Develop Reference

How to use onBackPressed() in Fragment and Activity?

I'm creating LoginActivity-> OtherActivity-> Fragment 1-> Fragment_2. When I click Back Button I'm back in Fragment_1 when again I click BackButton I'm in LoginActivity why?
I want come back to MainActivity after the click BackButton in Fragment _1 and after next click BackButton (in MainActivity) I want come back to home screen
How can I do this ?
In MainActivity i have:
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0 ) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}

Call addToBackStack when adding fragment. For example:
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.container, fragment);
ft.addToBackStack(backStateName);
ft.commit();
Also, call finish() on your LoginActivity before starting OtherActivity.

At first remove LoginActivity from stack when navigating to OtherActivity. After that use #ahomphophone's answer when presenting fragment. After that back stack should work as expected without needing override 'onBackPressed'.
Note: There is no MainActivity on your provided stack.
Update: If you want to stay in OtherActivity use this code
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0 ) {
getFragmentManager().popBackStack();
}
}

Android - How to exit application only when home page is reached?

I have a main activity that hosts a lot of fragments and a "home page" fragment. Every time I want to add a fragment, I will call this method inside the main activity.
public void addFragment(Fragment fragment) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
ft.add(R.id.fragmentContainer, fragment, "new_fragment");
ft.addToBackStack("new_fragment").commit();
}
Whenever the user presses the back button of the phone, I want the "home page" fragment to be the last page the user sees before he exits the application. How can I do that? I have tried this inside the onBackPressed() inside the MainActivity but it doesn't work (the back button is not working).
#Override
public void onBackPressed() {
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentByTag("new_fragment");
//if fragment is home page fragment, exit application
//else pop the newest fragment or go to home page fragment
if (fragment == fragDefault) {
finish();
} else {
if(fm.getBackStackEntryCount() == 0){
//display home page fragment here
}
}
}

You can check your back stack when you press the back button/key.
When adding your 'home page' Fragment, don't put it to the back stack.
Add all other Fragments when needed and put them to the back stack.
When user press the back button/key, if the back stack is empty, exit app, else pop up Fragment from back stack.
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
finish();
}
else {
getFragmentManager().popBackStack();
}

Alternatively you might want to try this:
if (f instanceof HomePageFragmentClass) {
finish();
} else {
//f.dosomething();
}
*I have not tested it yet, let me know if it works.

Back from fragment to Activity onBackPressed

My question is that, i've one activity and one fragment,from activity open that fragment but when i pressed back button it close application.
i try with this code.
for open fragment.
case R.id.button_contact:
Fragment fragment = new FragmentContact();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.frame_container,fragment).addToBackStack("Frag1").commit();
break;
for back button.
#Override
public void onBackPressed() {
getSupportFragmentManager().popBackStackImmediate("Frag1",0);
super.onBackPressed();
}

I'm assuming you just want to remove the fragment and have the activity remain?
In that case modify your onBackPressed method to be
#Override
public void onBackPressed() {
if (getSupportFragmentManager().findFragmentByTag("Frag1") != null) {
getSupportFragmentManager().popBackStackImmediate("Frag1",0);
} else {
super.onBackPressed();
}
}
This will remove the fragment from the activity if it is added and if it isn't, then the back button will act as normal and destroy the activity.

Just remove this line from onBackPressed().
getSupportFragmentManager().popBackStackImmediate("Frag1",0);
Its work.

You can do something like this. It will work with your stack:
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
} else {
getSupportFragmentManager().popBackStack();
}
This piece of code will pop the stack if there is any fragment. Otherwise the back button will close the activity

What these two lines are doing:
1). getSupportFragmentManager().popBackStackImmediate("Frag1",0);
As you are adding you fragment in activity backstack, so when you are calling on back press,
it remove fragment from stack, now in your stack activity is left, means stack size is one.
2). super.onBackPressed();
I think you are aware of calling super.onbackpress funcionality, here it will finish
your activity and stack size is 0 now, and app will close immidately if stack size is 0.
so you have to remove super.onbackpress() Method.

how to go back to previous fragment on pressing manually back button of individual fragment?

I have only one activity and multiple fragments in my application.
Two main fragment A(left) and B(right).
Fragment A1 called from A
B1 called from B
B2 called from B1
All fragments have individual back buttons.
So when I press back button of fragment A1, it should go back to A, similarly when Back button from B2 is pressed, B1 appears and from B1 to B and so on.
How to implement this type of functionality?

public void onBackPressed()
{
FragmentManager fm = getActivity().getSupportFragmentManager();
fm.popBackStack();
}

I have implemented the similar Scenario just now.
Activity 'A' -> Calls a Fragment 'A1' and clicking on the menu item, it calls the Fragment 'A2' and if the user presses back button from 'A2', this goes back to 'A1' and if the user presses back from 'A1' after that, it finishes the Activity 'A' and goes back.
See the Following Code:
Activity 'A' - OnCreate() Method:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activityA);
if (savedInstanceState == null) {
Fragment fragInstance;
//Calling the Fragment newInstance Static method
fragInstance = FragmentA1.newInstance();
getFragmentManager().beginTransaction()
.add(R.id.container, fragInstance)
.commit();
}
}
Fragment : 'A1'
I am replacing the existing fragment with the new Fragment when the menu item click action happens:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == R.id.action_edit_columns) {
//Open the Fragment A2 and add this to backstack
Fragment fragment = FragmentA2.newInstance();
this.getFragmentManager().beginTransaction()
.replace(R.id.container, fragment)
.addToBackStack(null)
.commit();
return true;
}
return super.onOptionsItemSelected(item);
}
Activity 'A' - onBackPressed() Method:
Since all the fragments have one parent Activity (which is 'A'), the onBackPressed() method lets you to pop fragments if any are there or just return to previous Activity.
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else {
getFragmentManager().popBackStack();
}
}
If you are looking for Embedding Fragments inside Fragments, please refer the link: http://developer.android.com/about/versions/android-4.2.html#NestedFragments

#trueblue's answer got me going with one minor but annoying issue. When there is only one fragment on the backstack and you press back button, that frame is removed and the app remains active with a blank screen. User needed to press back button one more time to exit the app. I modified the original code to the following in order to handle this situation
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else if(getFragmentManager().getBackStackEntryCount() == 1) {
moveTaskToBack(false);
}
else {
getFragmentManager().popBackStack();
}
}
When there is only 1 fragment in the backstack, we are basically telling android to move the whole app to back.
Update (and probably a better answer)
So after doing some more reading around this, I found out that you can add fragment manager transactions to back stack and then android handles back presses automatically and in a desired way. The below code snippet shows how to do that
Fragment fragment; //Create and instance of your fragment class here
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment).addToBackStack(null);
fragmentTransaction.commit();
fragmentTransaction.addToBackStack(null);
The last line shows how you add a transaction to back stack. This solves back press issue for fragments in most situations except for one. If you go on pressing back button, then eventually you will reach a point when there is only one fragment in the back stack. At this point, you will want to do one of the two things
Remove the activity housing the fragment from the back stack of the task in which activity is running. This is because you do not want to end up with a blank activity
If the activity is the only activity in the back stack of the task, then push the task in background.
In my case, it was the later, so I modified the overridden onBackPressed method from my previous answer to look like below
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 1) {
moveTaskToBack(false);
}
else {
super.onBackPressed();
}
}
This code is simpler because it has less logic and it relies on framework than on our custom code. Unfortunately I did not manage to implement code for first situation as I did not need to.

You have to implement your own backstack implementation as explained here.
You can call the popFragments() whenever you click the back button in a fragment and call pushFragments() whenever you navigate from one Fragment to other.

Just Do
getActivity().getFragmentManager().popBackStack();

Try this, Its Work for me.
public void onBackPressed() {
if (mainLayout.isMenuShown()) {
mainLayout.toggleMenu();
} else {
FragmentManager fm = getSupportFragmentManager();
Log.print("back stack entry", fm.getBackStackEntryCount() + "");
if (fm.getBackStackEntryCount() > 1) {
fm.popBackStack();
// super.onBackPressed();
// return;
} else {
if (doubleBackToExitPressedOnce) {
fm.popBackStack();
super.onBackPressed();
return;
}
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Press one more time to exit",
Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 3000);
}
}
}

Back button will traverse in the order, in which Fragments were added to backstack. This is provided as a navigation function by default. Now if you want to go to specific Fragment, you can show it from backstack.

You can handle it by adding tag in the backStack. Check my answer here :
https://stackoverflow.com/a/19477957/1572408
hope it helps

#Override
public void onResume() {
super.onResume();
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
// replace your fragment here
return true;
}
return false;
}
});
}
// Happy Coding

If you press back image you have to create method first like this
private void Backpresses() {
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.contant_main, new Home()).commit();
}
then you have to call like this when you press back image..
back.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Backpresses();
}
});
It work fine for me.

Programmatically go back to the previous fragment in the backstack

Say I have an activity that has fragments added programmatically:
private void animateToFragment(Fragment newFragment, String tag) {
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.fragment_container, newFragment, tag);
ft.addToBackStack(null);
ft.commit();
}
What is the best way to return to the previous fragment that was visible?
I found Trigger back-button functionality on button click in Android but I'm thinking simulating a back key event isn't the right way to go about it (and I can't get it to work either):
dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_BACK));
Calling finish() just closes the activity which I'm not interested in.
Is there a better way to go about this?

Look at the getFragmentManager().popBackStack() methods (there are several to choose from)
http://developer.android.com/reference/android/app/FragmentManager.html#popBackStack()

To elaborate on the other answers provided, this is my solution (placed in an Activity):
#Override
public void onBackPressed(){
FragmentManager fm = getFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
Log.i("MainActivity", "popping backstack");
fm.popBackStack();
} else {
Log.i("MainActivity", "nothing on backstack, calling super");
super.onBackPressed();
}
}

When we are updating/add the fragments,
Should Include the .addToBackStack().
getSupportFragmentManager().beginTransaction()
.add(detailFragment, "detail") // Add this transaction to the back stack (name is an optional name for this back stack state, or null).
.addToBackStack(null)
.commit();
After that if we give the getFragments.popBackStackImmediate() will return true if we add/update the fragments, and move back to the current screen.

