“学习“java之单例模式

饿汉式：

public User(){

private static User s=new User();

private User(){

}

public static User getUser()

{

return s;

}

}

懒汉式:

class User{

private static User s=null;

public User(){

if(s==null)

s=new User();

return s;

}

}

同步锁下的懒汉式:

class User{

private static User s=null;

public User(){

public static Single1 getInStanceBlock(){

if(s==null)

synchronized (User.class) {

if(s==null)

s = new User();

}

return s;

}

}