Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.Comparator;
import java.util.SortedSet;
import java.util.TreeSet;

public class Main {
    public static void main(String[] args) {
        SortedSet<Person> personsById = new TreeSet<>(Comparator.comparing(Person::getId));

        personsById.add(new Person(1, "X"));
        personsById.add(new Person(2, "Z"));
        personsById.add(new Person(3, "A"));
        personsById.add(new Person(4, "C"));
        personsById.add(new Person(4, "S")); // A duplicate Person

        System.out.println("Persons by  Id:");
        personsById.forEach(System.out::println);

        SortedSet<Person> personsByName = new TreeSet<>(Comparator.comparing(Person::getName));
        personsByName.add(new Person(1, "X"));
        personsByName.add(new Person(2, "Z"));
        personsByName.add(new Person(3, "A"));
        personsByName.add(new Person(4, "C"));

        System.out.println("Persons by  Name: ");
        personsByName.forEach(System.out::println);

    }

}

class Person {
    private int id;
    private String name;

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

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof Person)) {
            return false;
        }

        // id must be the same for two Persons to be equal
        Person p = (Person) o;
        if (this.id == p.getId()) {
            return true;
        }

        return false;
    }

    @Override
    public int hashCode() {
        return this.id;
    }

    @Override
    public String toString() {
        return "(" + id + ", " + name + ")";
    }
}