Develop Reference

BottomNavigationView - How to avoid recreation of Fragments and reuse them

I would like to make a bottom navigation bar in my project. Every view has it's own fragment. The problem is that every time i click on the button to change the view for example from recents to favorites it creates new fragment with completely new states(e.g. scroll position, text changed whatever my fragment contains). I know that in official Android documentation there was written that bottom navigation bar should reset the task states, but i think it is too uncomfortable for users.
I would like to have kind of similar functionality like instagram that you change from feed to explore and back to feed the scroll position the image caches everything remains saved. I tried almost every way to solve this problem the only thing that worked is by setting visibility GONE and setting visibility VISIBLE according to situation but i understand that it is not RIGHT way there should be better way of doing this and i am not talking about manually saving needed instances. I followed almost every tutorial about bottom nav fragments but the interesting thing is that no one is interested to make it use without calling new every time.
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frameLayout, FirstFragment.newInstance());
fragmentTransaction.commit();
bottomNavigationView = (BottomNavigationView) findViewById(R.id.navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment fragment = null;
switch (item.getItemId()) {
case R.id.menu_dialer:
fragment = FirstFragment.newInstance();
break;
case R.id.menu_email:
fragment = SecondFragment.newInstance();
break;
case R.id.menu_map:
fragment = ThirdFragment.newInstance();
break;
}
if (fragment != null) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frameLayout, fragment);
fragmentTransaction.commit();
}
return true;
}
});
I also tried the onAttach and Deattach solutions but again no success.
VIDEO LINK : new i tried Nino Handler version it only works when i tap on the same fragment button
Maybe it is connected that i am using canary version or something wrong in my gradle dependencies?
NEW UPDATES:
public class MainActivity extends AppCompatActivity {
private TextView mTextMessage;
private static final String TAG_FRAGMENT_ONE = "fragment_one";
private static final String TAG_FRAGMENT_TWO = "fragment_two";
private FragmentManager fragmentManager;
private Fragment currentFragment;
String TAG = "babken";
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
Fragment fragment = null;
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_ONE);
if (fragment == null) {
fragment = FragmentFirst.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_ONE);
break;
case R.id.navigation_dashboard:
fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_TWO);
if (fragment == null) {
fragment = FragmentSecond.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_TWO);
break;
}
return true;
}
};
private void replaceFragment(#NonNull Fragment fragment, #NonNull String tag) {
if (!fragment.equals(currentFragment)) {
fragmentManager
.beginTransaction()
.replace(R.id.armen, fragment, tag)
.commit();
currentFragment = fragment;
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentManager = getSupportFragmentManager();
Fragment fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_ONE);
if (fragment == null) {
fragment = FragmentFirst.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_ONE);
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}
}

I had similar issue, but this code solved my problem.
public class MainActivity extends AppCompatActivity {
boolean doubleBackToExitPressedOnce = false;
final Fragment fragment1 = new HomeFragment();
final Fragment fragment2 = new DashboardFragment();
final Fragment fragment3 = new NotificationsFragment();
final FragmentManager fm = getSupportFragmentManager();
Fragment active = fragment1;
BottomNavigationView navigation;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
setFragment(fragment1, "1", 0);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
setFragment(fragment1, "1", 0);
return true;
case R.id.navigation_dashboard:
setFragment(fragment2, "2", 1);
return true;
case R.id.navigation_notifications:
setFragment(fragment3, "3", 2);
return true;
}
return false;
}
};
public void setFragment(Fragment fragment, String tag, int position) {
if (fragment.isAdded()) {
fm.beginTransaction().hide(active).show(fragment).commit();
} else {
fm.beginTransaction().add(R.id.main_container, fragment, tag).commit();
}
navigation.getMenu().getItem(position).setChecked(true);
active = fragment;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
startActivity(new Intent(MainActivity.this, SettingsActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onBackPressed() {
if (active == fragment1) {
if (doubleBackToExitPressedOnce) {
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();
} else {
setFragment(fragment1, "1", 0);
}
}
}

