使用比较器和自定义 ArrayAdapter 对带有对象的 ArrayList 进行排序

Question

如何使用 Comparator 对对象的 ArrayList 进行正确排序，然后将排序后的数组传递给自定义数组适配器？

我试过这样的：

ArrayList 的内容class：

public class CoursesData {
private String url;
private String name;
private String lessonsCount;
private String isFree;
private String price;
private String language;
private String difficulty;

private AuthorData author;

.....getters-setters
}

比较器：

class CoursesPriceComparator implements Comparator <CoursesData> {
public int compare (CoursesData left, CoursesData right){
    return left.getPrice().compareTo(right.getPrice());
}
}

在 OnCreate 中设置适配器：

        mAdapter = new CoursesItemAdapter(getActivity(),
            R.layout.catalog_list_item,
            Collections.sort(parserJson.getCourses(), new CoursesPriceComparator()));

..并在此处出现错误：

...因为我使用的是自定义 ArrayAdapter，它类似于：

class CoursesItemAdapter extends ArrayAdapter<CoursesData> {
private Activity myContext;
private ArrayList<CoursesData> datas;

public CoursesItemAdapter(Context context, int textViewResourceId, ArrayList<CoursesData> objects){
    super(context, textViewResourceId, objects);

    myContext = (Activity) context;
    datas = objects;
}

public View getView(int position, View convertView, ViewGroup parent){
    ViewHolder viewHolder;

    if(convertView == null) {
        LayoutInflater inflater = myContext.getLayoutInflater();
        convertView = inflater.inflate(R.layout.catalog_list_item, null);

        viewHolder = new ViewHolder();
        viewHolder.postNameView = (TextView) convertView.findViewById(R.id.courses_name);
        viewHolder.postDifficultyView = (TextView) convertView.findViewById(R.id.difficulty);
        viewHolder.postAuthorView = (TextView) convertView.findViewById(R.id.author);

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


    viewHolder.postNameView.setText(datas.get(position).getName());
    viewHolder.postAuthorView.setText(datas.get(position).getAuthor().getName());
    viewHolder.postDifficultyView.setText(datas.get(position).getDifficulty());

    return convertView;
}
    static class ViewHolder{
    TextView postNameView;
    TextView postAuthorView;
    TextView postDifficultyView;
}

我需要如何修改此适配器以使其与 Comparable 一起使用？

感谢您的帮助。

Answer 1

您对 Collections.sort( return 排序集合的假设是错误的。

mAdapter = new CoursesItemAdapter(getActivity(),
            R.layout.catalog_list_item,
            Collections.sort(parserJson.getCourses(), new CoursesPriceComparator()));

应该是

ArrayList< CoursesData > data = parserJson.getCourses();
Collections.sort(parserJson.getCourses(), new CoursesPriceComparator())
mAdapter = new CoursesItemAdapter(getActivity(),
            R.layout.catalog_list_item,
            data);

Collection.sort return 类型无效。在这里查看 documentation

使用比较器和自定义 ArrayAdapter 对带有对象的 ArrayList 进行排序

Sorting ArrayList with objects using Comparator and Custom ArrayAdapter

sorting

android

arraylist

comparator

android-arrayadapter