android - 交互式 ListView

Question

我试图在不扩展 ListActivity 类的情况下创建交互式 ListView。布局应该是左侧的 RatingBar 和标签向右。这是我目前的代码，没有任何编译错误，但在应用程序启动时崩溃:

public class ProDroid_BAActivity extends Activity {
    private static final String[] items = { "lorem", "ipsum", "dolor", "sit",
        "amet", "consectetuer", "adipiscing", "elit", "morbi", "vel",
        "ligula", "vitae", "arcu", "aliquet", "mollis", "etiam", "vel",
        "erat", "placerat", "ante", "porttitor", "sodales", "pellentesque",
        "augue", "purus" };

ListView listv = (ListView) findViewById(R.id.listView1);
ArrayAdapter<RowModel> adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ArrayList<RowModel> list = new ArrayList<RowModel>();
    for (String s : items) {
        list.add(new RowModel(s));
    }

    adapter = new RatingAdapter(list);
    listv.setAdapter(adapter);

}

private RowModel getModel(int position) {
    return adapter.getItem(position);
}

class RatingAdapter extends ArrayAdapter<RowModel> {

    public RatingAdapter(ArrayList<RowModel> list) {
        super(ProDroid_BAActivity.this, R.layout.row, R.id.label, list);

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = super.getView(position, convertView, parent);

        ViewHolder holder = (ViewHolder) row.getTag();
        if (holder == null) {
            holder = new ViewHolder(row);
            row.setTag(holder);

            RatingBar.OnRatingBarChangeListener l = new RatingBar.OnRatingBarChangeListener() {
                public void onRatingChanged(RatingBar ratingBar,
                        float rating, boolean fromTouch) {
                    Integer myPosition = (Integer) ratingBar.getTag();
                    RowModel model = getModel(myPosition);

                    model.rating = rating;

                    LinearLayout parent = (LinearLayout) ratingBar
                            .getParent();
                    TextView label = (TextView) parent
                            .findViewById(R.id.label);

                    label.setText(model.toString());
                }
            };

            holder.rate.setOnRatingBarChangeListener(l);



        }

        RowModel model = getModel(position);

        holder.rate.setTag(new Integer(position));
        // holder.text.setTag(new Integer(position));
        holder.rate.setRating(model.rating);
        // holder.text.setText(model.label);

        return row;
    }

}

class RowModel {
    String label;
    float rating = 2.0f;

    RowModel(String label) {
        this.label = label;
    }

    public String toString() {
        if (rating >= 3.0) {
            return (label.toUpperCase());
        }

        return (label);
    }
}
 }

Answer 1

移动线:

ListView listv = (ListView) findViewById(R.id.listView1);

在设置内容 View 后的 onCreate() 方法中。