail.com