onKey method never execute

onKey method never execute - android

I implemented an override to the back button key in the device. now for some reason the method onKey never execute and there fore when i click on the back button the application is minimize to the back instead doing the onKey code.
i am not sure what is the problem so i will upload my all code.
This is my code:
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
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_DOWN) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
String frag_name = getFragmentManager().getBackStackEntryAt(getFragmentManager().getBackStackEntryCount() - 1).getName();
Log.d("frag name is", frag_name);
Fragment fragment = null;
switch (frag_name){
case "back_to_attending":
fragment = new AttendingListFragmentController();
break;
case "back_to_invitations":
fragment = new InvitationsFragmentController();
break;
case "waiting_list":
fragment = new WaitingEventListFragmentController();
break;
default:
break;
}
if(fragment != null){
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.popBackStackImmediate();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment,frag_name).addToBackStack(frag_name).commit();
}
}
}
return false;
}
});
}

Try this:
public class MyClass implements OnKeyListener {
...
Then override the method onKey
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
//do what you want
return false;
}

What results do you get when you override onBackPressed() ?

Related

Hardware “back” button doesn't work after typing in edittext

in my form fragment Hardware "back" button work not correctly. For example when I opened fragment and when I didn't start typing, and I pressed Hardware "back" button it's work excellent. But when I started typing and after typing press to Hardware "back" button not working.
my form fragment i am using OnResume() method use to handle back button process.
#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){
//getView().clearFocus();
getActivity().getSupportFragmentManager().popBackStack();
return true;
}
return false;
}
});
}

Override onBackPressed()
#Override
public void onBackPressed()
{
moveTaskToBack(true);
}

EditText creditcatno= (EditText)view.findviewByid(R.id.ed1);
public void onResume() {  super.onResume();   creditcatno1.setOnKeyListener(new View.OnKeyListener() {  #Override  public boolean onKey(View v, int keyCode, KeyEvent event) {   if (keyCode == KeyEvent.KEYCODE_BACK) {  // call previous Fragment here  return true;   }  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 && keyCode == KeyEvent.KEYCODE_BACK) {  // handle back button's click listener  //Toast.makeText(getActivity(), "Back press", Toast.LENGTH_SHORT).show();  getActivity().getSupportFragmentManager().popBackStack();  return true;  }  return false;  }  });  }

Make a static string variable:
public static String currentFragment = "";
When openning the fragment set this variable value as your fragment name:
MainActivity.currentFragment = "your fragment name";
Now in the onbackpress method which is in the MainActivity:
#Override
public void onBackPressed() {
if(currentFragment.equals("your fragment name"){
// your onbackpress code for fragment
}else{
super.onBackPressed();
}
}

Android: Back button OnKeyListener inside Fragment is not working

The onKeyListener() in a Fragment is not working now. Here's the part of the code.
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment, null);
...
view.setFocusableInTouchMode(true);
view.requestFocus();
view.setOnKeyListener(new View.OnKeyListener() {
// true if the listener has consumed the event, false otherwise.
// the key event happens twice, when pressing and taking off.
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK && !touched) {
Log.i(TAG, "onKey() method");
touched = true;
return true;
} else {
return false;
}
}
});
return view;
}
Is there anything I am missing?

try this:
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
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_DOWN) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
//go to previous fragemnt
//perform your fragment transaction here
//pass data as arguments
return true;
}
}
return false;
}
});
}

This worked for me, for both Fragment & DialogFragment.
For Fragment:
#Override
public void onResume() {
super.onResume();
// Disable back press
requireView().setFocusableInTouchMode(true);
requireView().requestFocus();
requireView().setOnKeyListener((v, keyCode, event) -> keyCode == KeyEvent.KEYCODE_BACK);
}
For DialogFragment:
#Override
public void onResume() {
super.onResume();
requireDialog().setOnKeyListener((dialog, keyCode, event) ->
// Disable back pressed
keyCode == android.view.KeyEvent.KEYCODE_BACK
);
}

how to disable the back button in device by implement 1 function

i am trying to disable the back button in my device with the following code.
the code is working but i would like that the function that handle all the back button request in the fragments will derived from the Main Activity
this is the back button handler:
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
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_DOWN) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
Toast.makeText(getActivity(), "Please navigate via the menu", Toast.LENGTH_SHORT).show();
return true;
}
}
return false;
}
});
}

It's easier to override onBackPressed function:
private boolean disabled = true;
#Override
public void onBackPressed() {
if (!disabled) {
super.onBackPressed();
}
}
With this you can easy change disable flag and enable back button when needed.

