title: Android countdown timer to time in future
body: <p>I have an activity that receives two values, one for hour and one for minute. A future time, eg: 21:30</p>
  
  <p>How can I set a countdown timer to run from the current time until the future time that was received ?</p>
  
  <p>here is my timer code, currently set to 30sec for testing</p>
  
  <pre><code>    CountDownTextView = (TextView) findViewById(R.id.CountDownTextView);
  
      new CountDownTimer(30000, 1000) {
  
           public void onTick(long millisUntilFinished) {
               CountDownTextView.setText("" + millisUntilFinished / 1000);
           }
  
           public void onFinish() {
               CountDownTextView.setText("Unlocking!");
           }
        }.start();
  </code></pre>
  
  <p>Many thanks</p>