数据未在gridView Android中显示

我想加载要显示在gridView中的数据。

它运行没有任何错误。但是，屏幕保持空白，并且不会显示gridView。

这是我的代码

MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    fragment f = new fragment();
    FragmentManager manager = getSupportFragmentManager();
    FragmentTransaction transaction = manager.beginTransaction();
    transaction.add(R.id.main_id,f).commit();

}

fragment.java

public class fragment extends Fragment {

    public final String [] Names={"Ahmed","Ahmed1","Ahmed2","Ahmed3","Ahmed4","Ahmed5","Ahmed6","Ahmed7","Ahmed8"};
    public final int [] Images={R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,R.drawable.e,R.drawable.f,R.drawable.g,R.drawable.h};
    private CustomAdapter c;
    private GridView g;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view =  inflater.inflate(R.layout.fragment_fragment, container, false);
        c= new CustomAdapter(getActivity().getApplicationContext(),Names,Images);

        g=(GridView) view.findViewById(R.id.gridview);

        g.setAdapter(c);

        g.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                Toast.makeText(getActivity().getApplicationContext(), "You Clicked at " + Names[+position], Toast.LENGTH_SHORT).show();

            }
        });

        return view;
    }

定制适配器

public class CustomAdapter extends BaseAdapter {

    private Context context;
    private String[] Values;
    private int[] imageIds;

    public CustomAdapter(Context c, String[] Values, int[] imageIds) {
        this.context = c;
        this.Values = Values;
        this.imageIds = imageIds;
    }


    @Override
    public int getCount() {
        return 0;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View grid;

            if(convertView==null) {
                grid= new View (context);
                grid = inflater.inflate(R.layout.item, null);
                TextView textView = (TextView) grid.findViewById(R.id.itemName);
                ImageView imageView = (ImageView) grid.findViewById(R.id.itemImage);
                textView.setText(Values[position]);
                imageView.setImageResource(imageIds[position]);
            }
            else {
                grid = (View) convertView;
            }

        return grid;
    }
}

fragment_fragment.xml

<GridView
        android:numColumns="auto_fit"
        android:gravity="center"
        android:columnWidth="100dp"
        android:stretchMode="columnWidth"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/gridview"
        />

item.xml

 <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:id="@+id/itemImage"
        android:src="@drawable/a"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="item"
        android:id="@+id/itemName"
        android:layout_marginStart="10dp"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="10dp"
        />