chermehdi

public final class MyImmutableObject {

	/**
	 * Both String and Integer Classes Are Immutable
	 */
	private final String ObjectName;

	private final Integer ObjectId;

chermehdi

public class SimpleSingleton {

	// this will hold the instance of the class
	private static SimpleSingleton instance = new SimpleSingleton();

	// this will be our constructor it's empty for no reason you can put
	// anything necessary to instantiate your class
	private SimpleSingleton() {}

	//this is the static method to return the instance of the class 	

chermehdi

public class SimpleSingleton {

	// this will hold the instance of the class
	private static SimpleSingleton instance;

	// this will be our constructor it's empty for no reason you can put
	// anything necessary to instantiate your class
	private SimpleSingleton() {}

	//this is the static method to return the instance of the class 	

chermehdi

public class SimpleSingleton {

	// this will hold the instance of the class
	private static SimpleSingleton instance;
	
	//static block invocation is done first 
	static{
		try{
			instance = new SimpleSingleton();
		}catch(Exception e){

chermehdi

import java.io.Serializable;

public class SimpleSingleton implements Serializable {
	
	private static long serialVersionUID = 1L;

	// this will hold the instance of the class
	private static SimpleSingleton instance = new SimpleSingleton();

	// this will be our constructor it's empty for no reason you can put

chermehdi

public enum EnemyType {
	BIGENEMY,
	SMALLENEMY,
	SMARTENEMY
}

chermehdi

public abstract class Enemy {
	private EnemyType enemyType;

	public Enemy(EnemyType enemyType) {
		this.enemyType = enemyType;
	}

	// this is for subclasses to implement
	protected abstract void construct();

chermehdi

public class SmartEnemy extends Enemy {

	public SmartEnemy() {
		super(EnemyType.SMARTENEMY);
		construct();
	}

	// you can do all kinds of stuff here i'm
	// just keeping it simple and only printing a message to the console

chermehdi

public class SmallEnemy extends Enemy {

	public SmallEnemy() {
		super(EnemyType.SMALLENEMY);
		construct();
	}

	@Override
	protected void construct() {

chermehdi

public class EnemyFactory {

	public static Enemy create(EnemyType enemyType) {

		Enemy enemy = null;
		
		switch (enemyType) {

		case SMALLENEMY: