How to interrupt a running Thread in Java

Problem Description

How to interrupt a running Thread?

Solution

Following example demonstrates how to interrupt a running thread interrupt() method of thread and check if a thread is interrupted using isInterrupted() method.

public class GeneralInterrupt extends Object implements Runnable {
   public void run() {
      try {
         System.out.println("in run() - about to work2()");
         work2();
         System.out.println("in run() - back from work2()");
      } catch (InterruptedException x) {
         System.out.println("in run() - interrupted in work2()");
         return;
      }
      System.out.println("in run() - doing stuff after nap");
      System.out.println("in run() - leaving normally");
   }
   public void work2() throws InterruptedException {
      while (true) {
         if (Thread.currentThread().isInterrupted()) {
            System.out.println("C isInterrupted()="+ Thread.currentThread().isInterrupted());
            Thread.sleep(2000);
            System.out.println("D isInterrupted()="+ Thread.currentThread().isInterrupted());
         }
      }
   }
   public void work() throws InterruptedException {
      while (true) {
         for (int i = 0; i < 100000; i++) {
            int j = i * 2;
         }
         System.out.println("A isInterrupted()="+ Thread.currentThread().isInterrupted());
         if (Thread.interrupted()) {
            System.out.println("B isInterrupted()="+ Thread.currentThread().isInterrupted());
            throw new InterruptedException();
         }
      }
   }
   public static void main(String[] args) {
      GeneralInterrupt si = new GeneralInterrupt();
      Thread t = new Thread(si);
      t.start();
      try {
         Thread.sleep(2000);
      } catch (InterruptedException x) { }
		
      System.out.println("in main() - interrupting other thread");
      t.interrupt();
      System.out.println("in main() - leaving");
   }
}

Result

The above code sample will produce the following result.

in run() - about to work2()
in main() - interrupting other thread
in main() - leaving
C isInterrupted() = true
in run() - interrupted in work2()