I've created a fragment that shows gridview and when any griditem is clicked it leds to another fragment. But when I press the physical backbutton the app closes instead of going back to previous fragment (i.e. fragment containing gridview). How can I solve this?
try this one
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0 ){
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
'addToBackStack' is used for moving back to previous fragment, you can use a common Function
in your Main activity for changing fragment.
public void change_fragment(Fragment fragment, int frame) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction trans = manager.beginTransaction();
//trans.setCustomAnimations(R.anim.enterfrom_left, R.anim.exit_to_right,R.anim.enterfrom_left, R.anim.exit_to_right);
trans.replace(frame, fragment);
trans.addToBackStack("hai" + frame);
trans.commit();
}
you can call it from Main activity like this
change_fragment(new Frag(),R.id.fl_main_frag_container);
you can call it from another fragment like this
((MainActivity)getContext()).change_fragment(new Frag(), R.id.fl_main_frag_container);
I have an activity which uses fragments, when the activity is first created, it displays a first fragment which is not added to back stack cause I don't want to have an empty activity when user presses back.
The fragments loaded after that are added to back stack.
So I have the behavior I want, except: user can open fragments and press back to go back to the previous fragment, up until they reach the first fragment because if they press back at this time, the activity is closed, which I don't want.
So I'd like to know a good solution to prevent back button pressed but only when the first fragment is displayed.
Add .addToBackStack(null) when you call the new fragment from activity.
FragmentTransaction mFragmentTransaction = getFragmentManager()
.beginTransaction();
....
mFragmentTransaction.addToBackStack(null);
-Add onBackPressed() to your activity
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
this.finish();
}
else {
getFragmentManager().popBackStack();
}
}
Solved like this:
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount()> 0) {
super.onBackPressed();
}
}
in your activity class add below code in onBackPressed method;
#Override
public void onBackPressed() {
int backstack = getSupportFragmentManager().getBackStackEntryCount();
if (backstack > 0) {
getSupportFragmentManager().popBackStack();
}
else{
super.onBackPressed();
//System.exit(0);
}
}
hope this help.
I have an activity which has three fragments. I have also overridden the onBackPressed() method on my activity. When the user navigates to any of my fragments the standard behaviour of the back button occurs. Except for when I launch a fragment not from its "parent".
Imagine this: My activity has no UI. It only has 5 fragments. When the user is on either fragment1, fragment2 or fragment3 and presses the back button he must get out of the app (ie.by calling finish() in only activity the app has). Fragment1Child conceptually is a "child" of fragment1 and fragment2Child is a "child" of fragment2. When going from fragment1 or fragment2 to their children and pressing back I get the expected behaviour. When though, I go from fragment3 to fragment2Child and then press back I am presented correctly with with fragment2. Now when I press back the Activity.finalize() method I have is executed but the app is not closed. Instead I get back to fragment3!
Here is my onBackPressed() method that checks what the is the current fragment shown and decides what to do accordingly
#Override
public void onBackPressed() {
Log.d(TAG, "MainACtivity.onBackPressed()");
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
if (mDrawerLayout.isDrawerOpen(GravityCompat.START)) {
Log.d("NIBHA", " Drawere ++++++++++++++++++++++");
mDrawerLayout.closeDrawers();
} else {
Fragment fragment = getSupportFragmentManager().findFragmentById(
R.id.fragment_container);
Log.d("Nibha", "" + fragment);
if (fragment instanceof DeliveryOrder
|| fragment instanceof IncomingShipment
|| fragment instanceof RentalAgreement) {
Log.d(TAG, "EXITING APP");
finish();
return;
}
if (fragment instanceof IncomingShipmentDetail
&& getIntent().getAction().equals("RA")) {
Log.d(TAG, "IS DETAIL CALLED FROM RA");
transaction.replace(R.id.fragment_container,
new IncomingShipment());
transaction.commit();
}
super.onBackPressed();
}
}
Problem seems to be that super.onBackPressed(); is not being called. Remove return statement and change the following to else if:
if (fragment instanceof IncomingShipmentDetail
&& getIntent().getAction().equals("RA")) {
Log.d(TAG, "IS DETAIL CALLED FROM RA");
transaction.replace(R.id.fragment_container,
new IncomingShipment());
transaction.commit();
}
I have an Activity and many fragments inflated in same FrameLayout
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
example: mainActivity > any fragment (press back button) > activity is blank.
