Program: How to get least value element from a set?

To get least value element of user design objects, we need to implement sorting logic on TreeSet. To implement your own sorting functionality with TreeSet on user defined objects, you have to pass Comparator object along with TreeSet constructor call. The Comparator implementation holds the sorting logic. You have to override compare() method to provide the sorting logic on user defined objects. Now you can get least value element from set by using first() method depending on your sorting logic.

package com.java2novice.treeset;

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

public class MyLeastElementInSet {

	public static void main(String a[]){
		
		TreeSet<Empl1> salComp = new TreeSet<Empl1>(new MySalCompr());
		salComp.add(new Empl1("Ram",3000));
		salComp.add(new Empl1("John",6000));
		salComp.add(new Empl1("Crish",2000));
		salComp.add(new Empl1("Tom",2400));
		System.out.println("Least salary emp: "+salComp.first());
	}
}

class MySalCompr implements Comparator<Empl1>{

	@Override
	public int compare(Empl1 e1, Empl1 e2) {
		if(e1.getSalary() > e2.getSalary()){
			return 1;
		} else {
			return -1;
		}
	}
}

class Empl1{
	
	private String name;
	private int salary;
	
	public Empl1(String n, int s){
		this.name = n;
		this.salary = s;
	}
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
	public String toString(){
		return "Name: "+this.name+"-- Salary: "+this.salary;
	}
}

Least salary emp: Name: Crish-- Salary: 2000