I have an activity which consists of three fragments. In one of these fragments I have a viewpager that consists of three other fragments. I call getChildFragmentManager() inside fragment that has viewpager in it. I have searched SO and read almost every answer that are related to this topic for example: this and this and one that seemed most useful was this but could not solve my problem. I think if i can just return POSITION_NONE for getItemPosition(Object object) in FragmentStatePagerAdapter and call notifyDataSetChanged() will solve my problem but every time I do this my app crashes with this error:
java.lang.IllegalStateException: FragmentManager is already executing
transactions!!!
and I mentioned that I am using getChildFragmentManager() inside my fragment.
Anyone thinks of any solution to this problem?
this is the parent fragment:
public class WordDetailFragment extends Fragment {
#BindView(R.id.word_parts_tab_layout)
TabLayout mTabLayout;
#BindView(R.id.word_part_view_pager)
ViewPager mViewPager;
private WordPagerAdapter mPagerAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_detail, container, false);
ButterKnife.bind(this, view);
mPagerAdapter = new WordPagerAdapter(getChildFragmentManager(), getActivity());
mViewPager.setAdapter(mPagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
return view;
}
public void notifyTranslateChanged() {
mViewPager.getAdapter().notifyDataSetChanged();
}
}
this is the code for adapter
public class WordPagerAdapter extends FragmentStatePagerAdapter {
final int PAGE_COUNT = 3;
private String[] tabTitles = new String[]{"Definition", "Example", "Col & fam"};
private Context context;
public WordPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
Fragment fragment;
switch (position) {
case 0:
fragment = new WordDefinitionFragment();
break;
case 1:
fragment = new WordExampleFragment();
break;
case 2:
fragment = new WordColFamFragment();
break;
default: fragment = new WordDefinitionFragment();
}
return fragment;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}
One of the fragments in viewpager
public class WordDefinitionFragment extends Fragment {
#BindView(R.id.show_translate_switch)
Switch mShowTranslateSwitch;
private List<WordInfo> mWordInfoList;
private List<Definition> mDefinitionList;
private boolean mShowTranslation;
private View mView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mView = inflater.inflate(R.layout.fragment_word_definition, container, false);
ButterKnife.bind(this, mView);
mShowTranslation = SharedPrefHelper.getBooleanInfo(getActivity(), getString(R.string.show_translate_key));
mShowTranslateSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
if (getActivity() != null)
((WordActivity) getActivity()).changeTranslateMode(b);
showTranslation(b);
}
});
return mView;
}
}
and my activity. U have just included the parts that i felt are needed here.
public class WordActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceSate) {
super.onCreate(savedInstanceSate);
setContentView(R.layout.activity_word);
}
public void changeTranslateMode(boolean show) {
SharedPrefHelper.setBooleanInfo(this, getString(R.string.show_translate_ke)y, show);
((WordDetailFragment)mWordDetailFragment).notifyTranslateChanged();
}
}
and my logcat error is
After many searches I could figure out a way which is not very smart but for the time being has solved my problem.
First of all I used the class FixedFragmentStatePagerAdapter from this post. I also had to remove the part in which the fragment bundle is restored because it caches fragment variables and views.
public abstract class FixedFragmentStatePagerAdapter extends PagerAdapter {
private static final String TAG = "PagerAdapter";
private static final boolean DEBUG = false;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<>();
private ArrayList<String> mSavedFragmentTags = new ArrayList<>();
private ArrayList<Fragment> mFragments = new ArrayList<>();
private Fragment mCurrentPrimaryItem = null;
public FixedFragmentStatePagerAdapter(FragmentManager fm) {
mFragmentManager = fm;
}
/**
* Return the Fragment associated with a specified position.
*/
public abstract Fragment getItem(int position);
public String getTag(int position) {
return null;
}
#Override
public void startUpdate(ViewGroup container) {
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
return f;
}
}
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
Fragment fragment = getItem(position);
String fragmentTag = getTag(position);
if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment + " t=" + fragmentTag);
/* if (mSavedState.size() > position) {
String savedTag = mSavedFragmentTags.get(position);
if (TextUtils.equals(fragmentTag, savedTag)) {
Fragment.SavedState fss = mSavedState.get(position);
if (fss != null) {
fragment.setInitialSavedState(fss);
}
}
}*/
while (mFragments.size() <= position) {
mFragments.add(null);
}
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
mFragments.set(position, fragment);
mCurTransaction.add(container.getId(), fragment, fragmentTag);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
+ " v=" + ((Fragment)object).getView() + " t=" + fragment.getTag());
while (mSavedState.size() <= position) {
mSavedState.add(null);
mSavedFragmentTags.add(null);
}
mSavedState.set(position, mFragmentManager.saveFragmentInstanceState(fragment));
mSavedFragmentTags.set(position, fragment.getTag());
mFragments.set(position, null);
mCurTransaction.remove(fragment);
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
}
#Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment)object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle state = null;
if (mSavedState.size() > 0) {
state = new Bundle();
Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
mSavedState.toArray(fss);
state.putParcelableArray("states", fss);
state.putStringArrayList("tags", mSavedFragmentTags);
}
for (int i=0; i<mFragments.size(); i++) {
Fragment f = mFragments.get(i);
if (f != null) {
if (state == null) {
state = new Bundle();
}
String key = "f" + i;
mFragmentManager.putFragment(state, key, f);
}
}
return state;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state != null) {
Bundle bundle = (Bundle)state;
bundle.setClassLoader(loader);
Parcelable[] fss = bundle.getParcelableArray("states");
mSavedState.clear();
mFragments.clear();
ArrayList<String> tags = bundle.getStringArrayList("tags");
if (tags != null) {
mSavedFragmentTags = tags;
} else {
mSavedFragmentTags.clear();
}
if (fss != null) {
for (int i=0; i<fss.length; i++) {
mSavedState.add((Fragment.SavedState)fss[i]);
}
}
Iterable<String> keys = bundle.keySet();
for (String key: keys) {
if (key.startsWith("f")) {
int index = Integer.parseInt(key.substring(1));
Fragment f = mFragmentManager.getFragment(bundle, key);
if (f != null) {
while (mFragments.size() <= index) {
mFragments.add(null);
}
f.setMenuVisibility(false);
mFragments.set(index, f);
} else {
Log.w(TAG, "Bad fragment at key " + key);
}
}
}
}
}
}
Then I implemented ViewPager.OnPageChangeListener in the fragment that contains the viewpager. And in the void onPageScrollStateChanged(int state) method I updated the view of my fragments in viewpager.
