android.support.v7 with `ActionBarActivity` no men

问题:

In the new update Google has released a new API support library, that supports the ActionBar in API level 7+.

I used ActionBarSherlock until this update and I wrote the code to load the menu:

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.activity_main, menu);
    return true;
}

and the menu file:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/item_menu_ok" android:icon="@drawable/ic_action_ok"
        android:title="@string/ok" android:showAsAction="always"></item>
    <item android:id="@+id/item_menu_cancel" android:icon="@drawable/ic_action_cancel"
        android:title="@string/cancel" android:showAsAction="always"></item>
</menu>

To set up the menu buttons on the action bar. This code worked perfectly with ActionBarSherlock. But when I changed the action bar to the new support library, the buttons are not shown in the action bar. Even if they are set as android:showAsAction="always". And when I debug the code, the function menu.getSize() return 2, and that is correct, but no buttons are shown..

Why are the buttons not shown in the new support library?

回答1:

Try pressing the MENU button on your device or emulator, and see if they appear in the overflow.

If they do, then the problem is that your <menu> XML needs to change. Menu XML that works with ActionBarSherlock and the native API Level 11+ action bar will not work with the AppCompat action bar backport.

Your menu XML would need to look like this:

<?xml version="1.0" encoding="utf-8"?>
<menu
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:yourapp="http://schemas.android.com/apk/res-auto"
>
    <item android:id="@+id/item_menu_ok" android:icon="@drawable/ic_action_ok"
        android:title="@string/ok" yourapp:showAsAction="always"></item>
    <item android:id="@+id/item_menu_cancel" android:icon="@drawable/ic_action_cancel"
        android:title="@string/cancel" yourapp:showAsAction="always"></item>
</menu>

And you would need to use the same yourapp prefix for anything else related to the action bar (e.g., yourapp:actionLayout).

You can see this covered in the action bar documentation.

回答2:

I'd like to add a little to the answer.

If you want to see both text and an icon, please use withText in showAsAction I've just tested it; when I used always or ifRoom without withText, I only saw an icon.