In onCreate:
layout = (FrameLayout)findViewById(R.id.content_frame);
layout.setVisibility(View.GONE);
When I start a fragment:
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, profileFragment);
ft.addToBackStack(null);
ft.commit();
layout.setVisibility(View.VISIBLE);
I suppose I need to make the frameLayout's visibility GONE again on back pressed, but how do I do this?
I tried onBackPressed and set layout.setVisibility(View.GONE); but I cannot go back through fragments, as I go directly to main page.
If you have more than one fragment been used in the activity or even if you have only one fragment then the first fragment should not have addToBackStack defined. Since this allows back navigation and prior to this fragment the empty activity layout will be displayed.
// fragmentTransaction.addToBackStack() // dont include this for your first fragment.
But for the other fragment you need to have this defined otherwise the back will not navigate to earlier screen (fragment) instead the application might shutdown.
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
}
else {
int fragments = getSupportFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
finish();
} else if (getFragmentManager().getBackStackEntryCount() > 1) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
}
To add a fragment
getSupportFragmentManager().beginTransaction()
.replace(R.id.layout_main, dashboardFragment, getString(R.string.title_dashboard))
.addToBackStack(getString(R.string.title_dashboard))
.commit();
Sorry for the late response.
You don't have to add ft.addToBackStack(null); while adding first fragment.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, profileFragment);
// ft.addToBackStack(null); --remove this line.
ft.commit();
// ... rest of code
If you want to track by the fragments you should override the onBackPressed method, like this
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 1) {
finish();
} else {
super.onBackPressed();
}
}
You can override onBackPressed and check to see if there is anything on the backstack.
#Override
public void onBackPressed() {
int fragments = getFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
// make layout invisible since last fragment will be removed
}
super.onBackPressed();
}
Just don't add the first fragment to back stack
Here is the Kotlin code that worked for me.
val ft = supportFragmentManager.beginTransaction().replace(container, frag)
if (!supportFragmentManager.fragments.isEmpty()) ft.addToBackStack(null)
ft.commit()
On a recent personal project, I solved this by not calling addToBackStack if the stack is empty.
// don't add the first fragment to the backstack
// otherwise, pressing back on that fragment will result in a blank screen
if (fragmentManager.getFragments() != null) {
transaction.addToBackStack(tag);
}
Here's my full implementation:
String tag = String.valueOf(mCurrentSectionId);
FragmentManager fragmentManager = mActivity.getSupportFragmentManager();
Fragment fragment = fragmentManager.findFragmentByTag(tag);
if (fragment != null) {
// if the fragment exists then no need to create it, just pop back to it so
// that repeatedly toggling between fragments doesn't create a giant stack
fragmentManager.popBackStackImmediate(tag, 0);
} else {
// at this point, popping back to that fragment didn't happen
// So create a new one and then show it
fragment = createFragmentForSection(mCurrentSectionId);
FragmentTransaction transaction = fragmentManager.beginTransaction()
.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
.replace(R.id.main_content, fragment, tag);
// don't add the first fragment to the backstack
// otherwise, pressing back on that fragment will result in a blank screen
if (fragmentManager.getFragments() != null) {
transaction.addToBackStack(tag);
}
transaction.commit();
}
irscomp's solution works if you want to end activity when back button is pressed on first fragment. But if you want to track all fragments, and go back from one to another in back order, you add all fragments to stack with:
ft.addToBackStack(null);
and then, add this to the end of onCreate() to avoid blank screen in last back pressed; you can use getSupportFragmentManager() or getFragmentManager() depending on your API:
FragmentManager fm = getSupportFragmentManager();
fm.addOnBackStackChangedListener(new OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
if(getSupportFragmentManager().getBackStackEntryCount() == 0) finish();
}
});
Final words: I don't suggest you to use this solution, because if you go from fragment1 to fragment 2 and vice versa 10 times, when you press back button 10 times it will do it in back order which users will not want it.
