Develop Reference

Adding back button to fragment

I have a bottom navigation bar that contains 4 fragments and when a tab is selected a new instance of that fragment is loaded.
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
Fragment fragment = null;
switch (item.getItemId()) {
case R.id.navigation_home:
fragment = HomeFragment.newInstance();
break;
case R.id.navigation_cards:
fragment = CardsFragment.newInstance();
break;
case R.id.navigation_deals:
fragment = DealsFragment.newInstance();
break;
case R.id.navigation_settings:
fragment = SettingsFragment.newInstance();
break;
}
if (fragment != null) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.content, fragment);
fragmentTransaction.commit();
}
return true;
}
};
Now in my HomeFragment there is a RecyclerView that On Item Select it opens a new Fragment:
myViewHolder.cardView.setOnClickListener(view -> {
System.out.println("clicked");
Fragment fragment = new TargetDetailsFragment();
FragmentTransaction ft = ((AppCompatActivity) context).getSupportFragmentManager()
.beginTransaction();
ft.replace(R.id.content, fragment).addToBackStack(null);
ft.commit();
});
I want to add a back button to the TargetDetails Fragments that takes you back to the home page when selected and I attempted doing that by implementing OnBackStackChangedListener in the Main activity
#Override
public void onBackStackChanged() {
shouldDisplayHomeUp();
}
public void shouldDisplayHomeUp(){
//Enable Up button only if there are entries in the back stack
boolean canback = getSupportFragmentManager().getBackStackEntryCount()>0;
getSupportActionBar().setDisplayHomeAsUpEnabled(canback);
}
#Override
public boolean onSupportNavigateUp() {
//This method is called when the up button is pressed. Just the pop back stack.
getSupportFragmentManager().popBackStack();
return true;
}
}
but the problem is when I click on it its reloads the HomeFragment Again but I simply want it to go back to the saved instance of that Fragment

Here is my code that I have used for the ViewPager, the idea is to see if the current page number is 0 than to proceed super.onBackPressed(); otherwise go to the previous fragment:
#Override
public void onBackPressed() {
if(vpPager.getCurrentItem()!=0) {
vpPager.setCurrentItem(vpPager.getCurrentItem()-1, true);
} else {
super.onBackPressed();
}
}

By adding below code in your Activity.
The fragment back stack can be managed.
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
//additional code
} else {
getFragmentManager().popBackStack();
}
}

Hello #Bolu Okunaiya i think you should try this it will help you to manage backstack to desired fragment without loading same fragment again.
For Stop loading previous fragment you should use "add" instead of "replace" with your FragmentTransaction

Inside your MainActivity
#Override
public void onBackStackChanged() {
//shouldDisplayHomeUp();
Fragment currentFragment = getActivity().getFragmentManager()
.findFragmentById(R.id.fragment_container);
if (currentFragment instanceof TargetDetails) {
Log.v(TAG, "your current fragment is TargetDetails");
popBackStackImmediate(); //<<<< immediate parent fragment will open,which is your HomeFragement
}
}
To use popBackStackImmediate() you need to *replace FragmentA with FragmentB and use addToBackstack() before commit().

addToBackStack not working with onBackPressed method

I have created a tabbed activity inside a navigation drawer activity. I have linked the lists inside the navigation drawer with individual fragments. I also used the command ft.addToBackStack(null) before ft.commit(). It was perfectly fine and I was able to use it to close the fragments inside the navigation drawer. now I have created webviews inside the fragments of the tabbed activity (home page). I added the onBackPressed to go back inside the webview and now the addToBackStack method stopped working.
For the navigation drawer fragments,
private void dispaySelectedScreen(int id) {
Fragment fragment = null;
switch (id) {
case R.id.fragment1:
fragment = new Fragment1();
break;
case R.id.fragment2:
fragment = new Fragment2();
break;
case R.id.fragment3:
fragment = new Fragment3();
break;
case R.id.fragment4:
fragment = new fragment4();
break;
}
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_main, fragment);
ft.addToBackStack(null);
ft.commit();
}
onBackPressed Method
#Override
public void onBackPressed() {
if (hWebView.canGoBack()) {
hWebView.goBack();
} else if (!getFragmentManager().popBackStackImmediate())
if (sWebView.canGoBack()) {
sWebView.goBack();
} else if (!getFragmentManager().popBackStackImmediate())
if (dWebView.canGoBack()) {
dWebView.goBack();
} else if (!getFragmentManager().popBackStackImmediate());
}
Please help me out!!!

