线程安全的单例懒汉式
package com.day0206_2;
/**
* 使用同步机制将单例模式中的懒汉式改写成线程安全的
*
*/
public class BankTest {
}
class Bank{
private Bank(){
}
private static Bank instance =null;
public static Bank getInstance(){//synchronized
//方式一：效率稍差
// synchronized(Bank.class) {
// if (instance == null) {
// instance = new Bank();
// }
//
// return instance;
// }
//方式二：效率更高
if (instance==null) {
synchronized (Bank.class) {
if (instance == null) {
instance = new Bank();
}
}
}
return instance;
}
}
