RecyclerView在fragment中通过activity获取位置
RecyclerView in fragment through activity get position
所以这是我的问题，我只有一个 activity 来自我启动我的 viewpager 片段，在我的 viewpager 中我有 4 个包含 recyclerView 的片段。每个片段都包含由网络上的数据填充的项目，当我点击其中一个时，我得到一个 WebView 片段，但是当我点击后退按钮时，我失去了我的 poisiton，因为它正在重新创建整个 activity。
我不知道如何不重新创建 activity 并恢复我的旧位置，或者重新创建它但不更改项目的位置并恢复我的旧位置。这是我的代码。我应该把什么放在哪里？！一些帮助会非常非常好。
谢谢！！
我的ActivityClass:
public class LauncherActivity extends AppCompatActivity implements ListFragment.OnNewSelectedInterface{
public static final String VIEWPAGER_FRAGMENT = "view_pager";
private ImageView mImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_launcher);
RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.activity_launcher);
mImageView = (ImageView) findViewById(R.id.logoImageView);
mImageView.startAnimation(AnimationUtils.loadAnimation(this, R.anim.rotate_indefinitely));
if(!isNetworkAvailable()){
alertUserAboutError();
} else {
relativeLayout.postDelayed(new Runnable() {
@Override
public void run() {
ViewPagerFragment savedFragment = (ViewPagerFragment)
getSupportFragmentManager().findFragmentByTag(VIEWPAGER_FRAGMENT);
if(savedFragment == null) {
ViewPagerFragment viewPagerFragment = new ViewPagerFragment();
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.activity_launcher, viewPagerFragment, VIEWPAGER_FRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
}
}, 2000);
}
}
@Override
public void onListNewSelected(int index, ArrayList<Articles> articles) {
WebViewFragment webViewFragment = new WebViewFragment();
Bundle bundle = new Bundle();
bundle.putInt(ViewPagerFragment.KEY_NEW_INDEX, index);
bundle.putParcelableArrayList(ListFragment.KEY_LIST, articles);
webViewFragment.setArguments(bundle);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.activity_launcher, webViewFragment, WebViewFragment.WEBVIEWFRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
private boolean isNetworkAvailable() {
ConnectivityManager manager = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
boolean isAvailable = false;
if (networkInfo != null && networkInfo.isConnected()) {
isAvailable = true;
}
return isAvailable;
}
private void alertUserAboutError() {
AlertDialogFragment alertDialogFragment = new AlertDialogFragment();
alertDialogFragment.show(getFragmentManager(), "error_dialog");
}
}
我的 ViewPagerClass :
public class ViewPagerFragment extends Fragment {
public static final String KEY_NEW_INDEX = "key_new_index";
private ViewPager mViewPager;
private TabLayout mTabLayout;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.fragment_view_pager, container, false);
final OldFactFragment oldFactFragment = new OldFactFragment();
final SportFragment sportFragment = new SportFragment();
final BuzzFragment buzzFragment = new BuzzFragment();
final NewsFragment newsFragment = new NewsFragment();
mViewPager = (ViewPager) view.findViewById(R.id.viewPager);
mTabLayout = (TabLayout) view.findViewById(R.id.tabLayout);
mViewPager.setOffscreenPageLimit(4);
mViewPager.setAdapter(new FragmentPagerAdapter(getChildFragmentManager()) {
@Override
public Fragment getItem(int position) {
if(position == 0){
return oldFactFragment;
} else if (position == 1) {
return newsFragment;
} else if (position == 2){
return sportFragment;
} else return buzzFragment;
}
@Override
public CharSequence getPageTitle(int position) {
if(position == 0){
return "Pastly";
} else if (position == 1) {
return "politic";
} else if (position == 2){
return "sport";
} else return "buzz";
}
@Override
public int getCount() {
return 4;
}
});
mTabLayout.setupWithViewPager(mViewPager);
return view;
}
}
我的 ListFragment（ViewPager 中 4 个片段的父 class）：
public abstract class ListFragment extends Fragment {
public static final String KEY_LIST = "key_list";
public interface OnNewSelectedInterface {
void onListNewSelected(int index, ArrayList<Articles> articles);
}
protected static final String TAG = ListFragment.class.getSimpleName();
protected ArrayList<Articles> mArticlesList;