try this code: override onBackPressed() in your tabbed activity (home page).
#Override
public void onBackPressed() {
FragmentManager fm = getSupportFragmentManager();
if (hWebView.canGoBack()) {
hWebView.goBack();
} else if (!getFragmentManager().popBackStackImmediate())
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
} else {
super.onBackPressed();
}
}

Single Instance fragment back stack managerment

I am working on single activity based principle. But I am facing a problem when the same fragment is open again because its again adds in fragment backstack entry. So backstack contains multiple backstack entries for same fragment. This creates problem on back navigation.
Example :- A|B|C|D|A|C|A
So when I press back key same fragment is displaying multiple times. Is there any way to reuse the existing fragment from backstack entry.
I am managing my backstack like this :-
fragmentManager.beginTransaction().setCustomAnimations(R.anim.fragment_enter,
R.anim.fragment_exit, R.anim.pop_enter, R.anim.pop_exit).
add(R.id.frameLayout, fragment).addToBackStack(backStateName).commit();
Any kind of help will be appreciated.

private void createOrResumeFragment(String fragmentTag){
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction ft = manager.beginTransaction();
boolean fragmentPopped = manager.popBackStackImmediate (fragmentTag, 0);
Fragment fragment = manager.findFragmentByTag(fragmentTag);
if(!fragmentPopped && fragment == null){
//Create an new instance if it is null and add it to stack
fragment = new MyFragment();
ft.addToBackStack(fragmentTag);
}
ft.replace(R.id.framelayout, fragment);
ft.commit();
}

Trying this using the fragment list
See the Answer Here
Initialize the fragments list
static List<String> fragments = new ArrayList<String>();
on Start of first fragment on Activity add this
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction().replace(R.id.frame, new AFragment()).commit();
fragments.add("package.fragment.AFragment");
}
Code to fragment change and take in back stack
String backStateName = fragment.getClass().getName();
FragmentManager manager = getSupportFragmentManager();
//fragment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
if(!fragments.contains(backStateName)) {
// ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
// ft.setCustomAnimations(R.anim.fade_in, R.anim.fade_out);
ft.replace(R.id.frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
fragments.add(backStateName);
System.out.println("backStateName" + fragments);
}
else
{
ft.replace(R.id.frame, fragment);
ft.commit();
}
onBackpressed
#Override
public void onBackPressed() {
if(fragments.size()>0)
{
fragments.remove(fragments.size()-1);
}
super.onBackPressed();
}
for back remove stack
final android.app.FragmentManager fm = getFragmentManager();
fm.addOnBackStackChangedListener(new android.app.FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
if (getSupportFragmentManager().getBackStackEntryCount() ==0) {
// dLayout.closeDrawers();
finish();
}
else
{
// dLayout.closeDrawers();
}
}
});

Before adding or replacing the fragment on backstack, check that if the fragment already in backstack or not.
boolean fragmentPopped = fragmentManager.popBackStackImmediate(backStateName, 0);
if (fragmentPopped) {
// fragment is popped from backStack
} else {
// add or replace your fragment here
}

public void changeFragment(Fragment fragment) {
FragmentManager fragmentManager = getSupportFragmentManager();
Fragment currentVisibleFragment = fragmentManager.findFragmentById(R.id.container);
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.container, fragment, fragment.getClass().getSimpleName());
if (!currentVisibleFragment.getClass().getSimpleName().trim().equalsIgnoreCase(fragment.getClass().getSimpleName().trim())) {
for (int i = fragmentManager.getBackStackEntryCount() - 1; i > 0; i--) {
if (fragmentManager.getBackStackEntryAt(i).getName().equalsIgnoreCase(fragment.getClass().getSimpleName())) {
fragmentManager.popBackStack(fragmentManager.getBackStackEntryAt(i).getId(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
}
fragmentTransaction.addToBackStack(fragment.getClass().getSimpleName());
} else {
fragmentManager.popBackStack();
fragmentTransaction.addToBackStack(fragment.getClass().getSimpleName());
}
fragmentTransaction.commit();
}
boolean doubleBackToExitPressedOnce = false;
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
super.onBackPressed();
} else {
if (doubleBackToExitPressedOnce) {
super.onBackPressed();
finish();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Are you sure you want to exit?", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 2000);
}
}
Call the method to replace fragment with single entry in backstack
changeFragment(new YourFragmentClassName());

