[英]Run Thread 2 threads with wait and notify
我是Java多线程编程的新手。 在这里,我想通过运行线程1 wait()notift()然后运行线程2 wait()notify()来运行两个线程。
有人可以帮助我实现下面给出的预期输出
码
class RunnableDemo implements Runnable {
private Thread t;
private String threadName;
RunnableDemo( String name) {
threadName = name;
System.out.println("Creating " + threadName );
}
public void run() {
System.out.println("Running " + threadName );
synchronized (t){
try {
for(int i = 1; i < = 5; i--) {
System.out.println("Thread: " + threadName + ", " + i);
wait();
notify();
}
}catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start () {
System.out.println("Starting " + threadName );
if (t == null) {
t = new Thread (this, threadName);
t.start ();
}
}
}
public class TestThread {
public static void main(String args[]) {
RunnableDemo R1 = new RunnableDemo( "Thread-1");
R1.start();
RunnableDemo R2 = new RunnableDemo( "Thread-2");
R2.start();
}
}
预期输出为
Creating Thread-1
Starting Thread-1
Creating Thread-2
Starting Thread-2
Running Thread-1
Thread: Thread-1, 1
Running Thread-2
Thread: Thread-2, 1
............
Running Thread-1
Thread: Thread-1, 5
Running Thread-2
Thread: Thread-2, 5
当前输出为
Creating Thread-1
Starting Thread-1
Creating Thread-2
Starting Thread-2
Running Thread-1
Thread: Thread-1, 1
Running Thread-2
Thread: Thread-2, 1
Exception in thread "Thread-1" Exception in thread "Thread-2" java.lang.IllegalMonitorStateException
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:502)
at RunnableDemo.run(TestThread.java:16)
at java.lang.Thread.run(Thread.java:745)
java.lang.IllegalMonitorStateException
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:502)
at RunnableDemo.run(TestThread.java:16)
at java.lang.Thread.run(Thread.java:745)
您正在等待/通知错误。
为了通知另一个线程,您必须在另一个对象上调用notify 。
您的代码所做的是:线程将自己置于等待状态...以便稍后进行通知。
从这个意义上讲:退后一步,了解如何正确使用这两种方法; 例如,从这里开始阅读。
您应该在同一对象上使用wait()
和notify()
进行通信。
class RunnableDemo implements Runnable {
private ThreadMonitor lock;
private String threadName;
private String otheThreadName;
RunnableDemo(String name, ThreadMonitor lock, String otheThreadName) {
this.threadName = name;
this.lock = lock;
this.otheThreadName = otheThreadName;
System.out.println("Creating " + threadName);
}
public void run() {
synchronized (lock) {
try {
for (int i = 1; i <= 5; i++) {
while (!lock.getRunningThread().equals(threadName)) {
lock.wait();
}
System.out.println("Running " + threadName);
System.out.println("Thread: " + threadName + ", " + i);
lock.setRunningThread(otheThreadName);
lock.notify();
}
} catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start() {
System.out.println("Starting " + threadName);
Thread t = new Thread(this, threadName);
t.start();
}
}
public class TestThread {
public static void main(String args[]) {
ThreadMonitor lock = new ThreadMonitor("Thread-1");
RunnableDemo R1 = new RunnableDemo("Thread-1", lock, "Thread-2");
R1.start();
RunnableDemo R2 = new RunnableDemo("Thread-2", lock, "Thread-1");
R2.start();
}
}
class ThreadMonitor {
private String runningThread;
public ThreadMonitor(String runningThread) {
this.runningThread = runningThread;
}
public String getRunningThread() {
return runningThread;
}
public void setRunningThread(String threadName) {
runningThread = threadName;
}
}
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