Rendering Problems: java.lang.NullPointerException at android.support.v7.widget.RecyclerView in Android Studio 1.1.0

Question

I have recently updated android sdk to api 22 and android studio 1.1.0. After that I am getting rendering issues on RecyclerView. Here is what I am getting

Answer 1

I have had the same error. line 1216 of RecyclerView is:

return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0;

mLayout being null at the time is the issue, I am not sure why it is null, but it appears you have to call setLayoutManager() on your RecyclerView immediately after setContentView() or inflate(). My code was running a background thread before I tried to access the RecyclerView and call its setLayoutManager(). Once I changed to the following, it works

i.e.

this.setContentView(R.layout.schedule);
rv = (RecyclerView) this.findViewById(R.id.schedule_listview);
rv.setLayoutManager(new LinearLayoutManager(this));

I am still not quite understand why have to do that though

Answer 2

You just forgot to set a LayoutManager: https://developer.android.com/reference/android/support/v7/widget/RecyclerView.html#setLayoutManager(android.support.v7.widget.RecyclerView.LayoutManager)

Answer 3

i just removed the property android:scrollbars="vertical" and everything will be fine

Answer 4

You dont need to remove any line, but to add the following line to your code:

recyclerView.setLayoutManager(new LinearLayoutManager(recyclerView.getContext()));

This way, there is no problem for the Vertical scrolling on the RecyclerView.

Hope it helps!

Answer 5

Just in case people are still wondering, you should update to the latest SDK platform for API 22 via the SDK Manager, and update to the latest recycler view by updating the Support repository via the SDK Manager, and in your build.gradle file to use the latest version (22.0.0)

Answer 6

My problem was solved when I took out this line from the xml file for the RecyclerView:

android:scrollbars="vertical"

I am using the following dependencies:

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.android.support:recyclerview-v7:22.0.0'
    compile 'com.android.support:cardview-v7:22.0.0'
}

EDIT: The root of this issue was pointed out by commentators on this solution - to solve the problem, you can just ensure that the LayoutManager for the RecyclerView is set before you display the RecyclerView with the scrollbars property set.