if/else Statements

Syntax

java
if (condition) {
    // executes when condition is true
} else if (anotherCondition) {
    // executes when anotherCondition is true
} else {
    // executes when all conditions are false
}

The condition must be a boolean expression — Java does not allow numeric values as conditions (unlike C/C++).

Single-statement Body

Braces are optional when the body is a single statement:

java
if (score >= 60)
    System.out.println("Pass");
else
    System.out.println("Fail");

Exam tip: Always trace which else belongs to which if. An else matches the nearest preceding unmatched if.

Dangling else

java
int x = 1;
if (x > 0)
    if (x > 5)
        System.out.println("big");
    else
        System.out.println("small");  // belongs to (x > 5), not (x > 0)

Ternary Operator

A condensed if/else that produces a value:

java
String result = (score >= 60) ? "Pass" : "Fail";

Both branches must be compatible types. The ternary is an expression, not a statement — it cannot stand alone without being assigned or used.

switch as an Alternative

When testing a single variable against many constant values, switch is often clearer than chained if/else if. See lesson 2-2 for details.

Key Rules

Quick Example

java
int temperature = 72;

if (temperature < 32) {
    System.out.println("Freezing");
} else if (temperature < 60) {
    System.out.println("Cold");
} else if (temperature < 80) {
    System.out.println("Comfortable");
} else {
    System.out.println("Hot");
}
// Output: Comfortable