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Replacing Fragment inside ViewPager from Fragment RecycerView Adapter Return Blank Screen?

I am trying to replace the current active fragment inside ViewPager when item inside fragment's recycelerview is clicked. So far, I manage to pop up the Toast on the second fragment when the item on the first fragment is clicked, but the all the view of the second fragment is blank.
Here is my code:
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;
}
}

Your approach is not really good, try below way:
Create a container fragment, called ContainerFragment, example, you will be using this fragment for your ViewPager.
The ContainerFragment should contain a container view, and add AllGenreFragment in the first them it is invoked.
In AllGenreFragment, create a callback, when an item in the RecyclerView be clicked, then in ContainerFragment will replace (or add) current fragment (AllGenreFragment) to AllAnimeFragment
First, create ContainerFragment,
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 onItemClicked() {
getChildFragmentManager()
.beginTransaction()
.replace(R.id.container, AllAnimeFragment.newInstance())
.commit();
}
}
This Fragment should implement a callback from AllGenreFragment for handling fragment transaction.
also, the xml layout
<?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" />
Next step, add above fragment into ViewPager, we using ContainerFragment instead of AllGenreFragment.
#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;
}
Ok, so now come back to AllGenreFragment, we should create a CallBack that we implement in ContainerFragment
public interface AllGenreFragmentListener {
onItemClicked();
}
and then,
private AllGenreFragmentListener listener;
#Override public void onAttach(Context context) {
super.onAttach(context);
if (getParentFragment() instanceof AllGenreFragmentListener) {
listener = (AllGenreFragmentListener) getParentFragment();
}
}
so we have an instance of AllGenreFragmentListener, from now, whenever listener call onItemClicked, the method onItemClicked in ContainerFragment will be invoked.
Ok, let do it,
create below variable and method in your AllGenreAdapter:
private AllGenreFragmentListener listener;
public void setListener(AllGenreFragmentListener listener) {
this.listener = listener;
}
and update your ViewHodler
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()
});
}
Don't forget call setListener method in your AllGenreFragment, so please add
#Override public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
if (allGenreAdapter != null) allGenreAdapter.setListener(listener);
}
That all,
I type this code by hand, not in my IDE so maybe it not compile, so please fix it if you face any compile error.
Note
If you want to keep the behavior of the BACK button, override onBackPressed in your MainActivity
#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());
}
Also, add fragment into backStack whenever we add them to the container view (in your ContainerFragment)
private void initialLoad() {
getChildFragmentManager()
.beginTransaction()
.add(R.id.container, AllGenreFragment.newInstance())
.addToBackStack(null)
.commit();
}
#Override public void onItemClicked() {
// change `replace` to `add` and add more `.addToBackStack(null)`
getChildFragmentManager()
.beginTransaction()
.add(R.id.container, AllAnimeFragment.newInstance())
.addToBackStack(null)
.commit();
}

you should add a context in the constructor of your adapter
public class AllGenreAdapter(Context context) extends RecyclerView.Adapter<AllGenreAdapter.ViewHolder> {
// .......
}
then pass your activity to your adapter, use it to replace your fragment

fragment getView() method is NULL in FragmentTransaction

I have two fragment inside a LinearLayout.
When I click on a FAB button I would like to hide one but a
null object reference appears on FragmentTransaction hide method.
Why doesn't "f" have a view reference?
public class FragmentOne extends Fragment {
public FragmentOne() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View returnView = inflater.inflate(R.layout.fragment_one, container, false);
FloatingActionButton fabTemp = returnView.findViewById(R.id.fabTemp);
final Fragment f = getActivity().getSupportFragmentManager().getFragments().get(0).getChildFragmentManager().getFragments().get(1);
final FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
fabTemp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
transaction.setCustomAnimations(android.R.animator.fade_in,
android.R.animator.fade_out);
if (f.isHidden()) {
transaction.show(f);
} else {
transaction.hide(f);
}
transaction.commit();
}
});
return returnView;
}
I solved in another way despite not being as i wanted
final View frag = getView().findViewById(R.id.frgSettemp);
frag.setVisibility(View.GONE);

In onCreateView just inflate and return the view.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View returnView = inflater.inflate(R.layout.fragment_one, container, false);
return returnView;
}
Try the other processing in onViewCreated #override method. like this
#Override
public void onViewCreated(View v, Bundle savedInstanceState) {
super.onViewCreated(v, savedInstanceState);
FloatingActionButton fabTemp = getView().findViewById(R.id.fabTemp);
final Fragment f = getActivity().getSupportFragmentManager().getFragments().get(0);
final FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
fabTemp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
transaction.setCustomAnimations(android.R.animator.fade_in,
android.R.animator.fade_out);
if (f.isHidden()) {
transaction.show(f);
} else {
transaction.hide(f);
}
transaction.commit();
}
});
}
Hope this will help.