Android Navigation architecture component.
The following code works for me:
findNavController().popBackStack()

These answers does not work if i don't have addToBackStack() added to my fragment transaction but, you can use:
getActivity().onBackPressed();
from your any fragment to go back one step;

Add those line to your onBackPressed() Method. popBackStackImmediate() method will get you back to the previous fragment if you have any fragment on back stack
`
if(getFragmentManager().getBackStackEntryCount() > 0){
getFragmentManager().popBackStackImmediate();
}
else{
super.onBackPressed();
}
`

This solution works perfectly for bottom bar based fragment navigation when you want to close the app when back pressed in primary fragment.
On the other hand when you are opening the secondary fragment (fragment in fragment) which is defined as "DetailedPizza" in my code it will return the previous state of primary fragment. Cheers !
Inside activities on back pressed put this:
Fragment home = getSupportFragmentManager().findFragmentByTag("DetailedPizza");
if (home instanceof FragmentDetailedPizza && home.isVisible()) {
if (getFragmentManager().getBackStackEntryCount() != 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
} else {
//Primary fragment
moveTaskToBack(true);
}
And launch the other fragment like this:
Fragment someFragment = new FragmentDetailedPizza();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.replace(R.id.container_body, someFragment, "DetailedPizza");
transaction.addToBackStack("DetailedPizza");
transaction.commit();

Kotlin Answer
First, call Fragment Manager.
After, to use onBackPressed()
method.
Coding in Android Studio 4.0 with Kotlin:
fragmentManager?.popBackStack()

Programmatically go back to the previous fragment using following code.
if ( getFragmentManager().getBackStackEntryCount() > 0)
{
getFragmentManager().popBackStack();
return;
}
super.onBackPressed();

To make that fragment come again, just add that fragment to backstack which you want to come on back pressed, Eg:
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Fragment fragment = new LoginFragment();
//replacing the fragment
if (fragment != null) {
FragmentTransaction ft = ((FragmentActivity)getContext()).getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack("SignupFragment");
ft.commit();
}
}
});
In the above case, I am opening LoginFragment when Button button is pressed, right now the user is in SignupFragment. So if addToBackStack(TAG) is called, where TAG = "SignupFragment", then when back button is pressed in LoginFragment, we come back to SignUpFragment.
Happy Coding!

By adding fragment_tran.addToBackStack(null) on last fragment, I am able to do come back on last fragment.
adding new fragment:
view.findViewById(R.id.changepass).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.container, new ChangePassword());
transaction.addToBackStack(null);
transaction.commit();
}
});

Following Kotlin code useful to me
1. Added in Simple Activity class with multiple fragments used
override fun onBackPressed() {
if (supportFragmentManager.backStackEntryCount > 0) {
Log.i(TAG, "=============onBackPressed - Popping backstack====")
supportFragmentManager.popBackStack()
} else {
Log.i(TAG, "=============onBackPressed called because nothing on backstack====")
super.onBackPressed()
}
}
2. Added in BottomNavigationView Activity class with multiple fragments used
override fun onBackPressed() {
Log.e(TAG, "=============onBackPressed")
val navController = findNavController(R.id.nav_host_fragment)
when (navController.currentDestination!!.id) {
R.id.navigation_comments, R.id.navigation_my_posts -> {
menuItemPosition = 0
navController.navigate(R.id.navigation_home)
Log.i(TAG, "=============onBackPressed - Popping backstack with First fragment ====")
}
else -> {
Log.i(TAG, "=============onBackPressed called because nothing on backstack====")
super.onBackPressed()
}
}
}

I came here looking or the same idea, and in the meantime i came up with own, which I believe is not that bad and works if with ViewPager.
So what I did, is to override the onBackPressed method in the parent activity that holds the viewPager, and set it to always go back minus 1 position until it reaches the first fragment, then closes the activity.
#Override
public void onBackPressed() {
if(viewPager.getCurrentItem()>0){
viewPager.setCurrentItem(viewPager.getCurrentItem()-1);
} else {
super.onBackPressed();
this.close();
}
}
private void close(){
this.finish();
}
This might have a downfalls, like it only goes back one way left each time, so it might not work great if there are tabs and you switch positions with fragments skipped, ( going from 0 to 2, and then pressing back would put you on 1, instead of 0)
For my case tho, with 2 fragments in viewPager without tabs, it does the job nicely.

getActivity().getSupportFragmentManager().popBackStackImmediate();
OR
getActivity().onBackPressed();

Try below code:
#Override
public void onBackPressed() {
Fragment myFragment = getSupportFragmentManager().findFragmentById(R.id.container);
if (myFragment != null && myFragment instanceof StepOneFragment) {
finish();
} else {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
}