android - 为什么折叠 ExpandableListView 组会取消选中我的复选框？

Question

我有一个由 BaseExpandableListAdapter 支持的 ExpandableListView。子列表项都是复选框。

我展开一个组，选中一个复选框，然后折叠该组。然后取消选中该复选框。

我的日志输出是:

-- I check the checkbox:
02-27 13:51:29.674: D/ExpandableListAdapter(3583): Option '2' CHECKED
--- I collapse the group, which unchecks the checkbox:
02-27 13:51:30.850: D/ExpandableListAdapter(3583): Option '2' UNCHECKED

如您所见，折叠组会调用(可能是间接调用)我对该组中所有复选框的 OnCheckedChangedListener。

我的代码是:

public class TestExpandableListActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ExpandableListView elv = 
            (ExpandableListView) findViewById(R.id.optionsELV);
        ExpandableListAdapter ela = new ExpandableListAdapter(this);
        elv.setAdapter(ela);
    }
    public class ExpandableListAdapter extends BaseExpandableListAdapter {
        private static final String TAG = "ExpandableListAdapter";
        private final String[] groups;
        private final String[][] children;
        private final boolean[][] childrenChecked;
        private final Context context;
        public ExpandableListAdapter(Context c) {
            this.context = c;
            groups = new String[] { "Options A", "Options B" };
            children = 
                new String[][] {{"A", "B", "C"},{"1", "2", "3"}};
            childrenChecked = 
                new boolean[][] {{false, false, false},{false, false, false}};
        }
        public View getChildView(
                final int groupPos, 
                final int childPos,
                boolean isLastChild, 
                View convertView, 
                ViewGroup parent) {
            CheckBox cb = new CheckBox(context);
            cb.setText(children[groupPos][childPos]);
            cb.setChecked(childrenChecked[groupPos][childPos]);
            cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
                public void onCheckedChanged(
                        CompoundButton buttonView, 
                        boolean isChecked) {
                    Log.d(TAG, 
                            String.format("Option '%s' %s", 
                                    children[groupPos][childPos], 
                                    isChecked ? "CHECKED" : "UNCHECKED"));
                    childrenChecked[groupPos][childPos] = isChecked;
                }
            });
            return cb;
        }
        public int getGroupCount() {
            return groups.length;
        }
        public int getChildrenCount(int groupPos) {
            return children[groupPos].length;
        }
        public String getGroup(int groupPos) {
            return groups[groupPos];
        }
        public String getChild(int groupPos, int childPos) {
            return children[groupPos][childPos];
        }
        public long getGroupId(int groupPos) {
            return (1024 * (groupPos + 1));
        }
        public long getChildId(int groupPos, int childPos) {
            return (1024 * (groupPos + 1)) + (childPos + 1);
        }
        public View getGroupView(
                int groupPos, 
                boolean isExpanded, 
                View convertView, 
                ViewGroup parent) {
            TextView tv = new TextView(context);
            tv.setText(groups[groupPos]);
            return tv;
        }
        public boolean hasStableIds() {
            return true;
        }
        public boolean isChildSelectable(int groupPos, int childPos) {
            return true;
        }
    }
}

我的布局(注意我已经正确地将 choiceMode 设置为 multipleChoice)是:

<?xml version="1.0" encoding="utf-8"?>
<ExpandableListView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/optionsELV"
    android:choiceMode="multipleChoice"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

为什么折叠组会取消选中我的所有复选框？我怎样才能防止这种情况发生？

Answer 1

我想我找到了解决方案 — 使用 CheckedTextView 而不是 CheckBox。

public View getChildView(
        final int groupPos, 
        final int childPos,
        boolean isLastChild, 
        View convertView, 
        ViewGroup parent) {
    final CheckedTextView ctv = new CheckedTextView(context);
    ctv.setChecked(childrenChecked[groupPos][childPos]);
    ctv.setCheckMarkDrawable(
            ctv.isChecked()
            ? android.R.drawable.checkbox_on_background 
            : android.R.drawable.checkbox_off_background);
    ctv.setText(children[groupPos][childPos]);
    ctv.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            ctv.toggle();
            Log.d(TAG, 
                String.format("Option '%s' %s", 
                    children[groupPos][childPos], 
                    ctv.isChecked() ? "CHECKED" : "UNCHECKED"));
            childrenChecked[groupPos][childPos] = ctv.isChecked();
            ctv.setCheckMarkDrawable(
                    ctv.isChecked() 
                    ? android.R.drawable.checkbox_on_background 
                    : android.R.drawable.checkbox_off_background);
        }
    });
    return ctv;
}

CheckedTextView doco 确实说 CheckedTextView 在 ListView 中有用——“这在 ListView 中使用时很有用，因为它的 setChoiceMode 已设置为除 CHOICE_MODE_NONE 之外的其他东西”——但我非常不清楚 CheckBox 和 CheckedTextView 之间的区别，以及为什么 CheckBox 似乎完全不起作用。

谁能告诉我 CheckBox 和 CheckedTextView 之间的区别是什么，以及为什么 CheckBox 在 ExpandableListView 中的功能如此奇怪？