TreeSet with custom comparable.

 Using comparable to set the order of Objects in TreeSet
 * Here we are creating a class Contact and each object of this class will represent contact of a person.
 * In TreesetDemo1 class, we will create multiple objects of this class with different values of variables.
 * After creating objects, we will add them to TreeSet and test their order.
 *
 * Here we are implementing Com parable interface to the class that will provide object to be placed into ordered way into TreeSet.
* It has only single method compareTo(OtherObject obj) that will return int value.
* The Object that implements Comparable interface properly, is placed into ordered way automatically.


package collection.demos;

import java.util.TreeSet;



class Contact implements Comparable<Contact>{

    String name;

    String email;

    long phone;



    public Contact(String name, String email, long phone) {

        this.name = name;

        this.email = email;

        this.phone = phone;

    }

    public String toString() {

        return name+"\t"+email+"\t"+phone;

    }



    public int compareTo(Contact o) {

        int diff=name.compareTo(o.name);

        return diff;

    }



}

public class TreeSetDemo2 {

    public static void main(String[] args) {

        TreeSet<Contact> contacts=new TreeSet<Contact>();

        Contact c1=new Contact("zyan","zyan@gmail.com",123467);

        Contact c2=new Contact("corb","cord@gmail.com",534544);

        Contact c3=new Contact("gogle","gogle@gmail.com",33444);

        Contact c4=new Contact("sraf","straf@gmail.com",255346);

        contacts.add(c1);

        contacts.add(c2);

        contacts.add(c3);

        contacts.add(c4);

        for (Contact c : contacts) {

            System.out.println(c);

        }

    }

}

/*

OUTPUT

corb        cord@gmail.com        534544

gogle        gogle@gmail.com        33444

sraf        straf@gmail.com        255346

zyan        zyan@gmail.com        123467

 */