Develop Reference

onCreateView not called tab fragment

I currently have this tab view which I followed from this tutorial. Everything works fine until I noticed that the onCreateView is not called on any of the tab. I've looked around here and there for solution but I still can't solve.
Here is my code:
activity_pref_main_container.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:id="#+id/main_layout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".PrefActivityMain">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
<android.support.design.widget.TabLayout
android:id="#+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/toolbar"
android:background="?attr/colorPrimary"
android:elevation="6dp"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"/>
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_below="#id/tab_layout"/>
</RelativeLayout>
PrefMainActivity.class
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pref_main_container);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle(R.string.preference_title);
setSupportActionBar(toolbar);
new PrefActivityListAsync(this,this,specialization).execute();
new PrefActivityListAsync(this,this,position).execute();
new PrefActivityListAsync(this,this,type).execute();
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("Specialization"));
tabLayout.addTab(tabLayout.newTab().setText("Position"));
tabLayout.addTab(tabLayout.newTab().setText("Type"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PrefAdapter adapter = new PrefAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
viewPager.setOffscreenPageLimit(2);
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
PrefAdapder.class
public class PrefAdapter extends FragmentPagerAdapter {
int mNumOfTabs;
public PrefAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
PrefActivitySpecialization tab1 = new PrefActivitySpecialization();
return tab1;
case 1:
PrefActivityPosition tab2 = new PrefActivityPosition();
return tab2;
case 2:
PrefActivityType tab3 = new PrefActivityType();
return tab3;
default:
return null;
}
}
#Override
public int getCount() {
return 0;
}
}
one out of three fragment class
PrefActivitySpecialization.class
public class PrefActivitySpecialization extends
android.support.v4.app.Fragment {
private ArrayList<DataPrefSpecialization> dataPrefSpecializationArrayList;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup
container, Bundle savedInstanceState) {
View view =
inflater.inflate(R.layout.activity_pref_specialization_container, container,
false);
dataPrefSpecializationArrayList = ((PrefActivityMain)
getActivity()).getDataPrefSpecialization();
for(int i = 0; i < dataPrefSpecializationArrayList.size(); i++){
Log.d("Check Specialization
",dataPrefSpecializationArrayList.get(i).getName());
}
return inflater.inflate(R.layout.activity_pref_specialization_container, container, false);
}
}

You should make changes at two place:
1) Change
#Override
public int getCount() {
return 0;
}
to
#Override
public int getCount() {
return mNumOfTabs;
}
2) Change
return inflater.inflate(R.layout.activity_pref_specialization_container, container, false);
to
return view;

public PrefAdapter(FragmentManager fm, int NumOfTabs)
You must declare Count No NumOfTabs
int getCount ()-> How many items are in the data set represented by this
Adapter.
#Override
public int getCount()
{
return mNumOfTabs;
}
Do not'
return inflater.inflate(R.layout.activity_pref_specialization_container, container, false);
Do
return view ;

Your getCount() method is returning 0;

There is another (possibly easier) way to connect the view pager with the tab layout-
First, in your PrefAdapter class, override the getPageTitle() method and return your tab titles for the respective tab positions from there.
In your PrefMainActivity class, remove all the lines like-
tabLayout.addTab(...)
Add the following line instead-
tabLayout.setupWithViewPager(viewPager);

Edittext automatically gets focus when move between pages in a view pager

I have an activity which hosts two fragments inside a view pager. I used the same layout to inflate those fragments. The layout has two edit texts placed inside a linear layout which is inside a relative layout. The problem is when I switch from fragment A to fragment B, he first edit text has focus in fragment A and when I return back from fragment B to fragment A, instead of the first edit text having focus, the second edit text gets the focus. How to solve it. I provide the layouts and source code below. I have not return any code inside the fragment classes.
Activity:
public class LoginActivity extends BaseActivity {
public static final String selectedTabPosition = "selectedTabPosition";
//Tab tag name
private static String TAB_1_TAG = "Email";
private static String TAB_2_TAG = "Mobile";
private TabLayout mTabLayout;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
TAB_1_TAG = getResources().getString(R.string.tab_email);
TAB_2_TAG = getResources().getString(R.string.tab_mobile);
//Initialise views
mViewPager = (ViewPager) findViewById(R.id.viewpager);
mTabLayout = (TabLayout) findViewById(R.id.tabs);
//set tab with view pager
setupViewPager(mViewPager);
mTabLayout.setupWithViewPager(mViewPager);
setupTabIcons();
mViewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
#Override
public void onPageSelected(int position) {
dismissKeyboard(mViewPager);
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
}
/**
* Adding custom view to tab
*/
private void setupTabIcons() {
LinearLayout tabOne = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.tab_custom, null);
TextView tvIconOne = (TextView) tabOne.findViewById(R.id.tv_tab_title);
tvIconOne.setText(TAB_1_TAG);
mTabLayout.getTabAt(0).setCustomView(tabOne);
setTypeface(tvIconOne, CustomFonts.Prime_regular);
mTabLayout.getTabAt(0).getCustomView().setSelected(true);
LinearLayout tabTwo = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.tab_custom, null);
TextView tvIconTwo = (TextView) tabTwo.findViewById(R.id.tv_tab_title);
tvIconTwo.setText(TAB_2_TAG);
setTypeface(tvIconTwo, CustomFonts.Prime_regular);
mTabLayout.getTabAt(1).setCustomView(tabTwo);
}
/**
* Adding fragments to ViewPager
*
* #param viewPager The view pager
*/
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
LoginFragment loginFragmentEmail = new LoginFragment();
Bundle emailBundle = new Bundle();
emailBundle.putInt(selectedTabPosition, 0);
loginFragmentEmail.setArguments(emailBundle);
LoginFragment loginFragmentMobile = new LoginFragment();
Bundle phoneBundle = new Bundle();
phoneBundle.putInt(selectedTabPosition, 1);
loginFragmentMobile.setArguments(phoneBundle);
adapter.addFrag(loginFragmentEmail, TAB_1_TAG);
adapter.addFrag(loginFragmentMobile, TAB_2_TAG);
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 addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
}
Fragment:
public class LoginFragment extends BaseFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
View rootView = inflater.inflate(R.layout.fragment_login, container, false);
return rootView;
}
activity_login.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white"
android:orientation="vertical">
<ImageView
android:id="#+id/iv_title"
android:layout_width="200dp"
android:layout_height="45dp"
android:layout_centerHorizontal="true"
android:layout_marginTop="30dp"
/>
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="#dimen/custom_tab_layout_height"
android:layout_below="#+id/iv_title"
android:layout_marginTop="#dimen/spacing_10"
app:tabGravity="fill"
app:tabIndicatorColor="#color/app_color_dark"
app:tabMode="fixed"/>
<View
android:id="#+id/view"
android:layout_width="match_parent"
android:layout_height="#dimen/divider_height_small"
android:layout_below="#+id/tabs"
android:background="#color/gray_medium"/>
<com.helper.CustomNonSwipeableViewpager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/view"
app:layout_behavior="#string/appbar_scrolling_view_behavior"/>
</RelativeLayout>
fragment_login.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="#dimen/spacing_50"
android:orientation="vertical">
<EditText
android:id="#+id/et_email"
android:layout_width="match_parent"
android:layout_height="#dimen/spacing_48"
/>
<EditText
android:id="#+id/et_password"
android:layout_width="match_parent"
android:layout_height="#dimen/spacing_48"
android:layout_marginTop="#dimen/spacing_15"/>
</LinearLayout>
</RelativeLayout>
AndroidManifest.xml:
<activity
android:name=".activities.LoginActivity"
android:screenOrientation="portrait"
/>
In the AndrodManifest file, tried the
android:windowSoftInputMode = stateHidden and android:windowSoftInputMode = adjustPan
CustomNonSwipeableViewpager.java:
public class CustomNonSwipeableViewpager extends ViewPager {
public CustomNonSwipeableViewpager(Context context) {
super(context);
}
public CustomNonSwipeableViewpager(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent event) {
// Never allow swiping to switch between pages
return false;
}
#Override
public boolean onTouchEvent(MotionEvent event) {
// Never allow swiping to switch between pages
return false;
}
}
ScreenShots:
Before moving to FragmentB:
In Fragment B:
Return back to Fragment A from Fragment B:

You can disable the focus on the EditText during runtime of the fragment:
EditText et_email_view = (EditText) rootView.findViewById(R.id.et_email);
et_email_view.setFocusable(false);

Use requestFocus attribute to your first editText which will always cause that editText to gain focus.
Make following changes in your fragment_login.xml file,
<EditText
android:id="#+id/et_email"
android:layout_width="match_parent"
android:layout_height="#dimen/spacing_48">
<requestFocus />
</EditText>

For example in my case viewPager is covering editText. I set translationZ at editText(translationZ="2") and viewPage(translationZ="1") and it helped me.

Android: Can't update textview in Fragment from Activity. NullPointerException

I'm trying to update textview in fragment from another activity. But I'm getting a NUllPointerException when calling the setText method. I have tried the following, but still getting the NPE.
1. Tried accessing the fragments textview with FindViewbyId in activity.
2. Tried using a method in fragment and calling it from activity and passing the value as parameters
FragHome Activity
public class FragHome extends AppCompatActivity implements TabLayout.OnTabSelectedListener {
Handler bluetoothIn;
private static TextView tmpF, humF, CoF;
String tempGL, HumGL, coGL, devname;
double dblTemp, dblCo;
final int handlerState = 0; // used to identify handler message
private BluetoothAdapter btAdapter = null;
private TabLayout tabLayout;
private ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_frag_home);
//Adding toolbar to the activity
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
//Initializing the tablayout
tabLayout = (TabLayout) findViewById(R.id.tabLayout);
//Initializing viewPager
viewPager = (ViewPager) findViewById(R.id.pager);
//Adding the tabs using addTab() method
tabLayout.addTab(tabLayout.newTab().setText("Temperature"));
tabLayout.addTab(tabLayout.newTab().setText("Humidity"));
tabLayout.addTab(tabLayout.newTab().setText("CO"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
//Creating our pager adapter
Pager adapter = new Pager(getSupportFragmentManager(), tabLayout.getTabCount());
//Adding adapter to pager
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
//Adding onTabSelectedListener to swipe views
tabLayout.setOnTabSelectedListener(this);
bluetoothIn=new Handler() {
String readMessage;
String[] values = new String[]{""};
public void handleMessage(android.os.Message msg) {
if (msg.what == handlerState) {
readMessage = (String) msg.obj;
values = readMessage.split("#");
for (int j = 0; j < values.length; j++) {
int rem = j % 3;
if (rem == 0) {
tmpF.setText(values[j] + " C");
tempGL = String.valueOf(values[j]);
try {
dblTemp = Double.parseDouble(tempGL);
} catch (NumberFormatException e) {
e.printStackTrace();
}
} else if (rem == 1) {
CoF.setText(values[j] + " ppm");
coGL = values[j];
try {
dblCo = Double.parseDouble(coGL);
} catch (NumberFormatException e) {
e.printStackTrace();
}
} else if (rem == 2) {
humF.setText(values[j] + " %");
HumGL = values[j];
}
}
}
}
};
btAdapter=BluetoothAdapter.getDefaultAdapter(); // get Bluetooth
}
#Override
public void onTabSelected(TabLayout.Tab tab) {
// mViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
}
Pager
public class Pager extends FragmentStatePagerAdapter {
//integer to count number of tabs
int tabCount;
//Constructor to the class
public Pager(FragmentManager fm, int tabCount) {
super(fm);
//Initializing tab count
this.tabCount= tabCount;
}
//Overriding method getItem
#Override
public Fragment getItem(int position) {
//Returning the current tabs
switch (position) {
case 0:
Tab1 tab1 = new Tab1();
return tab1;
case 1:
Tab2 tab2 = new Tab2();
return tab2;
case 2:
Tab3 tab3 = new Tab3();
return tab3;
default:
return null;
}
}
//Overriden method getCount to get the number of tabs
#Override
public int getCount() {
return tabCount;
}
}
Tab1
public class OneFragment extends Fragment {
View view;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_one, container, false);
return view;
}
}
fragment_one.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="shinil.tablayout.OneFragment"
android:id="#+id/rltnvnv">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Temperature"
android:textSize="40dp"
android:textStyle="bold"
android:id="#+id/textviewtemp"
android:layout_centerInParent="true"/>
</RelativeLayout>
frag_home.xml
LinearLayout
android:id="#+id/main_layout"
android:orientation="vertical"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<!-- our toolbar -->
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
<!-- our tablayout to display tabs -->
<android.support.design.widget.TabLayout
android:id="#+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"/>
<!-- View pager to swipe views -->
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="fill_parent"/>
</LinearLayout>
The NPE occurs when I try to settext from the activity. Please help

