Serial Delay Util

SerialDelayUtil.java

public class SerialDelayUtil {
  private final SerialDelayHandler serialDelayHandler;

  public SerialDelayUtil() {
    this.serialDelayHandler = new SerialDelayHandler(Looper.getMainLooper());
  }

  /**
   * <p>
   *  Runs the runnable after millisDelay, but every time this function is called
   *  all previous calls that are still enqueued will be cancelled and the current
   *  call will be enqueued.
   * </p>
   * <p>
   *  Example 1:<br/>
   *  <code><br/>
   *  serialDelayUtil.postDelayed(runnable1, 5000);<br/>
   *  serialDelayUtil.postDelayed(runnable2, 5000);<br/>
   *  serialDelayUtil.postDelayed(runnable3, 5000);<br/>
   *  </code><br/>
   *  In this example only runnable3 will be run
   * </p>
   * <p>
   *  Example 2:<br/>
   *  <code><br/>
   *  serialDelayUtil.postDelayed(runnable1, 5000);<br/>
   *  Thread.sleep(6000);<br/>
   *  serialDelayUtil.postDelayed(runnable2, 5000);<br/>
   *  </code><br/>
   *  In this example both runnable1 and runnable2 will be run
   * </p>
   * <p>
   *   Note: The runnable will always be run on the {@link Looper#getMainLooper()}
   * </p>
   *
   * @param runnable Runnable to perform after delay
   * @param millisDelay Milliseconds to wait before calling run on runnable
   */
  public void postDelayed(Runnable runnable, int millisDelay) {
    serialDelayHandler.removeMessages(SerialDelayHandler.MSG_RUN_TASK);
    serialDelayHandler.sendMessageDelayed(serialDelayHandler.obtainMessage(SerialDelayHandler.MSG_RUN_TASK, runnable), millisDelay);
  }

  private static class SerialDelayHandler extends Handler {
    private static final int MSG_RUN_TASK = 1;
    private SerialDelayHandler(Looper looper) {
      super(looper);
    }
    @Override
    public void handleMessage(Message msg) {
      switch (msg.what) {
        case MSG_RUN_TASK: {
          Runnable runnable = (Runnable) msg.obj;
          runnable.run();
          break;
        }
      }
    }
  }
}