Function Object in Java

Question

I wanna implement a javascript like method in java , is this possible ?

Say , I have a Person class :

public class Person {
 private String name ;
 priva         


        

Answer 1

import java.util.Arrays;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

public class FuntionAsParameter {


    public static void main(final String[] args) {

        Person p1 = new Person("Jenny", 20);
        Person p2 = new Person("Kate", 22);

        List pList = Arrays.asList(new Person[]{p1, p2});

        Function, List> theFunction = Function.>identity()
            .andThen(personList -> personList
                .stream()
                .map(person -> new Person(person.getName(), person.getAge() + 1))
                .collect(Collectors.toList()));

        // You can use this directly
        List directly = theFunction.apply(pList);
        directly.forEach(person -> System.out.println(person));

        // Or use it as an input parameter
        List toMethod = modList(pList, theFunction);
        toMethod.forEach(person -> System.out.println(person));

        // Or you might prefer this way
        List thirdWay = modList(pList,
                (list) -> list.stream()
                        .map(person -> new Person(person.getName(), person.getAge() + 1))
                        .collect(Collectors.toList())
        );
        thirdWay.forEach(person -> System.out.println(person));
    }

    private static List modList(List personList, Function, List> theFunction) {
        return theFunction.apply(personList);
    }


}

class Person {

    private String name;
    private int age;

    public Person(final String name, final int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public String toString() {
        return "Person{" +
            "name='" + name + '\'' +
            ", age=" + age +
            '}';
    }
}