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Android TabLayout and ViewPager Fragment using RxJava

Let's say that I have a ViewPager that will have 2 Fragments. From those Fragments, I create a PublishSubject which I would like to subscribe to within the MainActivity. However, the issue is during the onCreate(), I would not be able to grab that specific PublishSubject from the Fragment since it seems like it hasn't been created yet. Therefore, I end up with an NPE if I tried to make a subscription for it.
Is there a way to pass the PublishSubject once the Fragment is created by the ViewPager to the MainActivity? Or should I be trying to do something else instead. I've tried looking through other issues, but I couldn't find anything that is similar with something like this.
Some Code to illustrate what I mean:
Fragment
public class ExampleFragment extends Fragment {
PublishSubject<SomeObject> mPublishSubject = PublishSubject.create();
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstance){
// Regular fragment stuff here
}
public PublishSubject<SomeObject> getPublishSubject() {
return mPublishSubject;
}
}
ViewPager
public class ExamplePagerAdapter extends FragmentStatePagerAdapter {
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new ExampleFragment();
case 1:
return new SomeOtherFragment();
default:
return null;
}
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
private PublishSubject<SomeObject> mSubjectFromTheFragment;
private ExamplePagerAdapter mPagerAdapter;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("tab1"));
tabLayout.addTab(tabLayout.newTab().setText("tab2"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
mViewPager = (ViewPager) findViewById(R.id.view_pager);
mPagerAdapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
mViewPager.setAdapter(mPagerAdapter);
// Set listener
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
// Code to implement the methods
});
// When or where do I set PublishSubject
mPublishSubject = ?
// The subscription
mPublishSubject.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe(/** Some new Action1<> etc. **/ )
}
}
Any help or pointing me to some kind of direction is really appreciated!

No Id found viewpager

I have an app with 3 tabs. A tab has a fragment with a button to go another view within the same tab. My implementation is simple. I have main_activity with view pager. Here is snippet of main_activity.xml.
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
Below the MainActivity.java
public class MainActivity extends AppCompatActivity {
public SectionsPageAdapter mSectionPageAdapter;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mSectionPageAdapter = new SectionsPageAdapter(getSupportFragmentManager());
mViewPager = (ViewPager) findViewById(R.id.pager);
setupViewPager(mViewPager);
//Assigns the ViePager to TabLayout
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
}
//Defines the number of tabs by setting appropriate fragment and tab name.
private void setupViewPager(ViewPager viewPager){
SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());
adapter.addFragment(new FirsTab(),"TAB1");
adapter.addFragment(new SecondTab(),"TAB2");
adapter.addFragment(new ThirdTab(),"TAB3");
viewPager.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
When I replace the FirstTab with FirsTabSubFragment with getChildFragmentManager() I get a "no view found" error.
java.lang.IllegalArgumentException: No view found for id 0x7f0d0073 (com.none.app:id/pager) for fragment FirsTabSubFragment{607b4a6 #0 id=0x7f0d0073}
Below the code for FirtTab.java
public class FirstTab extends Fragment{
private Button btnScan;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.scan_layout, container, false);
btnScan = (Button) view.findViewById(R.id.btnScan);
btnScan.setOnClickListener(new View.OnClickListener(){
public void onClick(View view) {
getChildFragmentManager()
.beginTransaction()
.replace(R.id.pager, new FirsTabSubFragment())
.addToBackStack(null)
.commit();
}
});
return view;
}
A replacement with a getFragmentmanager() results in a empty view. Can anyone advice me on this topic?

Android: how to update recyclerview inside fragment which is inside viewpager upon button click

I have a recyclerview inside a fragment which is inside viewpager. I have button outside viewpager. How to update the recyclerview upon clicking the button.
public class Level2MainActivity_grid1 extends AppCompatActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.level2mainlayout_place1);
// I am putting a viewpager with fragments into them and put tabs
ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);
PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager(), Titles, Numboftabs);
viewPager.setAdapter(pagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabLayout);
tabLayout.setupWithViewPager(viewPager);
Button buttonId = (Button) findViewById(R.id.planmytraveludupitown);
buttonId.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//I want to save some things and do the changes in the recyclerview of tab 0;
}
});
}
}
The framgment code in tab 0 of the viewpager, in which i am using recyclerview is as below:
public class Udupiwhattosee extends Fragment {
private RecyclerView rv;
private List<Udupiwhattoseearray> udupiwhattoseearray;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
RecyclerView v =(RecyclerView) inflater.inflate(R.layout.tab_1,container,false);
v.setLayoutManager(new LinearLayoutManager(getActivity()));
v.setHasFixedSize(true);
initializeData();
WhattoseeRVAdapter adapter = new WhattoseeRVAdapter(udupiwhattoseearray,container.getContext());
v.setAdapter(adapter);
return v;
}
private void initializeData(){
udupiwhattoseearray = new ArrayList<>();
udupiwhattoseearray.add(new Udupiwhattoseearray("Udupi Sri Krishna Temple", "Udupi, Karanata,INDIA", R.drawable.udupi));
udupiwhattoseearray.add(new Udupiwhattoseearray("Udupi place 2", "Udupi, Karanata,INDIA", R.drawable.udup_krishna_math_gopura_udupi));
udupiwhattoseearray.add(new Udupiwhattoseearray("Udupi Place 3", "Udupi, Karanata,INDIA", R.drawable.udupi_rath));
udupiwhattoseearray.add(new Udupiwhattoseearray("Udupi place 4", "Udupi, Karanata,INDIA", R.drawable.udupi_window));
}

recycler_view.post(new Runnable() {
public void run() {
adapter.notifyDataSetChanged();
}
});
HERE you will see the working of interface ,try this hope its gonna work fine