Use below callback:
Fragment Class:
public class FragmentOne extends Fragment {
private ViewCallback mCallback;
public FragmentOne(ViewCallback mCallback) {
this.mCallback = mCallback;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_one, container, false);
mCallback.updateTextView((TextView) view.findViewById(R.id.fragmentTextView));
return view;
}
public interface ViewCallback {
void updateTextView(TextView view);
}
}
Below is the Activity class:
public class MainCallbackActivity extends Activity implements CallbackFragment.ViewCallback {
public TextView textView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_callback);
FragmentOne fragment = new FragmentOne(this);
getFragmentManager().beginTransaction().add(R.id.frameLayout, fragment).commit();
}
#Override
protected void onResume() {
super.onResume();
if (textView != null)
textView.setText("Updating Fragment TextView in Activity..!!");
}
#Override
public void updateTextView(TextView view) {
this.textView = view;
}
}
Implment that call back in your activity class..then update the textview.

Dynamically replace fragment when using tablayout and viewpager in android

I have struggled in the past couple of days to find the solution to this problem:
I have one activity which contains a tab layout and a view pager. The view pager is filled with fragments using an adapter. Tabs are created with this viewpager and are fixed. My question is how can I change the layout of tabs dynamically (for example after a button click) ?
This is xml file
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:theme="#style/ThemeOverlay.AppCompat.Dark" />
<android.support.design.widget.TabLayout
android:id="#+id/tablayout"
android:layout_width="match_parent"
android:layout_height="65dp"
android:background="#color/white"
app:tabMode="fixed"
app:tabGravity="fill"
android:theme="#style/ThemeOverlay.AppCompat.Dark" />
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
</LinearLayout>
This is Activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupToolbar();
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tablayout);
setupTabLayout(tabLayout);
}
private void setupToolbar(){
...
}
public void setupViewPager(ViewPager viewPager) {
pageAdapter = new FragmentPageAdapter(getApplicationContext(), getSupportFragmentManager());
pageAdapter.addFragment(ContentFragment.newInstance(), "Following", R.drawable.following);
pageAdapter.addFragment(ContentFragment.newInstance(), "Discover", R.drawable.flower);
pageAdapter.addFragment(ContentFragment.newInstance(), "", R.drawable.camera);
pageAdapter.addFragment(ProfileFragment.newInstance(), "Profile", R.drawable.profile);
pageAdapter.addFragment(ContentFragment.newInstance(), "Task List", R.drawable.list);
viewPager.setAdapter(pageAdapter);
}
public void setupTabLayout(TabLayout tabLayout) {
try {
tabLayout.setupWithViewPager(viewPager);
for (int i = 0; i < tabLayout.getTabCount(); i++) {
TabLayout.Tab tab = tabLayout.getTabAt(i);
tab.setCustomView(pageAdapter.getTabView(i));
}
tabLayout.requestFocus();
}
catch(Exception ex){
Log.e("errr2", ex.getMessage());
}
}
This is adapter:
public class FragmentPageAdapter extends FragmentStatePagerAdapter {
private Context mContext;
private List<Fragment> mFragments = new ArrayList<>();
private List<String> mFragmentTitles = new ArrayList<>();
private List<Integer> mFragmentIcons = new ArrayList<>();
public FragmentPageAdapter(Context context, FragmentManager fm) {
super(fm);
this.mContext = context;
}
public void addFragment(Fragment fragment, String title, int drawable) {
mFragments.add(fragment);
mFragmentTitles.add(title);
mFragmentIcons.add(drawable);
}
#Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
#Override
public int getItemPosition(Object object)
{
return POSITION_UNCHANGED;
}
#Override
public int getCount() {
return mFragments.size();
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitles.get(position);
}
public View getTabView(int position) {
View tab = LayoutInflater.from(mContext).inflate(R.layout.tabbar_view, null);
TextView tabText = (TextView) tab.findViewById(R.id.tabText);
ImageView tabImage = (ImageView) tab.findViewById(R.id.tabImage);
tabText.setText(mFragmentTitles.get(position));
tabImage.setBackgroundResource(mFragmentIcons.get(position));
if (position == 3) {
tab.setSelected(true);
}
return tab;
}
}
The normal way to replace a fragment is by calling
fragmentManager.beginTransaction().replace(placeholderId, editPrifileFragment).commit();
but what should I use for placeholderId in this case ? because in activity layout I don't have a placeholder for fragments, just a viewpager.
So how can I replace the fragment dynamically and also keep the back button functionality ?
I have searched a lot and found some hacky solutions , but I think this is a very common situation and should have a better solution.
thanks.