I wouldn't keep the fragment instances globally.
Instead add a tag to the fragment when creating them
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.container, new PlaceholderFragment(), TAG_PLACEHOLDER)
.commit();
Then you can always retrieve it like this:
Fragment fragment = getSupportFragmentManager().findFragmentByTag(TAG_PLACEHOLDER);
if (fragment == null) {
fragment = new PlaceholderFragment();
}
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.container, fragment, TAG_PLACEHOLDER)
.commit();
UPDATE: I updated my answer and to provide a complete solution:
private static final String TAG_FRAGMENT_ONE = "fragment_one";
private static final String TAG_FRAGMENT_TWO = "fragment_two";
private static final String TAG_FRAGMENT_THREE = "fragment_three";
private FragmentManager fragmentManager;
private Fragment currentFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// instantiate the fragment manager
fragmentManager = getSupportFragmentManager();
Fragment fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_ONE);
if (fragment == null) {
fragment = FirstFragment.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_ONE);
bottomNavigationView = (BottomNavigationView) findViewById(R.id.navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment fragment = null;
switch (item.getItemId()) {
case R.id.menu_dialer:
// I'm aware that this code can be optimized by a method which accepts a class definition and returns the proper fragment
Fragment fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_ONE);
if (fragment == null) {
fragment = FirstFragment.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_ONE);
break;
case R.id.menu_email:
Fragment fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_TWO);
if (fragment == null) {
fragment = SecondFragment.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_TWO);
break;
case R.id.menu_map:
Fragment fragment = fragmentManager.findFragmentByTag(TAG_FRAGMENT_THREE);
if (fragment == null) {
fragment = ThirdFragment.newInstance();
}
replaceFragment(fragment, TAG_FRAGMENT_THREE);
break;
}
return true;
}
});
}
private void replaceFragment(#NonNull Fragment fragment, #NonNull String tag) {
if (!fragment.equals(currentFragment)) {
fragmentManager
.beginTransaction()
.replace(R.id.frameLayout, fragment, tag)
.commit();
currentFragment = fragment;
}
}
ADDITIONAL INFO: If you want to be sure that the fragment states don't change and if you also want to be able to swipe the fragments you should consider using a ViewPager with a FragmentStatePagerAdapter and change the current fragment in the adapter with every click event

I wrote a Kotlin Extension function for FragmentManager class
fun FragmentManager.switch(containerId: Int, newFrag: Fragment, tag: String) {
var current = findFragmentByTag(tag)
beginTransaction()
.apply {
//Hide the current fragment
primaryNavigationFragment?.let { hide(it) }
//Check if current fragment exists in fragmentManager
if (current == null) {
current = newFrag
add(containerId, current!!, tag)
} else {
show(current!!)
}
}
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.setPrimaryNavigationFragment(current)
.setReorderingAllowed(true)
.commitNowAllowingStateLoss()
}
This can be called by supportFragmentManager.swtich(R.id.container,newFrag,newFrag.TAG) from onNavigationItemSelected

All the previous answers are using fragmentTransaction.replace(...). This will replace the current fragment by destroying it (which is causing the problem). Therefore all those solutions won't actually work.
This is the closest thing I could get to as a solution for this problem:
private void selectContentFragment(Fragment fragmentToSelect)
{
FragmentTransaction fragmentTransaction = this.getSupportFragmentManager().beginTransaction();
if (this.getSupportFragmentManager().getFragments().contains(fragmentToSelect)) {
// Iterate through all cached fragments.
for (Fragment cachedFragment : this.getSupportFragmentManager().getFragments()) {
if (cachedFragment != fragmentToSelect) {
// Hide the fragments that are not the one being selected.
fragmentTransaction.hide(cachedFragment);
}
}
// Show the fragment that we want to be selected.
fragmentTransaction.show(fragmentToSelect);
} else {
// The fragment to be selected does not (yet) exist in the fragment manager, add it.
fragmentTransaction.add(R.id.fragment_container, fragmentToSelect);
}
fragmentTransaction.commit();
}
To make this work, you should keep track of the fragments in an array (or in separate variables) in your Activity. I for reference pre-instantiated all fragments in a SparseArray.

You can use attach() and detach() methods:
private FirstFragment firstFragment = FirstFragment.newInstance();
private SecondFragment secondFragment= SecondFragment.newInstance();
private ThirdFragment thirdFragment = ThirdFragment.newInstance();
navigation.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_dialer:
changeFragment(firstFragment, "firstFragment");
return true;
case R.id.menu_email:
changeFragment(secondFragment, "secondFragment");
return true;
case R.id.menu_map:
changeFragment(thirdFragment, "thirdFragment");
return true;
}
return false;
}
});
public void changeFragment(Fragment fragment, String tagFragmentName) {
FragmentManager mFragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();
Fragment currentFragment = mFragmentManager.getPrimaryNavigationFragment();
if (currentFragment != null) {
fragmentTransaction.detach(currentFragment);
}
Fragment fragmentTemp = mFragmentManager.findFragmentByTag(tagFragmentName);
if (fragmentTemp == null) {
fragmentTemp = fragment;
fragmentTransaction.add(R.id.content, fragmentTemp, tagFragmentName);
} else {
fragmentTransaction.attach(fragmentTemp);
}
fragmentTransaction.setPrimaryNavigationFragment(fragmentTemp);
fragmentTransaction.setReorderingAllowed(true);
fragmentTransaction.commitNowAllowingStateLoss();
}

So I have been researching for this for a long time and figured out that there is no way to reuse fragment with AUTOMATICALLY saved states you have to save your needed states manually then retrieve them whenever a new fragment is created but what about scroll position it is too hard and even in some cases it is impossible to save scroll view position state(e.g. recycler view). So i used the concept called VISIBILITY when i click on the button that fragment becomes visible others hide automatically.

How about that.
You declare the fragments in the class.
Fragment firstFragment,secondFragment,thirdFragment;
then in the switch-case you can code as that:
switch (item.getItemId()) {
case R.id.menu_dialer:
if(firstFragment != null) {
fragment = firstFragment;
}else{
fragment = FirstFragment.newInstance();
}
break;
case R.id.menu_email:
// the same ...
break;
case R.id.menu_map:
//the same ...
break;
}

Thomas's answer nearly helped me but had an issue that whenever I open new fragments the very first time, they overlapped but doesn't get overlapped once I open them again by pressing the menu buttons.
So I modified his code and obtained the solution using the following code:
private fun selectContentFragment(fragmentToSelect: Fragment) {
val fragmentTransaction = fragmentManager?.beginTransaction()
if (fragmentManager?.fragments?.contains(fragmentToSelect)!!) {
// Show the fragment that we want to be selected.
fragmentTransaction?.show(fragmentToSelect)
} else {
// The fragment to be selected does not (yet) exist in the fragment manager, add it.
fragmentTransaction?.add(R.id.container, fragmentToSelect)
}
// Iterate through all cached fragments.
for (cachedFragment in fragmentManager?.fragments!!) {
if (cachedFragment !== fragmentToSelect) {
// Hide the fragments that are not the one being selected.
// Uncomment following line and change the name of the fragment if your host isn't an activity and a fragment otherwise whole view will get hidden.
// if (!cachedFragment.toString().contains("HomeContainerFragment"))
fragmentTransaction?.hide(cachedFragment)
}
}
fragmentTransaction?.commit()
}
Make sure you're not passing the fragment's new instance every time.
This will work:
selectContentFragment(
when (item.itemId) {
R.id.home -> frag1
R.id.photoGallery -> frag2
else -> Home()
}
)
where frag1 and frag2 are global variables defined as:
val frag1 = Home()
val frag2 = PhotoGallery()
This will not work:
selectContentFragment(
when (item.itemId) {
R.id.home -> Home()
R.id.photoGallery -> PhotoGallery()
else -> Home()
}
)
It wasted my several hours. Hope it helps others!

**This code very helpful for me. Just like youtube. **
private Deque<Integer> fragmentIds = new ArrayDeque<>(3);
int itemId;
private HomeFragment homeFragment = new HomeFragment();
private FavouriteFragment favouriteFragment = new FavouriteFragment();
private NearmeFragment nearmeFragment = new NearmeFragment();
BottomNavigationView bottomNavigationView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentIds.push(R.id.action_home);
showTabWithoutAddingToBackStack(homeFragment);
bottomNavigationView = findViewById(R.id.bottom_navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(onNavigationItemClicked);
}
private BottomNavigationView.OnNavigationItemSelectedListener onNavigationItemClicked = new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
itemId= item.getItemId();
if(fragmentIds.contains(itemId)){
fragmentIds.remove(itemId);
}
fragmentIds.push(itemId);
showTabWithoutAddingToBackStack(getFragment(item.getItemId()));
return true;
}
};
private Fragment getFragment(int fragmentId) {
switch (fragmentId) {
case R.id.action_home:
return homeFragment;
case R.id.action_favorites:
return favouriteFragment;
case R.id.action_nearme:
return nearmeFragment;
}
return homeFragment;
}
private void showTabWithoutAddingToBackStack(Fragment fragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragment, fragment.getClass().getSimpleName()).commit();
}
#Override
public void onBackPressed() {
if(fragmentIds.getLast() != R.id.action_home){
fragmentIds.addLast(R.id.action_home);
}
fragmentIds.pop();
bottomNavigationView.getMenu().getItem(fragmentIds.size()-1).setChecked(true);
if (!fragmentIds.isEmpty()) {
showTabWithoutAddingToBackStack(getFragment(fragmentIds.peek()));
} else {
finish();
}
}

For Kotlin user may help this code :
First create a FragmentManager extension class
fun FragmentManager.replace(containerId: Int, fragment: Fragment, tag: String) {
var current = findFragmentByTag(tag)
beginTransaction()
.apply {
//Hide the current fragment
primaryNavigationFragment?.let { hide(it) }
//Check if current fragment exists in fragmentManager
if (current == null) {
current = fragment
add(containerId, current!!, tag)
} else {
show(current!!)
}
}
.setTransition(FragmentTransaction.TRANSIT_ENTER_MASK)
.setPrimaryNavigationFragment(current)
.setReorderingAllowed(true)
.commitNowAllowingStateLoss()
}
Now simply call it on your
onNavigationItemSelected
supportFragmentManager.replace(R.id.fragment_id,YourFragmentClass,yourFragment.TAG)

I had the same issue but I resolved it by creating multiple fragment hosts then I added fragments in fragmentHost. And when bottom nav itemSelected I just make the required host fragment visible and other host fragmentsHost to visibility gone.
This method may be wrong but it works perfectly for me.
And we don't have to manually handle the states of fragment only we need to handle backpress of activity.
But this method does not pause the fragments.
And I don't know how to handle the pauses and resumes of fragments so please reply to me.
Maybe This will help you.
This is my fragmentHosts Home Activity:
<androidx.fragment.app.FragmentContainerView
android:id="#+id/homeFragmentHost"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottom_NavBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:visibility="gone"/>
<androidx.fragment.app.FragmentContainerView
android:id="#+id/libraryFragmentHost"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottom_NavBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:visibility="gone"/>
<androidx.fragment.app.FragmentContainerView
android:id="#+id/myStuffFragmentHost"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottom_NavBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:visibility="gone"/>
<androidx.fragment.app.FragmentContainerView
android:id="#+id/moreFragmentHost"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottom_NavBar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:visibility="gone"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/bottom_NavBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:menu="#menu/app_bottom_nav_menu"
tools:ignore="BottomAppBar" />
Home Activity onCreate:
supportFragmentManager.beginTransaction().replace(R.id.homeFragmentHost,HomeFragment()).commitNow()
supportFragmentManager.beginTransaction().replace(R.id.libraryFragmentHost,LibraryFragment()).commitNow()
supportFragmentManager.beginTransaction().replace(R.id.myStuffFragmentHost,MyStuffFragment()).commitNow()
supportFragmentManager.beginTransaction().replace(R.id.moreFragmentHost,MoreFragment()).commitNow()
homeFragmentHost.visibility = View.VISIBLE
Bottom nav Item Selected listener
override fun onNavigationItemSelected(item: MenuItem): Boolean {
return when(item.itemId){
R.id.homeFragment -> loadFragmentHost(homeFragmentHost)
R.id.libraryFragment -> loadFragmentHost(libraryFragmentHost)
R.id.myStuffFragment -> loadFragmentHost(myStuffFragmentHost)
R.id.moreFragment -> loadFragmentHost(moreFragmentHost)
else -> false
}
loadFragmentHost function
private fun loadFragmentHost(view:FragmentContainerView): Boolean {
val list = arrayListOf(homeFragmentHost,libraryFragmentHost,myStuffFragmentHost,moreFragmentHost)
list.remove(view)
view.visibility = View.VISIBLE
list.forEach {
it.visibility = View.GONE
}
return true
}

public class MainActivity extends AppCompatActivity {
boolean doubleBackToExitPressedOnce = false;
final Fragment fragment1 = new HomeFragment();
final Fragment fragment2 = new DashboardFragment();
final Fragment fragment3 = new NotificationsFragment();
final FragmentManager fm = getSupportFragmentManager();
Fragment active = fragment1;
BottomNavigationView navigation;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
setFragment(fragment1, "1", 0);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()) {
case R.id.navigation_home:
setFragment(fragment1, "1", 0);
return true;
case R.id.navigation_dashboard:
setFragment(fragment2, "2", 1);
return true;
case R.id.navigation_notifications:
setFragment(fragment3, "3", 2);
return true;
}
return false;
}
};
public void setFragment(Fragment fragment, String tag, int position) {
if (fragment.isAdded()) {
fm.beginTransaction().hide(active).show(fragment).commit();
} else {
fm.beginTransaction().add(R.id.main_container, fragment, tag).commit();
}
navigation.getMenu().getItem(position).setChecked(true);
active = fragment;
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
startActivity(new Intent(MainActivity.this, SettingsActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onBackPressed() {
if (active == fragment1) {
if (doubleBackToExitPressedOnce) {
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();
} else {
setFragment(fragment1, "1", 0);
}
}
}
Maintain Bottom sheet fragment Reusable
BackPress Maintain
double back press to exit

