Fragment pressing back button

Question

I am now having an activity containing fragments    1     2     3     4    If pressing buttons    3     it can be redirected to  4   I would like to implement the back button as shown follow    when pressing back  at  4    it return to  3   when pressing back  at  3    it return to  2   when pressing back  at  1    the activity finishes     When it comes to the current implementation  it finish the activity instead of popping up the Fragment  Would you please tell me what I should do or keep in mind      Override public boolean onKeyDown int keyCode  KeyEvent event         if  keyCode  KeyEvent KEYCODE BACK                     finish                          return super onKeyDown keyCode  event

User · Answer

you can use this one in onCreateView  you can use transaction or replace      OnBackPressedCallback callback   new OnBackPressedCallback true                     Override                 public void handleOnBackPressed                           what you want to do                                       requireActivity   getOnBackPressedDispatcher   addCallback this  callback

User · Answer

What I do in this cases is I implement the onBackPressed   function from the Activity    Override public void onBackPressed        super onBackPressed       FragmentManager fm   getSupportFragmentManager       MyFragment myFragment    MyFragment  fm findFragmentById R id my fragment       if  myFragmen isVisible             Do what you want to do          How this works for you too

User · Answer

Try this simple solution    In your activity implement onBackPressed    Override     public void onBackPressed            if  getSupportFragmentManager   getBackStackEntryCount    gt  1                getSupportFragmentManager   popBackStack              else               finish                      This will work if you want to pop the top fragment on each back press  Note - While adding fragment to activity always do add the transaction to back stack for this to work

User · Answer

i use  a methode to change fragments it has thw following code   getSupportFragmentManager   beginTransaction   setCustomAnimations R anim enter  R anim exit  R anim pop enter  R anim pop exit  replace R id content frame  mContent  mContent getClass   getSimpleName    addToBackStack null                   commit      and for the back  button this     Override     public void onBackPressed                note  you can also use  getSupportFragmentManager            FragmentManager mgr   getSupportFragmentManager            if  mgr getBackStackEntryCount      1                   No backstack to pop  so calling super             finish              else               mgr popBackStack                      the important thing to note is i use 1 for checking getBackStackEntryCount this is because if you dont use it and use 0 user sees nothing for the last back button

User · Answer

Make sure to add the following    if  event getAction    KeyEvent ACTION DOWN                  return true    in the onKey block of code to avoid the event calling twice

User · Answer

if you are using webview inside a fragment than use this in your onCreateView method  webView setOnKeyListener new View OnKeyListener              Override         public boolean onKey View view  int i  KeyEvent keyEvent                if  i  KeyEvent KEYCODE BACK  amp  amp  webView canGoBack                     webView goBack                    return true                            return false                      and import this class  import android view KeyEvent

User · Answer

In your onCreate   in your activity housing your fragments add a backstack change listener like so       fragmentManager addOnBackStackChangedListener new FragmentManager OnBackStackChangedListener              Override         public void onBackStackChanged                 List lt Fragment gt  f   fragmentManager getFragments                Fragment frag   f get 0               currentFragment   frag getClass   getSimpleName                         Nb  my fragmentManager is declared global  Now every time you change fragment the currentFragment String will become the name of the current fragment  Then in the activities onBackPressed   you can control the actions of your back button as so        Override     public void onBackPressed          switch  currentFragment            case  FragmentOne                  your code here              return          case  FragmentTwo                  your code here             return          default              fragmentManager popBackStack                   default action for any other fragment  return to previous             I can confirm that this method works for me   Update   Kotlin  override fun onBackPressed          when supportFragmentManager fragments 0  javaClass simpleName            FragmentOne  - gt  doActionOne            FragmentTwo  - gt  doActionTwo           else - gt  supportFragmentManager popBackStack

User · Answer

You also need to check Action Down or Action UP event  If you will not check then onKey   Method will call 2 times   getView   setFocusableInTouchMode true   getView   requestFocus     getView   setOnKeyListener new OnKeyListener              Override         public boolean onKey View v  int keyCode  KeyEvent event                    if  event getAction      KeyEvent ACTION DOWN                        if  keyCode    KeyEvent KEYCODE BACK                            Toast makeText getActivity     Back Pressed   Toast LENGTH SHORT  show                        return true                                                          return false                              Working very well for me

