How do I use && and || in if statements in Java?

The Problem

I don’t know how to use && (AND) and || (OR) operators in if statements in Java.

The Solution

In Java, we can use the logical AND (&&) and logical OR (||) operators to combine multiple boolean expressions in if statements and evaluate multiple conditions at once.

This answer demonstrates how to:

• Use && to evaluate whether all conditions are true.
• Use || to evaluate whether at least one condition is true.
• Combine && and || to evaluate more complex logical conditions.

Using && (Logical AND)

The && operator is used to execute code only when all the conditions for an entire expression are true.

public class Main {
    public static void main(String[] args) {
        int age = 25;
        boolean hasDrivingLicense = true;

        if (age > 18 && hasDrivingLicense) {
            System.out.println("You are eligible to drive.");
        }
    }
}

In this example, the following message is only printed if both age > 18 and hasDrivingLicense are true:

 You are eligible to drive.

Using || (Logical OR)

The || operator is used to execute code when at least one of the conditions is true for the entire expression.

public class Main {
    public static void main(String[] args) {
        boolean isWeekend = true;
        boolean isHoliday = false;

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

In this example, the following message is printed if either isWeekend or isHoliday is true.

You can relax today.

Combining && and ||

You can also combine the && and || operators in a single if statement to create more complex logical expressions.

public class Main {
    public static void main(String[] args) {
        int age = 17;
        boolean hasParentalConsent = true;

        if (age >= 18 || (age >= 16 && hasParentalConsent)) {
            System.out.println("You are allowed to participate.");
        }
    }
}

In this example, the following message is printed if age >= 18 is true or if both age >= 16 and hasParentalConsent are true.

You are allowed to participate.

Summary

• The && operator is used when all conditions need to be true.
• The || operator is used when at least one condition needs to be true.
• The && and || operators are combined to create more complex logical conditions.

| Condition 1 | Condition 2 | && (AND) Result | || (OR) Result | |-------------|-------------|--------------------|-------------------| | true | true | true | true | | true | false | false | true | | false | true | false | true | | false | false | false | false |

In the truth table above:

• The && operator returns true only if both conditions are true.
• The || operator returns true if at least one condition is true.