单例模式

/**
 * 饿汉，直接new对象
 */
class SingleEHan{
    private  static final SingleEHan s = new SingleEHan();

    private SingleEHan(){

    }

    public static  SingleEHan getInstance(){
        return s;
    }
}

/**
 * 懒汉式双重判断单例模式
 * 特点：延迟加载
 */
public class Single {
    private static Single s = null;

    private Single() {

    }

    public static Single getInstance() {
        if (s == null) {

            synchronized (Single.class) {
                if (s == null) {
                    return s = new Single();
                }
            }
        }
        return s;
    }


}