![](/img/trans.png)
[英]How to re-position the grid layout elements in fragments on orientation change?
[英]how to save ArrayLists Position at orientation change
我目前在更改方向更改后恢復ArrayList的位置時遇到錯誤,以增強用戶體驗。 我嘗試存儲ArrayList並已使movieData可打包。 當在方向更改后使用調試器時,saveInstance顯然不是null,並且包含int值,並且可能包含可拆分的Array List,我真的不知道為什么此代碼尚無法使用。
片段類別:
public class MovieGridFragment extends Fragment {
public clickInterfaceHelper clickListener;
private GridView movieGridView;
private int index;
public List<movieData> movieDataList = new ArrayList<>();
public ArrayList<movieData> restoreList;
public MovieGridFragment() {} //empty constructor
@Override
public void onAttach(Context context) {
super.onAttach(context);
}
public void setClickListener(clickInterfaceHelper listener) {
this.clickListener = listener;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null)
index = savedInstanceState.getInt("INDEX");
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
setHasOptionsMenu(true);
if(movieDataList.isEmpty() && networkChecker.isNetworkAvailableChecker(getContext())) {
movieDataList = new ArrayList<movieData>();
}
if(!movieDataList.isEmpty() && !networkChecker.isNetworkAvailableChecker(getContext())) {
movieDataList = new ArrayList<movieData>();
}
View rootView = inflater.inflate(R.layout.movie_display_fragment, container, false);
movieGridView = (GridView) rootView.findViewById(R.id.gv_movie_display);
if(savedInstanceState != null && savedInstanceState.containsKey("OLDMOVIEDATA")) {
//index = savedInstanceState.getInt("INDEX");
//movieDataList.addAll(Arrays.asList((movieData[]) savedInstanceState.getSerializable("OLDMOVIEDATA")));
restoreList = savedInstanceState.getParcelableArrayList("OLDMOVIEDATA");
movieAdapter adapter = new movieAdapter(getActivity(),restoreList);
adapter.notifyDataSetChanged();
//movieGridView.setAdapter(adapter);
movieGridView.smoothScrollToPosition(index);
}
else {
movieAdapter adapter = new movieAdapter(getActivity(), movieDataList);
adapter.notifyDataSetChanged();
movieGridView.setAdapter(adapter);
}
movieGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if(clickListener != null)
clickListener.clickOnItem(position);
}
});
return rootView;
}
@Override
public void onSaveInstanceState(Bundle outState) {
//outState.putSerializable("OLDMOVIEDATA",movieData.movieDataArray);
outState.putParcelableArrayList("OLDMOVIEDATA",restoreList);
outState.putInt("INDEX",movieGridView.getFirstVisiblePosition());
super.onSaveInstanceState(outState);
}
}
適配器:
public class movieAdapter extends ArrayAdapter<movieData> {
public movieAdapter(Context context, List<movieData> movieObject) {
super(context, 0, movieObject);
}
public View getView(int pos, View convertingView, ViewGroup viewGroup) {
movieData movieDatas = getItem(pos);
String url="http://image.tmdb.org/t/p/w185"+movieDatas.getMovieImagePath();
if(convertingView == null)
convertingView = LayoutInflater.from(getContext()).inflate(R.layout.image_display,viewGroup,false);
ImageView imageView = (ImageView) convertingView.findViewById(R.id.iv_movie_image);
Picasso.with(getContext()).load(url.trim()).into(imageView);
return convertingView;
}
}
主要活動:
public class MainActivity extends AppCompatActivity implements clickInterfaceHelper {
public static String sorterString = null;
public static String urlBase = "https://api.themoviedb.org/3/movie/";
public static String urlFinal = null;
RequestQueue requestQueue;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState == null) {
MovieGridFragment fragment = new MovieGridFragment();
fragment.setClickListener(this);
getSupportFragmentManager().beginTransaction()
.add(R.id.activity_container, fragment)
.commit();
movieData.movieDataPosition = 0;
}
if(savedInstanceState != null) {
sorterString = savedInstanceState.getString("SORTER");
}
if(sorterString==null)
sorterString="popular?";
if(sorterString!="favorite" && sorterString!=null) {
if(networkChecker.isNetworkAvailableChecker(this)) {
movieRequest();
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu_act, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if(id == R.id.m_popularity_action) {
