不是封闭的 class 错误 (Android)

Question

在下面的一段代码中，我在自定义适配器中尝试传递 DisplayWishesActivity.this 时遇到错误。 DisplayWishesActivity 是另一个 activity，尚未修改。（错误行请参考代码）

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

我不知道是什么让你这样做，但这是错误的。语法：

ClassName.this

只能在ClassNameclass中使用。在您的情况下，当您尝试使用

DisplayWishesActivity.this

它给出一个错误，因为你不在 DisplayWishesActivity class 中。您需要 DisplayWishesActivity class 的实例来调用 WishAdapter class 的构造函数。尝试创建一个 DisplayWishesActivity class 的实例，或者只是找到一个 class 的实例来替换

DisplayWishesActivity.this

这应该可以解决问题。

不是封闭的 class 错误 (Android)

Not an enclosing class Error (Android)

android

android-adapter

android-activity