Question

我是Android新手，目前想要创建一个片段来显示gridview布局。但是我无法显示图片并返回以下错误：

      java.lang.NullPointerException
      at miui.util.AttributeResolver.i(SourceFile:35)
      at miui.util.AttributeResolver.resolveInt(SourceFile:145)
      at miui.util.AttributeResolver.isUsingMiuiTheme(SourceFile:179)
      at miui.os.Environment.isUsingMiui(SourceFile:99)
      at android.view.ViewConfigurationInjector.get(ViewConfigurationInjector.java:18)
      at android.view.ViewConfigurationHelper.get(ViewConfigurationHelper.java:10)
      at android.view.ViewConfiguration.get(ViewConfiguration.java:357)
      at android.view.View.<init>(View.java:3452)
      at android.widget.ImageView.<init>(ImageView.java:114)
      at info.androidhive.slidingmenu.GridViewAdapter.getView(GridViewAdapter.java:52)
      at android.widget.AbsListView.obtainView(AbsListView.java:2257)

下面是我的片段代码

public class HomeFragment扩展了Fragment {

public HomeFragment(){}
private GridViewAdapter adapter;
private GridView gridView;
private int columnWidth;
private Utils utils;
private PrefManager pref;
private Integer[] photosList;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {


    View rootView = inflater.inflate(R.layout.fragment_home, container, false);
    gridView = (GridView) rootView.findViewById(R.id.grid_view);
    gridView.setVisibility(View.VISIBLE);
    gridView.setAdapter(new GridViewAdapter(getActivity()));
    return rootView;
}

}

以下是我的gridview适配器代码

public class GridViewAdapter extends BaseAdapter {

    private Activity _activity;
    private LayoutInflater inflater;
    private int imageWidth;
    private Context context;

    public GridViewAdapter(Activity activity) {
        this._activity=activity;

    }

    @Override
    public int getCount() {
        return this.photoList.length;
    }

    @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 (inflater == null)
            inflater = (LayoutInflater) _activity
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.grid_item_photo, null);
            imageView = new ImageView(context);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        }
        else {
            imageView = (ImageView) convertView;
        }
        imageView.setImageResource(photoList[position]);
        return imageView;
    }

    public Integer[] photoList = {

            R.drawable.ic_whats_hot, R.drawable.ic_home,
            R.drawable.ic_launcher, R.drawable.ic_communities,
            R.drawable.ic_people, R.drawable.ic_whats_hot
    };
}

错误行显示从上下文获取图像时我的行有问题，可能会建议吗？

imageView = new ImageView(context);

Answer 1

您的上下文对象为null。因为你有活动的背景。所以使用这个

imageView = new ImageView(_activity);

Answer 2

由于您的上下文返回null，我们需要提供一个非null的参数。一些提供上下文的常见类是Activity，Application，Service和View。在第9行中，初始化一个Activity对象_activity。

由于此对象具有上下文，因此您可以使用它来代替“上下文”。

imageView = new ImageView(_activity);

Answer 3

您正在使用未初始化的上下文。

请使用从HomeFragment通过GridViewAdapter解析的_activity。

错误是你的＆＃34; context＆＃34;从未在GridViewAdapter中初始化。

替换为imageView = new ImageView(_activity);

无法使用片段在Gridview中显示图像

3 个答案: