android - 如何实现微调器的MatrixCursor？

我有一个SQLite查询，返回一个Cursor。我想通过实现Cursor向MatrixCursor添加一些额外的行（以防止单击时自动选择真实数据的第一项）。然后，我想将它们映射到SimpleCursorAdapter。我一直在阅读帖子（和代码），但仍然对如何将其编码为下面列出的现有代码感到困惑。

    Cursor cursor = myDB.query(DATABASE_TABLE_NAME, resultColumns, whereClause,
            whereArgs, null, null, null, null);

    // Create Spinner View object from layout resource
    Spinner spinner = (Spinner) findViewById(R.id.spinner);

    SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
            android.R.layout.simple_spinner_item, // Use a template
                                                  // that displays a
                                                  // text view
            cursor, // Give the cursor to the adapter
            new String[] {"ename"}, // Map the NAME column in the
                                                 // people database to...
            new int[] {android.R.id.text1});

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
    spinner.setOnItemSelectedListener(new MyOnItemSelectedListener());

最佳答案

如果要从简单的MatrixCursor构建Cursor，则必须解析整个初始的Cursor并追加所需的行：

//...
    MatrixCursor mc = new MatrixCursor(resultColumns);
    // add extra rows, this will probably not work if you want to insert them
    // between the initial cursor rows because of the _id column that need autoincrement values
    mc.addRow(new Object[] { new Long(-2), "Extra name1" });
    mc.addRow(new Object[] { new Long(-1), "Extra name2" });
    // I don't know what your cursor holds, I assumed you have the _id column(long value)
    // and a name(String value)
    int size = cursor.getCount();
    for (int i = 0; i < size; i++) {
        cursor.moveToPosition(i);
            mc.addRow(new Object[] {
            cursor.getLong(cursor.getColumnIndex(/*the _id column*/)),
            cursor.getString(cursor.getColumnIndex(/* the name column(ename?!?)*/)) });
    }
    SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
            android.R.layout.simple_spinner_item, mc, new String[] {"ename"}, new int[] {android.R.id.text1});
//...

如果这样做只是为了避免在显示OnItemSelectedListener时触发Spinner，也许您可​​以采用另一种方法。例如，在您的听众中：

    //boolean status = true; flag in MyOnItemSelectedListener

    @Override
    public void onItemSelected(AdapterView<?> parent, View view,
            int position, long id) {
        if (status) {
            status = false;// this is the first listener trigger so you probably want to ignore it
            return;
        }
        // do stuff here
    }

注意：我不知道上述解决方案有多好。如果您看一下，此Spinner相关问题可能有更好的解决方案。