CODEWITHSUNDEEP
androidandroid-recyclerview
stackex
stackex

Reputation: 3215

App crash when invoking RecycleView on Fragment

Okay, I've found many issue about this here (stackoverflow.com/questions/27416834/app-crashing-when-trying-to-use-recyclerview-on-android-5-0), here (stackoverflow.com/questions/26446162/andorid-recyclerview-layoutmanager-exception), or here (code.google.com/p/android/issues/detail?id=81588). I want to comment there, but can't. All of them suggest to set layoutmanager as soon as it inflated. I've done it and the app is still crash and showing this error: 

java.lang.NullPointerException: Attempt to invoke virtual method void android.support.v7.widget.RecyclerView$LayoutManager.onMeasure(android.support.v7.widget.RecyclerView$Recycler, android.support.v7.widget.RecyclerView$State, int, int) on a null object reference

below is my code snippet

MyFragment.java 

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView =  inflater.inflate(R.layout.my_fragment, container, false);

        mRecyclerView = (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
        mRecyclerView.setHasFixedSize(true);

        final RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(getActivity(), 2);
        mRecyclerView.setLayoutManager(mLayoutManager);

        myDataset = // initiaized data

        mAdapter = new MyAdapter(getActivity().getApplicationContext(), myDataset);
        mRecyclerView.setAdapter(mAdapter);

        return rootView;
    }

my_fragment.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" tools:context=".MyFragment">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</FrameLayout>

Upvotes: 1

Views: 801

Answers (2)

stackex
stackex

Reputation: 3215

Finally I've found a solution. Currently I try to provide navigation tab to an activity. Each tab content is shown on a fragment. I try to adapt it from SDK example. The problem is as @nikis said, the adapter didn't call the fragment. According to this tutorial, I should use adapter that extends FragmentPagerAdapter instead of PagerAdapter as shown in original example. That means that I need to override getItem method on FragmentPagerAdapter instead of InstantiateItem on PagerAdapter.

Upvotes: 1

terencey
terencey

Reputation: 3332

I've reformatted your code a little, it should help you debug further.

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.my_fragment, container, false);

        mRecyclerView = (RecyclerView)
            rootView.findViewById(R.id.my_recycler_view);

        if (mRecyclerView != null) {
            mRecyclerView.setLayoutManager(
                new GridLayoutManager(getActivity(), 2));
            mRecyclerView.setHasFixedSize(true);

            myDataset = // initiaized data
            mAdapter = new MyAdapter(
                getActivity().getApplicationContext(), myDataset);
            mRecyclerView.setAdapter(mAdapter);
        } else {
            Log.e("Error", "Unable to find recyclerView");
        }
        return rootView;
    }

Upvotes: 1

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