Your ViewPager Fragment should hold the placeholderId.
So in your Fragment (which is part of the ViewPager) you can call getChildFragmentManager() to add Fragment like you usually do.
childFragmentManager.beginTransaction().add(placeholderId, editPrifileFragment).addToBackStack(null).commit();

Tab selector not working on previous tab click when swipe on viewpager

I'm following this example..
I'm having one issue, when I swipe on ViewPager respective fragment appear but when I swipe from from left to right or right to left and select previous Tab the Tab indicator appear on new selected Tab but respective fragment not appear on ViewPager.
Please help me, where I'm getting wrong?

It was bug in support lib 23.0.0 but it is solved in 23.0.1. First of all update your suppory library using SDK manager from the extras section.
and write the following line in app gradle file.
compile 'com.android.support:appcompat-v7:23.0.1'
compile 'com.android.support:design:23.0.1'
for your reference
https://developer.android.com/topic/libraries/support-library/revisions.html
and read the Changes for Design Support library in Android Support Library, revision 23.0.1 section

This is what i use and works fine.
Adapter:
public class SCFragmentPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragments = new ArrayList<>();
private final List<String> mFragmentTitles = new ArrayList<>();
private Context mContext;
private FragmentManager mFragmentManager;
public SCFragmentPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.mFragmentManager = fm;
this.mContext = context;
}
#Override
public int getCount() {
return mFragments.size();
}
// Return the correct Fragment based on index
#Override
public Fragment getItem(int position) {
return mFragments.get(position);
}
public void addFragment(Fragment fragment, String title) {
mFragments.add(fragment);
mFragmentTitles.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
// Return the tab title to SlidingTabLayout
return mFragmentTitles.get(position);
}
public Fragment getActiveFragment(ViewPager container, int position) {
String name = makeFragmentName(container.getId(), position);
return mFragmentManager.findFragmentByTag(name);
}
private static String makeFragmentName(int viewId, int index) {
return "android:switcher:" + viewId + ":" + index;
}
}
Activity:
public class SCWelcomeActivity extends AppCompatActivity implements
SCWelcomeFragment.OnFragmentInteractionListener,
SCSyncFragment.OnFragmentInteractionListener,
SCRegisterFragment.OnFragmentInteractionListener,
SCConfirmationFragment.OnFragmentInteractionListener {
private static final String TAG = SCWelcomeActivity.class.getSimpleName();
private ViewPager viewPager = null;
private TabLayout tabLayout = null;
private Toolbar toolbar = null;
private SCFragmentPagerAdapter adapter = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scwelcome);
// Layout manager that allows the user to flip through the pages
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
// Initialize the Sliding Tab Layout
tabLayout = (TabLayout) findViewById(R.id.tablayout);
// Connect the viewPager with the sliding tab layout
tabLayout.setupWithViewPager(viewPager);
tabLayout.setTabMode(TabLayout.MODE_SCROLLABLE);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
}
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
#Override
public void onFragmentInteraction(Uri uri) {
}
private void setupViewPager(ViewPager viewPager) {
adapter = new SCFragmentPagerAdapter(getSupportFragmentManager(), SCWelcomeActivity.this);
adapter.addFragment(SCWelcomeFragment.newInstance(), getString(R.string.title_tab1));
adapter.addFragment(SCSyncFragment.newInstance(), getString(R.string.title_tab2));
adapter.addFragment(SCRegisterFragment.newInstance(), getString(R.string.title_tab3));
adapter.addFragment(SCConfirmationFragment.newInstance(), getString(R.string.title_tab4));
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(4);
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
}
Fragment Example :
public class SCWelcomeFragment extends Fragment {
private OnFragmentInteractionListener mListener;
public static SCWelcomeFragment newInstance() {
SCWelcomeFragment fragment = new SCWelcomeFragment();
return fragment;
}
public SCWelcomeFragment() {
super();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_scwelcome, container, false);
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
}
Layout:
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/coordinator"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="#+id/viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="130dp"
android:fitsSystemWindows="true"
android:gravity="bottom"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
android:layout_gravity="center"
android:theme="#style/ThemeOverlay.AppCompat.Dark"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light" />
<android.support.design.widget.TabLayout
android:id="#+id/tablayout"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>
Please try to implement the adapter as i do. Pay close attention that in mine Adapter all instances are saved in the
private final List<Fragment> mFragments = new ArrayList<>();
In your case you are always returning a new instance. So that's why a set the setOffscreenPageLimit(4). to 4 so they are kept in memory as well.