You should call only
final Fragment f = getActivity().getSupportFragmentManager().getFragments().get(0);
or
final Fragment f = getActivity().getSupportFragmentManager().getFragments().get(1);
What you have done will return null for sure.

How to transfer the value to recylerview of one which is received from another fragment?

i have made two fragments in my app.
1st fragment (EditFrag) and 2nd fragment (ListTable). i want to transfer the value of 1st fragment(from EditText of 1st fragment) to the recyclerView of 2nd fragment.
how should i do that.....i can't find right documentation.
Thank you for your concern!
MainActivity:
public class MainActivity extends AppCompatActivity implements EditFrag.TransferValue{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListTable frag1=new ListTable();
FragmentManager manager=getSupportFragmentManager();
FragmentTransaction transaction=manager.beginTransaction();
transaction.add(R.id.table_value_container,frag1,"fragment");
transaction.commit();
EditFrag frag2=new EditFrag();
FragmentManager manager1=getSupportFragmentManager();
FragmentTransaction transaction1=manager1.beginTransaction();
transaction1.add(R.id.table_container,frag2,"fragment_edit");
transaction1.commit();
}
#Override
public void sendValue(String value) {
Log.d("ashu","button is pressed");
ListTable listTable = (ListTable) getSupportFragmentManager().findFragmentById(R.id.table_value_container);
listTable.receiveValue(value);
}
}
2nd fragment(ListTable):
public class ListTable extends Fragment {
public TextView myEditText1;
private RecyclerView recyclerView;
public ListTable() {
// Required empty public constructor
}
public static ListTable newInstance(String param1, String param2) {
ListTable fragment = new ListTable();
Bundle args = new Bundle();
Log.d("ashu", "new instance is called :");
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.d("ashu", "oncreata called by inflating: ");
View view = inflater.inflate(R.layout.fragment_list_table, container, false);
myEditText1 = (TextView) container.findViewById(R.id.table_value);
recyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
MyAdapter a = new MyAdapter();
recyclerView.setAdapter(a);
return view;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
public void receiveValue(String value) {
myEditText1.setText(value);
}
public class MyAdapter extends RecyclerView.Adapter<MyDataViewHolder> {
#Override
public MyDataViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
Log.d("ashu", "oncreateview holder of adapter ia called");
LayoutInflater inflater = (LayoutInflater) parent.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.fragment_list_table, parent, false);
return new MyDataViewHolder(view);
}
#Override
public void onBindViewHolder(MyDataViewHolder holder, int position) {
holder.myEditText.setText("Table: " + position);
}
#Override
public int getItemCount() {
return 10;
}
}
public class MyDataViewHolder extends RecyclerView.ViewHolder {
public TextView myEditText;
public MyDataViewHolder(View itemView) {
super(itemView);
Log.d("ashu", "DAta view holder is called: ");
myEditText = (TextView) itemView.findViewById(R.id.table_value);
}
}
}
1st Fragment(EditFrag):
public class EditFrag extends Fragment {
TransferValue SendData;
EditText inputvalue;
Button click;
#Nullable
#Override
public View onCreateView(final LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.edit_frag_layout, container, false);
inputvalue = (EditText) view.findViewById(R.id.edit_text);
click = (Button) view.findViewById(R.id.click);
click.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String received = inputvalue.getText().toString();
SendData.sendValue(received);
}
});
return view;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
try {
SendData = (TransferValue) context;
} catch (ClassCastException e) {
Log.d("ashu", "implement the methods");
throw new ClassCastException("implemented the methods");
}
}
public interface TransferValue {
public void sendValue(String value);
}
}

create the instance of fragment2 from where want to receive the value to:
public static Fragment2 createInstance(String data) {
Fragment2 fragment = new Fragment2();
Bundle bundle = new Bundle();
bundle.putString("keyword", data);
fragment.setArguments(bundle);
return fragment;
}
and the get the data as below:
Bundle bundle = getArguments();
if (bundle != null) {
String data = bundle.getString("data");
}