protected ItemAdapter mArticleAdapter;
protected RecyclerView mRecyclerView;
protected OnNewSelectedInterface mListener;
protected RecyclerView.LayoutManager mManager;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
mListener = (OnNewSelectedInterface) getActivity();
View view = inflater.inflate(R.layout.fragment_list, container, false);
mRecyclerView = (RecyclerView) view.findViewById(R.id.recyclerview);
getInfos(getUrl());
return view;
}
protected abstract String[] getUrl();
private void getInfos(String[] url) {
if (isNetworkAvailable()) {
OkHttpClient client = new OkHttpClient();
for (int i = 0; i < getUrl().length; i++) {
Request request = new Request.Builder().url(url[i]).build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onResponse(Call call, Response response) throws IOException {
try {
String jsonData = response.body().string();
if (response.isSuccessful()) {
Log.v(TAG, jsonData);
getMultipleUrls(jsonData);
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
getCurrentArticles(mArticlesList);
}
});
} else {
alertUserAboutError();
}
} catch (IOException | JSONException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(Call call, IOException e) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
alertUserAboutError();
}
});
}
});
}
} else{
alertUserAboutError();
}
}
private void getMultipleUrls(String jsonData) throws JSONException {
if (mArticlesList == null) {
mArticlesList = getArticleForecast(jsonData);
} else {
mArticlesList.addAll(getArticleForecast(jsonData));
}
}
private void getCurrentArticles(ArrayList<Articles> articles) {
mArticleAdapter = new ItemAdapter(getActivity(), articles, mListener);
mRecyclerView.setAdapter(mArticleAdapter);
mManager = new LinearLayoutManager(getActivity());
mRecyclerView.setLayoutManager(mManager);
}
private boolean isNetworkAvailable() {
ConnectivityManager manager = (ConnectivityManager) getActivity().
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
boolean isAvailable = false;
if (networkInfo != null && networkInfo.isConnected()) {
isAvailable = true;
}
return isAvailable;
}
private void alertUserAboutError() {
AlertDialogFragment alertDialogFragment = new AlertDialogFragment();
alertDialogFragment.show(getActivity().getFragmentManager(), "error_dialog");
}
private ArrayList<Articles> getArticleForecast(String jsonData) throws JSONException {
JSONObject forecast = new JSONObject(jsonData);
JSONArray articles = forecast.getJSONArray("articles");
ArrayList<Articles> listArticles = new ArrayList<>(articles.length());
for (int i = 0; i < articles.length(); i++) {
JSONObject jsonArticle = articles.getJSONObject(i);
Articles article = new Articles();
String urlImage = jsonArticle.getString("urlToImage");
article.setTitle(jsonArticle.getString("title"));
article.setDescription(jsonArticle.getString("description"));
article.setImageView(urlImage);
article.setArticleUrl(jsonArticle.getString("url"));
listArticles.add(i, article);
}
return listArticles;
}
}
和我的 ItemAdapter（适配器 Class）：
public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ArticleViewHolder> {
private final ListFragment.OnNewSelectedInterface mListener;
protected ArrayList<Articles> mArticlesList;
protected Context mContext;
private int mPosition;
private int lastPosition = -1;
public ItemAdapter(Context contexts, ArrayList<Articles> mArticleLi, ListFragment.OnNewSelectedInterface listener){
mContext = contexts;
mArticlesList = mArticleLi;
mListener = listener;
}
@Override
public ArticleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_item_linear, parent, false);
view.findViewById(R.id.textView).setSelected(true);
ArticleViewHolder articleViewHolder = new ArticleViewHolder(view);
articleViewHolder.setIsRecyclable(false);
return articleViewHolder;
}
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
public void onBindViewHolder(ArticleViewHolder holder, int position) {
mPosition = position;
holder.bindArticle(mArticlesList.get(position));
