Java void Keyword
Usage and Examples

void Keyword in Java

In Java, the void keyword is used to indicate that a method does not return any value. It's a fundamental part of method declarations, especially when you want a method to perform an action (like printing, updating, or processing something) but not send a result back to the caller.

Why Do We Use void in Java?

Think of void as your way of saying: "Hey, this method is going to do something, but you don’t need to expect a result from it." It's a design choice that keeps your code clean, organized, and intention-driven.

Syntax of a void Method

accessModifier void methodName() {
    // method body
}

Example 1: A Simple void Method

public class HelloWorld {
    public static void greet() {
        System.out.println("Hello, world!");
    }

    public static void main(String[] args) {
        greet();  // Calling the method
    }
}

Hello, world!

Here, the method greet() does not return anything. It simply performs an action — printing a message.

Example 2: void Method with Parameters

public class MathUtils {
    public static void printSum(int a, int b) {
        System.out.println("Sum: " + (a + b));
    }

    public static void main(String[] args) {
        printSum(5, 7);
    }
}

Sum: 12

This method accepts parameters and performs a calculation, but since it’s declared with void, it doesn’t return the result — it just prints it.

Can a void Method Use return?

Yes, but with a twist. In a void method, you can use the return; statement only to exit early — not to return a value.

public class ConditionalReturn {
    public static void checkAge(int age) {
        if (age < 18) {
            System.out.println("You are underage.");
            return;
        }
        System.out.println("You are eligible.");
    }

    public static void main(String[] args) {
        checkAge(15);
        checkAge(21);
    }
}

You are underage.
You are eligible.

Notice how return; exits the method early without returning any data. This is useful for breaking out of the method under specific conditions.

What Happens If You Try to Return a Value in a void Method?

Java won’t allow it. You’ll get a compile-time error like this:

public static void brokenMethod() {
    return 42;  // ERROR! Can't return a value from a void method.
}

Error Message

error: incompatible types: unexpected return value

void vs return Type Comparison

Aspect	void Method	Method with Return Type
Returns a value?	No	Yes
Used for actions like printing/logging?	Yes	Sometimes, but usually for computations
Can use return;?	Yes (without value)	Yes (with value)
Example	void show()	int add(int a, int b)

Best Practices for Using void

• Use void when your method performs an operation but doesn't need to pass data back.
• Avoid making methods void if you’re relying on their output for further processing.
• Keep void methods focused on side effects like printing, logging, or updating UI or state.