You can use bundle in an order to pass data to fragment:
Example:
// Set bundle as arguments to the fragment
Bundle bundle = new Bundle();
bundle.putString(MyKey1, MyValue1);
bundle.putString(MyKey2, MyValue2);
MyFragment myFragment = new MyFragment();
myFragment.setArguments(bundle);
Inside onCreateView of fragment:
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.repairer_part_details_fragment, container, false);
String value1 = getArguments().getString(MyKey1);
String value2 = getArguments().getString(MyKey2);
return view;
}

There are many ways to do that. I see your codes above, and 2 fragments loaded at the same time. I usaually use one of 2 ways below to do it.
The first solution: You can use this link using obserable pattern to communication 2 fragments.
The second solution: you can use EventBus lib for communication, it 's very simple

After two different fragments have been replaced, first fragment is recreated when on pressed back button

I have three fragment and one activity. It works this way:
[activity]-> [MainFragment]->[MenuFragment]->[SignUpFragment]
When [SignUpFragment] is back pressed, the [MainFragment] is created twice.
I tried setRetaInInstance(true) and I checked savedInstanceState but I can not prevent [MainFragment] recreating.
This is my MainActivity:
public class MainActivity extends AppCompatActivity {
public Bundle mSavedInstanceState;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mSavedInstanceState = savedInstanceState;
setContentView(R.layout.activity_main);
}
#Override
protected void onResume() {
super.onResume();
callMainFragment();
}
private void callMainFragment() {
if (mSavedInstanceState == null) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.container_category, new MainFragment(), MainFragment.class.getSimpleName());
transaction.addToBackStack(null);
transaction.commit();
}
}
public ActionBar getMainActionBar(){
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
// Action Bar Display settings
actionBar.setDisplayShowCustomEnabled(true);
actionBar.setDisplayShowTitleEnabled(false);
// Custom view inflater
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// Custom layout view
View viewActionBar = inflater.inflate(R.layout.action_bar, null);
// Set custom view
actionBar.setCustomView(viewActionBar);
actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
}
return actionBar;
}
This is my MainFragment:
public class MainFragment extends BaseFragment implements AdapterView.OnItemClickListener, BuyersGuideCategoriesDelegate, View.OnClickListener {
private Bundle mSavedInstanceState;
private BuyersGuideCategoriesFragment mCategoriesFragment;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setRetainInstance(true);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
mSavedInstanceState = savedInstanceState;
if (mSavedInstanceState == null) {
mView = inflater.inflate(R.layout.fragment_main, container, false);
// Call Grid View Buyers Guide Fragment
mCategoriesFragment = new BuyersGuideCategoriesFragment();
mCategoriesFragment.mGridViewDelegate = this;
setIcons();
setTitles();
setTexts();
initListView();
}
return mView;
}
#Override
public void onResume() {
super.onResume();
ImageView menu = (ImageView) ((MainActivity) getActivity()).getMainActionBar().getCustomView().findViewById(R.id.action_bar_menu_icon);
menu.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if (mSavedInstanceState == null) {
MainActivity activity = (MainActivity) getActivity();
FragmentManager manager = activity.getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.container_category, new MenuFragment(),MenuFragment.class.getSimpleName());
transaction.addToBackStack(null);
transaction.commit();
}
}
}
This is my MenuFragment:
public class MenuFragment extends BaseFragment implements AdapterView.OnItemClickListener, View.OnClickListener {
private Bundle mSavedInstanceState;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
mSavedInstanceState = savedInstanceState;
if (savedInstanceState == null) {
mView = inflater.inflate(R.layout.fragment_menu, container, false);
setMenuItemsListViewAdapter();
}
return mView;
}
private void setMenuItemsListViewAdapter() {
ListView menuItems = (ListView) mView.findViewById(R.id.list_menu_items);
ListMenuItemsListViewAdapter adapter = new ListMenuItemsListViewAdapter(getContext(),getMenuItemNames());
menuItems.setAdapter(adapter);
menuItems.setOnItemClickListener(this);
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
switch ((String) parent.getAdapter().getItem(position)){
case SIGN_UP:
replaceFragment(R.id.container_category,new SignUpFragment(),SignUpFragment.class.getSimpleName());
break;
}
}
private void replaceFragment(int containerId,Fragment fragment, String fragmentTag){
if (mSavedInstanceState == null){
MainActivity activity = (MainActivity) getActivity();
FragmentManager manager = activity.getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(containerId,fragment,fragmentTag);
transaction.addToBackStack(null);
transaction.commit();
}
}
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.menu_back_icon:
replaceFragment(R.id.container_category, new MainFragment(),MainFragment.class.getSimpleName());
break;
}
}
}
And this is my SignUpFragment:
public class SignUpFragment extends BaseFragment implements View.OnClickListener{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (savedInstanceState == null) {
mView = inflater.inflate(R.layout.fragment_sign_up, container, false);
}
return mView;
}
}
EDIT 1: The MainFragment is recreated only when I return from SignUpFragment to MenuFragment. I am doing wrong using so many fragments? Should I use activity?

