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Fragment hardware back button event called twice

I am trying to implement back navigation through my fragments which are called in specific order: A->B->C and by going back with hardware button I would like them to remain order.
I am using fragmenttransaction.replace in order to switch fragment with no addToBackStack because it made my ActionBarMenu to misbehave.
Problem is that when I am on fragment C back button is going back directly to A. I found out that it is because click event is executed twice I am going to B and directly to A.
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
setOnBackButtonPresed();
}
private void setOnBackButtonPresed() {
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener( new View.OnKeyListener()
{
#Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
goBackToDays();
return false;
}
return false;
}
} );
}
private void goBackToDays() {
Log.e("fragmentC", "executing on back action")
}
logcat result:
03-15 08:37:17.353 21245-21245/com.test E/fragmentC: executing on back action
03-15 08:37:17.390 21245-21245/com.test E/fragmentC: executing on back action
Can anyone give me a hint how I can avoide twice button events?

I think "click event is executed twice" because you call both event ACTION_DOWN and ACTION_UP. Try this
#Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK && event.getAction()== KeyEvent.ACTION_DOWN)
{
goBackToDays();
return false;
}
return false;
}

2 things:
Even though you're replacing fragments, the old OnKeyListener stays there (and get's fired up later on). Try removing the old OnKeyListener on switching fragments.
Just as S-lightning pointed out, you need to bare in mind that there are two actions associated with a key event (KeyEvent.ACTION_DOWN and KeyEvent.ACTION_UP).

You can do two things
"it made my ActionBarMenu to misbehave." FIX this issue.
Override onBackPressed() on your Activity and find find out your current loaded fragment and replace with whichever you want.
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.your_view_container);
if (fragment instanceof FragmentThree) {
//replace with your fragment ie. FragmentTwo
} else if (fragment instanceof FragmentTwo) {
//replace with your fragment ie. FragmentOne
}

Return true if you want to "absorb" the key event and stop it from propagating up to the Activity, which has its own onBackPressed() implementation.
if( keyCode == KeyEvent.KEYCODE_BACK )
{
goBackToDays();
return true; // <-- should be TRUE, not FALSE
}
return false;

Override the onBackPressed() method in hosting activity.
do like this.
private void replaceFragment (Fragment fragment){
String backStateName = fragment.getClass().getName();
FragmentManager manager = getSupportFragmentManager();
boolean fragmentPopped = manager.popBackStackImmediate(backStateName, 0);
if (!fragmentPopped){ //fragment not in back stack, create it.
FragmentTransaction ft = manager.beginTransaction();
ft.replace(R.id.content_frame, fragment);
ft.addToBackStack(backStateName);
ft.commit();
}
}
.
.
#Override
public void onBackPressed(){
if (getSupportFragmentManager().getBackStackEntryCount() == 1){
finish();
}
else {
super.onBackPressed();
}
}
Here is the well explained answer. link

fragment back to the end , the screen is white [duplicate]

This question already has answers here:
White screen after going back through Fragments
(2 answers)
Closed 6 years ago.
I have a MainActivity, it has a lots of Fragment under it.
I set the return mechanism transaction.addToBackStack(null);
The function like this:
public void switchFragment(Fragment fragment) {
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.mainFrame, fragment, null);
transaction.addToBackStack(null);
transaction.commit();
}
My issue is when I click the back button to the end, the FrameLayout is white
I tried to add
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if (mainFrame==null)
return super.onKeyDown(keyCode, event);
}
}
It's not working. How do I avoid this white screen when I call back the Fragment to the end ? Any help would be great!

I took #ReazMushed's suggestion and changed like this:
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() ==1) {
finish();
}else{
super.onBackPressed()
}
}
And the white screen problem is gone!

From your question what I've understood is, you have a set of Fragment which is launched one after one and when you press the back button, they disappears one after one. When the first Fragment reaches and you click the back button again, it shows a white screen.
If I'm correct, you might have to track if the first Fragment is reached and then finish the Activity.
Implement the onBackPressed function in your MainActivity. You might consider doing something like this.
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 0)
getSupportFragmentManager().popBackStack();
else
finish(); // Finish the activity
}

Remove only fragment when back pressed

I create sample app to show some data to user when user start specific activity and click on specific button the app start new fragment (only fragment added to activity for now ) my problem is when user click back the fragment and the activity removed and go to parent activity. using this code to do that
android.support.v4.app.FragmentManager fragmentManager = ((FragmentActivity) context).getSupportFragmentManager();
fragmentManager.popBackStack();
also I use the same code in another action when user click in specific button fragment and back correctly.
Can anyone help me to solve that

Add fragments to back stack when create them and override onBackPressed in your activity.
To add fragment
FragmentManager mFragmentManager = ((FragmentActivity) context).getSupportFragmentManager();
FragmentTransaction ft = mFragmentManager.beginTransaction();
ft.addToBackStack("tag of fragment");
ft.add("your container id", fragment);
ft.commit();
onBackPress
#Override
public void onBackPressed() {
if (mFragmentManager.getBackStackEntryCount() > 0)
mFragmentManager.popBackStackImmediate();
else super.onBackPressed();
}

To remove only fragment you have to add that fragment in addToBackStack(TAG) so that when you press back it popout only Fragment which are added to stack

override onBackPressed() and remove fragment. Back stack for fragments works differently as it stores transaction not fragments. So can not pop back a fragment but a transaction

This is work for me to handle backpressin a fragment in a fragment to remove backstack.
#Override
public void onResume() {
super.onResume();
if (getView() == null) {
return;
}
getView().setFocusableInTouchMode(true);
getView().requestFocus();
getView().setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View view, int keyCode, KeyEvent keyEvent) {
if (keyEvent.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
Toast.makeText(getActivity(), "Clicked Back", Toast.LENGTH_SHORT).show();
getActivity().finish();
return true;
}
return false;
}
});
}

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.

Should the android back button be overriden

I want to go back to the last fragment in the back stack, so I want to make the back button popback the stack. Should I do this? and if so, should I override onBackPressed() or onKeyDown()?
#Override
public void onBackPressed()
{
Intent intent = new Intent(this,ABC.class);
startActivity(intent);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK ) {
// do something on back.
return true;
}
return super.onKeyDown(keyCode, event);
}
My fragments aren't being added to the back stack properly for some reason
I am using this to try to go back to the previous fragment, but the order is acting strange. What exactly should I do to make the order proper?
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft){
if(teamsFrag !=null)
{
if(manage.getBackStackEntryCount() > 0)
manage.popBackStack(manage.getBackStackEntryAt(manage.getBackStackEntryCount()-1).getName(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
//ft.detach(dataFrag);
}

Short answer? No.
Long answer? If you have to ask, No.
You should set your fragments up using the fragment manager so that the back button does what you want. You shouldn't override the back button instead of implementing your stack correctly.

I want to go back to the last fragment in the back stack, so I want to make the back button popback the stack.
This is the default behavior when you use FragmentTransaction#addToBackStack() while adding new Fragments with the FragmentManager.