OnJava8-Examples/threads/InterruptingIdiom.java

// threads/InterruptingIdiom.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// General idiom for interrupting a task
// {Args: 1100}
import java.util.concurrent.*;

class NeedsCleanup {
  private final int id;
  public NeedsCleanup(int ident) {
    id = ident;
    System.out.println("NeedsCleanup " + id);
  }
  public void cleanup() {
    System.out.println("Cleaning up " + id);
  }
}

class Blocked3 implements Runnable {
  private volatile double d = 0.0;
  @Override
  public void run() {
    try {
      while(!Thread.interrupted()) {
        // point1
        NeedsCleanup n1 = new NeedsCleanup(1);
        // Start try-finally immediately after definition
        // of n1, to guarantee proper cleanup of n1:
        try {
          System.out.println("Sleeping");
          TimeUnit.SECONDS.sleep(1);
          // point2
          NeedsCleanup n2 = new NeedsCleanup(2);
          // Guarantee proper cleanup of n2:
          try {
            System.out.println("Calculating");
            // A time-consuming, non-blocking operation:
            for(int i = 1; i < 2500000; i++)
              d += (Math.PI + Math.E) / d;
            System.out.println(
              "Finished time-consuming operation");
          } finally {
            n2.cleanup();
          }
        } finally {
          n1.cleanup();
        }
      }
      System.out.println("Exiting via while() test");
    } catch(InterruptedException e) {
      System.out.println(
        "Exiting via InterruptedException");
    }
  }
}

public class InterruptingIdiom {
  public static void
  main(String[] args) throws Exception {
    if(args.length != 1) {
      System.out.println(
        "usage: java InterruptingIdiom delay-in-mS");
      System.exit(1);
    }
    Thread t = new Thread(new Blocked3());
    t.start();
    TimeUnit.MILLISECONDS.sleep(new Integer(args[0]));
    t.interrupt();
  }
}
/* Output:
NeedsCleanup 1
Sleeping
NeedsCleanup 2
Calculating
Finished time-consuming operation
Cleaning up 2
Cleaning up 1
NeedsCleanup 1
Sleeping
Cleaning up 1
Exiting via InterruptedException
*/