我的ImageAdapter似乎有问题。它应该更新GridView但不会这样做。
代码：
public class MainActivityFragment extends Fragment {
ImageAdapter imageAdapter;
GridView gridView;
public MainActivityFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
gridView = (GridView) rootView.findViewById(R.id.gridView);
imageAdapter = new ImageAdapter(getActivity(),new ArrayList<Movie>());
gridView.setAdapter(imageAdapter);
return rootView;
}
@Override
public void onStart() {
super.onStart();
UpdateMovies();
}
private void UpdateMovies() {
FetchMoviesTask task = new FetchMoviesTask();
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(getActivity());
String sort = preferences.getString(getString(R.string.pref_sort_key), getString(R.string.pref_sort_default));
task.execute(sort);
}
public class ImageAdapter extends BaseAdapter {
private Context mContext;
private ArrayList<Movie> data;
public ImageAdapter(Context c, ArrayList<Movie> movies) {
mContext = c;
data = movies;
}
public int getCount() {
return data.size();
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(mContext.LAYOUT_INFLATER_SERVICE);
View gridView;
ImageView imageView;
if (convertView == null) {
// if it's not recycled, initialize some attributes
gridView = new GridView(mContext);
gridView = inflater.inflate(R.layout.grid_item_poster, null);
imageView = (ImageView)gridView.findViewById(R.id.poster);
} else {
imageView = (ImageView) convertView;
}
if (data.size() != 0) {
Log.v("IMAGE_ADAPTER","SetView= " + data.get(position).poster);
Picasso.with(mContext).load(data.get(position).poster).into(imageView);
}
return imageView;
}
public void updatePosters(ArrayList<Movie> newMovies) {
data.clear();
data.addAll(newMovies);
this.notifyDataSetChanged();
}
}
public class FetchMoviesTask extends AsyncTask<String, Void, ArrayList<Movie>> {
private final String LOG_TAG = FetchMoviesTask.class.getName();
private ArrayList<Movie> getMovieDataFromJson(String movieJsonStr, int numDays)
throws JSONException {
// These are the names of the JSON objects that need to be extracted.
final String MOV_LIST = "results";
final String MOV_ID = "id";
final String MOV_TITLE = "original_title";
final String MOV_OVERVIEW = "overview";
final String MOV_RATING = "vote_average";
final String MOV_DATE = "release_date";
final String MOV_POSTER = "poster_path";
JSONObject listJson = new JSONObject(movieJsonStr);
JSONArray movieArray = listJson.getJSONArray(MOV_LIST);
ArrayList<Movie> movies = new ArrayList<>();
for(int i = 0; i < movieArray.length(); i++) {
int id;
String title;
String overview;
String rating;
String date;
String poster;
// Get the JSON object representing the day
JSONObject movie = movieArray.getJSONObject(i);
id = movie.getInt(MOV_ID);
title = movie.getString(MOV_TITLE);
overview = movie.getString(MOV_OVERVIEW);
rating = movie.getString(MOV_RATING);
date = movie.getString(MOV_DATE);
poster = movie.getString(MOV_POSTER);
Movie newMovie = new Movie(id, title, overview, rating, date, poster);
movies.add(newMovie);
}
for (Movie s : movies) {
Log.v(LOG_TAG, "Movie entry: " + s.print());
}
return movies;
}
@Override
protected void onPostExecute(ArrayList<Movie> result) {
if(result != null){
Log.v(LOG_TAG,"DATA SET CHANGED! SIZE= " + result.size());
imageAdapter.updatePosters(result);
}
}
@Override
protected ArrayList<Movie> doInBackground(String... params) {
if(params.length == 0){
return null;
}
// 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 movieJsonStr = null;
String format = "JSON";
String units = "metric";
String apiKey = "********************";
int numDays = 7;
try {
// Construct the URL for the OpenWeatherMap query
// Possible parameters are avaiable at OWM's forecast API page, at
// http://openweathermap.org/API#forecast
final String MOVIE_BASE_URL = "http://api.themoviedb.org/3/discover/movie?";
final String SORT_PARAM = "sort_by";
final String DESC = ".desc";
final String API_PARAM = "api_key";
Uri builtUri = Uri.parse(MOVIE_BASE_URL).buildUpon()
.appendQueryParameter(SORT_PARAM,(params[0]+DESC))
.appendQueryParameter(API_PARAM,apiKey)
.build();
URL url = new URL(builtUri.toString());
Log.v(LOG_TAG, "Built URI " + builtUri.toString());
// Create the request to OpenWeatherMap, and open the connection
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// Read the input stream into a String
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
// Nothing to do.
