ExpandableListView 是否需要多个 viewHolders？

Question

我是不是用错了这个viewholder？我在第 165 行获得了 NPE。我错过了有明显的原因吗？如果我使用 expandablelistview，我需要一个组视图和一个子视图吗？我标记了第 165 行，试图让它更容易看清。

非常感谢

获得 NPE 的我的可扩展列表视图：

public class MyExpandableListAdapter extends BaseExpandableListAdapter {

    private Context mContext;
    private ArrayList<ContactNameItems> mListDataHeader;
    private ArrayList<Boolean> phoneNumberCheckStates;
    private ArrayList<String> selectedNumbers;

    private HashMap<String, List<ContactPhoneItems>> mListDataChild;

    private ViewHolder mViewHolder;

    public MyExpandableListAdapter(Context context,
            ArrayList<ContactNameItems> listDataHeader,
            HashMap<String, List<ContactPhoneItems>> listDataChild,
            ArrayList<String> listOfNumbers) {

        mContext = context;
        mListDataHeader = listDataHeader;
        mListDataChild = listDataChild;
        selectedNumbers = listOfNumbers;
    }

    @Override
    public int getGroupCount() {
        return mListDataHeader.size();
    }

    @Override
    public ContactNameItems getGroup(int groupPosition) {
        return mListDataHeader.get(groupPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {

        String contactName = getGroup(groupPosition).getName();
        Bitmap contactImage = getGroup(groupPosition).getImage();

        if (convertView == null) {

            LayoutInflater inflater = (LayoutInflater) mContext
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.contact_name_item, null);

            mViewHolder = new ViewHolder();

            mViewHolder.mContactName = (TextView) convertView
                    .findViewById(R.id.lblListHeader);

            mViewHolder.mContactImage = (ImageView) convertView
                    .findViewById(R.id.ivContactPhoto);

            convertView.setTag(mViewHolder);
        } else {

            mViewHolder = (ViewHolder) convertView.getTag();
        }

        if (contactImage != null) {
            mViewHolder.mContactImage.setImageBitmap(contactImage);

        } else {
            mViewHolder.mContactImage.setImageResource(R.drawable.default_contact);
        }

        mViewHolder.mContactName.setText(contactName);

        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return mListDataChild.get(mListDataHeader.get(groupPosition).getName())
                .size();
    }

    @Override
    public ContactPhoneItems getChild(int groupPosition, int childPosition) {
        return mListDataChild.get(mListDataHeader.get(groupPosition).getName())
                .get(childPosition);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public View getChildView(int groupPosition, final int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {

        String numberText = getChild(groupPosition, childPosition).getNumber();
        String typeText = getChild(groupPosition, childPosition).getPhoneType();

        final int mGroupPosition = groupPosition;

        if (convertView == null) {

            LayoutInflater inflater = (LayoutInflater) this.mContext
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.contact_detail_item, null);

            mViewHolder = new ViewHolder();

            mViewHolder.mPhoneNumber = (TextView) convertView
                    .findViewById(R.id.tv_phone_number);

            mViewHolder.mPhoneType = (TextView) convertView
                    .findViewById(R.id.tv_phone_type);

            mViewHolder.mCheckBox = (CheckBox) convertView
                    .findViewById(R.id.checkBox);

            convertView.setTag(mViewHolder);

        } else {

            mViewHolder = (ViewHolder) convertView.getTag();
        }

        mViewHolder.mPhoneNumber.setText(numberText);
        mViewHolder.mPhoneType.setText(typeText);

        phoneNumberCheckStates = new ArrayList<Boolean>();

        for (int i = 0; i < mListDataChild.size(); i++) {

            phoneNumberCheckStates.add(false);
        }

        if (phoneNumberCheckStates.get(childPosition)) {
            mViewHolder.mCheckBox.setChecked(true);
        } else {
            mViewHolder.mCheckBox.setChecked(false);
        }

        mViewHolder.mCheckBox.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

/*this is line 165*/    if (mViewHolder.mCheckBox.isChecked()) {  /*this is line 165*/
                    phoneNumberCheckStates.set(childPosition, true);

                    selectedNumbers.add(mListDataChild
                            .get(mListDataHeader.get(mGroupPosition).getName())
                            .get(childPosition).getNumber());

