Accessing XML Image Array within an ImageAdapter

问题:

My question is very similar to this thread, however it was never properly answered. I have an ImageAdapter setup as so;

public class ImageAdapter extends BaseAdapter {
    private Context mContext;
    int[] mImages;

    public ImageAdapter(Context c, int[] images) {
        mContext = c;
        mImages = images;
    }

    @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) {
        ImageView imageView;
        if (convertView == null) {
            // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(200, 200));
        } else {
            imageView = (ImageView) convertView;
        }
        imageView.setImageResource(mImages[position]);
        return imageView;
    }
}

And I want the images to be from an XML;

<integer-array name="images">
    <item>@drawable/image1</item>
    <item>@drawable/image2</item>
    <item>@drawable/image3</item>
</integer-array>

In my MainActivity class I have tried to get the image array and pass it into the ImageAdapter but I can't;

public class MainActivity extends AppCompatActivity {
    private int images[] = getResources().getIntArray(R.array.images);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        GridView gridview = (GridView) findViewById(R.id.gridView);
        gridview.setAdapter(new ImageAdapter(MainActivity.this, images));
    }
}

I am currently getting an error message:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference

with my app crashing on load up. I want to make my ImageAdapter display images from an XML in my GridView.

回答1:

try to use

 private int images[] = {R.drawable.image1, R.drawable.image3, R.drawable.image3};

instead of

 private int images[] = getResources().getIntArray(R.array.images);