XML : Error inflating class... (CardView)

When i start my app the error

android.view.InflateException: Binary XML file line #2: Error inflating class com.example.tobi.zoom_gallery.SquareCardView

is shown. I want to show 3 collumns of 40 x 40px images in a RecyclerView with GridLayout.

MainActivity:

  public class MainActivity extends AppCompatActivity {      RecyclerView recyclerView;  RecyclerView.Adapter adapter;  RecyclerView.LayoutManager layoutManager;      @Override  protected void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.activity_main);      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);      setSupportActionBar(toolbar);            /////////////////////////////////////////////        recyclerView = (RecyclerView) findViewById(R.id.RV);      recyclerView.setHasFixedSize(true);        adapter = new MyAdapter(getResources());      recyclerView.setAdapter(adapter);        layoutManager = new GridLayoutManager(this, 3);      recyclerView.setLayoutManager(layoutManager);        ///////////////////////////////////////////////////        }    @Override  public boolean onCreateOptionsMenu(Menu menu) {      // Inflate the menu; this adds items to the action bar if it is present.      getMenuInflater().inflate(R.menu.menu_main, menu);      return true;  }    @Override  public boolean onOptionsItemSelected(MenuItem item) {      // Handle action bar item clicks here. The action bar will      // automatically handle clicks on the Home/Up button, so long      // as you specify a parent activity in AndroidManifest.xml.      int id = item.getItemId();        //noinspection SimplifiableIfStatement      if (id == R.id.action_settings) {          return true;      }        return super.onOptionsItemSelected(item);  }    

MyAdapter (for RecyclerView):

  public class MyAdapter extends RecyclerView.Adapter<MyHolder>{        ArrayList<String> names;      Resources resources;        public MyAdapter(ArrayList<String> names, Resources resources) {          this.names = names;          this.resources = resources;      }        @Override      public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {            View itemView = LayoutInflater.                  from(parent.getContext()).                  inflate(R.layout.card_view_xml, parent, false);            return new MyHolder(itemView);        }        @Override      public void onBindViewHolder(MyHolder holder, int position) {            holder.imageView.setImageBitmap(BitmapFactory.decodeResource(resources, R.drawable.drawable));          }        @Override      public int getItemCount() {          return 50;      }    }    

MyHolder (the ViewHolder for a CardView):

  public class MyHolder extends RecyclerView.ViewHolder {        ImageView imageView;        public MyHolder(View v) {          super(v);          imageView = (ImageView) v.findViewById(R.id.imageview);        }  }    

SquareCardView (i use i a modified CardView to make it square; you'll se in the XML-file)

  public class SquareCardView extends android.support.v7.widget.CardView{        public SquareCardView(Context context) {          super(context);      }        @Override public void onMeasure(int widthMeasureSpec, int    heightMeasureSpec)          {          int width = MeasureSpec.getSize(widthMeasureSpec);          int height = MeasureSpec.getSize(heightMeasureSpec);          int size = width > height ? height : width;          setMeasuredDimension(size, size);      }  }    

The XMl-file (here i use the SquareCardView)

  <?xml version="1.0" encoding="utf-8"?>  <com.example.user.s.SquareCardView xmlns:android="http://schemas.android.com/apk/res/android"      xmlns:card_view="http://schemas.android.com/apk/res-auto"      android:layout_width="match_parent"      android:layout_height="match_parent"      android:orientation="vertical"      android:layout_margin="5dp"      android:padding="2dp"      >        <ImageView          android:layout_width="wrap_content"          android:layout_height="wrap_content"          android:id="@+id/imageview"          android:adjustViewBounds="true"          android:scaleType="fitCenter"          android:layout_gravity="center_horizontal"/>    </com.example.user.s.SquareCardView>    

And i get this error:

  android.view.InflateException: Binary XML file line #2: Error inflating class com.example.tobi.zoom_gallery.SquareCardView                                                                                     at android.view.LayoutInflater.createView(LayoutInflater.java:616)                                                                                     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)                                                                                     at android.view.LayoutInflater.inflate(LayoutInflater.java:482)                                                                                     at android.view.LayoutInflater.inflate(LayoutInflater.java:414)                                                                                     at com.example.tobi.zoom_gallery.MyAdapter.onCreateViewHolder(MyAdapter.java:30)                                                                                     at com.example.tobi.zoom_gallery.MyAdapter.onCreateViewHolder(MyAdapter.java:15)    

MyAdapter.java:30 is this piece of code in MyAdapter

  View itemView = LayoutInflater.                  from(parent.getContext()).                  inflate(R.layout.card_view_xml, parent, false);    

.

Please tell me why the Cardview can't be inflaten.