We can easily fix the previous example BrokenPrimeProducer.java with interrupt() method.
Pay attention to Thread.currentThread() vs. this -- inside run(), this and Thread.currentThread() refers to the same thread object, which is the one created by pp.start();. In cancel(), this refers to the thread created by pp.start();, Thread.currentThread() refers to the calling thread, which is the main thread.
CHAP7>cat PrimeProducer.java
import java.math.BigInteger;
import java.util.concurrent.*;
/**
* PrimeProducer
* <p/>
* Using interruption for cancellation
*/
class PrimeProducer extends Thread {
private final BlockingQueue<BigInteger> queue;
PrimeProducer(BlockingQueue<BigInteger> queue) {
this.queue = queue;
}
public void run() {
try {
BigInteger p = BigInteger.ONE;
System.out.println(Thread.currentThread() + " started.");
System.out.println(this + " started.");
while (!Thread.currentThread().isInterrupted())
queue.put(p = p.nextProbablePrime());
} catch (InterruptedException consumed) {
}
}
public void cancel() {
System.out.println(Thread.currentThread().toString() + " is calling interrupt().");
System.out.println(this + " will be interrupted.");
interrupt();
}
public static void main(String args[]) {
PrimeProducer pp = new PrimeProducer(new LinkedBlockingQueue<BigInteger>(5));
System.out.println(pp.queue.size());
pp.start();
try {
Thread.sleep(1000);
pp.cancel();
System.out.println(pp.queue.size());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
CHAP7>javac PrimeProducer.java
CHAP7>java PrimeProducer
0
Thread[Thread-0,5,main] started.
Thread[Thread-0,5,main] started.
Thread[main,5,main] is calling interrupt().
Thread[Thread-0,5,main] will be interrupted.
5
CHAP7>
