Javapackage coderr.kerwin.codetest.test;
public class Test {
public static void main(String[] args) throws InterruptedException {
TempObject obj1 = new TempObject(1,5);
TempObject obj2 = new TempObject(2,5);
TempObject obj3 = new TempObject(3,5);
new Thread(new SelfRunnable3(obj3, obj1)).start();
Thread.sleep(100);
new Thread(new SelfRunnable3(obj1, obj2)).start();
Thread.sleep(100);
new Thread(new SelfRunnable3(obj2, obj3)).start();
Thread.sleep(100);
}
static class SelfRunnable3 implements Runnable {
private TempObject prev;
private TempObject self;
private static int num = 1;
public SelfRunnable3(TempObject prev, TempObject self) {
this.prev = prev;
this.self = self;
}
@Override
public void run() {
while (num <= 75) {
System.out.println("p:"+prev.getId()+";s:"+self.getId()+";p-"+num);
synchronized (prev) {
System.out.println("p:"+prev.getId()+";s:"+self.getId()+";s-"+num);
synchronized (self) {
self.notify();
self.print(num);
num+=self.getCount();
}
try {
prev.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
static class TempObject {
private int id;
private int count;
public TempObject(int id, int count) {
super();
this.id = id;
this.count = count;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public synchronized void print(int num) {
for (int i = 0; i < count; i++) {
System.out.println("Thread " + id + ":" + num++);
}
}
}
}
一道面试题、同时开启三个线程A/B/C，A线程打印1,2,3,4,5;B线程打印6,7,8,9,10;C线程打印11,12,13,14,15;然后A线程继续打印16,17,18,19,20。。。。最后直到线程C打印71,72,73,74,75程序结束。。。如上代码已经实现了本题所要的效果、但是为什么最终程序打印到75后并没有结束、貌似出现了死锁。请问问题在哪里呢？求大神指教！！！！我调试看了下、貌似只有线程A顺利结束了。线程B和线程C并没有结束。
引用来自“铂金渣男”的评论
这个程序同一时间只有一个在执行，另两个在等待。所以在最后的阶段，C线程执行的时候 A,B都在等待，C执行notify的时候会唤醒A的等待，因此，A会执行，但是这个时候C已经把num赋值成了75，A执行 num <=75的时候不满足，因此A线程整个结束了。C执行完了会执行obj2.wait();而obj2的唤醒需要B线程执行obj2.notify()。B线程现在一直在等待，需要A线程执行obj1.notify()才会继续执行，但是A已经结束了，因此B无限等待，C无限等待public void run() { while (num <= 75) { System.out.println("p:"+prev.getId()+";s:"+self.getId()+";p-"+num); synchronized (prev) { System.out.println("p:"+prev.getId()+";s:"+self.getId()+";s-"+num); synchronized (self) { self.notify(); self.print(num); num+=self.getCount(); } try { prev.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } synchronized(self){ self.notify(); } }http://blog.csdn.net/zyplus/article/details/6672775
楼主可以去看看这个
public class T { public static void main(String[] args) throws InterruptedException { TempObject obj1 = new TempObject(1,5); TempObject obj2 = new TempObject(2,5); TempObject obj3 = new TempObject(3,5); new Thread(new SelfRunnable3(obj1, obj2)).start(); Thread.sleep(100); new Thread(new SelfRunnable3(obj2, obj3)).start(); Thread.sleep(100); new Thread(new SelfRunnable3(obj3, obj1)).start(); Thread.sleep(100); } static class SelfRunnable3 implements Runnable { private TempObject self;//当前 private TempObject successor;//后继 private static int num = 1; public SelfRunnable3(TempObject self,TempObject successor) { this.successor = successor; this.self = self; } @Override public void run() { while (num <= 75) { System.out.println("当前:"+self.getId()+"-----------------------"+"后继:"+successor.getId()); synchronized (self) { self.print(num); num += self.getCount(); synchronized (successor) { successor.notify(); } try { self.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } synchronized (successor) { successor.notify(); } } } static class TempObject { private int id; private int count; public TempObject(int id, int count) { super(); this.id = id; this.count = count; } public int getId() { return id; } public void setId(int id) { this.id = id; } public int getCount() { return count; } public void setCount(int count) { this.count = count; } public synchronized void print(int num) { for (int i = 0; i < count; i++) { System.out.println("Thread " + id + ":" + num++); } } } }