#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
// TODO Auto-generated method stub
if (keyCode == KeyEvent.KEYCODE_BACK) {
//leave it empty
}
return super.onKeyDown(keyCode, event);
}

It's generally not the best idea to disable the back button as the user expects that button to perform some sort of back navigation. Now that being said, if you have a specific reason you can disable the back button by overriding the onBackPressed at the activity level and not calling into super.

Put this code at your MainActivity:
#Override
public void onBackPressed() {
executeAtAndroidOnBackPressed();
}
#Override
public boolean onKeyDown(final int keyCode, final KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
executeAtAndroidOnBackPressed();
}
return false;
}
protected void executeAtAndroidOnBackPressed() {
// do nothing
}

Fragment pressing back button

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);
}

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();
}
}

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 && 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 && 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

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.

Try this simple solution:
In your activity implement onBackPressed
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 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

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<Fragment> 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" -> doActionOne()
"FragmentTwo" -> doActionTwo()
else -> supportFragmentManager.popBackStack()
}
}

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 && 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 && 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) :-) ;-)

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

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.

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)&& webView.canGoBack()){
webView.goBack();
return true;
}
return false;
}
});
and import this class
import android.view.KeyEvent;

You can use getFragmentManager().popBackStack() in basic Fragment to go back.

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.

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);

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.

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.

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

Try this, its helped me :)
#Override
public void onResume() { //Pressed return button - returns to the results menu
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) {
/*Here your code*/
return true;
}
return false;
}
});
}

just paste it in your activity main
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (getSupportFragmentManager().getBackStackEntryCount() > 1) {
getSupportFragmentManager().popBackStack();
} else {
finish();
}
}

Android Fragment handle back button press [duplicate]

This question already has answers here:
How to implement onBackPressed() in Fragments?
(58 answers)
Closed 6 years ago.
I have some fragments in my activity
[1], [2], [3], [4], [5], [6]
And on Back Button Press I must to return from [2] to [1] if current active fragment is [2], or do nothing otherwise.
What is the best practise to do that?
EDIT: Application must not return to [2] from [3]...[6]

When you are transitioning between Fragments, call addToBackStack() as part of your FragmentTransaction:
FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();
If you require more detailed control (i.e. when some Fragments are visible, you want to suppress the back key) you can set an OnKeyListener on the parent view of your fragment:
//You need to add the following line for this solution to work; thanks skayred
fragment.getView().setFocusableInTouchMode(true);
fragment.getView().requestFocus();
fragment.getView().setOnKeyListener( new OnKeyListener()
{
#Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
return true;
}
return false;
}
} );

I'd rather do something like this:
private final static String TAG_FRAGMENT = "TAG_FRAGMENT";
private void showFragment() {
final Myfragment fragment = new MyFragment();
final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.fragment, fragment, TAG_FRAGMENT);
transaction.addToBackStack(null);
transaction.commit();
}
#Override
public void onBackPressed() {
final Myfragment fragment = (Myfragment) getSupportFragmentManager().findFragmentByTag(TAG_FRAGMENT);
if (fragment.allowBackPressed()) { // and then you define a method allowBackPressed with the logic to allow back pressed or not
super.onBackPressed();
}
}

if you overide the onKey method for the fragment view you're gonna need :
view.setFocusableInTouchMode(true);
view.requestFocus();
view.setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
Log.i(tag, "keyCode: " + keyCode);
if( keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP) {
Log.i(tag, "onKey Back listener is working!!!");
getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
return true;
}
return false;
}
});

Use addToBackStack method when replacing one fragment by another:
getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).addToBackStack("my_fragment").commit();
Then in your activity, use the following code to go back from a fragment to another (the previous one).
#Override
public void onBackPressed() {
if (getParentFragmentManager().getBackStackEntryCount() > 0) {
getParentFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}

If you want to handle hardware Back key event than you have to do following code in your onActivityCreated() method of Fragment.
You also need to check Action_Down or Action_UP event. If you will not check then onKey() Method will call 2 times.
Also, If your rootview(getView()) will not contain focus then it will not work. If you have clicked on any control then again you need to give focus to rootview using getView().requestFocus(); After this only onKeydown() will call.
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.

