I have an Activity with two Fragments (List & Details), in onCreate(), I start the List Fragment if savedInstance is null like so
public static final int CLIENT_LIST_FRAGMENT = 1;
public static final int CLIENT_DETAILS_FRAGMENT = 2;
private int currentFragment = 0;
if (savedInstanceState == null) {
//On first run, start the list fragment
if (currentFragment == 0) {
ClientListFragment listFrag = new ClientListFragment();
getSupportFragmentManager().beginTransaction()
.add(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
} else {
switch (currentFragment) {
case CLIENT_LIST_FRAGMENT:
addListFragment();
break;
case CLIENT_DETAILS_FRAGMENT:
addDetailsFragment(0);
break;
}
}
}
And here is the method that add the DetailsFragment and ListFragment as needed
private void addListFragment(){
ClientDetailsFragment listFrag = new ClientDetailsFragment();
getSupportFragmentManager().beginTransaction()
.replace(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.addToBackStack("details")
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
}
private void addDetailsFragment(long companyId){
ClientDetailsFragment detailsFrag = ClientDetailsFragment.newInstance(companyId);
getSupportFragmentManager().beginTransaction()
.replace(R.id.container_client, detailsFrag, Constants.CLIENT_DETAILS_TAG)
.addToBackStack(null)
.commit();
currentFragment = CLIENT_DETAILS_FRAGMENT;
}
This works as expected except that when I click the back button from the Details Fragment, instead of taking me back to the List Fragment, it actually finishes the Activity. It goes back to the List Fragment for a split second and then finishes the host Activity and goes back to the calling Activity. How can I stop this behavior, after going through a lot of onBackpress related question on SO here is my overide of the onBackPressed
#Override
public void onBackPressed() {
if (currentFragment == CLIENT_DETAILS_FRAGMENT){
getSupportFragmentManager().popBackStackImmediate();
}else {
super.onBackPressed();
}
}
Thanks
Activity onBackPressed() should be:
For android.support.v4.app.Fragment
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 1)
getSupportFragmentManager().popBackStack();
else
finish();
}
For android.app.Fragment
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 1)
getFragmentManager().popBackStack();
else
finish();
}
I usually check whether the current fragment instance belongs to the fragment that invoked onBackPressed(). This code is untested; it's just to give you an idea on how to proceed. I hope you are not calling this.finish() on this Activity.
#Override
public void onBackPressed() {
Fragment fragment = getSuportFragmentManager().findFragmentByTag(Constants.CLIENT_DETAILS_TAG);
if (fragment instanceof ClientDetailsFragment) {
getSupportFragmentManager().popBackStackImmediate();
}
else {
super.onBackPressed();
}
}
Let me know if that helps.
Good Lord, I was chasing the wrong shadow for two days. I was listening, handling and overriding the wrong event.
This SO question saved me Why is onBackPressed() not being called?
And the gist is "onBackPressed() is invoked when user clicks on a hardware back button (or on the 'up' button in the navigation bar), not the button in the action bar. For this one you need to override onOptionsItemSelected() method. Example:"
I was catching this event the fragment and calling getActivity.onBackpressed. When I stopped this, it became obvious to me that the onBackPressed is not being called. Here is my solution, may not be optimal but it works
if (item.getItemId() == android.R.id.home){
if (currentFragment == CLIENT_DETAILS_FRAGMENT){
getSupportFragmentManager().popBackStackImmediate();
currentFragment = CLIENT_LIST_FRAGMENT;
return true;
}
}
if (currentFragment == 0) {
ClientListFragment listFrag = new ClientListFragment();
getSupportFragmentManager().beginTransaction()
.add(R.id.container_client, listFrag, Constants.CLIENT_LIST_FRAGMENT_TAG)
.commit();
currentFragment = CLIENT_LIST_FRAGMENT;
}
while changing this add to addToBackStack()
and,
change onBackPressed() like,
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 1) {
MainActivity.this.finish();
}
else {
getFragmentManager().popBackStack();
}
}
Hope, this will work.
Related
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().
In my app i have navigation drawer,So i have one MainActivity and rest are fragments. My app is working fine. Whenever i press back button it redirect to previous fragment.it works fine.but what i want is after successful payment i am displaying Successful payment page,on this page when user press back button i want to redirect to HomeFragment,but right now it goes to Placeorder fragment.
#Override
public void onBackPressed() {
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else {
getFragmentManager().popBackStack();
}
}
Override your onBackPress method:
#Override
public void onBackPressed() {
if (fragment != null && fragment.getChildFragmentManager().getBackStackEntryCount() > 0){
fragment.getChildFragmentManager().popBackStack();
}else {
super.onBackPressed();
}
}
One way would be saving previous fragment (previousFragment) variable while opening new fragment and making it null when you are in first or placeholder fragment .... then check value of previousFragment inside onBackPressed method , if null perform exit operation else replace fragment with previousFragment by which you will get back to previous fragment on back press.