Almost same as Goodlife's answer, but in Xamarin.Android way:
Load fragment (I wrote helper method for that, but it's not necessary):
public void LoadFragment(Activity activity, Fragment fragment, string fragmentTitle = "")
{
var fragmentManager = activity.FragmentManager;
var fragmentTransaction = fragmentManager.BeginTransaction();
fragmentTransaction.Replace(Resource.Id.mainContainer, fragment);
fragmentTransaction.AddToBackStack(fragmentTitle);
fragmentTransaction.Commit();
}
Back button (in MainActivity):
public override void OnBackPressed()
{
if (isNavDrawerOpen()) drawerLayout.CloseDrawers();
else
{
var backStackEntryCount = FragmentManager.BackStackEntryCount;
if (backStackEntryCount == 1) Finish();
else if (backStackEntryCount > 1) FragmentManager.PopBackStack();
else base.OnBackPressed();
}
}
And isNavDrawerOpen method:
bool isNavDrawerOpen()
{
return drawerLayout != null && drawerLayout.IsDrawerOpen(Android.Support.V4.View.GravityCompat.Start);
}
I still could not fix the issue through getBackStackEntryCount() and I solved my issue by making the main page a fragment too, so in the end I have an activity with a FrameLayout only; and all other fragments including the main page I inflate into that layout. This solved my issue.
I had the same problem when dealing with Firebase's Ui Login screen. When back button was pressed it left a blank screen.
To solve the problem I just called finish() in my onStop() method for said Activity. Worked like a charm.
If you have scenario like me where a list fragment opens another details fragment, and on back press you first need to show the list fragment and then get out the whole activity then, addToBackStack for all the fragment transactions.
and then on the activity, do like this (courtesy: #JRomero's answer, #MSaudi's comment)
#Override
public void onBackPressed() {
int fragments = getFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
// make layout invisible since last fragment will be removed
}
super.onBackPressed();
}
Just Comment or Remove transaction.addToBackStack(null) in your code.Below is code to change fragment in kotlin.
fun ChangeFragment(activity: MainActivity, fragment: Fragment) {
val transaction: FragmentTransaction =
activity.getSupportFragmentManager().beginTransaction()
transaction.replace(R.id.tabLayoutContainer, fragment)
transaction.commit()
}
I want to go back to another fragment by pressing the back button. I already read, that the addToBackStack (String tag) should help but it didn't really work.
Here is what I'm doing when switching fragments.
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.setCustomAnimations(R.anim.slide_in_left, R.anim.slide_out_right);
ft.replace(R.id.content_frame, new MainFragment());
ft.addToBackStack("Mainfragment");
ft.commit();
So now, the Fragment opens, and starts an AsyncTask where a loading circle appears. After the loading the data gets displayed. When I now press the back button once, the fragment goes back to the start of the AsyncTask where the loading circle is created. But the AsyncTask doesn't continue. When I press the back button again, the app closes.
I tried to add onBackPressed but it just told me, that this won't work in a Fragment. What would be the best way to go here?
Edit for clarification:
There's no error. It's just not working. It is like I don't even have the line addToBackStack –
I had the same situation before and I ended up with this solution. When you add or replace the Fragments, you need to add it to the backStack with a unique name. Then when the back button is pressed you can see which fragment was the active one with the method below inside the FragmentActivity that you created the Fragment.
private String getCurrentFragmentName() {
int backStackEntryCount = getSupportFragmentManager().getBackStackEntryCount();
String fragmentName;
if (backStackEntryCount > 0) {
fragmentName = getSupportFragmentManager().getBackStackEntryAt(backStackEntryCount - 1).getName();
} else {
fragmentName = "";
}
return fragmentName;
}
and in on onKeyDown() method do the following.
if (keyCode == KeyEvent.KEYCODE_BACK && getCurrentFragmentName().equals("your fragment name")) {
// Handle back press for this case.
return true;
} else if (keyCode == KeyEvent.KEYCODE_BACK
&& getCurrentFragmentName().equals("your another fragment")) {
// Handle back press for another Fragment
return true;
} else {
return super.onKeyDown(keyCode, event);
}
And this is the Place how I add the Fragment with backStack
transaction.addToBackStack("Your Fragment Name");