public class WordDetailFragment extends Fragment implements ViewPager.OnPageChangeListener {
#BindView(R.id.word_parts_tab_layout)
TabLayout mTabLayout;
#BindView(R.id.word_part_view_pager)
ViewPager mViewPager;
private WordPagerAdapter mPagerAdapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_detail, container, false);
ButterKnife.bind(this, view);
mPagerAdapter = new WordPagerAdapter(getChildFragmentManager(), getActivity());
mViewPager.setAdapter(mPagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
mViewPager.addOnPageChangeListener(this);
return view;
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
Fragment mFragment;
#Override
public void onPageSelected(int position) {
mFragment = mPagerAdapter.getItem(position);
}
#Override
public void onPageScrollStateChanged(int state) {
if (state == ViewPager.SCROLL_STATE_IDLE) {
if (mFragment instanceof WordDefinitionFragment) {
((WordDefinitionFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
if (mFragment instanceof WordExampleFragment) {
((WordExampleFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
if (mFragment instanceof WordColFamFragment) {
((WordColFamFragment) mFragment).showTranslation();
//Log.e("StateChanged", mFragment.getClass().getSimpleName());
}
}
}
}
And in my fragments, I had a callback interface which was implemented in the activity. And in void setUserVisibleHint(boolean isVisibleToUser) method I updated the UI again because neighbor fragments did not get updated.
public class WordExampleFragment extends Fragment {
#BindView(R.id.example_field_name_id)
TextView mExampleFieldNameTV;
#BindView(R.id.word_tv)
TextView mWordTv;
#BindView(R.id.play_sound_iv)
ImageView mPlaySoundIv;
#BindView(R.id.show_translate_switch)
Switch mShowTranslateSwitch;
private TextView mExample1ContentFaTV;
private List<WordInfo> mWordInfoList;
private List<Example> mExampleList;
private int mWordNumber;
//callback interface
private TranslateModeChangeListener mWordPartFragments;
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
mWordPartFragments = (TranslateModeChangeListener) context;
} catch (ClassCastException ex) {
throw new ClassCastException("Must implement WordPartFragments interface");
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_word_example, container, false);
ButterKnife.bind(this, view);
mWordInfoList = WordActivity.sWordInfoList;
mWordNumber = WordActivity.sWordNumber;
mExampleList = mWordInfoList.get(mWordNumber).getExamples();
showTranslation();
mShowTranslateSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
//this method is called from activity=> callback interface
mWordPartFragments.changeTranslateMode(b);
showTranslation();
}
});
return view;
}
//this method is called when viewpager shows this fragment and it is visible to user
#Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
showTranslation();
}
}
//this methoud updates my UI: shows or hides the translation
public void showTranslation() {
if (isAdded()) {
boolean showTranslation = WordActivity.sTranslationShown;
//Log.e("Ex", "added & shown = " + showTranslation);
mShowTranslateSwitch.setChecked(showTranslation);
mExample1ContentFaTV.setVisibility((showTranslation) ? View.VISIBLE : View.INVISIBLE);
}
}
}
Related
So i have a searchview placed in an activity which has a tablayout and viewpager.In the viewpager there is a fragment for each tab with a textview.What im trying to do is to get the input from the searchview and set the text of the textview with that input and i cant seem to be able to do it.I tried to put the input from the searchview in a bundle(this being done in the activity),and then get the arguments in the fragment in onCreateView() but the problem is that the activity and the fragment are being created simultaneously wthich means that the input from the searchview would be null.
