title: Get back to Android activity after background thread is complete
body: <p>I'm using Parse with my Android app, and my code looks like this:</p>
  
  <pre><code>public class SignupActivity extends Activity {
  //Collect signup data
  User.signupInBackground(data);
  }
  
  
  
  public class User{
  //User methods, constructors, etc
  public static void signup(data){
  ParseUser pUser = new ParseUser();
  //Build data into pUser
  pUser.signUpInBackground(new SignUpCallback() {
          public void done(ParseException e){
              if (e!=null){
                  Log.v("Signup",e.toString());
              }
          }
  
      });
  </code></pre>
  
  <p>So the question is, how do I notify my activity when the signUpInBackground process is complete? I can't have SignupActivity implement SignUpCallback because it's an abstract class and I have to extend Activity.</p>
  
  <p>Ultimately, what I'm trying to do is display a dialog box or waiting animation, and then get rid of it when the background thread is done. Alternatively, the background thread could launch an activity. The problem with this is that the User class and the anonymous inner class don't have their own Context, so they can't start activities.</p>
  
  <p>I'm fairly new at this, so thanks for your help.</p>