The if Statement · Java Conditions in Java | Java

The if Statement

Syntax

The if statement runs a block of code only when a condition is true.

if (condition) {
    // runs when condition is true
}

Example

public class Main {
    public static void main(String[] args) {
        int temperature = 38;
        if (temperature > 35) {
            System.out.println("It is very hot today. Stay hydrated!");
        }
        int balance = 200;
        if (balance < 500) {
            System.out.println("Low balance alert");
        }
        System.out.println("Program finished");
    }
}

Output

It is very hot today. Stay hydrated!
Low balance alert
Program finished

Note: If the block has a single statement you may leave out the braces, but always using { } avoids bugs when someone adds a second line later.

Common Mistake

int x = 5;
if (x = 10) { }      // compile error: int cannot be converted to boolean
if (x == 10) { }     // correct: comparison
if (x > 3); {        // the ; ends the if! the block always runs
    System.out.println("always printed");
}