When you are move between Fragments, call addToBackStack() :
FragmentTransaction ft = fragmentManager.beginTransation();
ft.replace( R.id.fragment, new MyFragment() ).addToBackStack( "ftransaction" ).commit();

Create first Fragment:
FragmentTransaction ft = fragmentManager.beginTransation();
ft.add(R.id.container, new FirstFragment()).addToBackStack(null).commit();
Second:
FragmentTransaction ft = fragmentManager.beginTransation();
ft.replace(R.id.container, new SecondFragment()).addToBackStack(null).commit();
and Third:
FragmentTransaction ft = fragmentManager.beginTransation();
ft.replace(R.id.container, new ThirdFragment()).commit();

android onClick change fragment

I want to change the Fragment when i click the button. The fragments are in the same adapter/viewpager.
FROM THIS FRAGMENT:
public class LoginFragment extends Fragment {
TextView linkToRegister;
public static final LoginFragment newInstance()
{
LoginFragment mf = new LoginFragment();
Bundle bd = new Bundle(1);
mf.setArguments(bd);
return mf;
}
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState )
{
View v = inflater.inflate(R.layout.fragment_login, container, false);
linkToRegister = (TextView) v.findViewById(R.id.link_to_register);
linkToRegister.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Change Fragment
}
});
return v;
}
}
TO THIS FRAGMENT:
public class RegisterFragment extends Fragment {
public static final String EXTRA_MESSAGE = "EXTRA_MESSAGE";
public static final RegisterFragment newInstance()
{
RegisterFragment mf = new RegisterFragment();
Bundle bd = new Bundle(1);
mf.setArguments(bd);
return mf;
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState )
{
View v = inflater.inflate(R.layout.fragment_register, container, false);
return v;
}
}
PagerAdapter:
public class WelcomePagerAdapter extends FragmentStatePagerAdapter {
private final List<Fragment> Welcomefragments;
public WelcomePagerAdapter(FragmentManager fm, List<Fragment> Welcomefragments) {
super(fm);
this.Welcomefragments = Welcomefragments;
}
#Override
public Fragment getItem(int position) {
return this.Welcomefragments.get(position);
}
#Override
public int getCount() {
return this.Welcomefragments.size();
}
}
Activity:
public class WelcomeActivity extends AppCompatActivity {
ViewPager welcomeViewPager;
WelcomePagerAdapter welcomePagerAdapter;
List<Fragment> welcomeFragments;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_welcome);
welcomeViewPager = (ViewPager) findViewById(R.id.viewPagerWelcome);
welcomeFragments = getWelcomeFragments();
welcomePagerAdapter = new WelcomePagerAdapter(getSupportFragmentManager(), welcomeFragments);
welcomeViewPager.setAdapter(welcomePagerAdapter);
}
public List<Fragment> getWelcomeFragments() {
List<Fragment> newFragment = new ArrayList<Fragment>();
newFragment.add(LoginFragment.newInstance());
newFragment.add(RegisterFragment.newInstance());
return newFragment;
}
}

Step 1: Define a callback interface in the Fragment and hook in the Activity when the Fragment attaches to it.
public class MyFragment extends Fragment {
public interface OnInteractionListener {
void doAction(); // Can include parameters here if needed
}
private OnInteractionListener listener;
#Override
public void onAttach(Context context) {
if (context instanceof OnInteractionListener) {
listener = (OnInteractionListener) context;
} else {
throw new ClassCastException(context + "must implement " + OnInteractionListener.class.getSimpleName());
}
super.onAttach(context);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_layout, container, false);
// ...
return v;
}
}
Step 2: Make sure your Activity implements that Interface
public class MyActivity extends AppCompatActivity implements MyFragment.OnInteractionListener {
#Override
public void doAction() {
// TODO: Implement this... e.g. switch fragments
}
...
}
Step 3: Inside the Fragment, you can invoke the callback whenever you want to perform some action
if (listener != null) {
listener.doAction();
}

From MainActivity(), get the navController and then use the navigate() function:
NavController navController = Navigation.findNavController(this,R.id.nav_host_fragment);
navController.navigate(R.id.nav_grid);