Unit 2.5: Compound Boolean Expressions

Logical Operators

Logical operators combine boolean expressions.

Compound Logic

Logical operators allow you to create complex conditions by joining multiple Boolean expressions. They evaluate to a single true or false result.

Operator	Name	Description
`!`	NOT	Inverts the value (`!true` is `false`).
`&&`	AND	True only if both operands are true.
`\|\|`	OR	True if at least one operand is true.

Truth Tables

A	B	`!A`	`A && B`	`A \|\| B`
`true`	`true`	`false`	`true`	`true`
`true`	`false`	`false`	`false`	`true`
`false`	`true`	`true`	`false`	`true`
`false`	`false`	`true`	`false`	`false`

Short-Circuit Evaluation

AND (&&): If the first operand is false, the result is false immediately. The second operand is not evaluated.
OR (||): If the first operand is true, the result is true immediately. The second operand is not evaluated.

Examples

Using Logical Operators

Task: Applying compound boolean logic and short-circuit protection.

public class LogicExample {
    public static void main(String[] args) {
        int age = 15;

    boolean hasLicense = false;
    
    // AND example
    if (age >= 16 && hasLicense) {
        System.out.println("Can drive");
    } else {
        System.out.println("Cannot drive");
    }
    
    // OR example
    boolean hasCash = false;
    boolean hasCredit = true;
    if (hasCash || hasCredit) {
        System.out.println("Can pay");
    }
    
    // Short-circuit protection against divide by zero
    int count = 0;
    int total = 100;
    
    // If count is 0, the second part (total / count) is skipped
    if (count != 0 && (total / count > 10)) {
        System.out.println("Valid average");
    } else {
        System.out.println("Cannot calculate");
    }
}

}