创建型（单例模式）

package com.lwf.create.singleton;

public class Singleton {
	private Singleton(){}
	private static Singleton st = new Singleton();
	public static Singleton getInstance(){
		return st;
	}
	public static void main(String[] args) {
		
	}
}

class LazySingleton{
	private LazySingleton(){}
	private static LazySingleton st = null;
	public static synchronized LazySingleton getInstance(){
		if(st == null)
			st =  new LazySingleton();
		return st;
	}
}
class Test{
	public static void main(String[] args) {
		Singleton st = Singleton.getInstance();
		LazySingleton lzSt = LazySingleton.getInstance();
	}
}