单击 ExpandableListview 中的项目时应用程序停止 Android

Question

我正在尝试创建一个 ExpandableListView，下面是我为可扩展列表创建数据的代码

DBHelper dbHelper;
ExpandableListAdapter listAdapter;
ExpandableListView expListView;
HashMap<String, List<String>> hashDataChild;
ArrayList<DetailsOfLocation> arrayList;

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

expListView = (ExpandableListView) v.findViewById(R.id.lvExp); // get the listview
initializeDatabase();
        prepareChildData();

listAdapter = new ExpandListAdapter(getActivity(), arrayList, hashDataChild);
        expListView.setAdapter(listAdapter);

return v;
}

public void initializeDatabase()
{
    dbHelper = new DBHelper(getActivity());

    try {
        dbHelper.createDataBase();
    } catch (IOException ioe) {
        throw new Error("Unable to create database");
    }

    try {
        dbHelper.openDataBase();
    } catch (SQLException sqle) {
        throw sqle;
    }
}

private void  prepareChildData(){
    hashDataChild = new HashMap<String, List<String>>();

//arrayList has a multiple column in it where it will be displayed as the header. The data is from the database

    Integer id = ((MyApplication) getActivity().getApplication()).getID();
    arrayList = new ArrayList<DetailsOfLocation>();
    arrayList = dbHelper.getList(id);

 //child is the child's data
    List<String> child = new ArrayList<String>();
    child.add("Other Info");
    child.add("Picture");
    child.add("Contact");

//the header and child is being inserted
    for(DetailsOfLocation list : arrayList){
            hashDataChild.put(String.valueOf(list), child);
        }
    }
}

当我调试它时，hashDataChild 具有我期望的值，其中每个 header 有 3 个 child。但是在我的 phone 上尝试时它崩溃了并且在 logcat 中没有显示任何内容。我用于创建可扩展列表视图的参考是 [this]:http://www.androidhive.info/2013/07/android-expandable-list-view-tutorial/

我在想可能是因为ExpandableListview OnGroupClickListener 没有工作？我该如何解决这个问题？它进入我的 onGroupClick 但不显示 child

的列表

 // Listview Group click listener
        expListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v,
                                        int groupPosition, long id) {
                Toast.makeText(
                        getActivity().getApplicationContext(),
                        arrayList.get(groupPosition)
                                + " : "
                                + hashDataChild.get(
                                arrayList.get(groupPosition)), Toast.LENGTH_SHORT)
                        .show();

                return false;
            }
        });

下面是我的可扩展适配器代码

public class ExpandListAdapter extends BaseExpandableListAdapter {

private Context _context;
private ArrayList<DetailsOfLocation> mDetailsWithNoLocation;
private HashMap<String, List<String>> mchildOfDetailsWithNoLocation; 

public ExpandListAdapter(Context context, ArrayList<DetailsOfLocation> detailsWithNoLocation, HashMap<String, List<String>> HashChildData) {
    this._context = context;
    this.mDetailsWithNoLocation = detailsWithNoLocation; //header
    this.mchildOfDetailsWithNoLocation = HashChildData; //hash data
}


@Override
public Object getChild(int groupPosition, int childPosititon) {
    return this.mchildOfDetailsWithNoLocation.get(this.mDetailsWithNoLocation.get(groupPosition)).get(childPosititon);
}

@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) {

    final String childText = (String) getChild(groupPosition, childPosition);

    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.expandlist_child_item, null);
    }

    TextView txtListChild = (TextView) convertView
            .findViewById(R.id.tvother_info);

    txtListChild.setText(childText);
    return convertView;
}

@Override
public int getChildrenCount(int groupPosition) {
    return this.mchildOfDetailsWithNoLocation.get(this.mDetailsWithNoLocation.get(groupPosition))
            .size();
}


@Override
public Object getGroup(int groupPosition) {
    return this.mDetailsWithNoLocation.get(groupPosition);
}

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

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

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


    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.expandlist_group_item, null);
    }

    TextView lblListDesc = (TextView) convertView.findViewById(R.id.tv_desc);
    TextView lblListRoom = (TextView) convertView.findViewById(R.id.tv_location);
    TextView lblListAudience = (TextView) convertView.findViewById(R.id.tv_audience);
    TextView lblListSpeaker = (TextView) convertView.findViewById(R.id.tv_speaker);


    DetailsOfLocation noLocationobj = mDetailsWithNoLocation.get(groupPosition);

    lblListDesc.setText(noLocationobj.getDesc());
    lblListRoom.setText("Room: "+noLocationobj.getLocation());
    lblListAudience.setText("Audience: "+noLocationobj.getAudience());
    lblListSpeaker.setText("Speaker/s: "+noLocationobj.getSpeaker());


    return convertView;
}

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

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

}

非常感谢您的帮助。

更新

我已经在我的 onGroupClick() 和 hashDataChild.get( arrayList.get(groupPosition)) is null 为什么即使在检查 arrayList 时它有值也是这样？

我想我找到了使用这个的原因

if(!hashDataChild.containsKey(arrayList))

我的 hashDataChild 不包含密钥我不知道为什么以及如何解决它为什么会这样？即使在我调试时它确实显示了它的键和我的 arrayList 的值？

我已经更改了 containsKey 并按照建议使用了 String.valueOf(arrayList.get(groupPosition))。但是我的 child 数据仍然没有显示，并且 onGroupClick() 中的 return false 它仍然关闭了我的应用程序。

Answer 1

好的，我试过你的代码，点击导致 NullPointerException，您在每次调用 mDetailsWithNoLocation 时都错过了 String.valueOf()，在您的适配器中更改这两个方法

@Override
public int getChildrenCount(int groupPosition) {
    return this.mchildOfDetailsWithNoLocation.get(String.valueOf(
            this.mDetailsWithNoLocation.get(groupPosition))).size();
}

@Override
public Object getChild(int groupPosition, int childPosititon) {
    return this.mchildOfDetailsWithNoLocation.get(String.valueOf(
            this.mDetailsWithNoLocation.get(groupPosition))).get(
            childPosititon);
}

现在应该有工作了.. 注意：您还应该 post 您 activity 在您的问题中编写代码，以使其他人更容易测试您的代码。我需要做一些猜测来测试这个..:)

单击 ExpandableListview 中的项目时应用程序停止 Android

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