java 单例模式

　　3、单例类必须给所有其他对象提供这一实例

方式一、懒汉式单例,线程不安全

public class SingleOne {
	//懒汉式单例,线程不安全
	private static SingleOne single = null;
	private SingleOne(){}//设置成私有防止外键new一个对象
	public static SingleOne getInstance(){
		if(single == null){
			System.out.println("new single");
			single =  new SingleOne();
		}
		return single;
	}

}

public class SingleTwo {
	//饿汉式单例,线程安全
	private static final SingleTwo single = new SingleTwo();
	private SingleTwo(){}
	public static SingleTwo getInstance(){
		System.out.println("new single ");
		return single;
	}
}

java 单例模式

原文：http://blog.csdn.net/zhangpan19910604/article/details/46842489