public class MainActivity extends AppCompatActivity {
BottomNavigationView bottomNavigationView;
Toaster toaster;
private final Fragment androidFragment = new AndroidFragment();
private final Fragment settingsFragment = new SettingsFragment();
Fragment active;
String TAG = MainActivity.class.getSimpleName();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toaster = new Toaster(this);
bottomNavigationView = findViewById(R.id.bottom_navigation);
renderFragment(androidFragment, "android");
active = androidFragment;
bottomNavigationView.setOnItemSelectedListener(
item -> {
Log.e(TAG, "onCreate: " + active );
if(item.getItemId() == R.id.action_android){
renderFragment(androidFragment, "android");
return true;
}
else if(item.getItemId() == R.id.action_settings){
renderFragment(settingsFragment, "settings");
return true;
}
return false;
}
);
}
private void renderFragment(Fragment fragment, String tag){
FragmentManager fragmentManager = getSupportFragmentManager();
if(fragment.isAdded()){
fragmentManager.beginTransaction().hide(active).show(fragment)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN).commit();
}
else {
if(active != null){
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container_view, fragment, tag)
.hide(active)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN).commit();
}
else {
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container_view, fragment, tag)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN).commit();
}
}
active = fragment;
}
}
This worked for me Guys.

Create the three fragments as members of the class and reuse them.
public class MainActivity extends AppCompatActivity {
private final Fragment mFirstFragment = new FirstFragment();
private final Fragment mSecondFragment = new SecondFragment();
private final Fragment mThirdFragment = new ThirdFragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
......
......
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frameLayout, mFirstFragment);
fragmentTransaction.commit();
bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
if (bottomNavigationView.getSelectedItemId() != item.getItemId()) {
switch (item.getItemId()) {
R.id.menu_dialer:
replaceFragment(mFirstFragment);
break;
case R.id.menu_email:
replaceFragment(mSecondFragment);
break;
case R.id.menu_map:
replaceFragment(mThirdFragment);
break;
}
}
return true;
}
});
}
private void replaceFragment(Fragment fragment) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.frameLayout, fragment);
fragmentTransaction.commit();
}
}

BottomNavigationView Back button not working properly

When is press back button my fragment is changing to home page, but bottom icon is not changing. I posted my all code here. If i select more then two navigation button from bottom navigation view items then when i press back button it'll redirect to last selected button item.
But now what happening is that suppose i'm on the last item say 'Notification' [as you can see in screenshot], now when i press back button it'll directly take me to 'Home' button, but what i want is that it should take me first to 'Search' button item and then to 'Home' not directly to 'home'.
How can i achieve this??
Here is the layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:design="http://schemas.android.com/apk/res-auto"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.segunfamisa.sample.bottomnav.MainActivity">
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#f1f1f1">
</FrameLayout>
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="start"
design:menu="#menu/bottom_nav_items" />
</LinearLayout>
Here is the activity:
public class MainActivity extends AppCompatActivity {
private static final String SELECTED_ITEM = "arg_selected_item";
private BottomNavigationView mBottomNav;
private int mSelectedItem;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mBottomNav = (BottomNavigationView) findViewById(R.id.navigation);
mBottomNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
selectFragment(item);
return true;
}
});
MenuItem selectedItem;
if (savedInstanceState != null) {
mSelectedItem = savedInstanceState.getInt(SELECTED_ITEM, 0);
selectedItem = mBottomNav.getMenu().findItem(mSelectedItem);
} else
{
selectedItem = mBottomNav.getMenu().getItem(0);
}
selectFragment(selectedItem);
}
#Override
protected void onSaveInstanceState(Bundle outState) {
outState.putInt(SELECTED_ITEM, mSelectedItem);
super.onSaveInstanceState(outState);
}
#Override
public void onBackPressed() {
MenuItem homeItem = mBottomNav.getMenu().getItem(0);
if (mSelectedItem != homeItem.getItemId()) {
// select home item
// homeItem.setCheckable(true);
Log.d("backpressids","**** "+mSelectedItem);
selectFragment(homeItem);
} else {
super.onBackPressed();
}
}
private void selectFragment(MenuItem item) {
Fragment frag = null;
item.setCheckable(true);
// init corresponding fragment
switch (item.getItemId()) {
case R.id.menu_home:
TabFragmentOne fragmentone = new TabFragmentOne();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.container, fragmentone);
ft.commit();
break;
case R.id.menu_notifications:
TabFragmentThree fragmentone_Three = new TabFragmentThree();
FragmentTransaction ft_three = getSupportFragmentManager().beginTransaction();
ft_three.replace(R.id.container, fragmentone_Three);
ft_three.commit();
break;
case R.id.menu_search:
TabFragmentTwo tabFragmentTwo = new TabFragmentTwo();
FragmentTransaction ft_two = getSupportFragmentManager().beginTransaction();
ft_two.replace(R.id.container,tabFragmentTwo);
ft_two.commit();
break;
}
// update selected item
mSelectedItem = item.getItemId();
updateToolbarText(item.getTitle());
if (frag != null) {
TabFragmentOne fragmentone = new TabFragmentOne();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.container, fragmentone);
ft.commit();
}
}
private void updateToolbarText(CharSequence text) {
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setTitle(text);
}
}
}
please help me any one.....

