Develop Reference

OnBackPress Not working for Fragment in Android

How can we get the onBackPressed callback only in the fragment class? Instead ,now it is going to the onBackPressed in the activity classes? I need to restrict sending the callback to Activity on backpress from fragment.
example::
#Override
public void onBackPressed() {
Log.d("SKT", "backPressHere");
}

Implement this in the Activity and restriction part you can handle via the interface.

The fragment itself does not have a return button, but instead you can put this code in the onBackPressed() method in the activity to which the fragment is attached, and with the getSupportFragmentManager() method you can control the examples of running fragments or delete and return do.
here is example :
#Override
public void onBackPressed() {
int count = getSupportFragmentManager().getBackStackEntryCount();
if (count == 0) {
// no fragment attach
super.onBackPressed();
} else {
// fragment attach
getSupportFragmentManager().popBackStack();
}
}

The fragment does not receive the onBackPressed callback. You should implement dispatching the event in the activity.
public interface BackPressedSupport{
/**
* return true if the fragment consumed the event. otherwise false.
*/
boolean onBackPressed();
}
In your Activity :
#Override
public void onBackPressed() {
Fragment f = getActiveFragment();
if (f instanceof BackPressedSupport && (BackPressedSupport f).onBackPressed()){
return;
}
super.onBackPressed();
// Other backPressed handling of activity.
}
public Fragment getActiveFragment() {
if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
return null;
}
String tag = getSupportFragmentManager().getBackStackEntryAt(getSupportFragmentManager().getBackStackEntryCount() - 1).getName();
return getSupportFragmentManager().findFragmentByTag(tag);
}
In your Fragment:
public MyFragment extends Fragment implements BackPressedSupport {
/* Your code */
#Override
public boolean onBackPressed() {
/* Handle backpressed */
Log.d("SKT", "backPressHere");
return true ; // tell the activity to stop handling this backPressed event
// return false; // keep the default behaviour
}
}

I want to close the app but do not go back to the previous Activity

I used an activity and several pieces in my app
sometimes when I'm on the first page (activity) and back pressed not going out of app and returns to the fragment or the same page
When this happens I've done a lot of work in the program
I used this code to fix this problem but
it also applied to the fragments
#Override
public void onBackPressed() {
this.finish();
}
Why returns to the fragment or the same page
How this problem is solved
I'm using this now
boolean doubleBackToExitPressedOnce = false;
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else if (!doubleBackToExitPressedOnce) {
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this, "Click to exit again", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 2000);
} else {
super.onBackPressed();
return;
}
}
Way is going to be a fragment
TabirFragment tabirFragment = new TabirFragment();
Bundle bundle = new Bundle();
bundle.putInt("id", id);
bundle.putString("name", name);
tabirFragment.setArguments(bundle);
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction().addToBackStack(null);
transaction.replace(R.id.main_activity, tabirFragment).commit();

If you have multiple activities on the stack, then:
finish() - finishes the activity where it is called from and you see
the previous activity.
There is also system.exit but that would not work in your case:
System.exit(0) - restarts the app with one fewer activity on the
stack. So, if you called ActivityB from ActivityA, and System.exit(0)
is called in ActivityB, then the application will be killed and
started immediately with only one activity ActivityA
I recommend you use finishAffinity(). It will finish the current activity as well as all activities immediately below it. I remind you that it is supported by only API level 16+

several pieces what? fragments, getting trouble to understand, anyway if you want to manage frag and onBackPress, use this
private void setUpBackStackListener() {
getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
#Override
public void onBackStackChanged() {
Fragment currentFragment = getFragmentManager().findFragmentById(R.id.am_frameLayout);
if (currentFragment != null) {
int myCount = getFragmentManager().getBackStackEntryCount();
if (LOG_DEBUG) Log.e(TAG, "backStackCount : " + myCount);
String currentFragName = currentFragment.getClass().getSimpleName();
if (currentFragName.equalsIgnoreCase(FragOne.class.getSimpleName())) {
shouldExit = true;
} else if (currentFragName.equalsIgnoreCase(FragTwo.class.getSimpleName())) {
shouldExit = false;
}
}
}
}
});
}
#Override
public void onBackPressed() {
if (shouldExit == true) {
if (LOG_DEBUG)
Log.e(TAG, " Yeah exit douche:" + shouldExit + " isLastEntry : Testing :" + isLastEntry);
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
,if this not you seeking, you might want to clear what you want in a bit subtle way

When you used multiple fragment and activity When you switch activity by using method startActivity(), always use method finish(); when you back pressed then you will never get multiple activity and fragment and use onBackPressed method on main activity.
boolean doubleBackToExitPressedOnce=false;
#Override
public void onBackPressed() {
//Checking for fragment count on backstack
if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
getSupportFragmentManager().popBackStack();
} else if (!doubleBackToExitPressedOnce) {
this.doubleBackToExitPressedOnce = true;
Toast.makeText(this,"Please click back again to exit.", Toast.LENGTH_SHORT).show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
doubleBackToExitPressedOnce = false;
}
}, 2000);
} else {
super.onBackPressed();
return;
}
}

The easiest solution i can give you is to keep no-history for the activity in the manifest file. and then override the back method for each activity.
<activity
android:name=".example"
android:noHistory="true">
</activity>

Onbackpressed redirect to particular fragment

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);
}
}

onBackPressed not working properly

I want to return back to MainActivity on clicking back button from each fragment and destroy Activity after returning back to the MainActivity.
I have tried something but it is continuously calling the fragment but not destroying it.
#Override
public void onBackPressed() {
startActivity(new Intent(this,MainActivity.class));
finish();
}

Do something like this in your MainActivity:
#Override
public void onBackPressed(){
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.frameLayout);
if (fragment instanceof YourFragment || fragment instanceof YourOtherFragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.frameLayout, new MainScreenFragment()).commit();
}else {
super.onBackPressed();
}
}

Add this to the Mainactivity
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
this.finish();
} else {
getFragmentManager().popBackStack();
}
}

Popbackstack Finishes Activity in OnBackPressed

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.