安卓可扩展列表视图和SQLite数据库

Question

安卓可扩展列表视图和SQLite数据库

7

我在我的数据库中有两个表 - 房间和设备。每个房间可以有多个设备。我想创建一个可扩展的列表视图，以房间名称作为组名，并将设备名称和状态作为子项（开启或关闭）。

有没有人能给我一个简单的想法，因为我对Android还比较新，而且所有的教程都很难理解。

这是我的数据库：

public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table if not exists rooms (
                                    id_room integer primary key autoincrement, "
                + "name_room text not null" 
                + ");");    
        db.execSQL("create table if not exists devices (
                                    id_device integer primary key autoincrement, "
                + "name_device text not null," 
                + "state_device text not null,"
                + "id_room references rooms"
                + ");");
    }

- hamzarh

1个回答

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- Barak · Accepted Answer

以下是一个非常简单、没有花哨的可扩展列表实现。

你需要在数据库助手类中编写两个方法来获取所需的游标。

public Cursor fetchGroup() {
    String query = "SELECT * FROM rooms"
    return mDb.rawQuery(query, null);
}

public Cursor fetchChildren(String room) {
    String query = "SELECT * FROM devices WHERE id_room = '" + room + "'";
    return mDb.rawQuery(query, null);
}

然后你需要在你的Activity中设置适配器：

public class MyExpandableListAdapter extends SimpleCursorTreeAdapter {
    public MyExpandableListAdapter(Cursor cursor, Context context,int groupLayout, 
        int childLayout, String[] groupFrom, int[] groupTo, String[] childrenFrom, 
        int[] childrenTo) {
            super(context, cursor, groupLayout, groupFrom, groupTo,
                  childLayout, childrenFrom, childrenTo);
        }
    }

    @Override
    protected Cursor getChildrenCursor(Cursor groupCursor) {
        Cursor childCursor = mDbHelper.fetchChildren(groupCursor.getString(groupCursor.getColumnIndex("id_room"));            
        getActivity().startManagingCursor(childCursor);
        childCursor.moveToFirst();
        return childCursor;
    }
}

最后，在您的活动中调用适配器并将其设置为列表：

private void fillData() {
    mGroupsCursor = mDbHelper.fetchGroup();
    getActivity().startManagingCursor(mGroupsCursor);
    mGroupsCursor.moveToFirst();

    ExpandableListView elv = (ExpandableListView) getActivity().findViewById(android.R.id.list);

    mAdapter = new MyExpandableListAdapter(mGroupsCursor, getActivity(),
        R.layout.rowlayout_expgroup,                     // Your row layout for a group
        R.layout.rowlayout_itemlist_exp,                 // Your row layout for a child
        new String[] { "id_room" },                      // Field(s) to use from group cursor
        new int[] { android.R.id.room },                 // Widget ids to put group data into
        new String[] { "name_device", "state_device" },  // Field(s) to use from child cursors
        new int[] { R.id.device, R.id.state });          // Widget ids to put child data into

        lv.setAdapter(mAdapter);                         // set the list adapter.
    }
}

希望这能有所帮助！

编辑

应该像下面这样全部组合起来：

public class List_Exp extends Activity {
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        mDbHelper = new YourDB(getActivity());
        mDbHelper.open();
        fillData();
    }

    private void fillData() { 
        // set list adapter here
    }

    public class MyExpandableListAdapter extends SimpleCursorTreeAdapter {
        // Your adapter
    }
}

编辑2

要捕获点击事件，需要在您的活动中设置监听器：

lv.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
    @Override
    public boolean onChildClick(ExpandableListView parent, View v,
        int groupPosition, int childPosition, long id) {
        // Your child click code here
        return true;
    }
});

lv.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
    @Override
    public boolean onGroupClick(ExpandableListView parent, View v,
        int groupPosition, int groupPosition, long id) {
        // Your group click code here
        return true;
    }
});