Question

创建包含超过100个项目（确切地说是111个）并部署应用程序的列表视图后，它会按预期运行，但只要我滚动列表，应用程序就会崩溃并返回ArrayIndexOutOfBoundsException。我真的不明白为什么长度和指数正在回归＆＃39; 19＆＃39;有谁知道为什么要显示19？需要做些什么来解决这个问题？

java.lang.ArrayIndexOutOfBoundsException：length = 19;指数= 19 在com.helloapps.helloworldapp.adapters.OrangeListAdapter.getPositionForSection（OrangeListAdapter.java:160）

XML

<ListView
    android:id="@android:id/list"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:choiceMode="singleChoice"
    android:fastScrollEnabled="true"
    android:scrollbarStyle="outsideInset"/>

爪哇

public class OrangeListAdapter extends BaseAdapter implements Filterable, SectionIndexer {

    private List<Orange> mData;
    private List<Orange> mFilteredData;
    private LayoutInflater mInflater;
    private ItemFilter mFilter;

    private Object[] mSections;
    private int[] mSectionsIndexedByPosition;
    private int[] mPositionsIndexedBySection;

    public OrangeListAdapter (List<Orange> data, Context context) {
        mData = data;
        mFilteredData = new ArrayList(mData);
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        setupSections();
    }

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

    @Override
    public Orange getItem(int position) {
        return mFilteredData.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_item_dualline, parent, false);
            holder = new ViewHolder();

            holder.title = (TextView) convertView.findViewById(R.id.item_name);
            holder.description = (TextView) convertView.findViewById(R.id.item_description);

            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        Orange orange = getItem(position);
        holder.title.setText(orange.getName());
        holder.description.setText(orange.getDescrption());
        if (orange.isSelected()) {
            convertView.setBackgroundColor(Color.parseColor("#FF6600"));
            holder.title.setTextColor(Color.parseColor("#FFFFFF"));
            holder.description.setTextColor(Color.parseColor("#FFFFFF"));
        } else {
            convertView.setBackgroundColor(Color.TRANSPARENT);
            holder.title.setTextColor(Color.parseColor("#FFFFFF"));
            holder.description.setTextColor(Color.parseColor("#B5B5B5"));
        }

        holder.title.setText(mFilteredData.get(position).getStation());
        holder.description.setText(mFilteredData.get(position).getZone());

        return convertView;
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ItemFilter();
        }
        return mFilter;
    }

    /**
     * View holder
     */
    static class ViewHolder {
        private TextView title;
        private TextView description;
    }

    private class ItemFilter extends Filter {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();

            if (TextUtils.isEmpty(constraint)) {
                results.count = mData.size();
                results.values = new ArrayList(mData);
            } else {
                //Create a new list to filter on
                List<Orange> resultList = new ArrayList<Orange>();
                for (Orange str : mData) {
                    if (str.getStation().toLowerCase().contains(constraint.toString().toLowerCase())) {
                        resultList.add(str);
                    }
                }
                results.count = resultList.size();
                results.values = resultList;
            }
            return results;
        }

        /**
         * Runs on ui thread
         * @param constraint the constraint used for the result
         * @param results the results to display
         */
        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            if (results.count == 0) {
                mFilteredData.clear();
                notifyDataSetInvalidated();
            } else {
                mFilteredData = (ArrayList<Orange>)results.values;
                notifyDataSetChanged();
            }
            setupSections();
        }
    }

    @Override
    public int getPositionForSection(int section) {
        return mPositionsIndexedBySection[section];
    }

    @Override
    public int getSectionForPosition(int position) {
        return mSectionsIndexedByPosition[position];
    }

    @Override
    public Object[] getSections() {
        return mSections;
    }

    private void setupSections() {
        String initial = "\0";
        List<String> sections = new ArrayList<String>();
        mSectionsIndexedByPosition = new int[mFilteredData.size()];
        mPositionsIndexedBySection = new int[mFilteredData.size()];

        int section = 0;
        for (int pos = 0; pos < mFilteredData.size(); pos++) {
            Orange orange = mFilteredData.get(pos);
            if (initial.charAt(0) != orange.getName().charAt(0)) {
                initial = orange.getName().substring(0, 1);
                section = sections.size();
                sections.add(initial);
                mPositionsIndexedBySection[section] = pos;
                mSectionsIndexedByPosition[pos] = section;
            } else {
                mSectionsIndexedByPosition[pos] = section;
            }
        }
        mSections = sections.toArray();
        mPositionsIndexedBySection = Arrays.copyOf(mPositionsIndexedBySection, mSections.length);
    }
}

Answer 1

您的数组声明只有19个位置，这意味着您可以访问最大索引18，因为数组索引以0开头，但在上面的代码中您正在访问第19个索引，那么它会抱怨您的索引超出范围那是18岁。

这条线对我来说有点问题：

mPositionsIndexedBySection = Arrays.copyOf(mPositionsIndexedBySection, mSections.length);

**To solve the problem**：确保根据大小将数据放入数组中。如果数组的大小为n，即19，那么你应该只将元素放到n-1索引，即18。

Answer 2

快速滚动条仅从SectionIndexer.getSections()读取您的部分一次，之后不会更改。

因此，当您的第一个列表包含超过19个部分时，似乎会出现问题，然后重新加载一个列表，您希望将部分数量减少到少于19，这也会减少mPositionsIndexedBySection的大小。

因为快速滚动条仍记得旧版块，并尝试获取第19部分的位置，所以会发生错误。

要解决此问题，请使用包含所有可用部分的固定数量的部分，仅在数据更改时更改mPositionsIndexedBySection和mSectionsIndexedByPosition。

修改：

请查看以下链接，了解如何正确实施SectionIndexer

http://androidopentutorials.com/android-listview-fastscroll/

http://responsiveandroid.com/2013/04/13/android-sectionindexer-with-alphabet.html

创建包含＆gt; 100项的列表视图后的java.lang.ArrayIndexOutOfBoundsException

2 个答案: