核心Java提供了对多线程程序的完全控制，您可以开发一个多线程程序，该程序可以根据您的要求完全挂起，恢复或停止。您可以对线程对象使用各种静态方法来控制其行为。下表列出了这些方法-
| Sr.No. | Method & Remark |
|---|---|
| 1 |
public void suspend() 该方法将线程置于挂起状态，可以使用resume()方法恢复该线程。 |
| 2 |
public void stop() 此方法完全停止线程。 |
| 3 |
public void resume() 此方法恢复一个线程，该线程已使用suspend()方法挂起。 |
| 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() 唤醒正在此对象的监视器上等待的单个线程。 |
请注意，最新版本的Java已弃用suspend()，resume()和stop()方法，因此您需要使用可用的替代方法。
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[]) {
</span><span class="typ">RunnableDemo</span><span class="pln"> R1 </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">RunnableDemo</span><span class="pun">(</span><span class="pln"> </span><span class="str">"Thread-1"</span><span class="pun">);</span><span class="pln">
R1</span><span class="pun">.</span><span class="pln">start</span><span class="pun">();</span><span class="pln">
</span><span class="typ">RunnableDemo</span><span class="pln"> R2 </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">RunnableDemo</span><span class="pun">(</span><span class="pln"> </span><span class="str">"Thread-2"</span><span class="pun">);</span><span class="pln">
R2</span><span class="pun">.</span><span class="pln">start</span><span class="pun">();</span><span class="pln">
</span><span class="kwd">try</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="typ">Thread</span><span class="pun">.</span><span class="pln">sleep</span><span class="pun">(</span><span class="lit">1000</span><span class="pun">);</span><span class="pln">
R1</span><span class="pun">.</span><span class="pln">suspend</span><span class="pun">();</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Suspending First Thread"</span><span class="pun">);</span><span class="pln">
</span><span class="typ">Thread</span><span class="pun">.</span><span class="pln">sleep</span><span class="pun">(</span><span class="lit">1000</span><span class="pun">);</span><span class="pln">
R1</span><span class="pun">.</span><span class="pln">resume</span><span class="pun">();</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Resuming First Thread"</span><span class="pun">);</span><span class="pln">
R2</span><span class="pun">.</span><span class="pln">suspend</span><span class="pun">();</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Suspending thread Two"</span><span class="pun">);</span><span class="pln">
</span><span class="typ">Thread</span><span class="pun">.</span><span class="pln">sleep</span><span class="pun">(</span><span class="lit">1000</span><span class="pun">);</span><span class="pln">
R2</span><span class="pun">.</span><span class="pln">resume</span><span class="pun">();</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Resuming thread Two"</span><span class="pun">);</span><span class="pln">
</span><span class="pun">}</span><span class="pln"> </span><span class="kwd">catch</span><span class="pln"> </span><span class="pun">(</span><span class="typ">InterruptedException</span><span class="pln"> e</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Main thread Interrupted"</span><span class="pun">);</span><span class="pln">
</span><span class="pun">}</span><span class="kwd">try</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Waiting for threads to finish."</span><span class="pun">);</span><span class="pln">
R1</span><span class="pun">.</span><span class="pln">t</span><span class="pun">.</span><span class="kwd">join</span><span class="pun">();</span><span class="pln">
R2</span><span class="pun">.</span><span class="pln">t</span><span class="pun">.</span><span class="kwd">join</span><span class="pun">();</span><span class="pln">
</span><span class="pun">}</span><span class="pln"> </span><span class="kwd">catch</span><span class="pln"> </span><span class="pun">(</span><span class="typ">InterruptedException</span><span class="pln"> e</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Main thread Interrupted"</span><span class="pun">);</span><span class="pln">
</span><span class="pun">}</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">println</span><span class="pun">(</span><span class="str">"Main thread exiting."</span><span class="pun">);</span><span class="pln">
}
}
上面的程序产生以下输出-
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.
