该段代码来源于:http://www.cnblogs.com/GarfieldEr007/p/5746362.html
package com.multithread.wait;
public class MyThreadPrinter2 implements Runnable {
private String name;
private Object prev;
private Object self;
private MyThreadPrinter2(String name, Object prev, Object self) {
this.name = name;
this.prev = prev;
this.self = self;
}
@Override
public void run() {
int count = 10;
while (count > 0) {
synchronized (prev) {
synchronized (self) {
System.out.print(name);
count--;
self.notify();
}
try {
prev.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
public static void main(String[] args) throws Exception {
Object a = new Object();
Object b = new Object();
Object c = new Object();
MyThreadPrinter2 pa = new MyThreadPrinter2("A", c, a);
MyThreadPrinter2 pb = new MyThreadPrinter2("B", a, b);
MyThreadPrinter2 pc = new MyThreadPrinter2("C", b, c);
new Thread(pa).start();
Thread.sleep(100); //确保按顺序A、B、C执行
new Thread(pb).start();
Thread.sleep(100);
new Thread(pc).start();
Thread.sleep(100);
}
} 问题:
1.究竟synchronized (){} 修饰代码块时,()里边究竟是什么东西, 应该怎么理解?
2.这个程序的 self.notify(); 和 prev.wait(); 究竟起了什么作用, 应该怎么理解?
小弟初学Java多线程, 在网上看了很多资料, 就是没能理解这个锁到底是怎么运行的, 什么机制, 最好能举个生活中的例子辅助理解一下。越通俗越好!!
谢谢各位大神了!!
package com.multithread.wait;
public class MyThreadPrinter2 implements Runnable {
private String name;
private Object prev;
private Object self;
private MyThreadPrinter2(String name, Object prev, Object self) {
this.name = name;
this.prev = prev;
this.self = self;
}
@Override
public void run() {
int count = 10;
while (count > 0) {
synchronized (prev) {
synchronized (self) {
System.out.print(name);
count--;
self.notify();
}
try {
prev.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
public static void main(String[] args) throws Exception {
Object a = new Object();
Object b = new Object();
Object c = new Object();
MyThreadPrinter2 pa = new MyThreadPrinter2("A", c, a);
MyThreadPrinter2 pb = new MyThreadPrinter2("B", a, b);
MyThreadPrinter2 pc = new MyThreadPrinter2("C", b, c);
new Thread(pa).start();
Thread.sleep(100); //确保按顺序A、B、C执行
new Thread(pb).start();
Thread.sleep(100);
new Thread(pc).start();
Thread.sleep(100);
}
} 问题:
1.究竟synchronized (){} 修饰代码块时,()里边究竟是什么东西, 应该怎么理解?
2.这个程序的 self.notify(); 和 prev.wait(); 究竟起了什么作用, 应该怎么理解?
小弟初学Java多线程, 在网上看了很多资料, 就是没能理解这个锁到底是怎么运行的, 什么机制, 最好能举个生活中的例子辅助理解一下。越通俗越好!!
谢谢各位大神了!!
2.self.notify(); 和 prev.wait(); 一个唤醒线程,一个使线程等待
3.锁机制类似于火车上的卫生间,一旦有人携带卫生间门上的锁进入卫生间里,别的线程只能在门外干等,然后反复确认锁是否被释放,如果释放了,别的线程才可以携带锁再次进入卫生间中
这样做,就能确保只有一个线程在上厕所,就不会出现多线程掠夺资源产生的线程安全问题了!