Have only one fragment in the backstack while using Navigation Drawer

I am using a navigation drawer.So when my application starts i am calling the homeFragment and keeping it in the backstack. Now if the user selects any options from the navigation drawer i am opening the respective fragment but without adding them to backstack. So what i want is that even when user has open 10 fragment, on pressing back they should be taken back to homeFragment only. But with my code the app exits on pressing back even homeFragment is in the backstack.
Code to openFragments
public static void replaceFragment(FragmentActivity activity, Fragment fragment, boolean addToBackStack) {
try {
String backStateName = fragment.getClass().getName();
String fragmentTag = backStateName;
FragmentManager manager = activity.getSupportFragmentManager();
boolean fragmentPopped = manager.popBackStackImmediate(fragmentTag, 0);
if (!fragmentPopped && manager.findFragmentByTag(fragmentTag) == null) {
FragmentTransaction ft = manager.beginTransaction();
ft.setCustomAnimations(R.anim.slide_in_right, R.anim.slide_out_left, R.anim.slide_in_left, R.anim.slide_out_right);
ft.replace(R.id.frag_container, fragment, fragmentTag);
if (addToBackStack) {
ft.addToBackStack(backStateName);
}
ft.commit();
}
} catch (Exception e) {
e.printStackTrace();
}
}
From MainActivity
private void init() {
setUpToolBar();
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerFrag = (NavigationDrawerFrag) getSupportFragmentManager().findFragmentById(R.id.frag_nav_drawer);
drawerFrag.setUp(drawerLayout, toolbar, R.id.frag_nav_drawer);
CommonFunctions.replaceFragment(this, new HomeFrag(), true);
}
On NavigationDrawer Item click
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (position == 1) {
CommonFunctions.replaceFragment(getActivity(), new ProfileFrag(), false);
} else if (position == 2) {
CommonFunctions.replaceFragment(getActivity(), new CelebrityFrag(), false);
} else if (position == 4) {
CommonFunctions.replaceFragment(getActivity(), new AboutUsFrag(), false);
} else if (position == 5) {
CommonFunctions.replaceFragment(getActivity(), new TermsAndConditions(), false);
}
lvNavItems.setItemChecked(position, true);
//lvNavItems.setSelection(position);
lvNavItems.setSelected(true);
mDrawerLayout.closeDrawer(fragContainer);
}

Add onBackPressed() method in activity to check backstack and if entry is more then zero so call popbackstack method.
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() != 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}

//Put this in your onNavigationItemSelected of MainActivity
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
//FrameLayout where you load your home fragment tools:layout="#layout/frag_home"
ft.replace(R.id.content_frame,nav_selected);
if(getSupportFragmentManager().getBackStackEntryCount() != 0){
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
getSupportFragmentManager().popBackStack();
}
//Don't add Home screen
if(id != R.id.nav_home){
ft.addToBackStack(null);
}
ft.commit();