You can use BottomNavigationView.setSelectedItemId(ITEM_ID) to select desired MenuItem:
In onBackPressed(), use mBottomNav.setSelectedItemId(R.id.menu_home) or mBottomNav.setSelectedItemId(homeItem.getItemId()).
Update onBackPressed() method as below:
#Override
public void onBackPressed() {
MenuItem homeItem = mBottomNav.getMenu().getItem(0);
if (mSelectedItem != homeItem.getItemId()) {
selectFragment(homeItem);
// Select home item
mBottomNav.setSelectedItemId(homeItem.getItemId());
} else {
super.onBackPressed();
}
}
Hope this will help~

If you want to go back to all the items on the stack (not only home), try the following code:
FragmentTransaction transaction = mFragmentManager.beginTransaction();
transaction.replace(R.id.container, fragment);
if (!isFirstFragment) {
transaction.addToBackStack(null);
}
transaction.commit();
Then, add this code onBackPressed:
#Override
public void onBackPressed() {
int count = getSupportFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
} else {
int index = ((getSupportFragmentManager().getBackStackEntryCount()) -1);
getSupportFragmentManager().popBackStack();
FragmentManager.BackStackEntry backEntry = getSupportFragmentManager().getBackStackEntryAt(index);
int stackId = backEntry.getId();
mBottomNavigationView.getMenu().getItem(stackId).setChecked(true);
}
}

I want to share my solution. I just added a counter checkBackSteck
binding.bnb - this is buttonNavigationView
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private val checkBackStack = ArrayList<Int>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
checkBackStack.add(0)
val mainFragment = MainFragment()
val libraryFragment = LibraryFragment()
val menuFragment = MenuFragment()
val statisticFragment = StatisticFragment()
val profileFragment = ProfileFragment()
binding.apply {
bnb.setOnItemSelectedListener {
when(it.itemId){
R.id.bnb_home -> {
supportFragmentManager.beginTransaction()
.setCustomAnimations(R.anim.fragment_in, R.anim.fragment_out)
.replace(R.id.fragmentContainerView, mainFragment)
.addToBackStack(null)
.commit()
checkBackStack.add(0)
true
}
R.id.bnb_library -> {
supportFragmentManager.beginTransaction()
.setCustomAnimations(R.anim.fragment_in, R.anim.fragment_out)
.replace(R.id.fragmentContainerView, libraryFragment)
.addToBackStack(null)
.commit()
checkBackStack.add(1)
true
}
R.id.bnb_menu ->{
supportFragmentManager.beginTransaction()
.setCustomAnimations(R.anim.fragment_in, R.anim.fragment_out)
.replace(R.id.fragmentContainerView, menuFragment)
.addToBackStack(null)
.commit()
checkBackStack.add(2)
true
}
R.id.bnb_statistic -> {
supportFragmentManager.beginTransaction()
.setCustomAnimations(R.anim.fragment_in, R.anim.fragment_out)
.replace(R.id.fragmentContainerView, statisticFragment)
.addToBackStack(null)
.commit()
checkBackStack.add(3)
true
}
R.id.bnb_profile -> {
supportFragmentManager.beginTransaction()
.setCustomAnimations(R.anim.fragment_in, R.anim.fragment_out)
.replace(R.id.fragmentContainerView, profileFragment)
.addToBackStack(null)
.commit()
checkBackStack.add(4)
true
}
else -> false
}
}
}
}
override fun onBackPressed() {
if (checkBackStack.size == 1){
super.onBackPressed()
} else {
supportFragmentManager.popBackStack()
binding.bnb.menu.getItem(checkBackStack.get(checkBackStack.count() - 2)).isChecked = true
checkBackStack.removeAt(checkBackStack.count() - 1)
}
}
}

