Question

getView（）方法用于在使用Picasso库解析后打印json响应没有被执行。当我调试我的代码时，它会跳过getView（）方法，输出为空白屏幕。

package com.example.saurabharora.movies;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.ImageView;

import com.squareup.picasso.Picasso;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment {

    String jsonstr;
    private ArrayAdapter<String> PostsAdapter;
    ArrayList posters = new ArrayList();

    public MainActivityFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {


        View rootView = inflater.inflate(R.layout.fragment_main, container, false);

        GridView gridView = (GridView) rootView.findViewById(R.id.image);
        gridView.setAdapter(new PostsAdapter(getActivity(), posters));

        return rootView;
    }

    private void updateMovies() {
        FetchMovies MovieTask = new FetchMovies();
        MovieTask.execute();
    }

    @Override
    public void onStart() {
        super.onStart();
        updateMovies();
    }

    public class FetchMovies extends AsyncTask<String, Void, String[]> {

        @Override
        protected String[] doInBackground(String... params) {
            // These two need to be declared outside the try/catch
            // so that they can be closed in the finally block.
            HttpURLConnection urlConnection = null;
            BufferedReader reader = null;

            // Will contain the raw JSON response as a string.
            String jsonstr = null;

            try {
                URL url = new URL("http://api.themoviedb.org/3/movie/top_rated?api_key=OPEN_MOVIES_API_KEY");
                urlConnection = (HttpURLConnection) url.openConnection();
                InputStream inputStream = urlConnection.getInputStream();
                StringBuffer buffer = new StringBuffer();
                reader = new BufferedReader(new InputStreamReader(inputStream));

                String line;
                while ((line = reader.readLine()) != null) {
                    buffer.append(line + "\n");
                }
                jsonstr = buffer.toString();
                //TextView response = (TextView) findViewById(R.id.list);
                //response.setText(jsonstr);
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                urlConnection.disconnect();
            }
            ArrayList posters = new ArrayList();

            try {
                JSONObject response = new JSONObject(jsonstr);
                JSONArray results = response.optJSONArray("results");

                for (int i = 0; i < results.length(); i++) {
                    JSONObject movie = results.getJSONObject(i);
                    posters.add(movie.optString("poster_path"));
                }
                Log.v("posterpath", posters.toString());
            } catch (JSONException e) {
                Log.e("MYAPP", "unexpected JSON exception", e);
            }

            return null;

        }

        protected void onPostExecute(String[] result) {
            if (result == null) {
                System.out.println("Error");
            }
            if (result != null) {
                PostsAdapter.clear();
                for (String MoviesStr : result) {
                    PostsAdapter.add(MoviesStr);
                }
                // New data is back from the server.  Hooray!
            }
        }
    }

    class PostsAdapter extends ArrayAdapter {

        Activity context;
        ArrayList posters = null;

        public PostsAdapter(Activity context, ArrayList posters) {
            super(context, R.layout.list, posters);

            this.context = context;
            this.posters = posters;
        }


        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null)
                convertView = context.getLayoutInflater().inflate(R.layout.list, parent, false);

            ImageView loadimages = (ImageView) convertView.findViewById(R.id.url);
            Picasso.with(context).load("http://image.tmdb.org/t/p/w185/" + posters.get(position)).into(loadimages);


            return convertView;
        }
    }
}

Answer 1

我认为您错过了@Override方法的getView()注释：

@Override
public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null)
                convertView = context.getLayoutInflater().inflate(R.layout.list, parent, false);

            ImageView loadimages = (ImageView) convertView.findViewById(R.id.url);
            Picasso.with(context).load("http://image.tmdb.org/t/p/w185/" + posters.get(position)).into(loadimages);


            return convertView;
        }

希望这会有所帮助：）

Answer 2

在代码中进行以下更改：

在onCreateView中： -

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                     Bundle savedInstanceState) {


View rootView = inflater.inflate(R.layout.fragment_main, container, false);

GridView gridView = (GridView) rootView.findViewById(R.id.image);
mPostsAdapter = new PostsAdapter(getActivity(), posters);
gridView.setAdapter(mPostsAdapter);

return rootView;
}

在AsyncTask中的onPostExecute中： -

protected void onPostExecute(String[] result) {
    if (result == null) {
        System.out.println("Error");
    }
    if (result != null) {
        mPostsAdapter.clear();
        for (String MoviesStr : result) {
            mPostsAdapter.add(MoviesStr);
        }
        // New data is back from the server.  Hooray!
    }
}

无法打印解析后从服务器获取的json响应。

2 个答案: