Logical operators in Java

Introduction

Logical operators help you combine or change true/false values to make decisions in your program.

Checking if two conditions are both true before doing something.

Deciding if at least one condition is true to proceed.

Making sure a condition is not true before continuing.

Combining multiple yes/no questions to control program flow.

Syntax

Java

condition1 && condition2  // AND operator
condition1 || condition2  // OR operator
!condition               // NOT operator

&& means both conditions must be true.

|| means at least one condition must be true.

! reverses true to false, and false to true.

Examples

This checks if age is over 18 and the person has an ID.

Java

if (age > 18 && hasID) {
    System.out.println("Allowed to enter");
}

This checks if it is a weekend or a holiday.

Java

if (isWeekend || isHoliday) {
    System.out.println("No work today");
}

This checks if it is not raining.

Java

if (!isRaining) {
    System.out.println("Go outside");
}

Sample Program

This program uses logical operators to decide if someone can drive, if they can relax today, and if they should go for a walk.

Java

public class LogicalOperatorsDemo {
    public static void main(String[] args) {
        boolean hasLicense = true;
        int age = 20;

        if (age >= 18 && hasLicense) {
            System.out.println("You can drive.");
        } else {
            System.out.println("You cannot drive.");
        }

        boolean isWeekend = false;
        boolean isHoliday = true;

        if (isWeekend || isHoliday) {
            System.out.println("You can relax today.");
        } else {
            System.out.println("You have to work today.");
        }

        boolean isRaining = false;
        if (!isRaining) {
            System.out.println("Let's go for a walk.");
        } else {
            System.out.println("Better stay inside.");
        }
    }
}

Important Notes

Remember that && stops checking if the first condition is false (short-circuit).

Similarly, || stops checking if the first condition is true.

Use parentheses to group conditions clearly when combining multiple logical operators.

Summary

Logical operators combine true/false values to control decisions.

&& means both must be true, || means one or both are true, ! reverses the value.

They help your program make smart choices based on multiple conditions.