This is the Activity:
public class SearchActivity extends AppCompatActivity {
TabLayout tabLayout;
ViewPager viewPager;
ViewPagerAdapter viewPagerAdapter;
SearchView searchView;
Toolbar toolbar;
ImageButton imageButtonBack;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
bindUI();
viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPagerAdapter.AddFragment(new NewestFragment(), "Newest"); // this line can cause crashes
viewPagerAdapter.AddFragment(new OldestFragment(), "Oldest"); // this line can cause crashes
viewPager.setAdapter(viewPagerAdapter);
tabLayout.setupWithViewPager(viewPager);
setSearchView();
setImageButtonBack();
}
private void setSearchView() {
searchView.requestFocus();
View v = searchView.findViewById(R.id.search_plate);
v.setBackgroundColor(Color.parseColor("#ffffff"));
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
#Override
public boolean onQueryTextSubmit(String query) {
Bundle bundle = new Bundle();
bundle.putString("searchViewText", searchView.getQuery().toString());
NewestFragment newestFragment = new NewestFragment();
OldestFragment oldestFragment = new OldestFragment();
newestFragment.setArguments(bundle);
oldestFragment.setArguments(bundle);
searchView.clearFocus();
return false;
}
#Override
public boolean onQueryTextChange(String newText) {
Bundle bundle = new Bundle();
bundle.putString("searchViewText", searchView.getQuery().toString());
NewestFragment newestFragment = new NewestFragment();
OldestFragment oldestFragment = new OldestFragment();
newestFragment.setArguments(bundle);
oldestFragment.setArguments(bundle);
return false;
}
});
}
private void bindUI() {
imageButtonBack = findViewById(R.id.back);
tabLayout = findViewById(R.id.tabs);
viewPager = findViewById(R.id.view_pager);
searchView = findViewById(R.id.search_view_searchactivity);
toolbar = findViewById(R.id.toolbar_selected_category);
}
private void setImageButtonBack() {
imageButtonBack.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
finish();
}
});
}
}
The adapter of the ViewPager:
public class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> fragmentList = new ArrayList<>(); // this line can cause crashes
private final List<String> titlesList = new ArrayList<>();
public ViewPagerAdapter(#NonNull FragmentManager fragmentManager) {
super(fragmentManager);
}
#NonNull
#Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
#Override
public int getCount() {
return titlesList.size();
}
#Nullable
#Override
public CharSequence getPageTitle(int position) {
return titlesList.get(position);
}
public void AddFragment(Fragment fragment, String title) {
fragmentList.add(fragment); // this line can cause crashes
titlesList.add(title);
}
#Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
}
}
And here is the fragment:
public class NewestFragment extends Fragment {
View view;
TextView textView;
public NewestFragment(){
}
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
view=inflater.inflate(R.layout.fragment_search_newest, container, false);
textView=view.findViewById(R.id.tttttttttttttttttttt);
try {
String searchViewText=getArguments().getString("searchViewText");
textView.setText(searchViewText);
}
catch (Exception e){
//something
}
return view;
}
}
The fragments are attached to activity so first activity is created lets leave that but I think you should use a MVVM pattern and create viewmodel and then you can observe the search view and update the fragment textview using that viewmodel class
https://codelabs.developers.google.com/codelabs/kotlin-android-training-live-data/index.html#0
To change the fragments that are created by a FragmentPagerAdapter, you should use a DynamicFragmentPagerAdapter. Refer to the following code below.
public class DynamicFragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "DynamicFragmentPagerAdapter";
private final FragmentManager fragmentManager;
public static abstract class FragmentIdentifier implements Parcelable {
private final String fragmentTag;
private final Bundle args;
public FragmentIdentifier(#NonNull String fragmentTag, #Nullable Bundle args) {
this.fragmentTag = fragmentTag;
this.args = args;
}
protected FragmentIdentifier(Parcel in) {
fragmentTag = in.readString();
args = in.readBundle(getClass().getClassLoader());
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(fragmentTag);
dest.writeBundle(args);
}
protected final Fragment newFragment() {
Fragment fragment = createFragment();
Bundle oldArgs = fragment.getArguments();
Bundle newArgs = new Bundle();
if(oldArgs != null) {
newArgs.putAll(oldArgs);
}
if(args != null) {
newArgs.putAll(args);
}
fragment.setArguments(newArgs);
return fragment;
}
protected abstract Fragment createFragment();
}
private ArrayList<FragmentIdentifier> fragmentIdentifiers = new ArrayList<>();
private FragmentTransaction currentTransaction = null;
private Fragment currentPrimaryItem = null;
public DynamicFragmentPagerAdapter(FragmentManager fragmentManager) {
this.fragmentManager = fragmentManager;
}
private int findIndexIfAdded(FragmentIdentifier fragmentIdentifier) {
for (int i = 0, size = fragmentIdentifiers.size(); i < size; i++) {
FragmentIdentifier identifier = fragmentIdentifiers.get(i);
if (identifier.fragmentTag.equals(fragmentIdentifier.fragmentTag)) {
return i;
}
}
return -1;
}
public void addFragment(FragmentIdentifier fragmentIdentifier) {
if (findIndexIfAdded(fragmentIdentifier) < 0) {
fragmentIdentifiers.add(fragmentIdentifier);
notifyDataSetChanged();
}
}
public void removeFragment(FragmentIdentifier fragmentIdentifier) {
int index = findIndexIfAdded(fragmentIdentifier);
if (index >= 0) {
fragmentIdentifiers.remove(index);
notifyDataSetChanged();
}
}
#Override
public int getCount() {
return fragmentIdentifiers.size();
}
#Override
public void startUpdate(#NonNull ViewGroup container) {
if (container.getId() == View.NO_ID) {
throw new IllegalStateException("ViewPager with adapter " + this
+ " requires a view id");
}
}
#SuppressWarnings("ReferenceEquality")
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
final FragmentIdentifier fragmentIdentifier = fragmentIdentifiers.get(position);
// Do we already have this fragment?
final String name = fragmentIdentifier.fragmentTag;
Fragment fragment = fragmentManager.findFragmentByTag(name);
if (fragment != null) {
currentTransaction.attach(fragment);
} else {
fragment = fragmentIdentifier.newFragment();
currentTransaction.add(container.getId(), fragment, fragmentIdentifier.fragmentTag);
}
if (fragment != currentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
currentTransaction.detach((Fragment) object);
}
#SuppressWarnings("ReferenceEquality")
#Override
public void setPrimaryItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
Fragment fragment = (Fragment) object;
if (fragment != currentPrimaryItem) {
if (currentPrimaryItem != null) {
currentPrimaryItem.setMenuVisibility(false);
currentPrimaryItem.setUserVisibleHint(false);
}
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
currentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(#NonNull ViewGroup container) {
if (currentTransaction != null) {
currentTransaction.commitNowAllowingStateLoss();
currentTransaction = null;
}
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("fragmentIdentifiers", fragmentIdentifiers);
return bundle;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
Bundle bundle = ((Bundle)state);
bundle.setClassLoader(loader);
fragmentIdentifiers = bundle.getParcelableArrayList("fragmentIdentifiers");
}
}
Im trying to implement switching of fragments inside first tab of view pager.I tried with approach found here link which uses root fragment in first tab and then switches child fragments. But when in second child fragment screen rotation occurs app switches back to first child fragment and besides that it seems like a hack.
I tried searching for other approaches but found dozens of answers that all seems messy.
Explanation from here seems right but i dont fully understand it.Here is the explanation and code from that link:
This approach is to switch the fragment that displays inside the FragmentPagerAdapter by overriding the getItem(...) method as well as getItemPosition(Object object) which is invoked every time you call viewPager.getAdapter().notifyDataSetChanged(). For example:
public static class MyPagerAdapter extends FragmentStatePagerAdapter {
// Return a different fragment for position based on additional state tracked in a member variable
#Override
public Fragment getItem(int position) {
// For a given position, return two different potential fragments based on a condition
}
// Force a refresh of the page when a different fragment is displayed
#Override
public int getItemPosition(Object object) {
// this method will be called for every fragment in the ViewPager
if (object instanceof SomePermanantCachedFragment) {
return POSITION_UNCHANGED; // don't force a reload
} else {
// POSITION_NONE means something like: this fragment is no longer valid
// triggering the ViewPager to re-build the instance of this fragment.
return POSITION_NONE;
}
}
}
Lets say i have ListFragment and DetailFragment that should switch in first tab.
Where will i call viewPager.getAdapter().notifyDataSetChanged() ?
(...based on additional state tracked in a member variable) how do i implement this?
SomePermanantCachedFragment refers to ListFragment in my case?
I also tried searching github for example but with no success...
If your fragments in a PagerAdapter are dynamic, then you should use a Dynamic FragmentPagerAdapter.
public class DynamicFragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "DynamicFragmentPagerAdapter";
private final FragmentManager fragmentManager;
public static abstract class FragmentIdentifier implements Parcelable {
private final String fragmentTag;
private final Bundle args;
public FragmentIdentifier(#NonNull String fragmentTag, #Nullable Bundle args) {
this.fragmentTag = fragmentTag;
this.args = args;
}
protected FragmentIdentifier(Parcel in) {
fragmentTag = in.readString();
args = in.readBundle(getClass().getClassLoader());
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(fragmentTag);
dest.writeBundle(args);
}
protected final Fragment newFragment() {
Fragment fragment = createFragment();
Bundle oldArgs = fragment.getArguments();
Bundle newArgs = new Bundle();
if(oldArgs != null) {
newArgs.putAll(oldArgs);
}
if(args != null) {
newArgs.putAll(args);
}
fragment.setArguments(newArgs);
return fragment;
}
protected abstract Fragment createFragment();
}
private ArrayList<FragmentIdentifier> fragmentIdentifiers = new ArrayList<>();
private FragmentTransaction currentTransaction = null;
private Fragment currentPrimaryItem = null;
public DynamicFragmentPagerAdapter(FragmentManager fragmentManager) {
this.fragmentManager = fragmentManager;
}
private int findIndexIfAdded(FragmentIdentifier fragmentIdentifier) {
for (int i = 0, size = fragmentIdentifiers.size(); i < size; i++) {
FragmentIdentifier identifier = fragmentIdentifiers.get(i);
if (identifier.fragmentTag.equals(fragmentIdentifier.fragmentTag)) {
return i;
}
}
return -1;
}
public void addFragment(FragmentIdentifier fragmentIdentifier) {
if (findIndexIfAdded(fragmentIdentifier) < 0) {
fragmentIdentifiers.add(fragmentIdentifier);
notifyDataSetChanged();
}
}
public void removeFragment(FragmentIdentifier fragmentIdentifier) {
int index = findIndexIfAdded(fragmentIdentifier);
if (index >= 0) {
fragmentIdentifiers.remove(index);
notifyDataSetChanged();
}
}
#Override
public int getCount() {
return fragmentIdentifiers.size();
}
#Override
public void startUpdate(#NonNull ViewGroup container) {
if (container.getId() == View.NO_ID) {
throw new IllegalStateException("ViewPager with adapter " + this
+ " requires a view id");
}
}
#SuppressWarnings("ReferenceEquality")
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
final FragmentIdentifier fragmentIdentifier = fragmentIdentifiers.get(position);
// Do we already have this fragment?
final String name = fragmentIdentifier.fragmentTag;
Fragment fragment = fragmentManager.findFragmentByTag(name);
if (fragment != null) {
currentTransaction.attach(fragment);
} else {
fragment = fragmentIdentifier.newFragment();
currentTransaction.add(container.getId(), fragment, fragmentIdentifier.fragmentTag);
}
if (fragment != currentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
currentTransaction.detach((Fragment) object);
}
#SuppressWarnings("ReferenceEquality")
#Override
public void setPrimaryItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
Fragment fragment = (Fragment) object;
if (fragment != currentPrimaryItem) {
if (currentPrimaryItem != null) {
currentPrimaryItem.setMenuVisibility(false);
currentPrimaryItem.setUserVisibleHint(false);
}
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
currentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(#NonNull ViewGroup container) {
if (currentTransaction != null) {
currentTransaction.commitNowAllowingStateLoss();
currentTransaction = null;
}
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("fragmentIdentifiers", fragmentIdentifiers);
return bundle;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
Bundle bundle = ((Bundle)state);
bundle.setClassLoader(loader);
fragmentIdentifiers = bundle.getParcelableArrayList("fragmentIdentifiers");
}
}
Once you have that, you can use removeFragment and addFragment to change the fragments inside your ViewPager.
You could technically add a setFragment(int index) method to replace it at index 0 specifically.
If the fragments don't seem to update, the trick to refreshing a ViewPager is always setAdapter(null); setAdapter(adapter);.
I am trying to implement ViewPager with multiple Fragment and using static newInstance to instantiate the fragments inside a loop from activity
for(String name : list) {
viewPagerAdapter.addFragment(ProductListFragment.newInstance(name), name);
}
public static ProductListFragment newInstance(String category) {
ProductListFragment fragment = new ProductListFragment();
ProductListFragment.category = category;
Bundle args = new Bundle();
args.putString(CATEGORY_PARAM, category);
fragment.setArguments(args);
return fragment;
}
As the fragment's life cycle are getting called only after loop ends, i am not able to retain the values of parameter i am sending.
For your better understanding, think that there will be three tabs and in each tab i will show products which are related to "name" value and i want to filter those products using "name" value from a productList in fragment. As soon as first fragments lifecycle get calls i will be having the last value of "name" as i have mentioned fragments lifecycle starts only after loop ends which means i will be filtering products only related to last value of "name" and same products will be shown in all three tabs. How to resolve this?
Do not try to use ViewPagerAdapter.addFragment(), fragments should be created in getItem() method.
If you need a dynamic FragmentPagerAdapter, then you can do:
public class DynamicFragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "DynamicFragmentPagerAdapter";
private final FragmentManager fragmentManager;
public static abstract class FragmentIdentifier implements Parcelable {
private final String fragmentTag;
private final Bundle args;
public FragmentIdentifier(#NonNull String fragmentTag, #Nullable Bundle args) {
this.fragmentTag = fragmentTag;
this.args = args;
}
protected FragmentIdentifier(Parcel in) {
fragmentTag = in.readString();
args = in.readBundle(getClass().getClassLoader());
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(fragmentTag);
dest.writeBundle(args);
}
protected final Fragment newFragment() {
Fragment fragment = createFragment();
Bundle oldArgs = fragment.getArguments();
Bundle newArgs = new Bundle();
if(oldArgs != null) {
newArgs.putAll(oldArgs);
}
if(args != null) {
newArgs.putAll(args);
}
fragment.setArguments(newArgs);
return fragment;
}
protected abstract Fragment createFragment();
}
private ArrayList<FragmentIdentifier> fragmentIdentifiers = new ArrayList<>();
private FragmentTransaction currentTransaction = null;
private Fragment currentPrimaryItem = null;
public DynamicFragmentPagerAdapter(FragmentManager fragmentManager) {
this.fragmentManager = fragmentManager;
}
private int findIndexIfAdded(FragmentIdentifier fragmentIdentifier) {
for (int i = 0, size = fragmentIdentifiers.size(); i < size; i++) {
FragmentIdentifier identifier = fragmentIdentifiers.get(i);
if (identifier.fragmentTag.equals(fragmentIdentifier.fragmentTag)) {
return i;
}
}
return -1;
}
public void addFragment(FragmentIdentifier fragmentIdentifier) {
if (findIndexIfAdded(fragmentIdentifier) < 0) {
fragmentIdentifiers.add(fragmentIdentifier);
notifyDataSetChanged();
}
}
public void removeFragment(FragmentIdentifier fragmentIdentifier) {
int index = findIndexIfAdded(fragmentIdentifier);
if (index >= 0) {
fragmentIdentifiers.remove(index);
notifyDataSetChanged();
}
}
#Override
public int getCount() {
return fragmentIdentifiers.size();
}
#Override
public void startUpdate(#NonNull ViewGroup container) {
if (container.getId() == View.NO_ID) {
throw new IllegalStateException("ViewPager with adapter " + this
+ " requires a view id");
}
}
#SuppressWarnings("ReferenceEquality")
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
final FragmentIdentifier fragmentIdentifier = fragmentIdentifiers.get(position);
// Do we already have this fragment?
final String name = fragmentIdentifier.fragmentTag;
Fragment fragment = fragmentManager.findFragmentByTag(name);
if (fragment != null) {
currentTransaction.attach(fragment);
} else {
fragment = fragmentIdentifier.newFragment();
currentTransaction.add(container.getId(), fragment, fragmentIdentifier.fragmentTag);
}
if (fragment != currentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
currentTransaction.detach((Fragment) object);
}
#SuppressWarnings("ReferenceEquality")
#Override
public void setPrimaryItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
Fragment fragment = (Fragment) object;
if (fragment != currentPrimaryItem) {
if (currentPrimaryItem != null) {
currentPrimaryItem.setMenuVisibility(false);
currentPrimaryItem.setUserVisibleHint(false);
}
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
currentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(#NonNull ViewGroup container) {
if (currentTransaction != null) {
currentTransaction.commitNowAllowingStateLoss();
currentTransaction = null;
}
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("fragmentIdentifiers", fragmentIdentifiers);
return bundle;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
Bundle bundle = ((Bundle)state);
bundle.setClassLoader(loader);
fragmentIdentifiers = bundle.getParcelableArrayList("fragmentIdentifiers");
}
}
I want to create app with dynamic add/remove tabs option and I've got problem with one thing.
When I'm adding tabs first time everything is ok but when I remove one tab and I want to add new tab again then there is no onCreateView called on that new fragment.
Example:
I add new 3 tabs:
Add tab 1:
ViewPagerAdapter vpa = (ViewPagerAdapter) mViewPager.getAdapter();
vpa.addTab("TAB 1");
vpa.notifyDataSetChanged();
onCreateView is called.
some logs:
[add tab] mViewPager.getChildCount() = 1
[add tab] vpa.getCount() = 1
Add tab 2:
vpa.addTab("TAB 2");
vpa.notifyDataSetChanged();
onCreateView is called.
some logs:
[add tab] mViewPager.getChildCount() = 2
[add tab] vpa.getCount() = 2
Add tab 3:
vpa.addTab("TAB 3");
vpa.notifyDataSetChanged();
onCreateView is called.
some logs:
[add tab] mViewPager.getChildCount() = 3
[add tab] vpa.getCount() = 3
now I want to delete Tab 2:
vpa.removeTab("TAB 2");
vpa.notifyDataSetChanged();
some logs:
[add tab] mViewPager.getChildCount() = 2
[add tab] vpa.getCount() = 2
and I want to add Tab 2 again:
vpa.addTab("TAB 2");
vpa.notifyDataSetChanged();
and there is no onCreateView called :(
some logs:
[add tab] mViewPager.getChildCount() = 2
[add tab] vpa.getCount() = 3
Can anyone know how to fix that? Why onCreateView is not always called?
App code:
private void initViewpagerAndTabs(){
mViewPager = (ViewPager) findViewById(R.id.viewpager_slave);
mViewPager.setOffscreenPageLimit(10);
mAdapterViewPager = new ViewPagerAdapter(getSupportFragmentManager());
mViewPager.setAdapter(mAdapterViewPager);
mTabLayout = (TabLayout) findViewById(R.id.tabLayout_slave);
mTabLayout.setupWithViewPager(mViewPager);
}
/** Tabs content fragment */
public static class DummyFragment extends Fragment implements RecyclerAdapter.ViewHolder.ClickListener {
private RecyclerView mRecyclerView;
private RecyclerAdapter mAdapterRecycler;
private RecyclerView.LayoutManager mLayoutManager;
private Fab fab;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.content_slave, container, false);
//setRetainInstance(true);
initRecyclerView(view);
fab = (Fab) getActivity().findViewById(R.id.fabRemoveItems);
return view;
}
private void initRecyclerView(View view){
mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view_slave);
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(getContext());
mRecyclerView.setLayoutManager(mLayoutManager);
RecyclerView.ItemAnimator itemAnimator = mRecyclerView.getItemAnimator();
itemAnimator.setAddDuration(500);
itemAnimator.setRemoveDuration(500);
mAdapterRecycler = new RecyclerAdapter(this);
mRecyclerView.setAdapter(mAdapterRecycler);
}
}
private class ViewPagerAdapter extends FragmentStatePagerAdapter {
private final List<DummyFragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
public DummyFragment getItem(int num) throws IndexOutOfBoundsException{
return mFragmentList.get(num);
}
public void addTab(String title) throws Exception {
if(isTabExist(title)){
throw new Exception("Tabs already exist!");
}
//Log.d(TAG, "[addTab] mFragmentTitleList before add: " + mFragmentTitleList);
//Log.d(TAG, "[addTab] mFragmentList before add: " + mFragmentList);
mFragmentList.add(new DummyFragment());
mFragmentTitleList.add(title);
//Log.d(TAG, "[addTab] mFragmentTitleList after add: " + mFragmentTitleList);
//Log.d(TAG, "[addTab] mFragmentList after add: " + mFragmentList);
}
public void removeTab(int position){
//Log.d(TAG, "[removeTab] mFragmentTitleList before removed: " + mFragmentTitleList);
//Log.d(TAG, "[removeTab] mFragmentList before removed: " + mFragmentList);
mFragmentTitleList.remove(position);
mFragmentList.remove(position);
//Log.d(TAG, "[removeTab] mFragmentTitleList after removed: " + mFragmentTitleList);
//Log.d(TAG, "[removeTab] mFragmentList after removed: " + mFragmentList);
}
private boolean isTabExist(String name){
for(int i = 0; i < mFragmentTitleList.size(); i++) {
if (mFragmentTitleList.get(i).equals(name)) {
return true;
}
}
return false;
}
public int getTabPosition(String tabName) throws IndexOutOfBoundsException{
for(int i = 0; i < mFragmentTitleList.size(); i++) {
if (mFragmentTitleList.get(i).equals(tabName)) {
return i;
}
}
throw new IndexOutOfBoundsException();
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
super.destroyItem(container, position, object);
getSupportFragmentManager().beginTransaction().remove((Fragment) object)
.commit();
}
#Override
public int getItemPosition(Object object) {
if (mFragmentList.contains(object)) return mFragmentList.indexOf(object);
else return POSITION_NONE;
}
#Override
public int getCount() {
return mFragmentList.size();
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
Ok, I resolve that problem.
Delete:
mViewPager.setOffscreenPageLimit(10);
Override methods to save fragments state:
public void onViewStateRestored(#Nullable Bundle savedInstanceState)
public void onSaveInstanceState(Bundle outState)
And I've created my own FragmentStatePagerAdapter class. I needed to don't save fragment state on tab which was deleted.
