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RecyclerView not updating on Fragment - Adapter shows null on notifyDataSetChanged()

I am trying to implement a sales app with 3 stages, whereby a user first adds the items, views the cart to checkout and prints a receipt. The first stage is done and works well. I am implementing this using one Activity with a tabbed layout and 3 fragments for each of the tabs.
On the activity for viewing the cart, I am using a RecyclerView which loads well when the activity is created, but once I add an item and try to view the list, there is no update. However, when I print the item list, the item has been added.
I have tried to update the RecyclerView using notifyDataSetChanged() but it gives me a null pointer exception. I have and tried several solutions but none has worked. Kindly assist.
Below is my code.
NewSaleActivity.java
public class NewSaleActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
private ActivityNewSaleBinding binding;
DrawerLayout drawerLayout;
NavigationView navigationView;
TabLayout tabLayout;
Context context;
ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
binding = ActivityNewSaleBinding.inflate(getLayoutInflater());
setContentView(binding.getRoot());
Toolbar toolbar = findViewById(R.id.new_sale_toolbar);
toolbar.setTitle(R.string.new_sale);
setSupportActionBar(toolbar);
drawerLayout = findViewById(R.id.new_sale_drawer);
navigationView = findViewById(R.id.new_sale_navigation);
navigationView.bringToFront();
navigationView.setNavigationItemSelectedListener(this);
navigationView.setCheckedItem(R.id.nav_sale);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawerLayout.addDrawerListener(toggle);
toggle.setDrawerIndicatorEnabled(true);
toggle.syncState();
context = getApplicationContext();
tabLayout = findViewById(R.id.tab_layout);
SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
viewPager = binding.viewPager;
viewPager.setAdapter(sectionsPagerAdapter);
viewPager.setOffscreenPageLimit(1);
TabLayout tabs = binding.tabLayout;
tabs.setupWithViewPager(viewPager);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
//When cart tab is selected
if(tab.getPosition() == 1) {
CartFragment cartFragment = new CartFragment();
cartFragment.loadItemsInCart();
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.nav_home:
Intent mainIntent = new Intent(NewSaleActivity.this, MainActivity.class);
startActivity(mainIntent);
finish();
break;
case R.id.nav_inventory:
Intent inventoryIntent = new Intent(NewSaleActivity.this, InventoryActivity.class);
startActivity(inventoryIntent);
finish();
break;
case R.id.nav_sale:
break;
case R.id.nav_logout:
UserLogout.userLogout(NewSaleActivity.this);
break;
}
drawerLayout.closeDrawer(GravityCompat.START);
return true;
}
}
CartFragment.java
public class CartFragment extends Fragment {
RecyclerView cartRecyclerView;
TextInputLayout grossTotalInput, discountInput, netTotalInput;
Button checkoutButton;
CartItemAdapter cartItemAdapter;
ArrayList<CartItem> cartItemList;
public CartFragment() {
// Required empty public constructor
}
public static CartFragment newInstance() {
CartFragment fragment = new CartFragment();
Bundle args = new Bundle();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
cartRecyclerView = view.findViewById(R.id.cart_recycler_view);
grossTotalInput = view.findViewById(R.id.gross_total_input);
discountInput = view.findViewById(R.id.discount_input);
netTotalInput = view.findViewById(R.id.net_total_input);
checkoutButton = view.findViewById(R.id.checkout_button);
Paper.init(requireContext());
cartItemList = Paper.book().read("cartItems", new ArrayList<CartItem>());
cartRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
cartItemAdapter = new CartItemAdapter(cartItemList);
cartRecyclerView.setAdapter(cartItemAdapter);
checkoutButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
checkoutOrder();
}
});
cartItemAdapter.notifyDataSetChanged();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_cart, container, false);
}
public void loadItemsInCart() {
ArrayList<CartItem> cartList = Paper.book().read("cartItems", new ArrayList<CartItem>());
for(CartItem cartItem : cartList) {
Log.d("cartItem", cartItem.getItemName());
}
cartItemAdapter.updateCartList(cartList);
Log.d("loadItemsInCart", "Load Items In Cart is triggered");
}
CartItemAdapter.java
public class CartItemAdapter extends RecyclerView.Adapter<CartItemAdapter.ViewHolder> {
private final ArrayList<CartItem> cartItems;
public CartItemAdapter(ArrayList<CartItem> cartItems) {
this.cartItems = cartItems;
}
public static class ViewHolder extends RecyclerView.ViewHolder {
public TextView itemCode, itemName, quantity, price;
public ViewHolder(View itemView) {
super(itemView);
this.itemCode = itemView.findViewById(R.id.item_code);
this.itemName = itemView.findViewById(R.id.item_name);
this.quantity = itemView.findViewById(R.id.item_quantity);
this.price = itemView.findViewById(R.id.item_price);
}
}
#NonNull
#Override
public ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
View cartListItem = layoutInflater.inflate(R.layout.add_to_cart_item, parent, false);
return new CartItemAdapter.ViewHolder(cartListItem);
}
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
holder.itemCode.setText(cartItems.get(position).getItemCode());
holder.itemName.setText(cartItems.get(position).getItemName());
holder.quantity.setText(cartItems.get(position).getQuantity().toString());
holder.price.setText(cartItems.get(position).getTotalAmount().toString());
}
#Override
public int getItemCount() {
return cartItems.size();
}
#SuppressLint("NotifyDataSetChanged")
public void updateCartList(ArrayList<CartItem> cartList) {
cartItems.clear();
this.cartItems.addAll(cartList);
notifyDataSetChanged();
}
}
The error message that I get is as below
java.lang.NullPointerException: Attempt to invoke virtual method 'void app.project.jsml_sales_app.adapters.CartItemAdapter.updateCartList(java.util.ArrayList)' on a null object reference
at app.project.jsml_sales_app.activities.fragments.CartFragment.loadItemsInCart(CartFragment.java:128)
at app.project.jsml_sales_app.activities.NewSaleActivity$1.onTabSelected(NewSaleActivity.java:78)
at com.google.android.material.tabs.TabLayout.dispatchTabSelected(TabLayout.java:1993)
at com.google.android.material.tabs.TabLayout.selectTab(TabLayout.java:1986)