Android how to hide tab from TabLayout

I need to hide first tab. First page should work but when user select it, it should be seems like on tabs is selected. How I can do this?
I found some solutions with TabHost and it useless to me.
public class TabFragmentClients extends Fragment {
public static TabLayout tabLayout;
public static ViewPager viewPager;
public static int int_items = 5 ;
FinanceClients FinanceClients;
public ClientsFragment clientsFragment;
public FinanceFragment financeFragment;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
/**
*Inflate tab_layout and setup Views.
*/
final View x = inflater.inflate(R.layout.tab_layout_clients,null);
tabLayout = (TabLayout) x.findViewById(R.id.tabs);
viewPager = (ViewPager) x.findViewById(R.id.viewpager);
/**
*Set an Apater for the View Pager
*/
viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));
/**
* Now , this is a workaround ,
* The setupWithViewPager dose't works without the runnable .
* Maybe a Support Library Bug .
*/
tabLayout.post(new Runnable() {
#Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
}
});
return x;
}

tabLayout = (TabLayout) findViewById(R.id.tabs);
((ViewGroup) tabLayout.getChildAt(0)).getChildAt(desiredPosition).setVisibility(View.GONE);//hides the tab

Did you try this?
tabLayout.setupWithViewPager(viewPager);
tabLayout.removeTabAt(0);

onClickListener (buttons) to switch view of ViewPager using Fragments

I'm developing an application, which consists of a FragmentActivity with three Fragments. I want to go from the first fragment to the third and last one with "next" buttons. For that, I'm using a viewPager and pagerAdpater (I disabled the paging/swiping on the viewpager). My "next" buttons have been implemented in their own fragments. I have one xml layout for each fragment and one for the fragmentActivity containing the viewpager.
I am trying to use an OnClickListener where I could use the setCurrentItem(index) method and go from the first to the last view.
The problem is that i don't know where I could put the OnClickListener, since I don't have the viewpager reference in my fragment.
How can I get the viewpager reference in my fragments? Do I have to put my OnClickListener method somewhere else?
Here is the code of one of my 3 Fragments:
public class InitializationStep1 extends Fragment{
private PagerAdapter mPagerAdapter;
CustomViewPager pager;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = (LinearLayout)inflater.inflate(R.layout.initialization_step1_layout, container, false);
Button button = (Button) v.findViewById(R.id.goToStep2);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
CustomViewPager pager = (CustomViewPager) v.findViewById(R.id.viewpager);
if(pager == null)
System.out.println("It's null..."); // always getting a null value
else
pager.setCurrentItem(0);
}
});
return v;
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
setUserVisibleHint(true);
}
}
and this is my FragmentActivity:
public class Initialization extends FragmentActivity{
private PagerAdapter mPagerAdapter;
CustomViewPager pager;
Button b1;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.viewpager_initialization_layout);
//initialize the pager
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, InitializationStep1.class.getName()));
fragments.add(Fragment.instantiate(this, InitializationStep2.class.getName()));
fragments.add(Fragment.instantiate(this, InitializationStep3.class.getName()));
this.mPagerAdapter = new PagerAdapter(super.getSupportFragmentManager(), fragments);
pager = (CustomViewPager)super.findViewById(R.id.viewpager);
pager.setPagingEnabled(false);
pager.setAdapter(this.mPagerAdapter);
pager.setCurrentItem(0);
}
}
To sum all this up, I have:
- implemented 3 Fragments (1, 2 and 3)
and I would like to get:
- Each Fragment containing a button to go to the next Fragment (1 -> 2 -> 3).
- The last fragment containing a "finish" button (because there is no next Fragment to navigate to)
I assume that this is a very simple action, but I'm relatively new in Android development and couldn't figure this out. I'm maybe trying to use the wrong component to do that.
Thanks

I just had the same problem, try this! In your Initialization FragmentActivity:
public CustomViewPager getpager(){
return pager;
}
In "InitializationStep1":
CustomViewPager pager;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = (LinearLayout)inflater.inflate(R.layout.initialization_step1_layout, container, false);
pager = ((Initialization)getActivity()).getpager();
Button next = (Button) v.findViewById(R.id.button1);
next.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
pager.setCurrentItem(2);
}
});
In this way, you can get the viewpager object that you declare in your FragmentActivity, so you can use it in each fragment to switch between fragments as you want!