Middle alignment not working when no tabs are added yet

[koesie10]

I am trying to use pstsPaddingMiddle="true" with a FragmentStatePagerAdapter. This adapter does not have any items when the fragment is first created and my app crashes with the following error:

java.lang.NullPointerException
            at com.astuetz.PagerSlidingTabStrip.onLayout(PagerSlidingTabStrip.java:419)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:543)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:887)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.support.v7.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:502)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14841)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1986)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1743)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:996)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5603)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
            at android.view.Choreographer.doCallbacks(Choreographer.java:574)
            at android.view.Choreographer.doFrame(Choreographer.java:544)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
            at dalvik.system.NativeStart.main(Native Method)```

The error points to https://github.com/jpardogo/PagerSlidingTabStrip/blob/master/library/src/com/astuetz/PagerSlidingTabStrip.java#L419 where the library assumes that there are always tabs, which is not true for my fragment.

Also, could issue #15 be reopened, as when I add a tab at the beginning to circumvent this error, it is still unusable. It looks like this, even though there are 3 tabs:
![image](https://cloud.githubusercontent.com/assets/1112623/5060983/c62222a2-6d7c-11e4-9437-fa8f30103448.png)
When moving to another tab, the new tab is not even shown.

[jpardogo]

I see the NPE.

What are you doing difference from the working example?

[koesie10]

The NPE is caused by only setting the contents of the adapter after it has been added. Initially, the contents of the adapter are empty. The error points to line 419 of PagerSlidingTabStrip where it tries to get the first child, which is initially not there because the count is 0.

tl;dr; The library doesn't work when there are no tabs in the adapter or if they are added later.

[jpardogo]

I will fix it asap. I see where it is happening, thanks.

[jpardogo]

Fixed in commit 7380d64659879ce5732c73443f8e824559cedc87