问题
I'm trying to make an ActionBar spinner that has separators. I have implemented a SpinnerAdapter that has 2 item view types (thanks to getViewTypeCount). The problem is that I'm being sent some convertViews from the other type.
Here's my SpinnerAdapter:
public abstract class SeparatorSpinnerAdapter implements SpinnerAdapter {
Context mContext;
List<Object> mData;
int mSeparatorLayoutResId, mActionBarItemLayoutResId, mDropDownItemLayoutResId, mTextViewResId;
public static class SpinnerSeparator {
public int separatorTextResId;
public SpinnerSeparator(final int resId) {
separatorTextResId = resId;
}
}
public abstract String getText(int position);
public SeparatorSpinnerAdapter(final Context ctx, final List<Object> data, final int separatorLayoutResId, final int actionBarItemLayoutResId,
final int dropDownItemLayoutResId, final int textViewResId) {
mContext = ctx;
mData = data;
mSeparatorLayoutResId = separatorLayoutResId;
mActionBarItemLayoutResId = actionBarItemLayoutResId;
mDropDownItemLayoutResId = dropDownItemLayoutResId;
mTextViewResId = textViewResId;
}
protected String getString(final int resId) {
return mContext.getString(resId);
}
@Override
public void registerDataSetObserver(final DataSetObserver observer) {
}
@Override
public void unregisterDataSetObserver(final DataSetObserver observer) {
}
@Override
public int getCount() {
if (mData != null) {
return mData.size();
}
return 0;
}
@Override
public Object getItem(final int position) {
return mData == null ? null : mData.get(position);
}
@Override
public boolean isEmpty() {
return getCount() == 0;
}
@Override
public long getItemId(final int position) {
return 0;
}
@Override
public boolean hasStableIds() {
return false;
}
@Override
public View getView(final int position, final View convertView, final ViewGroup parent) {
return getView(mActionBarItemLayoutResId, position, convertView, parent);
}
public boolean isSeparator(final int position) {
final Object item = getItem(position);
if (item != null) {
return item instanceof SpinnerSeparator;
}
return false;
}
@Override
public int getItemViewType(final int position) {
return isSeparator(position) ? 0 : 1;
}
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public View getDropDownView(final int position, final View convertView, final ViewGroup parent) {
return getView(isSeparator(position) ? mSeparatorLayoutResId : mDropDownItemLayoutResId, position, convertView, parent);
}
private View getView(final int layoutResId, final int position, final View convertView, final ViewGroup parent) {
View v;
Log.i("TAG", "getView #" + position + "\tVT=" + getItemViewType(position) + "\tCV="
+ (convertView == null ? " null " : convertView.getClass().getSimpleName()) + "\ttext=> " + getText(position));
if (convertView == null) {
final LayoutInflater li = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = li.inflate(layoutResId, parent, false);
} else {
v = convertView;
}
final TextView tv = (TextView) v.findViewById(mTextViewResId);
if (tv != null) {
tv.setText(getText(position));
if (isSeparator(position)) {
tv.setOnClickListener(null);
tv.setOnTouchListener(null);
}
}
return v;
}
}
One implementation:
public class IssuesMainFilterAdapter extends SeparatorSpinnerAdapter {
public IssuesMainFilterAdapter(final Context ctx, final List<Query> queries, final List<Project> projects) {
super(ctx, buildDataArray(queries, projects), R.layout.issues_filter_spinner_separator, R.layout.issues_filter_spinner_in_actionbar,
R.layout.issues_filter_spinner, R.id.issues_filter_spinner_text);
}
private static List<Object> buildDataArray(final List<Query> queries, final List<Project> projects) {
final List<Object> data = new ArrayList<Object>();
data.add(null); // "ALL"
data.add(new SpinnerSeparator(R.string.issue_filter_queries));
data.addAll(queries);
