title: Android Countdown Timer app crashes when the button is clicked
body: <p>I've just started coding in Android SDK and this is my first attempt at a Countdown Timer. I've set the timer to start at the press of the button with setOnClickListener(). The timer doesn't start but the app stops working when I click the button. The device displays a message saying the app has stopped working. </p>
  
  <p>I've written a method to format the time into minutes and seconds. And i've set the call in the onTick() method of the CountDownTimer.</p>
  
  <p>I've posted my code below. Please take a look and point me to where the problem is and what to do. Much appreciated.     </p>
  
  <pre><code>package com.example.day1;
  
  import android.app.Activity;
  import android.os.Bundle;
  import android.os.CountDownTimer;
  import android.view.View;
  import android.widget.Button; 
  import android.widget.TextView;
  public class MainActivity extends Activity {
  
  
  TextView Timer;//Textview to display the timer
      //This is the method to format the time into minutes and seconds 
  public String formatTime(long millis)
  {
      String output="00:00";
      long second=millis/1000;
      long minute=second/60;
      second=second%60;
      minute=minute%60;
      String sec=String.valueOf(second);
      String min=String.valueOf(minute);
      output=min+":"+sec;
      return output;
  }
  
  @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.countdown);
      Timer=(TextView) findViewById(R.id.text1);
      Button button1=(Button)findViewById(R.id.button1);
      button1.setOnClickListener(new View.OnClickListener() {
  
          @Override
          public void onClick(View v) {
  
  
      new CountDownTimer(60000,1000)
      {
          public void onTick(long millisUntilFinished){
      Timer.setText(formatTime(millisUntilFinished));
          }
      public void onFinish()
      {
          onStop();
      }
      }.start();
      }
           });
       }
           }
  </code></pre>