我正在尝试在onSaveinstanceState中保存对象（saveMOvie），以便在使用平板电脑调试代码时在屏幕上恢复它，主要和细节片段彼此相邻，对象（saveMOvie）的值为null但是在使用移动设备时在屏幕上只有一个片段的手机对象的值（saveMOvie）不等于null有人能告诉我为什么吗？
MainActivityFragment
public class MainActivityFragment extends Fragment {
Movie moviesStore[];
GridView gridView;
String[] moviesImages;
View rootView;
ImageAdapter imgadpt;
boolean flag;
OnNewsItemSelectedListener onis;
Movie saveMOvie = new Movie();
public interface OnNewsItemSelectedListener {
public void onMovieSelected(Movie movie);
}
public MainActivityFragment() {
}
public static boolean isTablet(Context context) {
return (context.getResources().getConfiguration().screenLayout
& Configuration.SCREENLAYOUT_SIZE_MASK)
>= Configuration.SCREENLAYOUT_SIZE_LARGE;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
menu.clear();//3shan myy7slash duplicate
inflater.inflate(R.menu.menu_main, menu);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
onis = (OnNewsItemSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnNewsItemSelectedListener");
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.open_settings_activity) {
Intent intent = new Intent(getActivity(), SettingsActivity.class);
startActivity(intent);
//refresh used when there is no connection
} else if (id == R.id.Refresh_activity) {
onStart();
}
return super.onOptionsItemSelected(item);
}
public void updateMovies() {
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
String mode = prefs.getString(getString(R.string.key),
getString(R.string.default_value));
if (mode.equals("popular") || mode.equals("top_rated")) {
new FetchMovies().execute(mode);
} else {
if (flag) {
android.support.v4.app.FragmentManager fm = getActivity().getSupportFragmentManager();
android.support.v4.app.FragmentTransaction fragmentTransaction = fm.beginTransaction();
FavouriteActivityFragment fav = new FavouriteActivityFragment();
fragmentTransaction.replace(R.id.frag_main, fav);
// fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
} else {
Intent intent = new Intent(getActivity(), FavouriteActivity.class);
startActivity(intent);
}
}
}
@Override
public void onStart() {
super.onStart();
transaction.commit();
flag = isTablet(getActivity());
ConnectivityManager cn = (ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo nf = cn.getActiveNetworkInfo();
if (nf == null && nf.isConnected() != true) {
Snackbar snackbar = Snackbar
.make(rootView, "Network Not Available", Snackbar.LENGTH_LONG)
.setAction("RECONNECT", new View.OnClickListener() {
@Override
public void onClick(View view) {
onStart();
}
});
snackbar.show();
}
updateMovies();
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelable("movie",saveMOvie);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if (savedInstanceState != null) {
onis.onMovieSelected(saveMOvie);
}
setHasOptionsMenu(true);
rootView = inflater.inflate(R.layout.fragment_main, container, false);
gridView = (GridView) rootView.findViewById(R.id.gridView);
return rootView;
}
public class FetchMovies extends AsyncTask<String, Void, Movie[]> {
private final String Log_Tag = FetchMovies.class.getSimpleName();
private Movie[] getMovieDataFromJson(String moviesJasonStr)
throws JSONException
{
final String lists = "results";
final String decription = "overview";
final String originalTitle = "original_title";
final String moviePoster = "poster_path";
final String userRating = "vote_average";
final String releaseDate = "release_date";
final String id = "id";
JSONObject moviesJason = new JSONObject(moviesJasonStr);
JSONArray moviesArray = moviesJason.getJSONArray(lists);
// String[] resultStrs = new String[moviesArray.length()];
moviesStore = new Movie[moviesArray.length()];
for (int i = 0; i < moviesArray.length(); i++) {
JSONObject oneMovieInfo = moviesArray.getJSONObject(i);
moviesStore[i] = new Movie();
moviesStore[i].setPlotSynopsis(oneMovieInfo.getString("overview"));
moviesStore[i].setUserRating(oneMovieInfo.getString("vote_average"));
moviesStore[i].setReleaseDate(oneMovieInfo.getString("release_date"));
moviesStore[i].setOriginalTitle(oneMovieInfo.getString("original_title"));
moviesStore[i].setMoviePoster(oneMovieInfo.getString("poster_path"));
moviesStore[i].setId(oneMovieInfo.getString("id"));
}
return moviesStore;
}
@Override
protected Movie[] doInBackground(String... params) {
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
// Will contain the raw JSON response as a string.
String moviesJasonStr = null;
StringBuilder baseUrl = new StringBuilder("https://api.themoviedb.org/3/movie/");
baseUrl.append(params[0]);
baseUrl.append("?api_key=");
baseUrl.append(BuildConfig.MOVIE_DP_API_KEY);
try {
// URL url = new URL("https://api.themoviedb.org/3/movie/popular?api_key=d51b32efc0520227b7c1c67e0f6417f6");
URL url = new URL(baseUrl.toString());
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
return null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
moviesJasonStr = buffer.toString();
Log.v(Log_Tag, "movies Jason String :" + moviesJasonStr);
} catch (IOException e) {
Log.e(Log_Tag, "Error ", e);
// Toast.makeText(getActivity(),"there is no internet connection",Toast.LENGTH_LONG).show();
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(moviesJasonStr);
} catch (JSONException e) {
Log.e(Log_Tag, e.getMessage(), e);
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Movie[] result) {
if (result != null) {
moviesImages = new String[result.length];
for (int i = 0; i < result.length; i++) {
StringBuilder baseUrl = new StringBuilder();
baseUrl.append("http://image.tmdb.org/t/p/w185/");
baseUrl.append(result[i].getMoviePoster());
moviesImages[i] = baseUrl.toString();
}
imgadpt = new ImageAdapter(getActivity(), moviesImages);
gridView.setAdapter(imgadpt);
// if(flag){
// onis.onMovieSelected(moviesStore[0]);}
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
String posterUrl = (String) imgadpt.getItem(position);
saveMOvie = moviesStore[position];
if (flag) {
onis.onMovieSelected(moviesStore[position]);
} else {
Intent intent = new Intent(getActivity(), DetailActivity.class);
intent.putExtra("movie", moviesStore[position]);
startActivity(intent);
}
}
});
} else {
Toast.makeText(getActivity(), "Cannot Fetch Data from api check your internet Connection", Toast.LENGTH_LONG).show();
}
}
}
}
答案 0 :(得分：0)
当调用onCreate(savedInstanceState)时，检查savedInstanceState是否为null，如果没有，则检查它是否为getExtras（因为它是一个Bundle）。
if (savedInstanceState != null)
savedInstanceState.getParcelable(key)
然后做任何你喜欢的对象。