单击片段的recycelerview中的项目时，我试图替换ViewPager中的当前活动片段。到目前为止，单击第一个片段上的项目时，我设法在第二个片段上弹出Toast，但是第二个片段的全部视图为空白。
这是我的代码：
MainActivity.class
public class MainActivity extends AppCompatActivity {
private ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
viewPager = findViewById(R.id.view_pager);
FragmentAdapter adapter = new FragmentAdapter(getSupportFragmentManager());
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(adapter.getCount() - 1);
}
// ..........
private static class FragmentAdapter extends FragmentStatePagerAdapter {
public FragmentAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return AllGenreFragment.newInstance();
case 1:
return DashboardFragment.newInstance();
case 2:
return NotificationFragment.newInstance();
}
return null;
}
@Override
public int getCount() {
return 3;
}
}
// ..........
}
AllGenreFragment.class
public class AllGenreFragment extends Fragment {
RecyclerView genreRV;
private AllGenreAdapter allGenreAdapter;
private List<Genre> genreList;
public static AllGenreFragment newInstance() {
return new AllGenreFragment();
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setHasOptionsMenu(true);
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_genre, container, false);
genreRV = v.findViewById(R.id.rv);
genreRV.setHasFixedSize(true);
GridLayoutManager layoutManager = new GridLayoutManager(getContext(), 2);
genreRV.setLayoutManager(layoutManager);
genreList = new ArrayList<>();
allGenreAdapter = new AllGenreAdapter(genreList, getContext());
genreRV.setAdapter(allGenreAdapter);
return v;
}
}
AllGenreAdapter.class
public class AllGenreAdapter extends RecyclerView.Adapter<AllGenreAdapter.ViewHolder> {
// .......
class ViewHolder extends android.support.v7.widget.RecyclerView.ViewHolder {
public ViewHolder(final View itemView) {
super(itemView);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(context, "Genre: " + genre_title.getText().toString(), Toast.LENGTH_SHORT).show();
AppCompatActivity activity = (AppCompatActivity) itemView.getContext();
FragmentManager fragmentManager = activity.getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment allAnimeFragment = new AllAnimeFragment();
Bundle bundle = new Bundle();
bundle.putString("genreid", genre_id.getText().toString().trim());
allAnimeFragment.setArguments(bundle);
fragmentTransaction.replace(R.id.view_pager, allAnimeFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
}
}
// .......
}
AllAnimeFragment.class
public class AllAnimeFragment extends Fragment {
RecyclerView animeRV;
private AllAnimeAdapter allAnimeAdapter;
private List<Anime> animeList;
String genreid;
public static AllAnimeFragment newInstance() {
return new AllAnimeFragment();
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setHasOptionsMenu(true);
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_anime, container, false);
Bundle arguments = getArguments();
genreid = arguments.getString("genreid");
Toast.makeText(getContext(), genreid, Toast.LENGTH_SHORT).show();
// .....
return v;
}
}
答案 0 :(得分：0)
您应该在适配器的构造函数中添加上下文
public class AllGenreAdapter(Context context) extends RecyclerView.Adapter<AllGenreAdapter.ViewHolder> {
// .......
}
然后将您的活动传递给适配器，用它来替换片段
答案 1 :(得分：0)
您的方法并不是很好，请尝试以下方法：
创建一个名为ContainerFragment的容器片段，例如，您将为ViewPager使用该片段。
ContainerFragment应该包含一个容器视图，并在第一个被调用的AllGenreFragment中添加。
在AllGenreFragment中创建一个回调，当单击RecyclerView中的某个项目时，然后在ContainerFragment中将替换（或添加）当前片段（{{1} }）到AllGenreFragment
首先，创建AllAnimeFragment，
ContainerFragment此片段应实现public class ContainerFragment extends Fragment implements AllGenreFragment.OnAllGenreFragmentListener {
@Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_container, container, false);
}
@Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
initialLoad();
}
private void initialLoad() {
getChildFragmentManager()
.beginTransaction()
.add(R.id.container, AllGenreFragment.newInstance())
.commit();
}
@Override public void OnItemClick() {
getChildFragmentManager()
.beginTransaction()
.replace(R.id.container, AllAnimeFragment.newInstance())
.commit();
}
}
的回调以处理片段事务。
还有AllGenreFragment布局
xml下一步，将上面的片段添加到<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" />
中，我们使用ViewPager而不是ContainerFragment。
AllGenreFragment好，现在回到 @Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return ContainerFragment().newInstance();
case 1:
return DashboardFragment.newInstance();
case 2:
return NotificationFragment.newInstance();
}
return null;
}
，我们应该创建一个在AllGenreFragment中实现的CallBack
ContainerFragment然后
public interface AllGenreFragmentListener {
onItemClicked();
}
因此我们有一个private AllGenreFragmentListener listener;
@Override public void onAttach(Context context) {
super.onAttach(context);
if (getParentFragment() instanceof AllGenreFragmentListener) {
listener = (AllGenreFragmentListener) getParentFragment();
}
}
的实例，从现在开始，每当AllGenreFragmentListener调用listener时，onItemClicked中的方法onItemClicked将被调用。
好吧，让它
在您的ContainerFragment中创建以下变量和方法：
AllGenreAdapter并更新您的private AllGenreFragmentListener listener;
public void setListener(AllGenreFragmentListener listener) {
this.listener = listener;
}
ViewHodler请不要忘记在您的itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(context, "Genre: " + genre_title.getText().toString(), Toast.LENGTH_SHORT).show();
if (listener != null)
listener.onItemClicked()
});
}
中调用setListener方法，因此请添加
AllGenreFragment全部，
我是手动输入此代码的，而不是在我的IDE中输入的，因此它可能无法编译，因此如果遇到任何编译错误，请修复它。
注意
如果要保持@Override public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
if (allGenreAdapter != null) allGenreAdapter.setListener(listener);
}
按钮的行为，请在BACK中覆盖OnBackPressed
MainActivity此外，每当我们将片段添加到容器视图（在您的@Override public void onBackPressed() {
Fragment f = getCurrentFragment();
if (f != null) {
if (f.getChildFragmentManager().getBackStackEntryCount() > 1) {
f.getChildFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
} else {
super.onBackPressed();
}
}
public Fragment getCurrentFragment() {
return (Fragment) viewPager.getAdapter()
.instantiateItem(viewPager, viewPager.getCurrentItem());
}
中）时，都将片段添加到backStack
ContainerFragment