User · Answer

Solution for Pressing or handling back button in Fragment  The way I solved my issue I am sure it will helps you too  1 If you don t have any Edit Text-box in your fragment you can use below code  Here MainHomeFragment is main Fragment  When I press back button from second fragment it will take me too MainHomeFragment        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  amp  amp  keyCode    KeyEvent KEYCODE BACK                    MainHomeFragment mainHomeFragment   new SupplierHomeFragment                    android support v4 app FragmentTransaction fragmentTransaction                           getActivity   getSupportFragmentManager   beginTransaction                    fragmentTransaction replace R id fragment container  mainHomeFragment                   fragmentTransaction commit                     return true                                    return false                       2 If you have another fragment named as Somefragment and it has Edit text-box then you can do it by this way  private EditText editText   Then In  onCreateView        editText    EditText  view findViewById R id editText    Then Override OnResume   Override public void onResume         super onResume         editText setOnKeyListener new View OnKeyListener              Override         public boolean onKey View v  int keyCode  KeyEvent event                if  keyCode    KeyEvent KEYCODE BACK                    editTextOFS clearFocus                    getView   requestFocus                              return false                         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  amp  amp  keyCode    KeyEvent KEYCODE BACK                    MainHomeFragment mainHomeFragment   new SupplierHomeFragment                    android support v4 app FragmentTransaction fragmentTransaction                           getActivity   getSupportFragmentManager   beginTransaction                    fragmentTransaction replace R id fragment container  mainHomeFragment                   fragmentTransaction commit                     return true                              return false                        That s all folks  amitamie com   -   -

User · Answer

You can use this    Worked for me    It seems as though fragment  3  is not removed from the view when back is pressed so you have to do it manually   First of all  dont use replace   but instead use remove and add separately  It seems as though replace   doesnt work properly   The next part to this is overriding the onKeyDown method and remove the current fragment every time the back button is pressed     Override  public boolean onKeyDown int keyCode  KeyEvent event      if  keyCode    KeyEvent KEYCODE BACK         if  getSupportFragmentManager   getBackStackEntryCount      0                this finish            return false            else               getSupportFragmentManager   popBackStack            removeCurrentFragment             return false                 return super onKeyDown keyCode  event        public void removeCurrentFragment     FragmentTransaction transaction   getSupportFragmentManager   beginTransaction     Fragment currentFrag    getSupportFragmentManager   findFragmentById R id f id

User · Answer

Easiest way ever   onResume      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  amp  amp  keyCode    KeyEvent KEYCODE BACK                       handle back button s click listener                 Toast makeText getActivity     Back press   Toast LENGTH SHORT  show                    return true                            return false                         Edit 1  If fragment having EditText   private EditText editText    onCreateView     editText    EditText  rootView findViewById R id editText     onResume      Override public void onResume         super onResume         editText setOnKeyListener new View OnKeyListener              Override         public boolean onKey View v  int keyCode  KeyEvent event                if  keyCode    KeyEvent KEYCODE BACK                    editText clearFocus                              return false                         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  amp  amp  keyCode    KeyEvent KEYCODE BACK                       handle back button s click listener                 Toast makeText getActivity     Back press   Toast LENGTH SHORT  show                    return true                            return false                         Note   It will work if you have EditText in fragment   Done

User · Answer

This is a working solution for me   dialog setOnKeyListener new DialogInterface OnKeyListener                          Override                     public boolean onKey DialogInterface dialog  int keyCode  KeyEvent event                            if  keyCode    KeyEvent KEYCODE BACK                                   DO WHAT YOU WANT ON BACK PRESSED                             return true                                                    return false                                              Edit  You can replace dialog with getView   for fragments

User · Answer

Still better solution could be to follow a design pattern such that the back-button press event gets propagated from active fragment down to host Activity  So  it s like   if one of the active fragments consume the back-press  the Activity wouldn t get to act upon it  and vice-versa   One way to do it is to have all your Fragments extend a base fragment that has an abstract  boolean onBackPressed    method    Override public boolean onBackPressed        if some condition           Do something       return true    Back press consumed       else            Back-press not consumed  Let Activity handle it       return false           Keep track of active fragment inside your Activity and inside it s onBackPressed callback write something like this   Override public void onBackPressed        if  activeFragment onBackPressed          super onBackPressed             This post has this pattern described in detail

User · Answer

use this  in kotlin   activity  onBackPressedDispatcher  addCallback this  object   OnBackPressedCallback true            override fun handleOnBackPressed                    in here you can do logic when backPress is clicked                   i think this is the most elegant way to do it

User · Answer

This worked for me   -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

User · Answer

You can use getFragmentManager   popBackStack   in basic Fragment to go back

[android] Fragment pressing back button

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