title: Respond to change in variable
body: <p>I have made a service that displays a toast showing the current time . The toast should be displayed when the value of "minute" changes. What should i do ?
  Here is the code. Is it necessary to create a listener to listen to change of the minute variable?
  Please help me.</p>
  
  <pre><code>public class Servicedemo extends Service{
  @Override
  public void onCreate() {
  
      super.onCreate();
      Toast.makeText(this, "Service Started", Toast.LENGTH_SHORT).show();
       String str;
  
          Calendar c=Calendar.getInstance();
          int hour=c.get(Calendar.HOUR);
          int min=c.get(Calendar.MINUTE);
          str=String.valueOf(hour)+":"+String.valueOf(min);
  
          Toast.makeText(this, str , Toast.LENGTH_SHORT).show();
  
  }
  
  @Override
  public void onDestroy() {
      // TODO Auto-generated method stub
      super.onDestroy();
      Toast.makeText(this, "Service Stopped", Toast.LENGTH_SHORT).show();
  }
  
  @Override
  public IBinder onBind(Intent intent) {
      // TODO Auto-generated method stub
      return null;
  }
  
  
  }
  </code></pre>