Create interfaces:
BackButtonHandlerInterface
public interface BackButtonHandlerInterface {
void addBackClickListener (OnBackClickListener onBackClickListener);
void removeBackClickListener (OnBackClickListener onBackClickListener);
}
OnBackClickListener
public interface OnBackClickListener {
boolean onBackClick();
}
In Activity:
public class MainActivity extends AppCompatActivity implements BackButtonHandlerInterface {
private ArrayList<WeakReference<OnBackClickListener>> backClickListenersList = new ArrayList<>();
#Override
public void addBackClickListener(OnBackClickListener onBackClickListener) {
backClickListenersList.add(new WeakReference<>(onBackClickListener));
}
#Override
public void removeBackClickListener(OnBackClickListener onBackClickListener) {
for (Iterator<WeakReference<OnBackClickListener>> iterator = backClickListenersList.iterator();
iterator.hasNext();){
WeakReference<OnBackClickListener> weakRef = iterator.next();
if (weakRef.get() == onBackClickListener){
iterator.remove();
}
}
}
#Override
public void onBackPressed() {
if(!fragmentsBackKeyIntercept()){
super.onBackPressed();
}
}
private boolean fragmentsBackKeyIntercept() {
boolean isIntercept = false;
for (WeakReference<OnBackClickListener> weakRef : backClickListenersList) {
OnBackClickListener onBackClickListener = weakRef.get();
if (onBackClickListener != null) {
boolean isFragmIntercept = onBackClickListener.onBackClick();
if (!isIntercept) isIntercept = isFragmIntercept;
}
}
return isIntercept;
}
}
In Fragment:
public class MyFragment extends Fragment implements OnBackClickListener{
private BackButtonHandlerInterface backButtonHandler;
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
backButtonHandler = (BackButtonHandlerInterface) activity;
backButtonHandler.addBackClickListener(this);
}
#Override
public void onDetach() {
super.onDetach();
backButtonHandler.removeBackClickListener(this);
backButtonHandler = null;
}
#Override
public boolean onBackClick() {
//This method handle onBackPressed()! return true or false
return false;
}
}
Update
Provide custom back navigation
class MyFragment : Fragment() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// This callback will only be called when MyFragment is at least Started.
val callback = requireActivity().onBackPressedDispatcher.addCallback(this) {
// Handle the back button event
}
// The callback can be enabled or disabled here or in the lambda
}
}

The most ideal way of doing this is found here:
Fragment: which callback invoked when press back button & customize it
public class MyActivity extends Activity
{
//...
//Defined in Activity class, so override
#Override
public void onBackPressed()
{
super.onBackPressed();
myFragment.onBackPressed();
}
}
public class MyFragment extends Fragment
{
//Your created method
public static void onBackPressed()
{
//Pop Fragments off backstack and do your other checks
}
}

#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){
if (mDrawerLayout.isDrawerOpen(GravityCompat.START)){
mDrawerLayout.closeDrawer(GravityCompat.START);
}
return true;
}
return false;
}
});
}

After looking at all solutions, I realised there is a much simpler solution.
In your activity's onBackPressed() that is hosting all your fragments, find the fragment that you want to prevent back press. Then if found, just return. Then popBackStack will never happen for this fragment.
#Override
public void onBackPressed() {
Fragment1 fragment1 = (Fragment1) getFragmentManager().findFragmentByTag(“Fragment1”);
if (fragment1 != null)
return;
if (getFragmentManager().getBackStackEntryCount() > 0){
getFragmentManager().popBackStack();
}
}

We created tiny library for handling back press across multiple fragments and/or in Activity. Usage is as simple as adding dependency in your gradle file:
compile 'net.skoumal.fragmentback:fragment-back:0.1.0'
Let your fragment implement BackFragment interface:
public abstract class MyFragment extends Fragment implements BackFragment {
public boolean onBackPressed() {
// -- your code --
// return true if you want to consume back-pressed event
return false;
}
public int getBackPriority() {
return NORMAL_BACK_PRIORITY;
}
}
Notify your fragments about back presses:
public class MainActivity extends AppCompatActivity {
#Override
public void onBackPressed() {
// first ask your fragments to handle back-pressed event
if(!BackFragmentHelper.fireOnBackPressedEvent(this)) {
// lets do the default back action if fragments don't consume it
super.onBackPressed();
}
}
}
For more details and other use-cases visit GitHub page:
https://github.com/skoumalcz/fragment-back

Or you could use getSupportFragmentManager().getBackStackEntryCount() to check what to do:
#Override
public void onBackPressed() {
logger.d("###### back stack entry count : " + getSupportFragmentManager().getBackStackEntryCount());
if (getSupportFragmentManager().getBackStackEntryCount() != 0) {
// only show dialog while there's back stack entry
dialog.show(getSupportFragmentManager(), "ConfirmDialogFragment");
} else if (getSupportFragmentManager().getBackStackEntryCount() == 0) {
// or just go back to main activity
super.onBackPressed();
}
}