setAnimation(holder.itemView, position);
holder.mImageView.setClipToOutline(true);
}
private void setAnimation(View viewToAnimate, int position) {
if (position > lastPosition) {
Animation animation = AnimationUtils.loadAnimation(viewToAnimate.getContext(), android.R.anim.slide_in_left);
viewToAnimate.startAnimation(animation);
lastPosition = position;
}
}
@Override
public int getItemCount() {
return mArticlesList.size();
}
public class ArticleViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener{
private TextView mTitle, mArticle;
private ImageView mImageView;
private ArticleViewHolder(View itemView) {
super(itemView);
mTitle = (TextView) itemView.findViewById(R.id.textView);
mArticle = (TextView) itemView.findViewById(R.id.showTextView);
mImageView = (ImageView) itemView.findViewById(R.id.imageView2);
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
}
private void bindArticle(Articles article) {
mTitle.setText(article.getTitle());
mArticle.setText(article.getDescription());
mArticle.setVisibility(View.INVISIBLE);
Glide.with(mContext).load(article.getImageView()).into(mImageView);
}
@Override
public void onClick(View view) {
mListener.onListNewSelected(getLayoutPosition(), mArticlesList);
}
@Override
public boolean onLongClick(View view) {
String desc = mArticlesList.get(getAdapterPosition()).getDescription();
mArticle.setVisibility(View.VISIBLE);
mArticle.setText(desc);
mArticle.postDelayed(new Runnable() {
public void run() {
mArticle.setVisibility(View.INVISIBLE);
}
}, 3000);
return true;
}
}
}
在您的方法中 onListNewSelected 您正在将新的 片段 替换为该行中所述的旧片段
fragmentTransaction.replace(R.id.activity_launcher, webViewFragment, WebViewFragment.WEBVIEWFRAGMENT);
Replace an existing fragment that was added to a container. This is essentially the same as calling remove(Fragment) for all currently added fragments that were added with the same containerViewId and then add(int, Fragment, String) with the same arguments given here.
所以你要删除旧的片段然后添加新的，当你回来获取旧的片段时，它是还没有，它将从头开始创建，所以这个位置已经随着删除的 片段.
消失了
在使用 add 方法时，将在前一个片段上方添加新的 片段 ，当您返回前一个片段时，它的状态已经存在 "Position"
所以这是我的问题，我只有一个 activity 来自我启动我的 viewpager 片段，在我的 viewpager 中我有 4 个包含 recyclerView 的片段。每个片段都包含由网络上的数据填充的项目，当我点击其中一个时，我得到一个 WebView 片段，但是当我点击后退按钮时，我失去了我的 poisiton，因为它正在重新创建整个 activity。
我不知道如何不重新创建 activity 并恢复我的旧位置，或者重新创建它但不更改项目的位置并恢复我的旧位置。这是我的代码。我应该把什么放在哪里？！一些帮助会非常非常好。 谢谢！！
我的ActivityClass:
public class LauncherActivity extends AppCompatActivity implements ListFragment.OnNewSelectedInterface{
public static final String VIEWPAGER_FRAGMENT = "view_pager";
private ImageView mImageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_launcher);
RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.activity_launcher);
mImageView = (ImageView) findViewById(R.id.logoImageView);
mImageView.startAnimation(AnimationUtils.loadAnimation(this, R.anim.rotate_indefinitely));
if(!isNetworkAvailable()){
alertUserAboutError();
} else {
relativeLayout.postDelayed(new Runnable() {
@Override
public void run() {
ViewPagerFragment savedFragment = (ViewPagerFragment)
getSupportFragmentManager().findFragmentByTag(VIEWPAGER_FRAGMENT);
if(savedFragment == null) {
ViewPagerFragment viewPagerFragment = new ViewPagerFragment();
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.activity_launcher, viewPagerFragment, VIEWPAGER_FRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
}
}, 2000);
}
}
@Override
public void onListNewSelected(int index, ArrayList<Articles> articles) {
WebViewFragment webViewFragment = new WebViewFragment();
Bundle bundle = new Bundle();
bundle.putInt(ViewPagerFragment.KEY_NEW_INDEX, index);
bundle.putParcelableArrayList(ListFragment.KEY_LIST, articles);
webViewFragment.setArguments(bundle);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.activity_launcher, webViewFragment, WebViewFragment.WEBVIEWFRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
private boolean isNetworkAvailable() {
ConnectivityManager manager = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
