详解多线程及Runable 和Thread的区别
Thread和Runnable区别
执行多线程操作可以选择
继承Thread类
实现Runnable接口
1.继承Thread类
以卖票窗口举例,一共5张票,由3个窗口进行售卖(3个线程)。
代码:
package thread; public class ThreadTest { public static void main(String[] args) { MyThreadTest mt1 = new MyThreadTest("窗口1"); MyThreadTest mt2 = new MyThreadTest("窗口2"); MyThreadTest mt3 = new MyThreadTest("窗口3"); mt1.start(); mt2.start(); mt3.start(); } } class MyThreadTest extends Thread{ private int ticket = 5; private String name; public MyThreadTest(String name){ this.name = name; } public void run(){ while(true){ if(ticket < 1){ break; } System.out.println(name + " = " + ticket--); } } }
执行结果:
窗口1 = 5
窗口1 = 4
窗口1 = 3
窗口1 = 2
窗口1 = 1
窗口2 = 5
窗口3 = 5
窗口2 = 4
窗口3 = 4
窗口3 = 3
窗口3 = 2
窗口3 = 1
窗口2 = 3
窗口2 = 2
窗口2 = 1
结果一共卖出了5*3=15张票,这违背了"5张票"的初衷。
造成此现象的原因就是:
MyThreadTest mt1 = new MyThreadTest("窗口1"); MyThreadTest mt2 = new MyThreadTest("窗口2"); MyThreadTest mt3 = new MyThreadTest("窗口3"); mt1.start(); mt2.start(); mt3.start();
一共创建了3个MyThreadTest对象,而这3个对象的资源不是共享的,即各自定义的ticket=5是不会共享的,因此3个线程都执行了5次循环操作。
2.实现Runnable接口
同样的例子,代码:
package thread; public class RunnableTest { public static void main(String[] args) { MyRunnableTest mt = new MyRunnableTest(); Thread mt1 = new Thread(mt,"窗口1"); Thread mt2 = new Thread(mt,"窗口2"); Thread mt3 = new Thread(mt,"窗口3"); mt1.start(); mt2.start(); mt3.start(); } } class MyRunnableTest implements Runnable{ private int ticket = 5; public void run(){ while(true){ if(ticket < 1){ break; } System.out.println(Thread.currentThread().getName() + " = " + ticket--); } } }
结果:
窗口1 = 5
窗口1 = 2
窗口3 = 4
窗口2 = 3
窗口1 = 1
结果卖出了预期的5张票。
原因在于:
MyRunnableTest mt = new MyRunnableTest(); Thread mt1 = new Thread(mt,"窗口1"); Thread mt2 = new Thread(mt,"窗口2"); Thread mt3 = new Thread(mt,"窗口3"); mt1.start(); mt2.start(); mt3.start();
只创建了一个MyRunnableTest对象,而3个Thread线程都以同一个MyRunnableTest来启动,所以他们的资源是共享的。
以上所述是小编给大家介绍的多线程及Runable 和Thread的区别详解整合,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对我们网站的支持!
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