How to hide action bar before activity is created,

Question

I need to implement splash screen in my honeycomb app. I use this code in activity's onCreate to show splash:

setContentView(R.layout.splash);
getActionBar().hide();

and this code to show main UI after sometime:

setContentView(R.layout.main);
getActionBar().show();

But before onCreate is called and splash appears, there is small amount of time when action bar shown.

How can I make action bar invisible?

I tried to apply theme to activity without action bar:

<item name="android:windowActionBar">false</item>

but in that case getActionBar() always returns null and I found no way to show it again.

Answer 1

Setting android:windowActionBar="false" truly disables the ActionBar but then, as you say, getActionBar(); returns null. This is solved by:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
    getActionBar().hide();

    setContentView(R.layout.splash); // be sure you call this AFTER requestFeature

This creates the ActionBar and immediately hides it before it had the chance to be displayed.

But now there is another problem. After putting windowActionBar="false" in the theme, the Activity draws its normal Window Title instead of an ActionBar.
If we try to avoid this by using some of the *.NoTitleBar stock themes or we try to put <item name="android:windowNoTitle">true</item> in our own theme, it won't work.
The reason is that the ActionBar depends on the Window Title to display itself - that is the ActionBar is a transformed Window Title.
So the trick which can help us out is to add one more thing to our Activity theme xml:

<item name="android:windowActionBar">false</item>
<item name="android:windowTitleSize">0dp</item>

This will make the Window Title with zero height, thus practically invisible .

In your case, after you are done with displaying the splash screen you can simply call

setContentView(R.layout.main);
getActionBar().show();

and you are done. The Activity will start with no ActionBar flickering, nor Window Title showing.

ADDON: If you show and hide the ActionBar multiple times maybe you have noticed that the first showing is not animated. From then on showing and hiding are animated. If you want to have animation on the first showing too you can use this:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_ACTION_BAR);

    // delaying the hiding of the ActionBar
    Handler h = new Handler();
    h.post(new Runnable() {     
        @Override
        public void run() {
            getActionBar().hide();
        }
    });

The same thing can be achieved with:

protected void onPostResume() {
    super.onPostResume();
    getActionBar().hide();

but it may need some extra logic to check if this is the first showing of the Activity.

The idea is to delay a little the hiding of the ActionBar. In a way we let the ActionBar be shown, but then hide it immediately. Thus we go beyond the first non-animated showing and next showing will be considered second, thus it will be animated.

As you may have guessed there is a chance that the ActionBar could be seen before it has been hidden by the delayed operation. This is actually the case. Most of the time nothing is seen but yet, once in a while, you can see the ActionBar flicker for a split second.

In any case this is not a pretty solution, so I welcome any suggestions.

Addition for v7 support actionbar user, the code will be:

getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
getSupportActionBar().hide();