A small introduction to lambdas in Java: MyLambda1 class

MyLambda1.java

package demo.java.lambdas;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class MyLambda1 {

    public static void main(String[] args) {
        List<Person> personList = new ArrayList<>();

        personList.add(new Person("Al", 30));
        personList.add(new Person("Bob", 26));
        personList.add(new Person("Carl", 28));
        personList.add(new Person("Don", 25));
        personList.add(new Person("Ethan", 27));
        personList.add(new Person("Frank", 22));

        List<Person> personList2 = new ArrayList<>();

        personList2.addAll(personList);

        // Using a lambda.
        personList.sort((Person p1, Person p2) ->
                Integer.valueOf(p1.getAge()).compareTo(Integer.valueOf(p2.getAge())));

        // Further reduction, getting rid of types.
        personList.sort((p1, p2) ->
                Integer.valueOf(p1.getAge()).compareTo(Integer.valueOf(p2.getAge())));

        // This can also be used as.
        Comparator<Person> perComparator = (p1,p2)->
                Integer.valueOf(p1.getAge()).compareTo(Integer.valueOf(p2.getAge()));

        personList2.sort(perComparator);

        Comparator<Person> perComparator2 = (p1,p2)-> {
            if (p1.getAge() == p2.getAge())
                return 0;
            return p1.getAge()>p2.getAge()?1:-1;
        };

        System.out.println(personList);
        System.out.println(personList2);
    }
}