if(sorterString != "popular?") {
sorterString = "popular?";
if(networkChecker.isNetworkAvailableChecker(this))
movieRequest();
}
return true;
}
if(id == R.id.m_action_voter) {
if(sorterString != "top_rated?") {
sorterString = "top_rated?";
if(networkChecker.isNetworkAvailableChecker(this))
movieRequest();
}
return true;
}
if(id == R.id.m_favorite_btn) {
if(sorterString != "favorite") {
SQLiteOpenHelper helper = new movieDataDbHelper(this);
SQLiteDatabase database = helper.getReadableDatabase();
Cursor cursor= database.query(movieDataContract.contractEntry.TABLE_NAME,
new String[] {
movieDataContract.contractEntry.ID,
movieDataContract.contractEntry.IMG_PATH},null,null,null,null,null);
if(cursor.getCount() == 0) {
Toast.makeText(this, "there are no favorite movies yet!",Toast.LENGTH_SHORT).show();
} else {
sorterString = "favorite";
showFavoriteFragment();
}
database.close();
helper.close();
cursor.close();
}
return true;
}
return super.onOptionsItemSelected(item);
}
public void showFavoriteFragment() {
favoriteMoviesDetailsFragment fragment = new favoriteMoviesDetailsFragment();
try {
getFragmentManager().beginTransaction().replace(R.id.activity_container,fragment).commit();
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
outState.putString("SORTER", sorterString);
outState.putInt("POSITION",movieData.movieDataPosition);
super.onSaveInstanceState(outState, outPersistentState);
}
public void movieRequest() {
final MovieGridFragment gridFragment = new MovieGridFragment();
gridFragment.setClickListener(this);
urlFinal = urlBase + sorterString + movieData.apiKey;
urlFinal.trim();
requestQueue = Volley.newRequestQueue(this);
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, urlFinal, null, new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray array = response.getJSONArray("results");
movieData.movieDataArray = new movieData[array.length()];
for (int i = 0; i < array.length(); i++) {
movieData movie = new movieData();
JSONObject jsonObject = array.getJSONObject(i);
movie.setMovieId(jsonObject.getString("id"));
movie.setMovieImagePath(jsonObject.getString("poster_path"));
movie.setMovieTitle(jsonObject.getString("original_title"));
movie.setMoviePlot(jsonObject.getString("overview"));
movie.setMovieVoting(jsonObject.getString("vote_average"));
movie.setMovieReleaseDate(jsonObject.getString("release_date"));
movieData.movieDataArray[i] = movie;
}
gridFragment.movieDataList = Arrays.asList(movieData.movieDataArray);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.activity_container, gridFragment);
try {
transaction.commitAllowingStateLoss();
} catch (Exception e) {
e.printStackTrace();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("volley", String.valueOf(error));
}
}
);
requestQueue.add(jsonObjectRequest);
}
@Override
public void clickOnItem(int id) {
movieData.movieDataPosition = id;
if(movieData.movieDataArray == null) {
movieRequest();
} else {
Intent intent = new Intent(this, detailsActivity.class);
intent.putExtra("FRAGMENT","MOVIE");
startActivity(intent);
}
}
@Override
public void favoriteMovieItem(int movieId) {
movieData.dbPosition = movieId;
Intent intent = new Intent(this,detailsActivity.class);
intent.putExtra("FRAGMENT","favorite");
startActivity(intent);
}
}
您已經使用了
@Override
public void onSaveInstanceState(Bundle outState) {
//outState.putSerializable("OLDMOVIEDATA",movieData.movieDataArray);
outState.putParcelableArrayList("OLDMOVIEDATA",restoreList);
outState.putInt("INDEX",movieGridView.getFirstVisiblePosition());
super.onSaveInstanceState(outState);
}
只需使用它來存儲您需要保存的位置。 使用“ onCreateView”中提供的捆綁包重新獲得位置。
如果不起作用,請將“ setRetainInstance(true)”放在片段的“ onCreate”函數中。 這將防止您的片段被破壞,然后在方向更改時一無所獲。 但是,我在某處讀到了使用具有UI元素的片段的方法不是正確的方法(但我從沒發現任何錯誤)。
如果您想要不使用“ setRetainInstance”的替代方法,請存儲(並還原)活動中的位置
public void onSaveInstanceState(Bundle outState)"
功能。 為此,請在片段中創建一個函數“ getPosition()”,在活動saveInstanceState中調用它,然后在片段中創建一個函數“ refresh(int position)”(並在還原后的位置值上調用它)在活動中加載/重新創建。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.