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
// Since it's JSON, adding a newline isn't necessary (it won't affect parsing)
// But it does make debugging a *lot* easier if you print out the completed
// buffer for debugging.
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
// Stream was empty. No point in parsing.
return null;
}
movieJsonStr = buffer.toString();
Log.v(LOG_TAG,"Movie JSON String: " + movieJsonStr);
} catch (IOException e) {
Log.e(LOG_TAG, "Error ", e);
// If the code didn't successfully get the weather data, there's no point in attemping
// to parse it.
return null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
try {
return getMovieDataFromJson(movieJsonStr, numDays);
}catch (JSONException e){
Log.e(LOG_TAG, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
}
}
fragment_main.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivityFragment">
<GridView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/gridView"
android:columnWidth="180dp"
android:gravity="center"
android:numColumns="auto_fit"
android:stretchMode="columnWidth"/>
grid_item_poster.xml
<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="120dp"
android:scaleType="centerCrop"
android:id="@+id/poster"
android:adjustViewBounds="true">
</ImageView>
奇怪的是，当我在onCreateView中创建我的ImageAdapter时添加带有元素的ArrayList时，它确实有效，但是当我将该列表保留为未填充时，它不会更新。
任何人都有任何线索该怎么办？ 一整天都在寻找解决方案。 ：d
提前致谢。
答案 0 :(得分：1)
我觉得你的getView()方法有问题我有一种奇怪的印象 - 我可能错了，但试试这个：
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(mContext.LAYOUT_INFLATER_SERVICE);
ImageView imageView;
if (convertView == null) {
convertView = inflater.inflate(R.layout.grid_item_poster, null);
imageView = (ImageView) convertView.findViewById(R.id.poster);
convertView.setTag(imageView);
} else {
imageView = (ImageView) convertView.getTag();
}
if (data.size() != 0 && data.get(position) != null) {
Log.v("IMAGE_ADAPTER","SetView= " + data.get(position).poster);
Picasso.with(mContext).load(data.get(position).poster).into(imageView);
} else {
//I think that you should reset image when there is a issue with data set
imageView.setImageResource(-1);
}
return imageView;
}
此外，此评论 - create a new ImageView for each item referenced by the Adapter无效，因为适配器重用视图位于屏幕之外，因此有时不会创建新的ImageView实例，列表会显示旧数据的新数据
修改
尝试创建新数据列表而不是清除旧数据列表：
public void updatePosters(ArrayList<Movie> newMovies) {
data = new ArrayList<Movies>();
data.addAll(newMovies);
this.notifyDataSetChanged();
}
答案 1 :(得分：0)
您getView未正确实施。首先，你想要在那里实现它是非常奇怪的，你正在膨胀一些东西只是为了从该布局获得一个ImageView。您可以在方法中实例化ImageView：
public View getView(int position, View convertView, ViewGroup parent) {
View view=convertView;
if (view == null) {
view=new ImageView(mContext);
view.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout
.LayoutParams.MATCH_PARENT,LinearLayout
.LayoutParams.WRAP_CONTENT));
view.setScaleType(ImageView.ScaleType.CENTER_CROP);
}
final String url=data.get(position).poster;
if (!TextUtis.isEmpty(url) {
Log.v("IMAGE_ADAPTER","SetView= " + url);
Picasso.with(mContext).load(url).into(((ImageView)view));
} else {
Picasso.with(mContext).load(android.R.color.transparent).into(((ImageView)view);
}
return view;
}