面向对象(下)-复习：单例模式

2022-10-12 22:55

324

58 字

3 分钟

package top.qaqaq.java.P340;

public class SingletonTest {

	public static void main(String[] args) {
		
		Bank bank1 = Bank.instance;
		
//		Bank.instance = null;
		Bank bank2 = Bank.instance;
		
		
		System.out.println(bank1 == bank2);
	}
}

class Bank{

	private Bank() {
		
	}
	
	public static final Bank instance = new Bank();
}

package top.qaqaq.java.P340;
/*
 * 饿汉式单例模式写法二：使用了静态代码块
 * 
 */
public class SingletonTest1 {

	public static void main(String[] args) {
		
	}
}

class Order{
	
	//1. 私有化类的构造器
	private Order() {
		
	}
	
	//2. 声明当前类对象，没有初始化
	//4. 此对象也必须声明为static的
	private static Order instance = null;
	
	static {
		instance = new Order();
	}
	
	//3. 声明public、static的返回当前类对象的方法
	public static Order getInstance() {
		return instance;
	}
}

Java