data.add(new SpinnerSeparator(R.string.issue_filter_projects));
data.addAll(projects);
return data;
}
@Override
public String getText(final int position) {
final Object item = getItem(position);
if (item == null) {
return getString(R.string.issue_filter_all);
} else if (item instanceof Query) {
return ((Query) item).name;
} else if (item instanceof Project) {
return ((Project) item).name;
} else if (item instanceof SpinnerSeparator) {
return getString(((SpinnerSeparator) item).separatorTextResId);
}
throw new InvalidParameterException("Item has unknown type: " + item);
}
}
As you may have noticed, I have set a log line into getView() so that I better understand what's going on:
05-06 14:01:28.721 I/TAG( 5879): getView #0 VT=1 CV=TextView text=> ####
05-06 14:01:28.721 I/TAG( 5879): getView #1 VT=0 CV=LinearLayout text=> ####
05-06 14:01:28.729 I/TAG( 5879): getView #2 VT=1 CV=TextView text=> ####
05-06 14:01:28.745 I/TAG( 5879): getView #3 VT=1 CV=TextView text=> ####
05-06 14:01:28.745 I/TAG( 5879): getView #4 VT=0 CV=LinearLayout text=> ####
05-06 14:01:28.745 I/TAG( 5879): getView #5 VT=1 CV=TextView text=> ####
05-06 14:01:28.753 I/TAG( 5879): getView #6 VT=1 CV=TextView text=> ####
05-06 14:01:28.768 I/TAG( 5879): getView #7 VT=1 CV=TextView text=> ####
05-06 14:01:28.768 I/TAG( 5879): getView #8 VT=1 CV=TextView text=> ####
05-06 14:01:28.768 I/TAG( 5879): getView #9 VT=1 CV=TextView text=> ####
05-06 14:01:28.776 I/TAG( 5879): getView #10 VT=1 CV=TextView text=> ####
05-06 14:01:28.792 I/TAG( 5879): getView #11 VT=1 CV=TextView text=> ####
05-06 14:01:32.081 I/TAG( 5879): getView #12 VT=1 CV=TextView text=> ####
05-06 14:01:34.690 I/TAG( 5879): getView #13 VT=1 CV=LinearLayout text=> ####
05-06 14:01:35.573 I/TAG( 5879): getView #14 VT=1 CV=TextView text=> ####
05-06 14:01:37.237 I/TAG( 5879): getView #15 VT=1 CV=TextView text=> ####
As you may have understood, my layouts for the real items are TextViews, and the separator layout is a LinearLayout.
As you can see, a "real" item (VT=1 in the log, see item #13) is being recycling a separator view (CV=LinearLayout). I would have thought that Android would provide a convertView of the same type, so the first separator would be recycled only if a view of the same type (i.e. another separator) would have to be created when scrolling.
回答1:
As David found out, this is related to the Android framework. As noted here, the framework doesn't expect Spinners to have different view types.
This is the workaround I used to make my SpinnerAdapter work as I wanted:
- store the view type in the view's tag;
- inflate a new layout if there is no view to convert OR if the current view type differs from the view to convert from.
Here's the code of my custom getView method:
private View getView(final int layoutResId, final int position, final View convertView, final ViewGroup parent) {
View v;
if (convertView == null || (Integer)convertView.getTag() != getItemViewType(position)) {
final LayoutInflater li = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = li.inflate(layoutResId, parent, false);
} else {
v = convertView;
}
v.setTag(Integer.valueOf(getItemViewType(position)));
final TextView tv = (TextView) v.findViewById(mTextViewResId);
if (tv != null) {
tv.setText(getText(position));
if (isSeparator(position)) {
tv.setOnClickListener(null);
tv.setOnTouchListener(null);
}
}
return v;
}
回答2:
The problem is here:
public View getView(final int position, final View convertView, final ViewGroup parent) {
return getView(mActionBarItemLayoutResId, position, convertView, parent);
}
This method will always return the same View type, whether called for a separator or a data item. You need to check the position here and return an appropriate view.
来源：https://stackoverflow.com/questions/16398468/why-is-android-recycling-the-wrong-view-type-in-my-spinneradapter