Handling fragment back stack with Navigation Drawer

I am implementing navigation drawer and works well. So i am calling fragment on navigation drawer click and it is also working and further more i am calling another fragment from Home page fragment and maintain the back stack for every fragment but the problem is back press from the child fragment i can't go to Home page fragment and just exited from application. I don't want this. What i want Click on
Navigation Drawer->HomePageFragment->AnotherChild Fragment(On List Item click of HomePageFragment)
but on back pressed without going to Homepage fragment its directly exit with application. Here is my code: (In Fragment Activity with Navigation Drawer)
class SlideitemListener implements ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
updateDisplay(position);
}
}
private void updateDisplay(int position) {
Fragment fragment = null;
switch (position) {
case 0:
fragment = new ScheduleFragment();
break;
case 1:
fragment = new Result_Fragment();
break;
case 2:
fragment = new Live_Match_Fragment();
break;
case 3:
// fragment = new Live_Match_Fragment();
break;
case 4:
fragment = new Team_Fragment();
break;
default:
break;
}
if (fragment != null) {
fragmentManager = getFragmentManager();
fragmentManager.popBackStackImmediate("0", 0);
int count = fragmentManager.getBackStackEntryCount();
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction.replace(R.id.frame_container, fragment)
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.addToBackStack(String.valueOf(count)).commit();
Log.e("Count in Activiy", ""+count);
// update selected item and title, then close the drawer
setTitle(menutitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
} else {
// error in creating fragment
Log.e("MainActivity", "Error in creating fragment");
}
}
Now in BackPressed() in FragmentActivity.
#Override
public void onBackPressed() {
if (fragmentManager.getBackStackEntryCount() <= 1) {
finish();
return;
}
super.onBackPressed();
}
Now calling another child fragment from HomePage fragment on Listview item click.
team_lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
TeamDetailFragment myDetailFragment = new TeamDetailFragment();
FragmentManager fragmentManager = getFragmentManager();
int count = fragmentManager.getBackStackEntryCount();
Log.e("Count in Fragment", "" + count);
FragmentTransaction fragmentTransaction = fragmentManager
.beginTransaction();
fragmentTransaction
.replace(R.id.frame_container, myDetailFragment)
.setTransition(
FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.addToBackStack(String.valueOf(count)).commit();
}
});
So anybody knows then help me. Help will be appreciate.

There is an issue with nested fragments in android
https://code.google.com/p/android/issues/detail?id=40323
Android doesn't handle back press well if transactions were in nested fragments.
To surpass this i am using the following fix inside My Activity
#Override
public void onBackPressed() {
// If the fragment exists and has some back-stack entry
if (myFragment != null && myFragment.getChildFragmentManager().getBackStackEntryCount() > 0) {
// Get the fragment fragment manager - and pop the backstack
myFragment.getChildFragmentManager().popBackStack();
}
// Else, nothing in the direct fragment back stack
else {
// Let super handle the back press
super.onBackPressed();
}
}

I've solved in the following way:
1st solution
#Override
public void onBackPressed() {
FragmentManager fragmentManager = getFragmentManager();
int backCount = fragmentManager.getBackStackEntryCount();
if(backCount > 1) {
super.onBackPressed();
} else {
finish();
}
}
2nd solution
#Override
public void onBackStackChanged() {
FragmentManager fragmentManager = getFragmentManager();
int backCount = fragmentManager.getBackStackEntryCount();
if(backCount == 0) {
finish();
}
}
These allow you to exploit the Android stack when you replace your fragment:
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, yourFragment)
.addToBackStack(null).commit();

When you press back button inside your fragment onBackPressed() method of your activity will be called if you have declared that..So handling back button for fragments within navigation drawer can be one in this way..
MainActvity
public static boolean isMainActivityShown ;
public static boolean isFragment1Shown=false ;
public static boolean isFragment2Shown=false ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
isMainActivityShown=true //inside onCreate method put isMainActivityShown true
.
.
.
{
Fragment currentFragment = new Fragment1();
isMainActivityShown=false; //when moving to fragment1
isFragment1Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
}
.
.
}
#Override
public void onBackPressed() {
if(isMainActivityShown)
{
finish();
}
else if(isFragment1Shown)
{
//write the code to handle back button when you are in Fragment1
}
else if(isFragment2Shown)
{ //When you are in Fragment 2 pressing back button will move to fragment1
Fragment currentFragment = new Fragment1();
isFragment2Shown=false;
isFragment1Shown=true;
FragmentManager frgManager;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();
}
}
Fragment1
Fragment currentFragment = new Fragment2();
MainActivity.isFragment1Shown=false;
MainActivity.isFragment2Shown=true;
frgManager = getFragmentManager();
frgManager.beginTransaction().replace(R.id.content_frame, currentFragment)
.commit();

Now you can replace finish() for fragmentManager.popBackStack(), method of android.support.v4.app.FragmentManager