Question

我有一个由颜色数组填充的自定义GridView。现在，当我点击该项目时，我想获得单元格的颜色。我有这个代码，但是当我单击该项时，获取java.lang.NullPointerException。

public class Colori_picker extends Activity {
private GridView grColori;
private ColorPickerAdapter mAdapter;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.color_picker);

    grColori= (GridView) findViewById(R.id.gridViewColors);
    grColori.setAdapter(new ColorPickerAdapter(this));


    grColori.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Object color = mAdapter.getItem(position);

             finish();
        }
    });
}

适配器

public class ColorPickerAdapter extends BaseAdapter {

private Context context;
// list which holds the colors to be displayed
private List<Integer> colorList = new ArrayList<Integer>();
// width of grid column
int colorGridColumnWidth;

public ColorPickerAdapter(Context context) {
    this.context = context;

    String colors[][] = {
            { "83334C", "B65775", "E07798", "F7A7C0", "FBC8D9", "FCDEE8" },
            { "000000", "434343", "666666", "999999", "CCCCCC", "EFEFEF" } };

    colorList = new ArrayList<Integer>();

    // add the color array to the list
    for (int i = 0; i < colors.length; i++) {
        for (int j = 0; j < colors[i].length; j++) {
            colorList.add(Color.parseColor("#" + colors[i][j]));
        }
    }
}

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;


    if (convertView == null) {
        imageView = new ImageView(context);
        // set the width of each color square
        imageView.setLayoutParams(new GridView.LayoutParams(colorGridColumnWidth, colorGridColumnWidth));

    } else {
        imageView = (ImageView) convertView;
    }

    imageView.setBackgroundColor(colorList.get(position));
    imageView.setId(position);

    return imageView;
}

public int getCount() {
    return colorList.size();
}

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

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

}

Answer 1

发生的事情是您声明了实例变量mAdapter但从未实例化它。您需要做的就是改变这个

grColori.setAdapter(new ColorPickerAdapter(this));

到此

mAdapter = new ColorPickerAdapter(this);
grColori.setAdapter(mAdapter);

Android GridView getItem颜色

1 个答案: