Java并发编程

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public class Deadlock extends Object {
private String objID;

public Deadlock(String id) {
objID = id;
}

public synchronized void checkOther(Deadlock other) {
print("entering checkOther()");
try { Thread.sleep(2000); }
catch ( InterruptedException x ) { }
print("in checkOther() - about to " + "invoke 'other.action()'");

//调用other对象的action方法，由于该方法是同步方法，因此会试图获得other对象的对象锁
other.action();
print("leaving checkOther()");
}

public synchronized void action() {
print("entering action()");
try { Thread.sleep(500); }
catch ( InterruptedException x ) { }
print("leaving action()");
}

public void print(String msg) {
threadPrint("objID=" + objID + " - " + msg);
}

public static void threadPrint(String msg) {
String threadName = Thread.currentThread().getName();
System.out.println(threadName + ": " + msg);
}

public static void main(String[] args) {
final Deadlock obj1 = new Deadlock("obj1");
final Deadlock obj2 = new Deadlock("obj2");

Runnable runA = new Runnable() {
public void run() {
obj1.checkOther(obj2);
}
};

Thread threadA = new Thread(runA, "threadA");
threadA.start();

try { Thread.sleep(200); }
catch ( InterruptedException x ) { }

Runnable runB = new Runnable() {
public void run() {
obj2.checkOther(obj1);
}
};

Thread threadB = new Thread(runB, "threadB");
threadB.start();

try { Thread.sleep(5000); }
catch ( InterruptedException x ) { }

threadPrint("finished sleeping");

threadPrint("about to interrupt() threadA");
threadA.interrupt();

try { Thread.sleep(1000); }
catch ( InterruptedException x ) { }

threadPrint("about to interrupt() threadB");
threadB.interrupt();

try { Thread.sleep(1000); }
catch ( InterruptedException x ) { }

threadPrint("did that break the deadlock?");
}
}