How to stop all runnable thread in java executor class?

The shutDown() method simply prevents additional tasks from being scheduled. Instead, you could call shutDownNow() and check for thread interruption in your Runnable.

// in your Runnable...
if (Thread.interrupted()) {
  // Executor has probably asked us to stop
}

An example, based on your code, might be:

final ExecutorService executor = Executors.newFixedThreadPool(1);
executor.submit(new Runnable() {
  public void run() {
    try {
      Thread.sleep(20 * 1000);
    } catch (InterruptedException e) {
      System.out.println("Interrupted, so exiting.");
    }
  }
});

if (executor.awaitTermination(10, TimeUnit.SECONDS)) {
  System.out.println("task completed");
} else {
  System.out.println("Forcing shutdown...");
  executor.shutdownNow();
}