OnClick Fragment to Fragment switch results in Blank Screen

When switching from one fragment to another fragment (within the second tab of my application), my second fragment is blank. I have tried the solutions linked here, but none seem to work:
Transaction of fragments in android results in blank screen
Android: Getting white screen with fragment transaction
MainActivity:
public class MainActivity extends AppCompatActivity {
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter, and add pages.
mViewPager = (ViewPager) findViewById(R.id.container);
mSectionsPagerAdapter.addPage(new Received());
mSectionsPagerAdapter.addPage(new Send());
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_alert_partners, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(getArguments().getInt(ARG_SECTION_NUMBER)==1) {
View rootView = inflater.inflate(R.layout.fragment_received, container, false);
return rootView;
}
else if(getArguments().getInt(ARG_SECTION_NUMBER)==2) {
View rootView = inflater.inflate(R.layout.fragment_send, container, false);
return rootView;
}
else {//main empty fragment in case of error. Never used in normal behaviour.
View rootView = inflater.inflate(R.layout.fragment_alert_partners, container, false);
return rootView;
}
}
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
//Create an Array list that will hold the pages.
ArrayList<Fragment> pages = new ArrayList<>();
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
return pages.get(position);
}
//Add a page
public void addPage(Fragment f) {
pages.add(f);
}
#Override
public int getCount() {
// Show 2 total pages.
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Received";
case 1:
return "Send";
}
return null;
}
}
}
SendFragment:
public class Send extends Fragment {
private OnFragmentInteractionListener mListener;
private TextView text1;
public Send() {
// 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 v = inflater.inflate(R.layout.fragment_send, container, false);
//Need getView() for fragment since setContentView must be set first but is not possible in fragment.
text1 = (TextView)v.findViewById(R.id.textview1);
text1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Send2 send2 = new Send2();
fragmentTransaction.addToBackStack(null);
fragmentTransaction.hide(Send.this);
fragmentTransaction.add(android.R.id.content, send2);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
});
return v;
}
public interface OnFragmentInteractionListener {
}
}
Send2Fragment:
public class Send2 extends Fragment {
private OnFragmentInteractionListener mListener;
public Send2() {
// 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
final View v = inflater.inflate(R.layout.fragment_send2, container, false);
return v;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
}
}

Had to add a framelayout at the end of the layout code for the fragment I was replacing:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/send1frameLayoutId">
</FrameLayout>
Then used this code to switch to a fragment in the same tab of the previous fragment:
Fragment send2 = new Send2();
FragmentManager fragmentManager = getChildFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.send1frameLayoutId, send2);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();

Where should I put my code when using a tabbed activity?

I am having a rather annoying problem using tabs in android. I am not sure how they work, problem I am having is knowing where to put the logic of my code. say for example on the first tab I wanted to apply a calendar and the second tab upload a file, for example where would I put this logic, I have 3 xml fragments and so far I have been trying to code the logic by the onCreateView. If anyone could explain how tabbed activities work I would be eternally grateful I used the default android set up for a tabbed activity and added 3 fragments.
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
if(getArguments().getInt(ARG_SECTION_NUMBER)==1) {
View rootView = inflater.inflate(R.layout.fragment_message, container, false);
return rootView;
}
else if(getArguments().getInt(ARG_SECTION_NUMBER)==2){
View rootView = inflater.inflate(R.layout.fragment_read, container, false);
TextView textView= (TextView)rootView.findViewById(R.id.textView_two);
textView.setText("Working");
return rootView;
}
else{
View rootView = inflater.inflate(R.layout.fragment_calendar, container, false);
// would I put my logic here?
return rootView;
}
}
}
Update 2
So now I am trying to listen for button presses and show a toast on one of the fragments,the button does not respond and the Toasts do not appear.
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
final View rootView=inflater.inflate(R.layout.fragment_calendar, container, false);
//final ActionBar actionBar = getSupportActionBar();
//actionBar.setDisplayHomeAsUpEnabled(false);
//actionBar.setTitle(null);
//Toast.makeText(getActivity(),"AKHBKH",Toast.LENGTH_LONG).show();
Button button1=(Button)rootView.findViewById(R.id.button_test1);
button1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Log.i("","");
Toast.makeText(getActivity(),"ddfdf",Toast.LENGTH_LONG).show();
}
});
PS I have tried all these on the Toast
getActivity()
getActivity().getApplicationContext()
getBaseContext()
getContext()

You can take three fragments and All the logic you want to implement should be in each of the fragment respectively. Take MainActivity to View all the fragments. Here i'll share my piece of code.
MainActivity
public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFragment(new Admin(), "ADMIN");
adapter.addFragment(new Faculty(), "FACULTY");
adapter.addFragment(new Student(), "STUDENT");
viewPager.setAdapter(adapter);
}
//----------------------------------------------------------------------------------------------
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
#Override
public void onBackPressed(){
//Do Here what ever you want do on back press;
}
}
I'll share the code of any one of the fragments: Admin
public class Admin extends Fragment {
EditText aid;
EditText apassword;
Button submit1,changepass;
String id = null, pass = null;
String table = null;
public Admin() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
final View rootView=inflater.inflate(R.layout.fragment_admin, container, false);
aid=(EditText)rootView.findViewById(R.id.admin_id);
apassword=(EditText)rootView.findViewById(R.id.admin_password);
changepass=(Button)rootView.findViewById(R.id.changePass);
submit1=(Button)rootView.findViewById(R.id.submit1);
submit1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
submit1();
}
});
changepass.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent in=new Intent(getActivity(),ChangePassword.class);
startActivity(in);
}
});
// Inflate the layout for this fragment
return rootView;
}
//For Admin login Authentication
public void submit1() {
id = aid.getText().toString();
pass = apassword.getText().toString();
Log.d("id", id);
Log.d("pass", pass);
table="admin";
// new ExecuteTask().execute(id, pass, table);
}}

Initially create an activity MainActivity.
You must create 3 fragments.Extend your activity from FragmentActivity and also implement ActionBar.TabListener
Refer this tutorial:
http://www.androidhive.info/2013/10/android-tab-layout-with-swipeable-views-1/

