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How to use UnaryOperator 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
Updated on: 13-Jul-2020
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