【发布时间】：2013-03-26 18:27:50
【问题描述】：
我正在开发一个应用程序，其中我需要一个 ListView，它的行有一个 TextView、2 个 CheckBox 和一个 Spinner。
但是，我遇到了 Spinner 的 onItemSelected() 的问题，因为每次显示每一行时都会调用它。在这种方法中，我使用所选选项更新数据库记录，但由于 Android 会自动调用它，每次项目都会重置，因为 Android 使用位置 0 调用它，这是数据库中更新的值。
我已经阅读了很多关于onItemSelected() 问题的链接和一些技巧，但所有这些链接都是在没有 ListView 的情况下使用的。这里有什么要点吗？
我试图在列表中跟踪实际显示哪些位置以使其工作，但它没有。我认为这是因为 Android 中的回收导致调用了已显示的 Spinners 的故障排除方法！
所以重点是：我如何区分对onItemSelected() 的真实调用，因为在显示 Spinner 时用户选择了 Android 调用？
这是我扩展 SimpleCursorAdapter 的适配器的代码。
非常感谢您。
public ParticipationAdapter(Context context, int layout, Cursor c, String[] from, int[] to) {
super(context, layout, c, from, to);
mActivity = (Activity)context;
ParticipationComment.ParticipationCommentManager commentManager = new ParticipationComment.ParticipationCommentManager(mActivity);
mParticipationCommentsCursor = commentManager.get();
mActivity.startManagingCursor(mParticipationCommentsCursor);
commentManager.detach();
mPositionsOfCursorIds = getPositionsOfCursorIds(mParticipationCommentsCursor);
mSpinnerPositionsDisplayed = new ArrayList<Integer>();
}
@Override
public View getView(final int participationPosition, View convertView, ViewGroup parent) {
final Cursor participationsCursor = getCursor();
mActivity.startManagingCursor(participationsCursor);
participationsCursor.moveToPosition(participationPosition);
View participationRow;
if (convertView == null) {
participationRow = LayoutInflater.from(mActivity).inflate(R.layout.participation_row_student, null);
} else {
mSpinnerPositionsDisplayed.remove((Integer)convertView.getTag());
participationRow = convertView;
}
participationRow.setTag(participationPosition);
Spinner commentSpinner = (Spinner)participationRow.findViewById(R.id.participation_comment_id_spinner);
SimpleCursorAdapter commentSpinnerAdapter = new SimpleCursorAdapter(
mActivity,
android.R.layout.simple_spinner_item,
mParticipationCommentsCursor,
new String[] {DatabaseManager.NAME},
new int[] {android.R.id.text1}
);
commentSpinnerAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
commentSpinner.setAdapter(commentSpinnerAdapter);
long participationCommentId = participationsCursor.getLong(participationsCursor.getColumnIndex(DatabaseManager.PARTICIPATION_COMMENT_ID));
if (participationCommentId != 0) {
commentSpinner.setSelection(mPositionsOfCursorIds.get(participationCommentId));
}
commentSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
participationsCursor.moveToPosition(participationPosition);
if (!mSpinnerPositionsDisplayed.contains(participationPosition)) {
// Android calls this method the first time a Spinner is displayed,
// to differentiate from a real user click we check if the current Spinner's position
// in the ListView is being shown
mSpinnerPositionsDisplayed.add(participationPosition);
} else {
ParticipationComment participationComment = new ParticipationComment((Cursor)parent.getItemAtPosition(position));
Participation.ParticipationManager participationManager = new Participation.ParticipationManager(mActivity);
Participation participation = new Participation(participationsCursor);
participation.setConnectionProfileParticipationCommentId(participationComment.getConnectionProfileId());
participation.setParticipationCommentId(participationComment.getIdOpenErp());
participation.setChanged(true);
participationManager.update(participation);
participationManager.detach();
}
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
// Not used
}
});
TextView studentName = (TextView)participationRow.findViewById(R.id.participation_student_name);
studentName.setText(participationsCursor.getString(participationsCursor.getColumnIndex(DatabaseManager.NAME)));
CheckBox expectedPresent = (CheckBox)participationRow.findViewById(R.id.participation_expected_present_value);
expectedPresent.setChecked(participationsCursor.getInt(participationsCursor.getColumnIndex(DatabaseManager.EXPECTED_PRESENT)) == 1);
CheckBox present = (CheckBox)participationRow.findViewById(R.id.participation_present_value);
present.setChecked(participationsCursor.getInt(participationsCursor.getColumnIndex(DatabaseManager.PRESENT)) == 1);
return participationRow;
}
【问题讨论】：