Program: How to fetch values with user define object as keys in Hashtable?

Below example shows how to use user defined objects as keys and fetch values. To do this, you have to implement equals and hashcode methods. In below example we are using Emp object as key, and it has implemented equals, and hashcode methods.

package com.java2novice.hashtable;

import java.util.Hashtable;

public class MyHashtableUserKeys {

	public static void main(String a[]){

		Hashtable<Emp,String> tm = new Hashtable<Emp, String>();
		tm.put(new Emp(134,"Ram",3000), "RAM");
		tm.put(new Emp(235,"John",6000), "JOHN");
		tm.put(new Emp(876,"Crish",2000), "CRISH");
		tm.put(new Emp(512,"Tom",2400), "TOM");
		System.out.println("Fecthing value by creating new key:");
		
		Emp e = new Emp(512,"Tom",2400);
		System.out.println(e+" ==> "+tm.get(e));
	}
}

class Emp{
	
	private String name;
	private int salary;
	private int id;
	
	public Emp(int id, String n, int s){
		this.id = id;
		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 "Id: "+this.id+" -- Name: "+this.name+" -- Salary: "+this.salary;
	}

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

	public int getId() {
		return id;
	}
	
	@Override
	public int hashCode() {
		System.out.println("In hashcode");
		return this.getId();
	}
	
	@Override
	public boolean equals(Object obj) {
		Emp e = null;
		if(obj instanceof Emp){
			e = (Emp) obj;
		}
		System.out.println("In equals");
		if(this.getId() == e.getId()){
			return true;
		} else {
			return false;
		}
		
	}
}

In hashcode
In hashcode
In hashcode
In hashcode
Fecthing value by creating new key:
In hashcode
In equals
Id: 512 -- Name: Tom -- Salary: 2400 ==> TOM