比较器<Object> 可打包

Question

经过数小时的搜索，我不知道如何使 Comparator 可打包。 我发现这个“Parcelable 的东西”有点“缺少内容”......（Parcelable 甚至没有 writeBoolean）

public class T implements Parcelable{

   ...

   public static Comparator<T> Compare = new Comparator<T>() {...}

   ...

   public void writeToParcel(Parcel out, int flags) {
        //how to write "Compare"
   }

   private T(Parcel in) {
        //how to read "Compare"
   }

}

谢谢。

编辑：

所以这里是关于为什么类 F 必须是 parcelable 的详细信息（简化和改编）。请注意，代码来自已完成的 iOS 项目。如果架构保持不变，这将有利于维护...... :-)

public class F implements Parcelable{
    …
    public ArrayList<T> listArray;
    public HashMap<String,Comparator<T>> sortElementMap;
}

_

public class T implements Parcelable{
    …
    public static Comparator<T> CompareByName = new Comparator<T>() {…}};
    public static Comparator<T> CompareByDate = new Comparator<T>() { … }};
}

首先，在一个配置类中（此处简化），允许轻松适应应用程序（T 的变量之间的列数据库匹配，过滤器/排序/搜索定义，...）

F f=new F();
f.sortElementMap.put("name",T.CompareByName)
f.sortElementMap.put("date",T.CompareByDate)

在之前的活动中

Intent intent=new Intent(…);
intent.putExtra("F",F);
startActivity(intent);

在当前活动中

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

…
    Intent intent = getIntent();
    f = (F)intent.getParcelableExtra("F");
}


// the list to be sorted
listArray=new ArrayList<String>(f.listArray);

listAdapter = new ListAdapter(this, R.layout.list_item, listArray);
    listView = (ListView) findViewById(R.id.listView);
    listView.setAdapter(listAdapter);
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        //@Override
        public void onItemClick(AdapterView arg0, View view,
                                int position, long id) {
        …
        }
    });


// the list with the different type of sorting

sortArray=new ArrayList<String>();
Iterator it = f.sortElementMap.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry pairs = (Map.Entry)it.next();
        sortArray.add((String) pairs.getKey());
    }

sortListAdapter = new ListAdapter(this, R.layout.list_item_sort, sortArray);
    sortListView = (ListView) findViewById(R.id.sortListView);
    sortListView.setAdapter(sortListAdapter);
    sortListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        //@Override
        public void onItemClick(AdapterView arg0, View view,
                                int position, long id) {

            applyCurrentSelectedSort();

        }
    });


void applyCurrentSelectedSort(){

    Iterator it = f.sortElementMap.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry pairs = (Map.Entry) it.next();

        for (int i = 0; i < sortListAdapter.getSelectedPosition().length; i++) {
            if (sortListAdapter.getSelectedPosition()[i]) {
                listAdapter.sort((java.util.Comparator<T>) pairs.getValue());
                break;
            }
        }
    }
}

Answer 1

public enum Comparators {

     BY_NAME(F.CompareByName),
     BY_DATE(F.CompareByDate);

     private Comparator comparator;

     Comparators(final Comparator comparator) {
          this.comparator = comparator;
     }

     public Comparator getComparator() {
          return comparator;
     }

}


...

class F implements Parcelable {

    List<String> comparatorNames = new ArrayList<>();

    ....   ..

    writeToParcel() {

         //write list
    }


    readFromParcel() {

         //read list
    }

}

然后在任何你想要的地方：

f = (F)intent.getParcelableExtra("F");
Comparator c = Comparators.valueOf(f.getComparatorName(0));