if, else if, else

The if statement executes a block of code only if a condition is true. Optionally, else and else if provide alternative paths.

Syntax:

if (condition) {
    // executes if condition is true
} else if (anotherCondition) {
    // executes if first condition false and anotherCondition true
} else {
    // executes if all previous conditions false
}

Examples:

int score = 85;

if (score >= 90) {
    System.out.println("Grade: A");
} else if (score >= 80) {
    System.out.println("Grade: B");
} else if (score >= 70) {
    System.out.println("Grade: C");
} else {
    System.out.println("Grade: F");
}

Without braces (allowed for single statement, but not recommended):

if (x > 0)
    System.out.println("Positive");

Important: Conditions must be boolean expressions.

int x = 5;
// if (x) { ... } // error: int cannot be converted to boolean
if (x != 0) { ... } // correct