On Back Pressed in Android Fragments

I have One Activity
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Activities.Dashboard.MainActivity">
<FrameLayout
android:id="#+id/main_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
</RelativeLayout>
And I have 10 Fragments i show them in main_container Frame Layout
How can i write code to go back to last fragment
This is my Activity code :
public class MainActivity extends AppCompatActivity{
#Override
protected void onCreate(Bundle savedInstanceState) {
fragmentManager = getSupportFragmentManager();
fragment = new HomeFragment();
final FragmentTransaction transaction =
fragmentManager.beginTransaction();
transaction.replace(R.id.main_container, fragment).commit();
}
}
In Home Fragment :
public class HomeFragment extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.bottom_bar_home, container, false);
fragmentManager = getActivity().getSupportFragmentManager();
// ...... etc
return view;
}
}
and all fragments the same code with another data.

It worked to me by this code :
I put in Base Activity :
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
And every call for fragment i put AddtoBackStack(null) :
fragment = new yourFragment();
final FragmentTransaction transaction = fragmentManager.beginTransaction();
transaction.replace(R.id.main_container,
fragment).addToBackStack(null).commit();

Try this:
if( getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
return;
}
super.onBackPressed();
You should read this related question as well:

Doesn't re-load fragments ViewPager

I have a problem with fragments and the ViewPager, my ViewPager is composed of five tabs, each one is a Fragment.
On the first load I don't have problem with these load, but when I open another fragment (Ahead the main), and go back to the main, the fragments where I was, and those, has been removed (invisible).
For fix that I need to "get away" for two pages before the central page loads.
Everything is only in API 21 (5.0.1), with Android Studio.
MainActivity.java:
public class MainActivity extends FragmentActivity {
private MainActivityFragment frag_MainActivity;
private CreditsFragment frag_Credits;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
frag_MainActivity = new MainActivityFragment(this);
frag_Credits = new CreditsFragment();
switchFrag("main");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_home) {
switchFrag("main");
return true;
} else if (id == R.id.action_credits) {
switchFrag("credits");
return true;
}
return super.onOptionsItemSelected(item);
}
public void switchFrag(String view){
Fragment frag = new Fragment();
if(view.equals("main")){
getActionBar().show();
frag = new MainActivityFragment(this);
} else if(view.equals("credits")){
getActionBar().hide();
frag = new CreditsFragment();
}
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, frag)
.addToBackStack(null).commit();
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
switchFrag("main");
return true;
}
return super.onKeyUp(keyCode, event);
}
public void closeApp() {
finish();
System.exit(0);
}
And the XML (activity_main.xml):
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/frame_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>
</RelativeLayout>
MainActivityFragment.java:
public class MainActivityFragment extends Fragment implements ActionBar.TabListener {
private ViewPager viewPager;
private MyAdapter mAdapter;
private ActionBar actionBar;
private String[] tabs = { "Lun", "Mar", "Merc", "Gio", "Ven"};
MainActivity main;
public MainActivityFragment(MainActivity instance) {
main = instance;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
viewPager = (ViewPager) main.findViewById(R.id.pager);
actionBar = main.getActionBar();
mAdapter = new MyAdapter(main.getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
if(actionBar.getTabCount() == 0){
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
}
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_main, container, false);
}
#Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {}
#Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {}
XML (fragment_settings.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=".MainActivityFragment">
<android.support.v4.view.ViewPager
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
If the Adapter is needed, here it is:
public class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return 5;
}
#Override
public android.support.v4.app.Fragment getItem(int position) {
switch(position){
case 0:
return new LunFragment();
case 1:
return new MarFragment();
case 2:
return new MerFragment();
case 3:
return new GioFragment();
case 4:
return new VenFragment();
}
return null;
}
}

Replace mAdapter = new MyAdapter(main.getSupportFragmentManager()); with mAdapter = new MyAdapter(main.getChildFragmentManager());. You need to create the fragments as inner fragments of your MainActivityFragment.