boolean isAvailable = false;
if (networkInfo != null && networkInfo.isConnected()) {
isAvailable = true;
}
return isAvailable;
}
private void alertUserAboutError() {
AlertDialogFragment alertDialogFragment = new AlertDialogFragment();
alertDialogFragment.show(getFragmentManager(), "error_dialog");
}
}
我的 ViewPagerClass :
public class ViewPagerFragment extends Fragment {
public static final String KEY_NEW_INDEX = "key_new_index";
private ViewPager mViewPager;
private TabLayout mTabLayout;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
final View view = inflater.inflate(R.layout.fragment_view_pager, container, false);
final OldFactFragment oldFactFragment = new OldFactFragment();
final SportFragment sportFragment = new SportFragment();
final BuzzFragment buzzFragment = new BuzzFragment();
final NewsFragment newsFragment = new NewsFragment();
mViewPager = (ViewPager) view.findViewById(R.id.viewPager);
mTabLayout = (TabLayout) view.findViewById(R.id.tabLayout);
mViewPager.setOffscreenPageLimit(4);
mViewPager.setAdapter(new FragmentPagerAdapter(getChildFragmentManager()) {
@Override
public Fragment getItem(int position) {
if(position == 0){
return oldFactFragment;
} else if (position == 1) {
return newsFragment;
} else if (position == 2){
return sportFragment;
} else return buzzFragment;
}
@Override
public CharSequence getPageTitle(int position) {
if(position == 0){
return "Pastly";
} else if (position == 1) {
return "politic";
} else if (position == 2){
return "sport";
} else return "buzz";
}
@Override
public int getCount() {
return 4;
}
});
mTabLayout.setupWithViewPager(mViewPager);
return view;
}
}
我的 ListFragment（ViewPager 中 4 个片段的父 class）：
public abstract class ListFragment extends Fragment {
public static final String KEY_LIST = "key_list";
public interface OnNewSelectedInterface {
void onListNewSelected(int index, ArrayList<Articles> articles);
}
protected static final String TAG = ListFragment.class.getSimpleName();
protected ArrayList<Articles> mArticlesList;
protected ItemAdapter mArticleAdapter;
protected RecyclerView mRecyclerView;
protected OnNewSelectedInterface mListener;
protected RecyclerView.LayoutManager mManager;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
mListener = (OnNewSelectedInterface) getActivity();
View view = inflater.inflate(R.layout.fragment_list, container, false);
mRecyclerView = (RecyclerView) view.findViewById(R.id.recyclerview);
getInfos(getUrl());
return view;
}
protected abstract String[] getUrl();
private void getInfos(String[] url) {
if (isNetworkAvailable()) {
OkHttpClient client = new OkHttpClient();
for (int i = 0; i < getUrl().length; i++) {
Request request = new Request.Builder().url(url[i]).build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onResponse(Call call, Response response) throws IOException {
try {
String jsonData = response.body().string();
if (response.isSuccessful()) {
Log.v(TAG, jsonData);
getMultipleUrls(jsonData);
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
getCurrentArticles(mArticlesList);
}
});
} else {
alertUserAboutError();
}
} catch (IOException | JSONException e) {
e.printStackTrace();
}
}
@Override
public void onFailure(Call call, IOException e) {
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
alertUserAboutError();
}
});
}
});
}
} else{
alertUserAboutError();
}
}
private void getMultipleUrls(String jsonData) throws JSONException {
if (mArticlesList == null) {
mArticlesList = getArticleForecast(jsonData);
} else {
mArticlesList.addAll(getArticleForecast(jsonData));
}
}
private void getCurrentArticles(ArrayList<Articles> articles) {
mArticleAdapter = new ItemAdapter(getActivity(), articles, mListener);
mRecyclerView.setAdapter(mArticleAdapter);
mManager = new LinearLayoutManager(getActivity());
mRecyclerView.setLayoutManager(mManager);
}
private boolean isNetworkAvailable() {
ConnectivityManager manager = (ConnectivityManager) getActivity().
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = manager.getActiveNetworkInfo();
boolean isAvailable = false;
if (networkInfo != null && networkInfo.isConnected()) {
isAvailable = true;
}
return isAvailable;
}
private void alertUserAboutError() {
AlertDialogFragment alertDialogFragment = new AlertDialogFragment();
alertDialogFragment.show(getActivity().getFragmentManager(), "error_dialog");
}
private ArrayList<Articles> getArticleForecast(String jsonData) throws JSONException {
JSONObject forecast = new JSONObject(jsonData);
JSONArray articles = forecast.getJSONArray("articles");
ArrayList<Articles> listArticles = new ArrayList<>(articles.length());
for (int i = 0; i < articles.length(); i++) {
JSONObject jsonArticle = articles.getJSONObject(i);
Articles article = new Articles();
String urlImage = jsonArticle.getString("urlToImage");
article.setTitle(jsonArticle.getString("title"));
article.setDescription(jsonArticle.getString("description"));
article.setImageView(urlImage);
article.setArticleUrl(jsonArticle.getString("url"));
listArticles.add(i, article);
}
return listArticles;
}
}
和我的 ItemAdapter（适配器 Class）：
public class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ArticleViewHolder> {
private final ListFragment.OnNewSelectedInterface mListener;
protected ArrayList<Articles> mArticlesList;
protected Context mContext;
private int mPosition;
private int lastPosition = -1;
public ItemAdapter(Context contexts, ArrayList<Articles> mArticleLi, ListFragment.OnNewSelectedInterface listener){
mContext = contexts;
mArticlesList = mArticleLi;
mListener = listener;
}
@Override
public ArticleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.list_item_linear, parent, false);
view.findViewById(R.id.textView).setSelected(true);
ArticleViewHolder articleViewHolder = new ArticleViewHolder(view);
articleViewHolder.setIsRecyclable(false);
return articleViewHolder;
}
@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
public void onBindViewHolder(ArticleViewHolder holder, int position) {
mPosition = position;
holder.bindArticle(mArticlesList.get(position));
setAnimation(holder.itemView, position);
holder.mImageView.setClipToOutline(true);
}
private void setAnimation(View viewToAnimate, int position) {
if (position > lastPosition) {
Animation animation = AnimationUtils.loadAnimation(viewToAnimate.getContext(), android.R.anim.slide_in_left);
viewToAnimate.startAnimation(animation);
lastPosition = position;
}
}
@Override
public int getItemCount() {
return mArticlesList.size();
}
public class ArticleViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener{
private TextView mTitle, mArticle;
private ImageView mImageView;
private ArticleViewHolder(View itemView) {
super(itemView);
mTitle = (TextView) itemView.findViewById(R.id.textView);
mArticle = (TextView) itemView.findViewById(R.id.showTextView);
mImageView = (ImageView) itemView.findViewById(R.id.imageView2);
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
}
private void bindArticle(Articles article) {
mTitle.setText(article.getTitle());
mArticle.setText(article.getDescription());
mArticle.setVisibility(View.INVISIBLE);
Glide.with(mContext).load(article.getImageView()).into(mImageView);
}
@Override
public void onClick(View view) {
mListener.onListNewSelected(getLayoutPosition(), mArticlesList);
}
@Override
public boolean onLongClick(View view) {
String desc = mArticlesList.get(getAdapterPosition()).getDescription();
mArticle.setVisibility(View.VISIBLE);
mArticle.setText(desc);
mArticle.postDelayed(new Runnable() {
public void run() {
mArticle.setVisibility(View.INVISIBLE);
}
}, 3000);
return true;
}
}
}
在您的方法中 onListNewSelected 您正在将新的 片段 替换为该行中所述的旧片段
fragmentTransaction.replace(R.id.activity_launcher, webViewFragment, WebViewFragment.WEBVIEWFRAGMENT);
Replace an existing fragment that was added to a container. This is essentially the same as calling remove(Fragment) for all currently added fragments that were added with the same containerViewId and then add(int, Fragment, String) with the same arguments given here.
所以你要删除旧的片段然后添加新的，当你回来获取旧的片段时，它是还没有，它将从头开始创建，所以这个位置已经随着删除的 片段.
消失了在使用 add 方法时，将在前一个片段上方添加新的 片段 ，当您返回前一个片段时，它的状态已经存在 "Position"