If you manage the flow of adding to back stack every transaction, then you can do something like this in order to show the previous fragment when the user presses back button (you could map the home button too).
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0)
getFragmentManager().popBackStack();
else
super.onBackPressed();
}

For Those Who Use Static Fragment
In a case if you have a static fragment then It would be preferable.
Make an instance object of your fragment
private static MyFragment instance=null;
in onCreate() of MyFragment initialize that instance
instance=this;
also make a function to get Instance
public static MyFragment getInstance(){
return instance;
}
also make functions
public boolean allowBackPressed(){
if(allowBack==true){
return true;
}
return false;
}
//allowBack is a boolean variable that will be set to true at the action
//where you want that your backButton should not close activity. In my case I open
//Navigation Drawer then I set it to true. so when I press backbutton my
//drawer should be get closed
public void performSomeAction(){
//.. Your code
///Here I have closed my drawer
}
In Your Activity You can do
#Override
public void onBackPressed() {
if (MyFragment.getInstance().allowBackPressed()) {
MyFragment.getInstance().performSomeAction();
}
else{
super.onBackPressed();
}
}

Working Code:
package com.example.keralapolice;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentManager.OnBackStackChangedListener;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
public class ChiefFragment extends Fragment {
View view;
// public OnBackPressedListener onBackPressedListener;
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle args) {
view = inflater.inflate(R.layout.activity_chief, container, false);
getActivity().getActionBar().hide();
view.setFocusableInTouchMode(true);
view.requestFocus();
view.setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
Log.i(getTag(), "keyCode: " + keyCode);
if (keyCode == KeyEvent.KEYCODE_BACK) {
getActivity().getActionBar().show();
Log.i(getTag(), "onKey Back listener is working!!!");
getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
// String cameback="CameBack";
Intent i = new Intent(getActivity(), home.class);
// i.putExtra("Comingback", cameback);
startActivity(i);
return true;
} else {
return false;
}
}
});
return view;
}
}

I think the easiest way is to create an interface, and in the Activity check if the fragment is of the interface type, and if so, call its method to handle the pop. Here's the interface to implement in the fragment.
public interface BackPressedFragment {
// Note for this to work, name AND tag must be set anytime the fragment is added to back stack, e.g.
// getActivity().getSupportFragmentManager().beginTransaction()
// .replace(R.id.fragment_container, MyFragment.newInstance(), "MY_FRAG_TAG")
// .addToBackStack("MY_FRAG_TAG")
// .commit();
// This is really an override. Should call popBackStack itself.
void onPopBackStack();
}
Here's how to implement it.
public class MyFragment extends Fragment implements BackPressedFragment
#Override
public void onPopBackStack() {
/* Your code goes here, do anything you want. */
getActivity().getSupportFragmentManager().popBackStack();
}
And in your Activity, when you handle the pop (likely in both onBackPressed and onOptionsItemSelected), pop the backstack using this method:
public void popBackStack() {
FragmentManager fm = getSupportFragmentManager();
// Call current fragment's onPopBackStack if it has one.
String fragmentTag = fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 1).getName();
Fragment currentFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
if (currentFragment instanceof BackPressedFragment)
((BackPressedFragment)currentFragment).onPopBackStack();
else
fm.popBackStack();
}

I'm working with SlidingMenu and Fragment, present my case here and hope helps somebody.
Logic when [Back] key pressed :
When SlidingMenu shows, close it, no more things to do.
Or when 2nd(or more) Fragment showing, slide back to previous Fragment, and no more things to do.
SlidingMenu not shows, current Fragment is #0, do the original [Back] key does.
public class Main extends SherlockFragmentActivity
{
private SlidingMenu menu=null;
Constants.VP=new ViewPager(this);
//Some stuff...
#Override
public void onBackPressed()
{
if(menu.isMenuShowing())
{
menu.showContent(true); //Close SlidingMenu when menu showing
return;
}
else
{
int page=Constants.VP.getCurrentItem();
if(page>0)
{
Constants.VP.setCurrentItem(page-1, true); //Show previous fragment until Fragment#0
return;
}
else
{super.onBackPressed();} //If SlidingMenu is not showing and current Fragment is #0, do the original [Back] key does. In my case is exit from APP
}
}
}