No view found for fragment

A number of people have queried on fixing fragments but my confusion may be based on the evolving nature of fragment APIs or I simply misunderstand them. I am pruning this code to show an attempt to how I am trying to use fragments to have multiple layouts on a big screen or a single layout on a smaller screen that goes to other layouts via buttons. The essential portion of my log is
12-03 21:17:29.711: E/FragmentManager(13440): No view found for id 0x7f090046
(com.ruleagents.rpgsheet:id/main_fragment) for fragment MainFragment{4053b368 #0 ....
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.ruleagents.rpgsheet/com.ruleagents.rpgsheet.SheetActivity}:
java.lang.IllegalArgumentException: No view found for id 0x7f090046
(com.ruleagents.rpgsheet:id/main_fragment) for fragment MainFragment{4053b368 #0 id=0x7f090046}
12-03 21:17:29.721: E/AndroidRuntime(13440): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1821)
My activity_main.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" >
<FrameLayout
android:id="#+id/container"
android:layout_width="0px"
android:layout_height="match_parent"
tools:context="com.ruleagents.rpgsheet.MainActivity"
tools:ignore="MergeRootFrame" />
</RelativeLayout>
attribute_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="#+id/linear1">
... nested layout that works independently
</LinearLayout>
main_fragment.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" android:orientation="vertical"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:id="#+id/main_fragment" >
<LinearLayout
...
</LinearLayout>
<LinearLayout
...
</LinearLayout>
<LinearLayout
...
</RelativeLayout>
With my MainActivity.java as:
package com.ruleagents.rpgsheet;
import java.io.BufferedReader;
...
public class MainActivity extends FragmentActivity { //ActionBarActivity {
SectionsPagerAdapter mSectionsPagerAdapter;
FragmentManager fragmentManager; // = getFragmentManager();
AttributeFragment af = new AttributeFragment();
MainFragment mf = new MainFragment();
String characterClass, level, att1, att2, att3;
//other local variables
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_fragment);
Configuration config = getResources().getConfiguration();
af.setArguments(getIntent().getExtras());
mf.setArguments(getIntent().getExtras());
fragmentManager = getSupportFragmentManager();
if (config.orientation == Configuration.ORIENTATION_LANDSCAPE) {
fragmentManager.beginTransaction().add(R.id.main_fragment, mf).commit();
fragmentManager.beginTransaction().add(R.layout.attribute_fragment, af).commit();
}else{
System.err.println("AAA creating portrait view");
fragmentManager.beginTransaction().add(R.id.container, mf).commit();
}
}
public void onMainButton(View view) {
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.main_fragment, mf);
ft.addToBackStack(null);
ft.commit();
}
public void onAttributesButton(View view) {
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.layout.attribute_fragment, af);
ft.addToBackStack(null);
ft.commit();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
// Unused PlaceholderFragment method ...
// unused FragmentPageAdapter ...
// local methods
}
My MainFragment.java
package com.ruleagents.rpgsheet;
... imports
public class MainFragment extends Fragment {
public MainFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
return inflater.inflate(R.layout.main_fragment, container, false);
}
#Override
public void onPause() {
super.onPause();
}
}
My SheetActivity.java
package com.ruleagents.rpgsheet;
... imports
public class SheetActivity extends ActionBarActivity {
// Local variables...
FragmentManager fragmentManager; // = getFragmentManager();
AttributeFragment af = new AttributeFragment();
MainFragment mf = new MainFragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
System.err.println("AAA in onCreate of SheetActivity");
Configuration config = getResources().getConfiguration();
//FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
//setContentView(R.layout.activity_main);
//setContentView(R.layout.whole_sheet);
System.err.println("AAA got config");
af.setArguments(getIntent().getExtras());
mf.setArguments(getIntent().getExtras());
fragmentManager = getSupportFragmentManager();
System.err.println("AAA got frag manager");
if (config.orientation == Configuration.ORIENTATION_LANDSCAPE) {
fragmentManager.beginTransaction().add(R.id.container, mf).commit();
fragmentManager.beginTransaction().add(R.id.container, af).commit();
}else{
System.err.println("AAA creating portrait view");
fragmentManager.beginTransaction().add(R.id.main_fragment, mf).commit();
}
}
public void onMainButton(View view) {
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.id.main_fragment, mf);
ft.addToBackStack(null);
ft.commit();
}
public void onSkillsButton(View view) {
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();
ft.addToBackStack(null);
ft.commit();
}
public void onAttributesButton(View view) {
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();
ft.replace(R.layout.attribute_fragment, af);
ft.addToBackStack(null);
ft.commit();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
// Local methods ...
// Unused PlaceholderFragment ...
// Unused SectionsPagerAdapter
}

When you are adding a fragment, the add() method needs the container id be in your activity layout that the fragment will go into. So, your error is because there is no main_fragment id in your activity_main.xml.