You should simulate function as below in abstract class fragment
/**
* Handle "Back" key pressed.
* #return TRUE if the "Back" key pressed was handled. FALSE indicate it's not handled and parent class can handle it.
*/
public abstract boolean onBackPressed()
And in MainActivity, you will handle this function
#Override
public void onBackPressed() {
if (mSelectedFragment != null && mSelectedFragment.onBackPressed()) {
return;
} else {
super.onBackPressed
}
}
inside your onBackPressed() do like this:
#Override
public void onBackPressed() {
if(getSupportFragmentManger.findFragmentByTag("paymentFragment") != null){
//add homeFragment;
}
else{
if(getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
}
else {
getFragmentManager().popBackStack();
}
}
}
you can set some global variable (true when payment is success else false) in Application class and in onbackpressed of your activity just check that variable is true or not.Then in backpressed of your activity call this function.
public void clearBackStack() {
FragmentManager manager = getSupportFragmentManager();
if (manager.getBackStackEntryCount() > 0) {
FragmentManager.BackStackEntry first = manager.getBackStackEntryAt(0);
manager.popBackStack(first.getId(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
}
}
Use:
fragmentTransaction.replace(R.id.fragment_container, mFeedFragment);
fragmentTransaction.commit();
Don't do this:
fragmentTransaction.addToBackStack(null);
Follow this simple method
declare an integer as
public int count;
initialise this count as count=0 in your main page
now include this in your main activity
#Override
public void onBackPressed() {
if (count == 1) {
if (exit) {
super.onBackPressed();
return;
} else {
Toast.makeText(this, "Press Back again to Exit.", Toast.LENGTH_SHORT).show();
exit = true;
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
exit = false;
}
}, 2000);
}
}else {
toolbar.setTitle("Home");
mDrawerLayout.closeDrawers();
count=1;
display(0);
}
}
Navigation drawer with fragments. I have placed one fragment on main activity. But if i back press the same fragment comes again. How can I handle this??
and secondly how to implement onBackpressed in fragments??
Can anybody help me out?
in onCreate of main activity I have
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment());
tx.commit();
and in back press of it I have
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
First you need to add the fragmnet to back stack so we could retrieve it later in onBackPressed()
Replace your fragmnet transaction with this
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment());
// HERE WE WILL ADD FRAGMENT TO BACKSTACK SO WE COULD GET BACK TO IT
tx.addToBackStack(null);
tx.commit();
Replace your onBackPressed with this
#Override
public void onBackPressed() {
// CHECKS HOW MANY FRAGMENTS ARE IN THE BACKSTACK
int count = getFragmentManager().getBackStackEntryCount();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if (count == 0) {
// IF NO FRAGMENT IN THE BACKSTACK CALL
super.onBackPressed();
} else {
// GET THE LAST OPENED FRAGMENT
getFragmentManager().popBackStack();
}
}
}
You can do this using Interface. That interface will implemented in each fragment. Here is a simple example:
public interface OnBackPressedListener {
void onBackPressed();
}
Here, if you implement this interface in your fragment then you will found this method:
#Override
public void onBackPressed() {
getActivity().finish(); // Or Do your specific task
}
Now your Activity that holds that fragment , that should use onBackPressed() callback. Write bellow code in that method
#Override
public void onBackPressed() {
if (YOUR_DRAWER.isDrawerOpen(GravityCompat.START)) {
YOUR_DRAWER.closeDrawer(Gravity.LEFT); //CLOSE Nav Drawer!
return;
}
Fragment fragment=getYourVisibleFragment();
if(fragment!=null){
((OnBackPressedListener)fragment).onBackPressed();
}else{
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
}
}
If you want to get Visible fragment then just use this method
public <F extends Fragment> F getVisibleFragment() {
List<Fragment> fragments = getSupportFragmentManager().getFragments();
if (fragments != null) {
for (Fragment fragment : fragments) {
if (fragment != null && fragment.isVisible()) {
return (F) fragment;
}
}
}
return null;
}
That's it :)
FragmentTransaction tx = getFragmentManager().beginTransaction();
tx.replace(R.id.mainFrame, new PlaceOrderFragment()).addToBackStack("your tag");
tx.commit();
Override onBackPress() and try following code.
#Override
public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onBackPressed();
//your other utility code if needed
} else {
getFragmentManager().popBackStack();
}
}
Hope this will work for you.
Replace ypu fragment in onCreate with fragment id , and then implement onBackpressed on the same activity and find that fragment with id and check is it visible or null and then perform operations based on it.
hope you got this.
I have implemented Navigation Drawer which is a subclass of Activity. I have many fragments in my application. My question goes here
Imagine there are 3 fragments :
Fragment_1 : Fragment_2 : Fragment_3
When I start my application, Fragment_1 is loaded
When I click on some components on Fragment_1, I'm navigated to Fragment_2 and so on..
