Setting ListView item checked from Adapter

Question

I have a ListView which displays 2 kinds of items. One of these kinds contains CheckedTextView. As an adapter I'm using custom adapter extending ArrayAdapter with data structure containing information about checked/unchecked states inside.

Some of the items are marked as selected (in my data structure) so of course I'd like the checkboxes to be marked when the ListView is created. I tried to do it on getView() method in adapter with CheckedTextView's setChecked() method but it doesn't work. I found information that it should be done on a ListView level with setItemChecked() and it does work but it doesn't make sense to me because to make it work I would have to loop all items in activity's onCreate() calling setItemChecked() for those selected. The list of items may be very long with only a few of them selected so it's a waste.

Why calling setChecked() in getView() isn't working? Is there a better way of doing this (I'm an Android newbie).

Below you have my checked item layout and the adapter.

Layout:

<?xml version="1.0" encoding="utf-8"?>
<CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="fill_parent"
    android:layout_height="?android:attr/listPreferredItemHeight"
    android:gravity="center_vertical"
    android:textAppearance="@style/listViewItemText"
    android:checkMark="?android:attr/listChoiceIndicatorMultiple"
    android:paddingLeft="6dp"
    android:paddingRight="6dp"
/>

Adapter:

package com.melog.re.droid.search;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.os.Parcel;
import android.os.Parcelable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckedTextView;
import android.widget.TextView;

import com.melog.re.droid.core.R;
import com.melog.re.droid.search.MultiCriterionValue.MultiCriterionSingleValue;
import com.melog.re.droid.search.MultiListAdapter.MultiChoiceItem;

public class MultiListAdapter extends ArrayAdapter<MultiChoiceItem> {
    private static final int VIEW_TYPES_COUNT = 2;

    public static final int VIEW_TYPE_GROUP = 0;
    public static final int VIEW_TYPE_ITEM = 1;

    private LayoutInflater mInflater;

    public MultiListAdapter(Context context, int textViewResourceId, List<MultiChoiceItem> objects) {
        super(context, textViewResourceId, objects);
        mInflater = LayoutInflater.from(context);
    }

    @Override
    public int getItemViewType(int position) {
        MultiChoiceItem item = getItem(position);
        return (item.children.size() == 0) ? VIEW_TYPE_ITEM : VIEW_TYPE_GROUP;
    }

    @Override
    public int getViewTypeCount() {
        return VIEW_TYPES_COUNT;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO: optymalizacja ViewHolder
        MultiChoiceItem item = getItem(position);
        int viewType = getItemViewType(position);
        switch (viewType) {
        case VIEW_TYPE_GROUP:
            if (convertView == null) {
                convertView = mInflater.inflate(R.layout.multi_choice_group_item, parent, false);
            }
            TextView groupLabel = (TextView) convertView.findViewById(android.R.id.text1);
            groupLabel.setText(item.toString());
            break;
        case VIEW_TYPE_ITEM:
            if (convertView == null) {
                convertView = mInflater.inflate(R.layout.multi_choice_child_item, parent, false);
            }
            CheckedTextView itemLabel = (CheckedTextView) convertView.findViewById(android.R.id.text1);
            itemLabel.setText(item.toString());
            itemLabel.setChecked(item.selected);
            break;
        }

        return convertView;
    }

    public static class MultiChoiceItem implements Parcelable {
        public static final int CONTENTS_DESCR = 1;

        public String label;
        public String value;
        public boolean selected = false;
        public ArrayList<MultiChoiceItem> children = new ArrayList<MultiChoiceItem>();

        public MultiChoiceItem(String l, String v, boolean sel) {
            label = l;
            value = v;
            selected = sel;
        }
        public MultiChoiceItem(MultiCriterionSingleValue v) {
            label = v.toString();
            value = v.value;
        }
        public MultiChoiceItem(Parcel in) {
            label = in.readString();
            value = in.readString();
            selected = (in.readInt() == 1);
        }
        @Override
        public String toString() {
            return label;
        }
        @Override
        public int describeContents() {
            return CONTENTS_DESCR;
        }
        @Override
        public void writeToParcel(Parcel dest, int flags) {
            dest.writeString(label);
            dest.writeString(value);
            dest.writeInt(selected ? 1 : 0);
        }

        public static final Parcelable.Creator<MultiChoiceItem> CREATOR = new Parcelable.Creator<MultiChoiceItem>() {
            public MultiChoiceItem createFromParcel(Parcel in) {
                return new MultiChoiceItem(in);
            }

            public MultiChoiceItem[] newArray(int size) {
                return new MultiChoiceItem[size];
            }
        };
}
}

And a piece of activity's onCreate()

...     
mAdapter = new MultiListAdapter(this, R.id.head, mItems);
setListAdapter(mAdapter);

final ListView listView = getListView();
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
listView.setItemsCanFocus(false);
...

Edit:

Until finding a better solution I implemented the checking in the Activity:

...
int len = mListView.getCount();
for (int i = 0; i < len; i++) {
    if (((MultiChoiceItem) mListView.getItemAtPosition(i)).selected) {
        mListView.setItemChecked(i, true);
    }
}
...

I thought that performance will be the only potential problem but I found another one - much more serious. The list has text filter enabled (mListView.setTextFilterEnabled(true)). Here's the failure scenario:

1. I'm opening new list
2. Im checking let's say 2-nd item
3. I start typing to filter some items
4. when the filtering is done, the 2-nd item is still checked even though it's not the one I checked

I assume that setItemChecked() marks a fixed position on the list checked while I need something that will mark the Item held on ths position - keeping the state even when the position on the list changes.

While performance issue could be (to some point) ignored - this new problem is really blocking me, so I would really appreciate any help with it.

Answer 1

If you use ListView.CHOICE_MODE_MULTIPLE or CHOICE_MODE_SINGLE the check states of the items will be overridden by ListView after getView is being called. You have to use the following construct:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
   ((ListView)parent).setItemChecked(position, true);
}

Another possiblity is to use ListView.CHOICE_MODE_NONE and manage the check states by yourself.