Conditionals

if / else if / else run a block of code only when a condition is true.

Syntax

if (age >= 18) {
    System.out.println("Adult");
} else if (age >= 13) {
    System.out.println("Teenager");
} else {
    System.out.println("Child");
}

Example

int temperature = 15;
if (temperature > 30) {
    System.out.println("Hot");
} else if (temperature > 15) {
    System.out.println("Mild");
} else {
    System.out.println("Cold");
}

Expected output

Cold

Common mistakes

• Using = (assignment) instead of == (comparison) — unlike some languages, this is actually a compile error in Java when the condition isn't a boolean, so it's caught early rather than silently doing the wrong thing.

Practice

Write a condition that prints "Pass" if a score is 50 or above, otherwise "Fail".

int score = 42;
if (score >= 50) {
    System.out.println("Pass");
} else {
    System.out.println("Fail");
}