Question

我遇到了这个问题，我有一个expandablelistview和一个倒数计时器。使用倒计时器我想扩展一个组并在剩余时间内更新textview。我没有在网上找到任何解决方案，这就是我在这里写作的原因。

如何从定时器访问View？

这是我的可扩展列表视图代码：

public class ExerciseListAdapter extends BaseExpandableListAdapter {

    private View childview, rowview;
    private List<List<Bitmap>> vajeImage;
    private ArrayList<ExerciseItem> headers;

    public ExerciseListAdapter(View ChView, View RView, List<List<Bitmap>> vaje, ArrayList<ExerciseItem> header) {
        this.childview = ChView;
        this.rowview = RView;
        this.vajeImage = vaje;
        this.headers = header;
    }

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

    @Override
    public int getChildrenCount(int i) {
        return vajeImage.get(i).size();
    }

    @Override
    public Object getGroup(int i) {
        return headers.get(i);
    }

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

    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return vajeImage.get(groupPosition).get(childPosition);
    }

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


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

    @Override
    public View getGroupView(int i, boolean b, View view, ViewGroup viewGroup) {
        LayoutInflater inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = inflater.inflate(R.layout.exercise_elv_row, viewGroup, false);
        TextView txHead = (TextView) view.findViewById(R.id.textViewExeHead);
        txHead.setText(headers.get(i).getIme());
        TextView txSub = (TextView) view.findViewById(R.id.textViewExeSub);
        txSub.setText(headers.get(i).getOpis());
        return view;
    }

    @Override
    public View getChildView(int i, int i1, boolean b, View view, ViewGroup viewGroup) {
        LayoutInflater inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = inflater.inflate(R.layout.exercise_elv_child_item, viewGroup, false);
        ImageView imview = (ImageView) view.findViewById(R.id.imageviewChild);
        imview.setImageBitmap(vajeImage.get(i).get(i1));
        return view;
    }

    @Override
    public boolean isChildSelectable(int i, int i1) {
        return true;
    }


}

这是我的计时器代码

public class MyCountDownTimer extends CountDownTimer {
    int current=0;
    ExpandableListView EL;
    TextView timeText;
    public MyCountDownTimer(long startTime, long interval, ExpandableListView list) {
        super(startTime, interval);
        EL=list;
        list.expandGroup(current);

        //this returns null pointer exception on TextView tx           
        list.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
            @Override
            public void onGroupExpand(int groupPosition) {
                if(EL.isGroupExpanded(groupPosition)) {
                    TextView tx = (TextView) EL.getChildAt(groupPosition).findViewById(R.id.textViewTime);
                    tx.setText("2");
                }
            }
        });
    }

    @Override
    public void onFinish() {
        //timeText.setText("Time's up!");
    }

    @Override
    public void onTick(long millisUntilFinished) {
        //timeText.setText("" + millisUntilFinished / 1000);
        Log.v("test","" + millisUntilFinished / 1000);
    }
}

修改

这里我尝试访问我的适配器的公共方法，适配器类是公共的，方法是公共的，但没有找到

                if(EL.isGroupExpanded(groupPosition)) {
                    //epl.setChildViewData(groupPosition, 0, "2");

                   epl=(ExpandableListAdapter)EL.getExpandableListAdapter();
                    //cannot resolve method "notifyDataSetChanged
                   epl.notifyDataSetChanged();

Answer 1

拨打电话时未创建您尝试访问的childview。因此，在您的setOnGroupExpandListener()中，尚未创建子视图，因此您获得该异常，因此您必须等到创建所有视图才能进行修改

我建议你将值传递给适配器，以便进行修改。像这样的东西

在ExerciseListAdapter文件中添加此HashMap

private HashMap<String, String> mMapStuff =new HashMap<String, String>();

还在适配器中添加此方法

public void setChildViewData(int groupPosition, int childPosition, String value){
    mMapStuff.put(groupPosition+""+childPosition, value);
}

现在使用getChildView()方法

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

    Some Other Code 
    .....

    //Note this should be your last line before the return statement
    String msg = mMapStuff.get(groupPosition+""+childPosition);
    if(msg != null)
        txtListChild.setText(msg);
    return convertView;
}

现在在setOnGroupExpandListener()添加此行

listAdapter.setChildViewData(groupPosition, 0, "2");

像这样

//this returns null pointer exception on TextView tx           
list.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
    @Override
    public void onGroupExpand(int groupPosition) {
        listAdapter.setChildViewData(groupPosition, 0, "2");
    }
});

让我知道这是否有效

如何在可扩展列表视图和倒计时计时器中获取组子视图？

1 个答案: