android - ActionBarCompat: Hide ActionBar before activity is created (bug?)

Question

So I was using the ActionBarSherlock and decided to switch to the new ActionBarCompat. With ABS, hiding the ActionBar was possible using the way described in this post: How to hide action bar before activity is created, and then show it again?

But, with the ActionBarCompat the app crashes on API14, because when you set android:windowActionBar as false the getSupportActionBar() method returns null, even if you have declared the getWindow().requestFeature(Window.FEATURE_ACTION_BAR); into the onCreate() method.

Funny thing is that if you call getActionBar() instead, you get the object and everything works fine.

So, is that a bug or am I missing something? Any ideas are welcome!

---

styles.xml file:

<style name="Theme.MyApp" parent="@style/Theme.AppCompat.Light.DarkActionBar">
    <item name="android:windowActionBar">false</item>
    <item name="android:windowTitleSize">0dp</item>
</style>

MyActivity.java file:

...
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Get the action bar feature. This feature is disabled by default into the theme
    // for specific reasons.
    getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
    ...
    // By default the action bar is hidden.
    getSupportActionBar().hide();
}

Answer 1

I got stuck with the same problem and, it seems to me, found a reason of this strange behavior. I looked through source of support library and got this:

Appcompat checks a value of mHasActionBar variable before creating new action bar in ActionBarActivityDelegate

final ActionBar getSupportActionBar() {
    // The Action Bar should be lazily created as mHasActionBar or mOverlayActionBar
    // could change after onCreate
    if (mHasActionBar || mOverlayActionBar) {
        if (mActionBar == null) {
            mActionBar = createSupportActionBar();
    ...

And we can change its value by calling supportRequestWindowFeature(int featureId) which is delegated by ActionBarActivity to a ActionBarActivityDelegate.

There are base delegate class ActionBarDelegateBase and its descendants ActionBarDelegateHC, ActionBarActivityDelegateICS, ActionBarActivityJB, one of which is chosen according to a version of running android. And method supportRequestWindowFeature is actually works fine almost in all of them, but it's overridden in ActionBarActivityDelegateICS like that

@Override
public boolean supportRequestWindowFeature(int featureId) {
    return mActivity.requestWindowFeature(featureId);
}

So it has no effect on the variable mHasActionBar, that's why getSupportActionBar() returns null.

We almost there. I came to two different solutions.

First way

1. import source project of appcompat from git

2. change overridden method in ActionBarActivityDelegateICS.java to something like this

   @Override
   public boolean supportRequestWindowFeature(int featureId) {
       boolean result = mActivity.requestWindowFeature(featureId);
       if (result) {
           switch (featureId) {
           case WindowCompat.FEATURE_ACTION_BAR:
               mHasActionBar = true;
           case WindowCompat.FEATURE_ACTION_BAR_OVERLAY:
               mOverlayActionBar = true;
           }
       }
       return result;
   }
   

3. place this line in activity's onCreate method before getSupportActionBar()

   supportRequestWindowFeature(WindowCompat.FEATURE_ACTION_BAR);
   

Second way

1. import project of appcompat from android SDK (which is with empty src directory)

2. add this method to your activity

   private void requestFeature() {
       try {
           Field fieldImpl = ActionBarActivity.class.getDeclaredField("mImpl");
           fieldImpl.setAccessible(true);
           Object impl = fieldImpl.get(this);
   
           Class<?> cls = Class.forName("android.support.v7.app.ActionBarActivityDelegate");
   
           Field fieldHasActionBar = cls.getDeclaredField("mHasActionBar");
           fieldHasActionBar.setAccessible(true);
           fieldHasActionBar.setBoolean(impl, true);
   
       } catch (NoSuchFieldException e) {
           Log.e(LOG_TAG, e.getLocalizedMessage(), e);
       } catch (IllegalAccessException e) {
           Log.e(LOG_TAG, e.getLocalizedMessage(), e);
       } catch (IllegalArgumentException e) {
           Log.e(LOG_TAG, e.getLocalizedMessage(), e);
       } catch (ClassNotFoundException e) {
           Log.e(LOG_TAG, e.getLocalizedMessage(), e);
       }
   }
   

3. call requestFeature() in onCreate method of your activity like this

   if (Build.VERSION.SDK_INT >= 11) {
       requestFeature();
   }
   supportRequestWindowFeature(WindowCompat.FEATURE_ACTION_BAR);
   

I used the second way. That's all.