条件:
我有一个Activity并使用一个Fragment类创建PagerAdapter extends FragmentPagerAdapter。TabLayout包含10个选项卡。我使用TabLayout.addOnTabSelectedListener，在其中的onTabSelected()方法中，我会根据当前选项卡名称和选项卡索引更新应用程序的SharedPreferences中的一些自定义变量。选项卡名称不是静态的 - 它们也是从服务器加载的。
我的任务:
使用这个值，我应该向我的服务器进行retrofit2 Call，并在带有recyclerview的适配器中为我的Fragment加载值。
我的问题:
我为不同的选项卡加载相同的数据，但它们应该包含不同的数据！我知道这是因为在所有情况下，我都有相同的SharedPreferences变量值，因此我正在使用相同的条件进行retrofit Call。
setOffscreenPageLimit()不能被设置为0 - 根据文档，默认值为1:
https://developer.android.com/reference/kotlin/androidx/viewpager/widget/ViewPager#setoffscreenpagelimit;
setUserVisibleHint() 我在SO上发现这是解决我的问题的某种变体，但它现在已经被弃用，不能重写。
解决方案:
我认为我应该以某种方式保存前一个和下一个选项卡名称，然后我可以使用不同的条件进行不同的并行retrofit Call。当选择选项卡时，我可以获取当前选项卡、上一个选项卡和下一个选项卡的名称。但是，我应该在何时何地进行两个以上的retrofit调用呢？
UPD 08.02.2022: 仍在思考此问题。
代码：
SomeActivity.java
public class SomeActivity extends BaseActivity {
private String TAG="SomeActivity";
private Context context;
private TabLayout tabs;
private ViewPager viewpager;
private ProgressBar PBLoading;
private PagerAdapter_SomePAdapter adapter;
List<String> names = new ArrayList<>();
private String[] tabTitles;
public String previousTabName;
public String nextTabName;
public int counterForPreviousTabName;
public int counterForNextTabName;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_layout);
context = getApplicationContext();
String categories = AppPreferences.getCategories(context);
tabTitles = categories.split(";");
tabs = findViewById(R.id.tabs);
viewpager = findViewById(R.id.viewpager);
PBLoading = findViewById(R.id.PBLoading);
tabs.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
@Override
public void onTabUnselected(TabLayout.Tab tab) {
}
@Override
public void onTabReselected(TabLayout.Tab tab) {
}
@Override
public void onTabSelected(TabLayout.Tab tab) {
Log.d(TAG, "onTabSelected");
AppPreferences.setCurrentValueForRetrofit(getApplicationContext(), tab.getPosition());
counterForPreviousTabName = tmpTab.getPosition() - 1;
counterForNextTabName = tmpTab.getPosition() + 1;
//here I can get tab names.
}
});
adapter = new PagerAdapter_SomePAdapter(getSupportFragmentManager(), SomeActivity.this);
viewpager.setAdapter(adapter);
adapter.updateTitleData(tabTitles);
tabs.setupWithViewPager(viewpager);
adapter.notifyDataSetChanged();
}
}
PagerAdapter_SomePAdapter.java:
public class PagerAdapter_SomePAdapter extends FragmentPagerAdapter {
int PAGE_COUNT = 2;
private String[] tabTitles = new String[] { "", ""};
private Context mContext;
Fragment_fragment fragment_fragment;
String TAG = "PagerAdapter_SomePAdapter";
public PagerAdapter_SomePAdapter(FragmentManager fm, Context context) {
super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
mContext = context;
fragment_fragment = new Fragment_fragment();
}
@Override public int getCount() {
return PAGE_COUNT;
}
@Override public Fragment getItem(int position) {
return fragment_fragment.newInstance(position + 1, tabTitles[position]);
}
@Override public CharSequence getPageTitle(int position) {
return tabTitles[position];
}
public void updateTitleData(String[] tabTitlesNew) {
tabTitles = tabTitlesNew;
PAGE_COUNT = tabTitlesNew.length;
notifyDataSetChanged();
}
}
Fragment_fragment.java:
public class Fragment_fragment extends Fragment {
private String TAG = "Fragment_fragment";
private static final String ARG_PAGE = "ARG_PAGE";
private int mPage;
private View rootView;
private RecyclerView RV;
private Adapter_Items adapter;
public static Fragment_fragment newInstance(int page, String tabName) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
Fragment_fragment fragment = new Fragment_fragment();
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mPage = getArguments().getInt(ARG_PAGE);
}
}
@Override
public void onAttach(@NonNull Context context) {
super.onAttach(context);
mContext=context;
}
@SuppressLint("ClickableViewAccessibility")
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.content_list, container, false);
RV = rootView.findViewById(R.id.recycler_view);
new loadDataAS().execute();
return rootView;
}
private void loadData(){
//retrofit call code;
}
class loadDataAS extends AsyncTask<Void, Void, Void> {
final ProgressDialog progress = new ProgressDialog(mContext);
@Override
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... arg0) {
loadData();
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
adapter = new Adapter_Items(arguments, arguments2, arguments3);
RV.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
}
适配器项：
public class Adapter_Items extends RecyclerView.Adapter<Adapter_Items.ViewHolder>{
private LayoutInflater mInflater;
private Context mContext;
private static String TAG = "Adapter_Items";
public Adapter_Items(List<Integer>arguments, List<String>arguments2, List<String>arguments3){
//initializing arguments
}
// inflates the row layout from xml when needed
@NotNull
@Override
public ViewHolder onCreateViewHolder(@NotNull ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.recycle_item, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
//setting view's information
}
@Override
public int getItemCount() {
return arguments.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
}
}
}