How to use UnaryOperator<T> interface in lambda expression in Java?

UnaryOperator<T> is a functional interface that extends the Function interface. It represents an operation that accepts a parameter and returns a result of the same type as its input parameter. The apply() method from Function interface and default methods: andThen() and compose() are inherited from the UnaryOperator interface. A lambda expression and method reference can use UnaryOperator objects as their target.

Syntax

@FunctionalInterface public interface UnaryOperator<T> extends Function<T, T>

Example-1

import java.util.function.UnaryOperator; public class UnaryOperatorTest1 {    public static void main(String[] args) {       UnaryOperator<Integer> operator = t -> t * 2;   // lambda expression       System.out.println(operator.apply(5));       System.out.println(operator.apply(7));       System.out.println(operator.apply(12));    } }

Output

10 14 24

Example-2

import java.util.function.UnaryOperator; public class UnaryOperatorTest2 {    public static void main(String[] args) {       UnaryOperator<Integer> operator1 = t -> t + 5;       UnaryOperator<Integer> operator2 = t -> t * 5;       // Using andThen() method       int a = operator1.andThen(operator2).apply(5);       System.out.println(a);       // Using compose() method       int b = operator1.compose(operator2).apply(5);       System.out.println(b);    } }

Output

50 30