Java 8 Lambda Void argument becomes mandatory even if you don’t want to pass it. In this post, we will look at how to remove it using a helper method in the interface.

interface MyInterface {
        U action(T t);

        public static MyInterface helperMethod(Runnable runnable) {
                runnable.run();
                return null;
        }
}

Let’s see how to call the action method with Void argument v.

public class CallLambda {

        public static void main(String[] args) {
                MyInterface a = (Void v) -> {
                        System.out.println("Call With Void argument!!!");
                        return null;
                };
        }

}

How to remove the Void argument while using Lambda?

We can easily do this with the helperMethod(). Let’s see how to use it.

public class CallLambda {
        public static void main(String[] args) {
                MyInterface action = MyInterface
                                .helperMethod(() -> System.out.println("Call without Void Argument"));
        }
}

Output:

Call without Void Argument

In short, we can use the Runnable interface to remove the Void argument.