                } else {
                    phoneNumberCheckStates.set(childPosition, false);

                    selectedNumbers.remove(mListDataChild
                            .get(mListDataHeader.get(mGroupPosition).getName())
                            .get(childPosition).getNumber());
                }
            }
        });

        return convertView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    public ArrayList<Boolean> getCheckedNumbers() {

        return phoneNumberCheckStates;
    }

    public ArrayList<String> getSelectedNumbers() {

        return selectedNumbers;
    }

    private class ViewHolder {

        TextView mContactName;
        TextView mPhoneNumber;
        TextView mPhoneType;
        ImageView mContactImage;
        CheckBox mCheckBox;
    }
}

如果有帮助，这里是日志：

01-25 04:34:31.695: E/AndroidRuntime(7074): FATAL EXCEPTION: main
01-25 04:34:31.695: E/AndroidRuntime(7074): java.lang.NullPointerException
01-25 04:34:31.695: E/AndroidRuntime(7074):     at com.psesto.journeysend.contactpicker.MyExpandableListAdapter$1.onClick(MyExpandableListAdapter.java:165)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.view.View.performClick(View.java:4204)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.widget.CompoundButton.performClick(CompoundButton.java:100)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.view.View$PerformClick.run(View.java:17355)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.os.Handler.handleCallback(Handler.java:725)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.os.Looper.loop(Looper.java:137)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at android.app.ActivityThread.main(ActivityThread.java:5041)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at java.lang.reflect.Method.invokeNative(Native Method)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at java.lang.reflect.Method.invoke(Method.java:511)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
01-25 04:34:31.695: E/AndroidRuntime(7074):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

我接受了 Towlie288 的回答，因为它为我指明了正确的方向。这是使一切正常的代码更改：

public class MyExpandableListAdapter extends BaseExpandableListAdapter {

    private Context mContext;
    private ArrayList<ContactNameItems> mListDataHeader;
    private ArrayList<String> selectedNumbers;

    private HashMap<String, List<ContactPhoneItems>> mListDataChild;

    private ChildViewHolder childViewHolder;
    private GroupViewHolder groupViewHolder;

    public MyExpandableListAdapter(Context context,
            ArrayList<ContactNameItems> listDataHeader,
            HashMap<String, List<ContactPhoneItems>> listDataChild,
            ArrayList<String> listOfNumbers) {

        mContext = context;
        mListDataHeader = listDataHeader;
        mListDataChild = listDataChild;
        selectedNumbers = listOfNumbers;

    }

    @Override
    public int getGroupCount() {
        return mListDataHeader.size();
    }

    @Override
    public ContactNameItems getGroup(int groupPosition) {
        return mListDataHeader.get(groupPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {

        String contactName = getGroup(groupPosition).getName();
        Bitmap contactImage = getGroup(groupPosition).getImage();

        if (convertView == null) {

            LayoutInflater inflater = (LayoutInflater) mContext
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.contact_name_item, null);

            groupViewHolder = new GroupViewHolder();

            groupViewHolder.mContactName = (TextView) convertView
                    .findViewById(R.id.lblListHeader);

            groupViewHolder.mContactImage = (ImageView) convertView
                    .findViewById(R.id.ivContactPhoto);

            convertView.setTag(groupViewHolder);
        } else {

            groupViewHolder = (GroupViewHolder) convertView.getTag();
        }

        if (contactImage != null) {
            groupViewHolder.mContactImage.setImageBitmap(contactImage);

