简历上的Android启动活动

Question

In my application, I have 5 Activities. A , B , C , D , E . Activities B , C , D , E extend Activity A which extends AppCompat. When the application starts from Android Studio, Activity A launches Activity B . From Activity B , the user can decide which activity to load either C , D , or E . My code works fine until the user exits the application and decides to launch it again. The application shows Activity A and does not take the user to Activity B . I want the user to see Activity B . How can I fix this?

Answer 1

Have you tried overriding the onResume() method to show activity B?

@Override
public void onResume(){
    super.onResume();
    setContentView(R.id.layout_B);
}

Answer 2

It sounds like you should define Activity B as your launcher in the Manifest, I am assuming Activity A was defined as the launcher by a template/default.

<activity name="{Activity B's name}">     
  <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="android.intent.category.LAUNCHER" />
   </intent-filter>
</activity>

Activity B will be the 'root' of your application, at the moment Activity B is added on-top of Activity A in the stack.

If Activity A is also doing a bunch of bootstrapping, another approach will be needed but more information is needed.

Answer 3

If you want to retain application state after your app closes, you may want to use SharedPreferences :

final String CURR_ACTIVITY_KEY = "curr_activity";
int currentActivityKey = 1;
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
prefs.edit().putInt(CURR_ACTIVITY_KEY, currentActivityKey).commit();