不是封閉類錯誤（Android）

Question

在下面的一段代碼中，當我嘗試傳遞DisplayWishesActivity.this時，在我的自定義適配器中出現錯誤。 DisplayWishesActivity是另一項尚未修改的活動。 （請參閱錯誤行的代碼）

import android.app.Activity; 
import android.content.Context; 
import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.TextView; 

import java.util.ArrayList; 

import data.DatabaseHandler; 
import model.MyWish; 


public class WishDetailActivity extends ActionBarActivity { 
    private DatabaseHandler databaseHandler; 
    private ArrayList<MyWish> wishList; 
    private WishAdapter wishAdapter; 
    private ListView listView; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_wish_detail); 

     wishList = new ArrayList<>(); 
     listView = (ListView) findViewById(R.id.list_id); 

     refreshData(); 
    } 

    private void refreshData(){ 
     wishList.clear(); 

     databaseHandler = new DatabaseHandler(getApplicationContext()); 

     ArrayList<MyWish> wishesFromDB = databaseHandler.getWishes(); 

     for(MyWish wish : wishesFromDB){ 
      String title = wish.getTitle(); 
      String date = wish.getRecordDate(); 
      String content = wish.getContent(); 

      MyWish myWish = new MyWish(); 

      myWish.setTitle(title); 
      myWish.setContent(content); 
      myWish.setRecordDate(date); 

      wishList.add(myWish); 

     } 
     databaseHandler.close(); 

     //setup adapter 

//*******ERROR********* -->>"DisplayWishesActivity is not an enclosing class"    

     wishAdapter = new WishAdapter(DisplayWishesActivity.this, R.layout.wish_row, wishList); 
    } 


    public class WishAdapter extends ArrayAdapter<MyWish>{   //Private Class 
     Activity activity; 
     int layoutResource; 
     MyWish wish; 
     ArrayList<MyWish> mData = new ArrayList<>(); 

     public WishAdapter(Activity act, int resource, ArrayList<MyWish> data) { 
      super(act, resource, data); 

      activity = act; 
      layoutResource = resource; 
      mData = data; 

      notifyDataSetChanged(); 
     } 

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

     @Override 
     public MyWish getItem(int position) { 
      return mData.get(position); 
     } 

     @Override 
     public int getPosition(MyWish item) { 
      return super.getPosition(item); 
     } 

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


     //This method is the heart of our custom adapter class, as this is the place where our custom ListView is created 

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

      if(row == null || row.getTag() == null){    // i.e. the our list view (row) is currently empty 
       LayoutInflater inflater = LayoutInflater.from(activity); 
       row = inflater.inflate(layoutResource, null); 
       holder = new ViewHolder(); 

       holder.mTitle = (TextView) row.findViewById(R.id.wish_title_in_list_id); 
       holder.mDate = (TextView) row.findViewById(R.id.date_in_list_id); 

       row.setTag(holder); 
      } 

      else{ 
       holder = (ViewHolder) row.getTag();   //prevents the system from doing all the work again, but instead recycles the views 
      } 

      holder.myWish = getItem(position); 

      holder.mTitle.setText(holder.myWish.getTitle()); 
      holder.mDate.setText(holder.myWish.getRecordDate()); 

      return row; 
     } 
    } 


    class ViewHolder{    //helps in recycling the listView, rather than instantiating it every time 
     MyWish myWish; 
     TextView mTitle;       
     TextView mId; 
     TextView mContent; 
     TextView mDate; 
    } 

} 

Answer 1

我不知道是什麼讓你這樣做，但這是錯誤的。語法：

ClassName.this 

只能在ClassName類中使用。在你的情況下，當你嘗試使用

DisplayWishesActivity.this 

它給出了一個錯誤，因爲你不在DisplayWishesActivity類。您需要一個DisplayWishesActivity類的實例來調用WishAdapter類的構造函數。嘗試創建DisplayWishesActivity類的實例，或者只是發現的類的實例，以取代

DisplayWishesActivity.this 

這應該解決的問題。