LogOptional.java

package com.example.demo;

import java.util.Optional;
import java.util.function.Function;
import java.util.function.UnaryOperator;

public class LogOptional {

	public static void main(String[] args) {
		UnaryOperator<?> log = x -> {
		    System.out.println(x);
		    return x;
    		};

		Optional.of("one").map(log);
		Optional.of(5).map(log);

	}
}