剑指offer 2. 实现Singleton模式

// 题目：单例模式
// 解法1：饿汉单例模式（线程不安全）
public class Main {

	private static final Main instance = new Main();
	
	private Main(){}
	
	public static Main getInstance(){
		return instance;
	}

}

//解法2：懒汉单例模式（线程安全）
public class Main{
	private static Main instance = null;
	
	private Main(){}
	
	public synchronized static Main getInstace(){
		if(instance == null){
			instance = new Main();
		}
		return instance;
	}
}