ListView的performFiltering（）期间发生异常

Question

我创建了ListView，我想在此列表视图中应用搜索过滤器。我已经执行了下面的代码。但它在执行过滤（）期间在Logcat中显示错误。

logcat的

W/PathParser: Points are too far apart 4.000000596046461
W/Filter: An exception occurred during performFiltering()!
          java.lang.NullPointerException: collection == null
              at java.util.ArrayList.<init>(ArrayList.java:94)
              at com.example.chaitanya.nearbyplace.CustomBaseAdapter$1.performFiltering(CustomBaseAdapter.java:156)
              at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
              at android.os.Handler.dispatchMessage(Handler.java:102)
              at android.os.Looper.loop(Looper.java:135)
              at android.os.HandlerThread.run(HandlerThread.java:61)
D/android.widget.Filter$FilterResults@39681f38: FilterResult

CustomeBaseAdapter

    public class CustomBaseAdapter extends BaseAdapter implements Filterable {
    Context context;
    List<RowItem> rowItems;

    List<String> arrayList;
    List<String> mOriginalValues; // Original Values
    LayoutInflater inflater;




    public CustomBaseAdapter(Context context, List<RowItem> items) {
        this.context = context;
        this.rowItems = items;
    }

    /*private view holder class*/
    private class ViewHolder {
        ImageView imageView;
        TextView txtTitle;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;

        LayoutInflater mInflater = (LayoutInflater)
                context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_item, null);
            holder = new ViewHolder();
            holder.txtTitle = (TextView) convertView.findViewById(R.id.label);
            holder.imageView = (ImageView) convertView.findViewById(R.id.icon);
            convertView.setTag(holder);
        }
        else {
            holder = (ViewHolder) convertView.getTag();
        }

        RowItem rowItem = (RowItem) getItem(position);

        holder.txtTitle.setText(rowItem.getTitle());
        holder.imageView.setImageResource(rowItem.getImageId());

        return convertView;
    }

    @Override
    public int getCount() {
        return rowItems.size();
    }

    @Override
    public Object getItem(int position) {
        return rowItems.get(position);
    }

    @Override
    public long getItemId(int position) {
        return rowItems.indexOf(getItem(position));
    }


    @Override
    public Filter getFilter() {
        Filter filter = new Filter() {

            @SuppressWarnings("unchecked")
            @Override
            protected void publishResults(CharSequence constraint,FilterResults results) {


                arrayList = (List<String>) results.values; // has the filtered values
                notifyDataSetChanged();  // notifies the data with new filtered values
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                Log.d(constraint.toString(),"constraint");
                FilterResults results = new FilterResults();        // Holds the results of a filtering operation in values
                List<String> FilteredArrList = new ArrayList<String>();

                if (mOriginalValues == null) {
                    mOriginalValues = new ArrayList<String>(arrayList); // saves the original data in mOriginalValues
                }

                /********
                 *
                 *  If constraint(CharSequence that is received) is null returns the mOriginalValues(Original) values
                 *  else does the Filtering and returns FilteredArrList(Filtered)
                 *
                 ********/
                if (constraint == null || constraint.length() == 0) {

                    // set the Original result to return
                    results.count = mOriginalValues.size();
                    results.values = mOriginalValues;
                } else {
                    constraint = constraint.toString().toLowerCase();
                    for (int i = 0; i < mOriginalValues.size(); i++) {
                        String data = mOriginalValues.get(i);
                        if (data.toLowerCase().contains(constraint.toString())) {
                            FilteredArrList.add(data);
                        }
                    }
                    // set the Filtered result to return
                    results.count = FilteredArrList.size();
                    results.values = FilteredArrList;
                }
                return results;
            }
        };
        return filter;
    }


}

MainActivity.java

  inputSearch.addTextChangedListener(new TextWatcher() {

    @Override
    public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
        // When user changed the Text
       MainActivity.this.adapter.getFilter().filter(cs.toString());
       // String text = inputSearch.getText().toString().toLowerCase(Locale.getDefault());
        //adapter.filter(text);
    }

    @Override
    public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
                                  int arg3) {
        // TODO Auto-generated method stub

    }

    @Override
    public void afterTextChanged(Editable arg0) {
        // TODO Auto-generated method stub
    }
});

此块if (mOriginalValues == null) { mOriginalValues = new ArrayList<String>(arrayList); // saves the original data in mOriginalValues }中的

if (mOriginalValues == null) {是CustomeBaseAdapter中的156行。

Answer 1

您的arrayList似乎无效。

更新CustomBaseAdapter构造函数，如下所示：

public CustomBaseAdapter(Context context, List<RowItem> items) {
        this.context = context;
        this.rowItems = items;

        arrayList = new ArrayList<String>();
        for(int i = 0; i < rowItems.size(); i++)
        {
            RowItem rowItem = (RowItem) getItem(position);
            arrayList.add(rowItem.getTitle());
        }
    }

performFiltering执行此操作：

...........
.......................

if (mOriginalValues == null) {
    mOriginalValues.addAll(arrayList); // saves the original data in mOriginalValues
}
............
...................