Question

尝试使用自ArrayAdapter派生的类中的自定义ListFragment添加列表视图后，尝试运行应用程序代码时出现错误。

logcat的：

09-12 02:21:27.818  31354-31354/com.example.anas.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.example.anas.myapplication, PID: 31354
    java.lang.NullPointerException
            at com.example.anas.myapplication.adapter.MaalomaListAdapter.getView(MaalomaListAdapter.java:74)

错误在以下行中生成方法getView（）：

viewHolder.ivMaaloma.setImageResource(R.drawable.maaloma_bg_1); 
viewHolder.tvMaaloma.setText(maaloma.getText());

为了更清楚地了解我尝试做什么，这是我的自定义ArrayAdapter课程（我在评论时标记错误行）：

MaalomaListAdapter.java：

public class MaalomaListAdapter extends ArrayAdapter<Maaloma> {

    private Context context;
    private int resource;
    private List<Maaloma> maalomaList;

    public MaalomaListAdapter(Context context, int resource, List<Maaloma> maalomaList) {
        super(context, resource, maalomaList);

        this.context = context;
        this.resource = resource;
        this.maalomaList = maalomaList;
    }

    public static int getResId(String resName, Class<?> c) {

        try {
            Field idField = c.getDeclaredField(resName);
            return idField.getInt(idField);
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        }
    }

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

        ViewHolder viewHolder;

        if(convertView == null) {
            // inflate item layout
            LayoutInflater inflater = ((Activity) this.context).getLayoutInflater();
            convertView = inflater.inflate(this.resource, parent, false);

            // init view holder
            viewHolder = new ViewHolder();
            viewHolder.ivMaaloma = (ImageView) convertView.findViewById(R.id.iv_maaloma_bg);
            viewHolder.tvMaaloma = (TextView) convertView.findViewById(R.id.tv_maaloma);

            convertView.setTag(viewHolder);
        } else {
            // recycling already inflated views
            viewHolder = (ViewHolder) convertView.getTag();
        }

        Maaloma maaloma = maalomaList.get(position);

        //int imageResId = getResId(maaloma.getImage(), Drawable.class);

        /**** ERROR COMES FROM THE FOLLOWING TWO LINES (WHICHEVER WAS FIRST) *****/
        viewHolder.ivMaaloma.setImageResource(R.drawable.maaloma_bg_1); 
        viewHolder.tvMaaloma.setText(maaloma.getText());

        return convertView;

    }

    private static class ViewHolder {
        private ImageView ivMaaloma;
        private TextView tvMaaloma;

    }
}

我认为错误仅存在于此类中，但我已准备好根据请求发布更多代码。感谢时间和精力。

Answer 1

错误期间使用的布局是什么？

您使用的布局可能没有 R.id.iv_maaloma_bg或R.id.tv_maaloma

ListFragment中的自定义ArrayAdapter错误

1 个答案: