AndroidX Activity ( AppCompatActivity )

mahmoud_hooda · May 11, 2026, 4:11pm

I was trying to call:

getSupportFragmentManager()

from the "Form" class, but I discovered that "Form" extends "AppInventorCompatActivity",

appinventor/components/src/com/google/appinventor/components/runtime/Form.java

d731035ec


      
          *     places and make the appropriate code changes.</p>
          *
          */
          
          @DesignerComponent(version = YaVersion.FORM_COMPONENT_VERSION,
             category = ComponentCategory.USERINTERFACE,
             description = "Top-level component containing all other components in the program",
             showOnPalette = false)
          @SimpleObject
          @UsesPermissions({INTERNET})
          public class Form extends AppInventorCompatActivity
             implements Component, ComponentContainer, HandlesEventDispatching,
             OnGlobalLayoutListener {
          
           private static final String LOG_TAG = "Form";
          
           private static final String RESULT_NAME = "APP_INVENTOR_RESULT";
          
           private static final String ARGUMENT_NAME = "APP_INVENTOR_START";
          
           public static final String APPINVENTOR_URL_SCHEME = "appinventor";

and "AppInventorCompatActivity" extends:
Activity

github.com/mit-cml/appinventor-sources

appinventor/components/src/com/google/appinventor/components/runtime/AppInventorCompatActivity.java

d731035ec


      
          import com.google.appinventor.components.runtime.util.theme.IceCreamSandwichThemeHelper;
          import com.google.appinventor.components.runtime.util.theme.ThemeHelper;
          
          /**
           * AppInventorCompatActivity provides a base implementation of Activity that handles the styling of
           * the application. This allows the user to change the Theme of the application in the REPL (to the
           * best of our ability). Any Activity in App Inventor should now extend this class to get the
           * correct theme.
           * @author ewpatton@mit.edu (Evan W. Patton)
           */
          public class AppInventorCompatActivity extends Activity implements AppCompatCallback {
          
            public enum Theme {
              PACKAGED,
              CLASSIC,
              DEVICE_DEFAULT,
              BLACK_TITLE_TEXT,
              DARK
            }
          
            private static final String LOG_TAG = AppInventorCompatActivity.class.getSimpleName();

instead of AndroidX "AppCompatActivity" / "FragmentActivity".

Because of this, modern AndroidX components such as "DialogFragment" cannot be used easily.

So my question is:
Why does App Inventor still use "Activity" instead of AndroidX "AppCompatActivity"?
Is there a compatibility or architectural reason behind this decision?

ewpatton · May 11, 2026, 4:36pm

Backward compatibility. For a long time we were supporting back to Android 2.1 even though Google dropped support for it. AppInventorCompatActivity pulls in the pieces we needed from older AppCompatActivity prior to Google's decision to drop support for Android versions prior to 4.0.

system · May 18, 2026, 4:37pm

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