INTERRUPTING A THREAD IN JAVA

A thread can interrupt a sleeping or waiting thread by using interrupt() method of thread class.

§  public void interrupt()

Example –

public class Interrupt extends Thread{

          public void run()

          {

                   for(int i=0;i<5;i++)

                   {

                             System.out.println(getName()+" Run : "+i);

                             try{

                                      Thread.sleep(2000);

                             }

                             catch(InterruptedException e)

                             {

                                      System.out.println("I am interrupted");

                             }

                   }

          }

          public static void main(String[] args) {

                   Interrupt i1 = new Interrupt();

                   i1.start();

                   i1.interrupt();

                   System.out.println("End of main thread");

          }

}

Output –

End of main thread

Thread-0 Run : 0

I am interrupted

Thread-0 Run : 1

Thread-0 Run : 2

Thread-0 Run : 3

Thread-0 Run : 4

Note – In the above program, main thread interrupts child thread by using thread object. Whenever we are calling interrupt() method and if the target thread isn’t in sleeping or waiting state, then there is no effect of interrupt() method call immediately. This call waits until thread enters into sleeping or waiting state. Once the target thread enters into sleeping or waiting state, then interrupt call will interrupt that thread. If the target thread never enters into sleeping and waiting state in its lifetime, then the interrupt call will wait.

Example –

public class Interrupt extends Thread{

          public void run()

          {

                   for(int i=0;i<5;i++)

                   {

                             System.out.println(getName()+" Run : "+i);

                             try{

                                      Thread.sleep(100);

                             }

                             catch(InterruptedException e)

                             {

                                      System.out.println("I am interrupted");

                             }

                   }

          }

          public static void main(String[] args) {

                   Interrupt i1 = new Interrupt();

                   i1.start();

                   i1.interrupt();

                   for(int i=0;i<5;i++)

                   {

                             System.out.println("main "+i);

                   }

          }

}