In your activity, after find Views by Id, you should "config" your ViewPager and TabLayout. Some necessary features maybe: "addOnPageChangeListener" for ViewPager and "setOnTabSelectedListener" for your TabLayout like this:
public class MainActivity extends AppCompatActivity {
private final int numOfPages = 4; //viewpager has 4 pages
private final String[] pageTitle = {"Food", "Movie", "Shopping", "Travel"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
for (int i = 0; i < numOfPages; i++) {
tabLayout.addTab(tabLayout.newTab().setText(pageTitle[i]));
}
//set gravity for tab bar
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), numOfPages);
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(onTabSelectedListener(viewPager));
}
private TabLayout.OnTabSelectedListener onTabSelectedListener(final ViewPager pager) {
return new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
pager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
};
}
I have a tutorial post about this and it works well! There is no error like yours.
Hope it help:
http://www.devexchanges.info/2015/08/android-material-design-viewpager-with.html

None of the above answers worked for me AS of end of 2016 the bug still exists in design support library 24+.
I was able to fix this issue by wrapping the tab layout inside a
co-ordinator layout

I have more shorter variant to fix this bug (android support design lib v.23.0.0):
...
//initialize views
mViewPager.setAdapter(pagerAdapter);
mTabLayout.setupWithViewPager(mViewPager);
mViewPager.clearOnPageChangeListeners();
mViewPager.addOnPageChangeListener(new WorkaroundTabLayoutOnPageChangeListener(mTabLayout));
...
And class WorkaroundTabLayoutOnPageChangeListener:
public class WorkaroundTabLayoutOnPageChangeListener extends TabLayout.TabLayoutOnPageChangeListener {
private final WeakReference<TabLayout> mTabLayoutRef;
public WorkaroundTabLayoutOnPageChangeListener(TabLayout tabLayout) {
super(tabLayout);
this.mTabLayoutRef = new WeakReference<>(tabLayout);
}
#Override
public void onPageSelected(int position) {
super.onPageSelected(position);
final TabLayout tabLayout = mTabLayoutRef.get();
if (tabLayout != null) {
final TabLayout.Tab tab = tabLayout.getTabAt(position);
if (tab != null) {
tab.select();
}
}
}
}

Are you using support library version 23.0.0. There was an issue https://code.google.com/p/android/issues/detail?id=183123 which looks similar to yours. If that is the case indeed, update your support library version to 23.0.1. This issue has been fixed.