        } else {
            groupViewHolder.mContactImage
                    .setImageResource(R.drawable.default_contact);
        }

        groupViewHolder.mContactName.setText(contactName);

        return convertView;
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return mListDataChild.get(mListDataHeader.get(groupPosition).getName())
                .size();
    }

    @Override
    public ContactPhoneItems getChild(int groupPosition, int childPosition) {
        return mListDataChild.get(mListDataHeader.get(groupPosition).getName())
                .get(childPosition);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    @Override
    public View getChildView(int groupPosition, final int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {

        String numberText = getChild(groupPosition, childPosition).getNumber();
        String typeText = getChild(groupPosition, childPosition).getPhoneType();

        final int mGroupPosition = groupPosition;

        if (convertView == null) {

            LayoutInflater inflater = (LayoutInflater) this.mContext
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.contact_detail_item, null);

            childViewHolder = new ChildViewHolder();

            childViewHolder.mPhoneNumber = (TextView) convertView
                    .findViewById(R.id.tv_phone_number);

            childViewHolder.mPhoneType = (TextView) convertView
                    .findViewById(R.id.tv_phone_type);

            childViewHolder.mCheckBox = (CheckBox) convertView
                    .findViewById(R.id.checkBox);

            childViewHolder.mCheckBox.setOnCheckedChangeListener(checkListener);

            convertView.setTag(childViewHolder);

        } else {

            childViewHolder = (ChildViewHolder) convertView.getTag();
        }

        childViewHolder.mPhoneNumber.setText(numberText);
        childViewHolder.mPhoneType.setText(typeText);

        ContactPhoneItems cpi = getChild(mGroupPosition, childPosition);

        childViewHolder.mCheckBox.setTag(cpi);
        childViewHolder.mCheckBox.setChecked(cpi.getSelected());

        // for managing the state of the boolean
        // array according to the state of the
        // CheckBox

        childViewHolder.mCheckBox
                .setOnClickListener(new View.OnClickListener() {

                    String contactNumber = mListDataChild
                            .get(mListDataHeader.get(mGroupPosition).getName())
                            .get(childPosition).getNumber();

                    public void onClick(View v) {

                        boolean isChecked = ((CheckBox) v).isChecked();

                        if (isChecked) {

                            selectedNumbers.add(contactNumber);

                        } else {

                            selectedNumbers.remove(contactNumber);
                        }

                        getChild(mGroupPosition, childPosition).setSelected(isChecked);
                        notifyDataSetChanged();
                    }
                });

        return convertView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    public ArrayList<String> getSelectedNumbers() {

        return selectedNumbers;
    }

    public final class GroupViewHolder {

        TextView mContactName;
        ImageView mContactImage;
    }

    public final class ChildViewHolder {

        TextView mPhoneNumber;
        TextView mPhoneType;
        CheckBox mCheckBox;
    }

    OnCheckedChangeListener checkListener = new OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(CompoundButton buttonView,
                boolean isChecked) {

            ContactPhoneItems c = (ContactPhoneItems) buttonView.getTag();
            c.setSelected(isChecked);
        }
    };
}

Answer 2

您的所有Views 在Adapter 中有一个ViewHolder 引用。这是没有意义的，因为列表中的每个视图都有自己的 ViewHolder 实例，您可以通过 View.getTag() 获得。

您可以将int[] 设置为您需要的位置作为CheckBox 的标签

    int[] positions = new int[2];
    positions[0] = childPosition;
    positions[1] = groupPosition;
    mViewHolder.mCheckBox.setTag(positions);

在onClick()

    CheckBox box = (CheckBox) v;
    int[] posTag = (int[]) v.getTag();

然后你有状态的复选框和其余的位置

Answer 3

如果Child 的视图正在重用Group 的视图，也就是其中的ViewHolder，就会发生这种情况。很明显，在第165行找不到mCheckBox，因为还没有设置。
只需在ViewHolder 中添加一个标志，以检查它是否是Child 的ViewHolder 即可解决您的问题。这里不需要有两种ViewHolder。
希望有帮助