Question

我有一个包含多列的SQLite数据库，其中一列是日期。我想将数据库中的数据填充到可扩展的列表视图中，并将日期作为标题。因此，对于共享相同日期值的所有行，我希望将它们显示为该特定日期的子项。

我使用arraylist来存储数据库中的数据。我得到了组标题，但是当我尝试扩展时，我得到空指针异常。该错误来自getChildView方法。

public class MyExpandableListAdapter extends BaseExpandableListAdapter {

    public Object getChild(int groupPosition, int childPosition) {
        return infoList.get(groupPosition).get(childPosition);
    }

    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        RelativeLayout infoLayout = (RelativeLayout) findViewById(R.id.infoLayout);
        String exercise = ((ArrayList<Object>) getChild(groupPosition, childPosition)).get(0).toString();
        String weight = ((ArrayList<Object>) getChild(groupPosition, childPosition)).get(1).toString();
        String reps = ((ArrayList<Object>) getChild(groupPosition, childPosition)).get(2).toString();
        ((TextView) infoLayout.findViewById(R.id.exercise)).setText(exercise);
        ((TextView) infoLayout.findViewById(R.id.weight)).setText(weight);
        ((TextView) infoLayout.findViewById(R.id.reps)).setText(reps);


        return infoLayout;
    }

    public int getChildrenCount(int groupPosition) {
        return infoList.get(groupPosition).size();
    }

    public Object getGroup(int groupPosition) {
        return dateList.get(groupPosition);
    }

    public int getGroupCount() {
        return dateList.size();
    }

    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        TextView dateView = new TextView(getApplicationContext());
        dateView.setText(getGroup(groupPosition).toString());
        return dateView;
    }

    public boolean hasStableIds() {
        return false;
    }

    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

这就是我填充arraylists的方式。包含子项的arraylist嵌套两次：最里面包含3个要显示在同一行上的对象，“middle”将最里面的arraylists组合在一起，以便它们出现在可扩展列表视图的正确分组下。

private DatabaseMethods dbm;
private ArrayList<String> dateList = new ArrayList<String>();
private ArrayList<ArrayList<ArrayList<Object>>> infoList = new ArrayList<ArrayList<ArrayList<Object>>>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.stats);
    dbm = new DatabaseMethods(this);
    dbm.read();
    Cursor dates = dbm.fetchGroup();
    int DATES_INDEX = dates.getColumnIndexOrThrow("date");
    while (dates.moveToNext()) {
        String date = dates.getString(DATES_INDEX);
        if (!dateList.contains(date)) {
            dateList.add(date);
        }
    }
    for (String date : dateList) {
        Cursor info = dbm.fetchChildren(date);
        int EXERCISE_INDEX = info.getColumnIndexOrThrow("exercise");
        int WEIGHT_INDEX = info.getColumnIndexOrThrow("weight");
        int REPS_INDEX = info.getColumnIndexOrThrow("reps");
        ArrayList<ArrayList<Object>> secondInnerInfoList = new ArrayList<ArrayList<Object>>();
        while (info.moveToNext()) {
            String exercise = info.getString(EXERCISE_INDEX);
            int weight = info.getInt(WEIGHT_INDEX);
            int reps = info.getInt(REPS_INDEX);
            ArrayList<Object> thirdInnerInfoList = new ArrayList<Object>();
            thirdInnerInfoList.add(exercise);
            thirdInnerInfoList.add(weight);
            thirdInnerInfoList.add(reps);
            secondInnerInfoList.add(thirdInnerInfoList);
        infoList.add(secondInnerInfoList);
        }

    }

Answer 1

编写一个方法来获取数据并将其转换为ArrayList或数组字符串。
在您的Activity声明和ArrayAdapter的init数据中，如： ArrayAdapter mAdapter = new ArrayAdapter（getApplicationContext（），android.R.layout.simple_list_item_1，yourArrayListOrArray）;
ListView.setAdapter（mAdapter）;

Answer 2

对于使用sqlite数据库的可扩展listview：您可以使用CursorTreeAdapter而不是使用BaseExpandablelistAdapter。这将很容易让您完成任务。请参考以下链接：

http://developer.android.com/reference/android/widget/CursorTreeAdapter.html

Answer 3

public View getChildView(int parentPosition, int childPosition, boolean isLastChild, View convertView,
        ViewGroup parent) {
    // TODO Auto-generated method stub


    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.child_view_list, null);
    }
    final String abc = (String) getChild(parentPosition, childPosition);

    TextView status_tv = (TextView) convertView
            .findViewById(R.id.child_tv);
    status_tv.setText(abc);

    //ImageView imgListChild=(ImageView) convertView.findViewById(R.id.child_iv);


    //imgListChild.set
    return convertView;
}

使用SQLite数据库的可扩展ListView

3 个答案: