Java 8 : UnaryOperator Functional Interface

UnaryOperator

UnaryOperator is a Function on a single operand that produces a result of the same type as its operand.

It Transforms the input value to a result of same type.
 

UnaryOperator Methods

UnaryOperator extends from Function. So, it inherits the Function interface methods apply(), andThen() and compose().

It also adds a static method identity() that returns a unary operator that always returns its input argument.
 

Example 1 :

package com.topjavatutorial;

import java.util.function.UnaryOperator;

public class TestUnaryOperator {

  public static void main(String[] args) {
    UnaryOperator<String> f1 = str -> str.toUpperCase();
    System.out.println(f1.apply("hello"));
  }

}

Output :

HELLO
 

Example 2 : UnaryOperator using Method Reference

package com.topjavatutorial;

import java.util.function.UnaryOperator;

public class TestUnaryOperator {

  public static void main(String[] args) {
    UnaryOperator<String> f2 = String::toUpperCase;
    System.out.println(f2.apply("hello"));
  }

}

Output :

HELLO
 

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