Java if Keyword

The if keyword in Java is used to create a conditional statement that executes a block of code only if a specified condition is true. It helps in making decisions in the code based on certain conditions.

Table of Contents

1. Introduction
2. if Keyword Syntax
3. Understanding if
4. Examples
   • Basic Usage
   • Using if-else
   • Using if-else if-else
5. Real-World Use Case
6. Conclusion

Introduction

The if keyword allows the program to make decisions and execute different blocks of code based on whether a condition is true or false. This helps in controlling the flow of the program.

if Keyword Syntax

The syntax for the if statement is as follows:

if (condition) {
    // code to be executed if the condition is true
}

Example:

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

Understanding if

The if statement evaluates a condition inside parentheses. If the condition is true, the block of code inside the curly braces {} is executed. If the condition is false, the code inside the curly braces is skipped.

Key Points:

• The condition must be a boolean expression (returns true or false).
• Curly braces {} can be omitted if there is only one statement to execute.

Examples

Basic Usage

To demonstrate the basic usage of the if keyword, we will check if a number is positive.

Example

public class IfExample {
    public static void main(String[] args) {
        int number = 10;

        if (number > 0) {
            System.out.println("The number is positive.");
        }
    }
}

Output:

The number is positive.

Using if-else

The if-else statement is used to execute one block of code if the condition is true and another block of code if the condition is false.

Example

public class IfElseExample {
    public static void main(String[] args) {
        int number = -5;

        if (number > 0) {
            System.out.println("The number is positive.");
        } else {
            System.out.println("The number is not positive.");
        }
    }
}

Output:

The number is not positive.

Using if-else if-else

The if-else if-else statement is used to check multiple conditions. It executes different blocks of code based on which condition is true.

Example

public class IfElseIfExample {
    public static void main(String[] args) {
        int number = 0;

        if (number > 0) {
            System.out.println("The number is positive.");
        } else if (number < 0) {
            System.out.println("The number is negative.");
        } else {
            System.out.println("The number is zero.");
        }
    }
}

Output:

The number is zero.

Real-World Use Case

Checking User Age

In real-world applications, the if statement can be used to check user inputs, such as determining if a user is eligible to vote.

Example

public class VotingEligibility {
    public static void main(String[] args) {
        int age = 20;

        if (age >= 18) {
            System.out.println("You are eligible to vote.");
        } else {
            System.out.println("You are not eligible to vote.");
        }
    }
}

Output:

You are eligible to vote.

Conclusion

The if keyword in Java is a fundamental part of controlling the flow of a program. It allows you to execute certain blocks of code based on whether a condition is true or false. By understanding and using the if keyword, you can make your Java programs more dynamic and responsive to different conditions.