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能够暂停、恢复或完全停止的多线程程序。有许多静态方法可以在线程对象上使用以控制其行为。
控制 Java 线程的方法
下表列出了用于控制 Java 中线程的方法:
表格：方法及其描述
| 序号 |
方法与描述 |
| 1 |
public void suspend()
此方法将线程置于暂停状态，并可使用 resume() 方法恢复。 |
| 2 |
public void stop()
此方法完全停止一个线程。 |
| 3 |
public void resume()
此方法恢复使用 suspend() 方法暂停的线程。 |
| 4 |
public void wait()
使当前线程等待直到另一个线程调用了 notify()。 |
| 5 |
public void notify()
唤醒正在等待此对象监视器的一个线程。 |
请注意，Java 的最新版本已经弃用了 suspend(), resume(), 和 stop() 方法，因此您需要使用可用的替代方案。
Java 线程控制示例
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);
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.");
}
}
上述程序产生的输出如下：
Output
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.