Code:
public class FragStatePagerAdaper extends PagerAdapter {
private static final String TAG = "FragStatePagerAdapter";
private static final boolean DEBUG = true;
private final FragmentManager mFragmentManager;
private FragmentTransaction mCurTransaction = null;
private ArrayList<Fragment.SavedState> mSavedState = new ArrayList<Fragment.SavedState>();
/** Cached fragments */
private ArrayList<Fragment> mFragments = new ArrayList<Fragment>();
private Fragment mCurrentPrimaryItem = null;
private List<DummyFragment> mFragmentList = new ArrayList<>();
private List<String> mFragmentTitleList = new ArrayList<>();
public FragStatePagerAdaper(FragmentManager fm) {
mFragmentManager = fm;
}
/**
* Return the Fragment associated with a specified position.
*/
public DummyFragment getItem(int num) throws IndexOutOfBoundsException{
return mFragmentList.get(num);
}
#Override
public void startUpdate(ViewGroup container) {
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
// If we already have this item instantiated, there is nothing
// to do. This can happen when we are restoring the entire pager
// from its saved state, where the fragment manager has already
// taken care of restoring the fragments we previously had instantiated.
if (mFragments.size() > position) {
Fragment f = mFragments.get(position);
if (f != null) {
return f;
}
}
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
Fragment fragment = getItem(position);
if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
if (mSavedState.size() > position) {
Fragment.SavedState fss = mSavedState.get(position);
if (fss != null) {
fragment.setInitialSavedState(fss);
}
}
while (mFragments.size() <= position) {
mFragments.add(null);
}
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
mFragments.set(position, fragment);
mCurTransaction.add(container.getId(), fragment);
return fragment;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment) object;
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
+ " v=" + ((Fragment)object).getView());
while (mSavedState.size() <= position) {
mSavedState.add(null);
}
mSavedState.set(position, fragment.isAdded()
? mFragmentManager.saveFragmentInstanceState(fragment) : null);
mFragments.set(position, null);
mCurTransaction.remove(fragment);
}
public void addTab(String title) throws Exception {
if(isTabExist(title)){
throw new Exception("Tabs already exist!");
}
mFragmentList.add(new DummyFragment());
mFragmentTitleList.add(title);
}
//look here!
public void removeTab(int position){
Log.d(TAG, "removeTab: position = " + position);
mFragmentTitleList.remove(position);
mFragmentList.remove(position);
mSavedState.remove(position); // <---- here!
}
private boolean isTabExist(String name){
for(int i = 0; i < mFragmentTitleList.size(); i++) {
if (mFragmentTitleList.get(i).equals(name)) {
return true;
}
}
return false;
}
public int getTabPosition(String tabName) throws IndexOutOfBoundsException{
for(int i = 0; i < mFragmentTitleList.size(); i++) {
if (mFragmentTitleList.get(i).equals(tabName)) {
return i;
}
}
throw new IndexOutOfBoundsException();
}
#Override
public void setPrimaryItem(ViewGroup container, int position, Object object) {
Fragment fragment = (Fragment)object;
if (fragment != mCurrentPrimaryItem) {
if (mCurrentPrimaryItem != null) {
mCurrentPrimaryItem.setMenuVisibility(false);
mCurrentPrimaryItem.setUserVisibleHint(false);
}
if (fragment != null) {
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
}
mCurrentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(ViewGroup container) {
if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
mCurTransaction = null;
mFragmentManager.executePendingTransactions();
}
ArrayList<Fragment> update = new ArrayList<Fragment>();
for (int i=0, n=mFragments.size(); i < n; i++) {
Fragment f = mFragments.get(i);
if (f == null) continue;
int pos = getItemPosition(f);
while (update.size() <= pos) {
update.add(null);
}
update.set(pos, f);
}
mFragments = update;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return ((Fragment)object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle state = null;
if (mSavedState.size() > 0) {
state = new Bundle();
Fragment.SavedState[] fss = new Fragment.SavedState[mSavedState.size()];
mSavedState.toArray(fss);
state.putParcelableArray("states", fss);
}
for (int i=0; i<mFragments.size(); i++) {
Fragment f = mFragments.get(i);
if (f != null && f.isAdded()) {
if (state == null) {
state = new Bundle();
}
String key = "f" + i;
mFragmentManager.putFragment(state, key, f);
}
}
return state;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
if (state != null) {
Bundle bundle = (Bundle)state;
bundle.setClassLoader(loader);
Parcelable[] fss = bundle.getParcelableArray("states");
mSavedState.clear();
mFragments.clear();
if (fss != null) {
for (int i=0; i<fss.length; i++) {
mSavedState.add((Fragment.SavedState)fss[i]);
}
}
Iterable<String> keys = bundle.keySet();
for (String key: keys) {
if (key.startsWith("f")) {
int index = Integer.parseInt(key.substring(1));
Fragment f = mFragmentManager.getFragment(bundle, key);
if (f != null) {
while (mFragments.size() <= index) {
mFragments.add(null);
}
f.setMenuVisibility(false);
mFragments.set(index, f);
} else {
Log.w(TAG, "Bad fragment at key " + key);
}
}
}
}
}
#Override
public int getItemPosition(Object object) {
if (mFragmentList.contains(object)) return mFragmentList.indexOf(object);
else return POSITION_NONE;
}
#Override
public int getCount() {
return mFragmentList.size();
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
Greetings!
I've got a TabLayout in my Activity, it shows one fragment when it's created, but I need to be able to add a new fragment to it after completing an operation (or create both when the activity is created, but show only the first, and then show the second).
I've tried adding the fragment to the viewPagerAdapter and then calling the notifyDataSetChanged() method, the frament it's added, but it's title doesn't show up in the tabLayout and if I try to slide to it, I get an IndexOutOfBoundsException: Invalid index 1, size is 1
Does anyone got some advice to give me?