So it's like
Fragment_1 > Fragment_2 > Fragment_3
When I press back key from Fragment_2, I'm navigated back to Fragment_1
But when I press back key from Fragment_3, I'm navigated back to Fragment_1 (instead of Fragment_2)
I want something like this in my application on Back Key press
Fragment_1 < Fragment_2 < Fragment_3
I have used Fragment, FragmentManager, FragmentTransaction as follows :
MyFragment fragment = new MyFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).addToBackStack(null)commit();
and I tried overriding onBackPressed() in my MainActivity :
#Override
public void onBackPressed() {
getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0)
super.onBackPressed();
}
Update your Activity#onBackPressed() method to:
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
The reason your implementation doesn't work is because the method FragmentManager#popBackStack() is asynchronous and does not happen right after it is called.
From the documentation:
This function is asynchronous -- it enqueues the request to pop, but the action will not be performed until the application returns to its event loop.
Reference: http://developer.android.com/reference/android/app/FragmentManager.html#popBackStack(java.lang.String,%20int)
You have to implement your own backstack implementation as explained here
Separate Back Stack for each tab in Android using Fragments
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.
in Short,
public void onBackPressed()
{
FragmentManager fm = getActivity().getSupportFragmentManager();
fm.popBackStack();
}
The tric is in FragmentManager#executePendingTransactions();.
This is what I use for nested fragments as well...:
/**
* if there is a fragment and the back stack of this fragment is not empty,
* then emulate 'onBackPressed' behaviour, because in default, it is not working.
*
* #param fm the fragment manager to which we will try to dispatch the back pressed event.
* #return {#code true} if the onBackPressed event was consumed by a child fragment, otherwise
*/
public static boolean dispatchOnBackPressedToFragments(FragmentManager fm) {
List<Fragment> fragments = fm.getFragments();
boolean result;
if (fragments != null && !fragments.isEmpty()) {
for (Fragment frag : fragments) {
if (frag != null && frag.isAdded() && frag.getChildFragmentManager() != null) {
// go to the next level of child fragments.
result = dispatchOnBackPressedToFragments(frag.getChildFragmentManager());
if (result) return true;
}
}
}
// if the back stack is not empty then we pop the last transaction.
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
fm.executePendingTransactions();
return true;
}
return false;
}
and in my onBackPressed :
if (!FragmentUtils.dispatchOnBackPressedToFragments(fm)) {
// if no child fragment consumed the onBackPressed event,
// we execute the default behaviour.
super.onBackPressed();
}
Use this code on tab change in your main activity to clear the stack.
int count = getFragmentManager().getBackStackEntryCount();
if(count>0){
for (int i = 0; i <count; i++) {
getFragmentManager().popBackStack();
}
}
Then on Back pressed of your main activity do this
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0) {
super.onbackpressed();
}
else {
getFragmentManager().popBackStack();
}
}
Here is working and tested code by me, This will help you
private static final int TIME_INTERVAL = 2000;
private long mBackPressed;
private void applyExit() {
if (mBackPressed + TIME_INTERVAL > System.currentTimeMillis()) {
finish();
} else {
Toast.makeText(this,"Press Again to exit",Toast.LENGTH_LONG).show();
}
mBackPressed = System.currentTimeMillis();
}
#Override
public void onBackPressed() {
fm = getSupportFragmentManager();
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
}
if (fm.getFragments().size() <= 1) {
applyExit();
} else {
for (Fragment frag : fm.getFragments()) {
if (frag == null) {
applyExit();
return;
}
if (frag.isVisible()) {
FragmentManager childFm = frag.getChildFragmentManager();
if (childFm.getFragments() == null) {
super.onBackPressed();
return;
}
if (childFm.getBackStackEntryCount() > 0) {
childFm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
return;
} else {
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
return;
}
}
}
}
}
My application structure look like:
SplashActivity -> MainActivity -> (switching between many fragments)
What I expect: finish application from main activity when fragment back stack count is zero. Here is my try:
In SplashAcitivty
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getIntent().getBooleanExtra("exit", false)) {
finish();
}
}
In MainActivity:
#Override
public void onBackPressed() {
// I need to implement this method
if( backstackCount() == 0){
Intent intent = new Intent(this, SplashActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.putExtra(SplashActivity.EXIT_KEY, true);
startActivity(intent);
}else{
super.onBackPressed();
}
}
So, please tell me how can I determine the back stack when it 's empty? Because I use SlideMenu library, all of my fragments switch many times, and they are added to back stack when switching. Look like this one:
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.content_frame, fragment)
.addToBackStack(null)
.commit();
Here is my code. It works fine for me:
#Override
public void onBackPressed() {
int backStackEntryCount = getSupportFragmentManager().getBackStackEntryCount();
if (backStackEntryCount == 0) {
goBack(); // write your code to switch between fragments.
} else {
super.onBackPressed();
}
}