How to stop tab change from running fragment onCreateView in Andriod

I have three tabs using the implementation below and they perform very well. When tab is changed the proper fragment is load and so on. The problem is that, when i get to the last tab and comeback to the first fragment, its like its oncreateview method is always triggered again running the other codes it in causing duplicates. Any help will be greatly appreciated.
//Activity on the tab is based
public class Dashboard extends AppCompatActivity {
private TabLayout tabLayout;
private ViewPager viewPager;
private MyViewPagerAdapter myViewPagerAdapter;
private int[] tabIcon = {R.drawable.ic_home, R.drawable.ic_message, R.drawable.ic_person};
android.support.v7.widget.Toolbar toolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.dashboard);
//Toolbar
toolbar = (android.support.v7.widget.Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//ViewPager
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
//Tablayout
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
tabLayout.getTabAt(0).setIcon(tabIcon[0]);
tabLayout.getTabAt(1).setIcon(tabIcon[1]);
tabLayout.getTabAt(2).setIcon(tabIcon[2]);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
switch(tab.getPosition()) {
case 0:
viewPager.setCurrentItem(0);
toolbar.setTitle("Home");
break;
case 1:
viewPager.setCurrentItem(1);
toolbar.setTitle("Messages");
break;
case 2:
viewPager.setCurrentItem(2);
toolbar.setTitle("Profile");
break;
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
private void setupViewPager(ViewPager viewPager){
myViewPagerAdapter = new MyViewPagerAdapter(getSupportFragmentManager());
myViewPagerAdapter.addFragments(new CategoryFragment(), "Categories");
myViewPagerAdapter.addFragments(new MessagesFragment(), "Messages");
myViewPagerAdapter.addFragments(new ProfileFragment(), "Profile");
viewPager.setAdapter(myViewPagerAdapter);
}
//View Pager Adapter
public class MyViewPagerAdapter extends FragmentPagerAdapter {
ArrayList<Fragment> fragments = new ArrayList<>();
ArrayList<String> tabTitles = new ArrayList<>();
public void addFragments(Fragment fragments, String titles){
this.fragments.add(fragments);
this.tabTitles.add(titles);
}
public MyViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public Fragment getItem(int position) {
return fragments.get(position);
}
#Override
public CharSequence getPageTitle(int position) {
//return tabTitles.get(position);
return null;
}
}
#Override
public void onBackPressed() {
super.onBackPressed();
}
}
//Main first fragment code
public class CategoryFragment extends Fragment {
private DBHandler dbHandler;
private ListView listView;
private ListAdapter adapter;
ArrayList<Categories> categoriesList = new ArrayList<Categories>();
public CategoryFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_home, container, false);
//Setting up the basic categories
dbHandler = new DBHandler(view.getContext());
//Get Categories from database
final Cursor cursor = dbHandler.getCategories(0);
if (cursor != null) {
if(cursor.moveToFirst()){
do{
Categories categories = new Categories();
categories.set_id(cursor.getInt(0));
categories.set_categoryname(cursor.getString(2));
categories.set_categoriescaption(cursor.getString(3));
categoriesList.add(categories);
}while (cursor.moveToNext());
}
cursor.close();
}
listView = (ListView) view.findViewById(R.id.categories);
adapter = new CategoryAdapter(view.getContext(), R.layout.cursor_row, categoriesList);
listView.setAdapter(adapter);
listView.setOnItemClickListener(
new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Integer cid = (int) (long) adapter.getItemId(position);
TextView categoryname = (TextView) view.findViewById(R.id.cursor);
String cname = categoryname.getText().toString();
Intent i = new Intent(view.getContext(), CategoryList.class);
i.putExtra("categoryname", cname);
i.putExtra("categoryid", cid);
startActivity(i);
}
}
);
return view;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
So when i swipe back here from the last tab. OncreateView runs again. How can i handle that and prevent duplicates. Thank you

By defaults ViewPager retains only 1 page in the view hierarchy in an idle state.So when you swipe to third tab the viepager destroys the first tab in order to retain the second one.
To solve this issue add this line
viewPager.setOffscreenPageLimit(3);
after you set your adapter.
Check here the documentation for more

Add fragment into viewPager's fragment

I have viewpager with 3 fragments (same layout - some EditText and Buttons) and I want to dynamically add small fragment above the viewpager fragment, write something in and then hide it.
This is what I tried:
MainActivity.java:
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
}
private class MyPagerAdapter extends FragmentPagerAdapter {
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int pos) {
switch(pos) {
case 0: return MainFragment.newInstance("1");
case 1: return MainFragment.newInstance("2");
case 2: return MainFragment.newInstance("3");
default: return MainFragment.newInstance("");
}
}
#Override
public int getCount() {
return 3;
}
}
}
MainFragment.java:
public class MainFragment extends android.support.v4.app.Fragment {
EditText contentEdit;
String content, ID;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ID = getArguments().getString("msg");
}
#Override
public View onCreateView(LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main, container, false);
contentEdit = (EditText) view.findViewById(R.id.editText);
contentEdit.setOnTouchListener(new OnSwipeTouchListener(getActivity()) {
public void onSwipeBottom() {
final ViewGroup newView = (ViewGroup) LayoutInflater.from(getActivity()).inflate(R.layout.fragment_title, container, false);
newView.findViewById(R.id.delete_button).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
container.removeView(newView);
}
});
container.addView(newView, 0);
}
public boolean onTouch(View v, MotionEvent event) {
return gestureDetector.onTouchEvent(event);
}
});
return view;
}
}

Try to put a frame layout above that viewPager layout BUT set it's visibility to GONE therefore it won't "exist". Now in your pager onItemClick listener for that small fragment you want to show call findViewByID(R.id.YourFrameLayout).setVisibility(View.VISIBLE); and when you want to hide it, well you get the idea. Don't forget to add your fragment to that container, e.g. YourFrameLayout