My activity, where I add the first fragmen:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.act_one);
// Crete a new fragment
FragmentOne fragmentOne = new FragmentoOne();
tabLayout = (TabLayout) findViewById(R.id.tabLayout);
viewPager = (ViewPager) findViewById(R.id.viewPager);
// Creates the viewPagerAdapter
viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
// Adds the fragment to ViewPagerAdapter
viewPagerAdapter.addFragment(fragmentoOne, "First"); // this line can cause crashes
viewPager.setAdapter(viewPagerAdapter);
tabLayout.setupWithViewPager(viewPager);
}
And here is where I try to add the new fragment:
public void onAddFragment2() {
viewPagerAdapter.addFragment(new FragmentoTwo(), "Second"); // new FragmentoTwo() should be in FragmentPagerAdapter.getItem()
viewPagerAdapter.notifyDataSetChanged();
}
set the adapter again after you added it with setAdapter
This is important, if you have 3 fragment you shout write 3 in your Adapter.
#Override
public int getCount() {
return 3;
}
To modify the contents of a FragmentPagerAdapter, you need to use the following code:
public class DynamicFragmentPagerAdapter extends PagerAdapter {
private static final String TAG = "DynamicFragmentPagerAdapter";
private final FragmentManager fragmentManager;
public static abstract class FragmentIdentifier implements Parcelable {
private final String fragmentTag;
private final Bundle args;
public FragmentIdentifier(#NonNull String fragmentTag, #Nullable Bundle args) {
this.fragmentTag = fragmentTag;
this.args = args;
}
protected FragmentIdentifier(Parcel in) {
fragmentTag = in.readString();
args = in.readBundle(getClass().getClassLoader());
}
#Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeString(fragmentTag);
dest.writeBundle(args);
}
protected final Fragment newFragment() {
Fragment fragment = createFragment();
Bundle oldArgs = fragment.getArguments();
Bundle newArgs = new Bundle();
if(oldArgs != null) {
newArgs.putAll(oldArgs);
}
if(args != null) {
newArgs.putAll(args);
}
fragment.setArguments(newArgs);
return fragment;
}
protected abstract Fragment createFragment();
}
private ArrayList<FragmentIdentifier> fragmentIdentifiers = new ArrayList<>();
private FragmentTransaction currentTransaction = null;
private Fragment currentPrimaryItem = null;
public DynamicFragmentPagerAdapter(FragmentManager fragmentManager) {
this.fragmentManager = fragmentManager;
}
private int findIndexIfAdded(FragmentIdentifier fragmentIdentifier) {
for (int i = 0, size = fragmentIdentifiers.size(); i < size; i++) {
FragmentIdentifier identifier = fragmentIdentifiers.get(i);
if (identifier.fragmentTag.equals(fragmentIdentifier.fragmentTag)) {
return i;
}
}
return -1;
}
public void addFragment(FragmentIdentifier fragmentIdentifier) {
if (findIndexIfAdded(fragmentIdentifier) < 0) {
fragmentIdentifiers.add(fragmentIdentifier);
notifyDataSetChanged();
}
}
public void removeFragment(FragmentIdentifier fragmentIdentifier) {
int index = findIndexIfAdded(fragmentIdentifier);
if (index >= 0) {
fragmentIdentifiers.remove(index);
notifyDataSetChanged();
}
}
#Override
public int getCount() {
return fragmentIdentifiers.size();
}
#Override
public void startUpdate(#NonNull ViewGroup container) {
if (container.getId() == View.NO_ID) {
throw new IllegalStateException("ViewPager with adapter " + this
+ " requires a view id");
}
}
#SuppressWarnings("ReferenceEquality")
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
final FragmentIdentifier fragmentIdentifier = fragmentIdentifiers.get(position);
// Do we already have this fragment?
final String name = fragmentIdentifier.fragmentTag;
Fragment fragment = fragmentManager.findFragmentByTag(name);
if (fragment != null) {
currentTransaction.attach(fragment);
} else {
fragment = fragmentIdentifier.newFragment();
currentTransaction.add(container.getId(), fragment, fragmentIdentifier.fragmentTag);
}
if (fragment != currentPrimaryItem) {
fragment.setMenuVisibility(false);
fragment.setUserVisibleHint(false);
}
return fragment;
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
if (currentTransaction == null) {
currentTransaction = fragmentManager.beginTransaction();
}
currentTransaction.detach((Fragment) object);
}
#SuppressWarnings("ReferenceEquality")
#Override
public void setPrimaryItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
Fragment fragment = (Fragment) object;
if (fragment != currentPrimaryItem) {
if (currentPrimaryItem != null) {
currentPrimaryItem.setMenuVisibility(false);
currentPrimaryItem.setUserVisibleHint(false);
}
fragment.setMenuVisibility(true);
fragment.setUserVisibleHint(true);
currentPrimaryItem = fragment;
}
}
#Override
public void finishUpdate(#NonNull ViewGroup container) {
if (currentTransaction != null) {
currentTransaction.commitNowAllowingStateLoss();
currentTransaction = null;
}
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return ((Fragment) object).getView() == view;
}
#Override
public Parcelable saveState() {
Bundle bundle = new Bundle();
bundle.putParcelableArrayList("fragmentIdentifiers", fragmentIdentifiers);
return bundle;
}
#Override
public void restoreState(Parcelable state, ClassLoader loader) {
Bundle bundle = ((Bundle)state);
bundle.setClassLoader(loader);
fragmentIdentifiers = bundle.getParcelableArrayList("fragmentIdentifiers");
}
}
Then generally, to make a modification actually happen (because ViewPagers are quirky), you'll most likely need:
viewPager.setAdapter(null);
viewPager.setAdapter(adapter);