How to know which Activity prior to the current Activity was called?

Question

I have several activities, which can call a special activity.

I’d like to know how to identify which Activity called.

It would be something like this:

I need this because I have a user registration Activity, which can be called through various places in my application. But I need to know which place it was called from, because depending on who called it should perform an action.

I thought I’d do it like this:

Intent intent = new Intent(basecontext,Registro_Activity.class);
intent.putExtra("ACTIVITYPAI", "ACTIVITY-A");
startActivity(intent);

And put that on every screen you call. But if there’s a way that you don’t have to use the putExtra, and the actual record of identifying where it came from, it would be better for me.

Answer 1

Using getCallingActivity():

If you start Activity with startActivityForResult, the method can be used getCallingActivity().getClassName():

private void startRegistroActivity() {
  Intent intent = new Intent(basecontext, Registro_Activity.class);
  startActivityForResult(intent, 100);
}

And on the second Activity:

@Override protected void onCreate(@Nullable Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  ...
  String className = getCallingActivity().getClassName();

}

Using Intents:

You can also use Intents, as you are already doing.

At first Activity:

Intent intent = new Intent(basecontext,Registro_Activity.class);
intent.putExtra("activity_name", this.getClass().getName());
startActivity(intent);

And in the second Activity:

@Override protected void onCreate(@Nullable Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  ...
  String className = getIntent().getStringExtra("activity_name");
}

Using Singletons or objects that live longer than Activity:

Another option is to use objects that live longer than Activity, such as Singletons.

Declare the Singleton:

public enum ActivityReference {

  INSTANCE;

  Class<?> callingActivity;

  public Class<?> getCallingActivity() {
    return callingActivity;
  }

  public void setCallingActivity(Class<?> callingActivity) {
    this.callingActivity = callingActivity;
  }
}

Keep the value in it:

ActivityReference.INSTANCE.setCallingActivity(this.getClass());
Intent intent = new Intent(this, Activity.class);
startActivity(intent);

Access it at a later date:

@Override protected void onCreate(@Nullable Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  ...
  Class<?> callingActivity = ActivityReference.INSTANCE.getCallingActivity();
}