极客教程Java 线程控制
核心Java提供了对多线程程序的完全控制。您可以根据需求开发一个可以暂停、恢复或完全停止的多线程程序。有多种静态方法可以在线程对象上使用，以控制它们的行为。下表列出了这些方法：
| 序号 | 方法和描述 |
|---|---|
| 1 | public void suspend() 此方法将线程置于挂起状态，并可以使用resume()方法恢复。 |
| 2 | public void stop() 此方法完全停止线程。 |
| 3 | public void resume() 此方法恢复已使用suspend()方法挂起的线程。 |
| 4 | public void wait() 使当前线程等待，直到另一个线程调用notify()。 |
| 5 | public void notify() 唤醒等待此对象监视器的单个线程。 |
请注意，最新版本的Java已经不再建议使用suspend()，resume()和stop()方法，因此你需要使用可用的替代方法。
示例
class RunnableDemo implements Runnable {
public Thread t;
private String threadName;
boolean suspended = false;
RunnableDemo( String name) {
threadName = name;
System.out.println("Creating " + threadName );
}
public void run() {
System.out.println("Running " + threadName );
try {
for(int i = 10; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
// Let the thread sleep for a while.
Thread.sleep(300);
synchronized(this) {
while(suspended) {
wait();
}
}
}
} 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 ();
}
}
void suspend() {
suspended = true;
}
synchronized void resume() {
suspended = false;
notify();
}
}
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();
try {
Thread.sleep(1000);
R1.suspend();
System.out.println("Suspending First Thread");
Thread.sleep(1000);
R1.resume();
System.out.println("Resuming First Thread");
R2.suspend();
System.out.println("Suspending thread Two");
Thread.sleep(1000);
R2.resume();
System.out.println("Resuming thread Two");
} catch (InterruptedException e) {
System.out.println("Main thread Interrupted");
}try {
System.out.println("Waiting for threads to finish.");
R1.t.join();
R2.t.join();
} catch (InterruptedException e) {
System.out.println("Main thread Interrupted");
}
System.out.println("Main thread exiting.");
}
}
上述程序产生以下输出 −
输出
Creating Thread-1
Starting Thread-1
Creating Thread-2
Starting Thread-2
Running Thread-1
Thread: Thread-1, 10
Running Thread-2
Thread: Thread-2, 10
Thread: Thread-1, 9
Thread: Thread-2, 9
Thread: Thread-1, 8
Thread: Thread-2, 8
Thread: Thread-1, 7
Thread: Thread-2, 7
Suspending First Thread
Thread: Thread-2, 6
Thread: Thread-2, 5
Thread: Thread-2, 4
Resuming First Thread
Suspending thread Two
Thread: Thread-1, 6
Thread: Thread-1, 5
Thread: Thread-1, 4
Thread: Thread-1, 3
Resuming thread Two
Thread: Thread-2, 3
Waiting for threads to finish.
Thread: Thread-1, 2
Thread: Thread-2, 2
Thread: Thread-1, 1
Thread: Thread-2, 1
Thread Thread-1 exiting.
Thread Thread-2 exiting.
Main thread exiting.