This is a very good and reliable solution: http://vinsol.com/blog/2014/10/01/handling-back-button-press-inside-fragments/
The guy has made an abstract fragment that handles the backPress behaviour and is switching between the active fragments using the strategy pattern.
For some of you there maybe a little drawback in the abstract class...
Shortly, the solution from the link goes like this:
// Abstract Fragment handling the back presses
public abstract class BackHandledFragment extends Fragment {
protected BackHandlerInterface backHandlerInterface;
public abstract String getTagText();
public abstract boolean onBackPressed();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(!(getActivity() instanceof BackHandlerInterface)) {
throw new ClassCastException("Hosting activity must implement BackHandlerInterface");
} else {
backHandlerInterface = (BackHandlerInterface) getActivity();
}
}
#Override
public void onStart() {
super.onStart();
// Mark this fragment as the selected Fragment.
backHandlerInterface.setSelectedFragment(this);
}
public interface BackHandlerInterface {
public void setSelectedFragment(BackHandledFragment backHandledFragment);
}
}
And usage in the activity:
// BASIC ACTIVITY CODE THAT LETS ITS FRAGMENT UTILIZE onBackPress EVENTS
// IN AN ADAPTIVE AND ORGANIZED PATTERN USING BackHandledFragment
public class TheActivity extends FragmentActivity implements BackHandlerInterface {
private BackHandledFragment selectedFragment;
#Override
public void onBackPressed() {
if(selectedFragment == null || !selectedFragment.onBackPressed()) {
// Selected fragment did not consume the back press event.
super.onBackPressed();
}
}
#Override
public void setSelectedFragment(BackHandledFragment selectedFragment) {
this.selectedFragment = selectedFragment;
}
}

rootView.setFocusableInTouchMode(true);
rootView.requestFocus();
rootView.setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
Fragment NameofFragment = new NameofFragment;
FragmentTransaction transaction=getFragmentManager().beginTransaction();
transaction.replace(R.id.frame_container,NameofFragment);
transaction.commit();
return true;
}
return false;
}
});
return rootView;

Add addToBackStack() to fragment transaction and then use below code for Implementing Back Navigation for Fragments
getSupportFragmentManager().addOnBackStackChangedListener(
new FragmentManager.OnBackStackChangedListener() {
public void onBackStackChanged() {
// Update your UI here.
}
});

if you are using FragmentActivity. then do like this
first call This inside your Fragment.
public void callParentMethod(){
getActivity().onBackPressed();
}
and then Call onBackPressed method in side your parent FragmentActivity class.
#Override
public void onBackPressed() {
//super.onBackPressed();
//create a dialog to ask yes no question whether or not the user wants to exit
...
}

You can use from getActionBar().setDisplayHomeAsUpEnabled() :
#Override
public void onBackStackChanged() {
int backStackEntryCount = getFragmentManager().getBackStackEntryCount();
if(backStackEntryCount > 0){
getActionBar().setDisplayHomeAsUpEnabled(true);
}else{
getActionBar().setDisplayHomeAsUpEnabled(false);
}
}

Add this code in your Activity
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
super.onBackPressed();
} else {
getFragmentManager().popBackStack();
}
}
And add this line in your Fragment before commit()
ft.addToBackStack("Any name");

in fragment class put this code for back event:
rootView.setFocusableInTouchMode(true);
rootView.requestFocus();
rootView.setOnKeyListener( new OnKeyListener()
{
#Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
if( keyCode == KeyEvent.KEYCODE_BACK )
{
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.frame_container, new Book_service_provider()).commit();
return true;
}
return false;
}
} );

Checking the backstack works perfectly
#Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if (keyCode == KeyEvent.KEYCODE_BACK)
{
if (getFragmentManager().getBackStackEntryCount() == 1)
{
// DO something here since there is only one fragment left
// Popping a dialog asking to quit the application
return false;
}
}
return super.onKeyDown(keyCode, event);
}

In your oncreateView() method you need to write this code and in KEYCODE_BACk condition you can write whatever the functionality you want
View v = inflater.inflate(R.layout.xyz, container, false);
//Back pressed Logic for fragment
v.setFocusableInTouchMode(true);
v.requestFocus();
v.setOnKeyListener(new View.OnKeyListener() {
#Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_DOWN) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
getActivity().finish();
Intent intent = new Intent(getActivity(), MainActivity.class);
startActivity(intent);
return true;
}
}
return false;
}
});

Develop Reference

The Android operating system is a mobile operating system that was developed by Google (GOOGL?) to be primarily used for touchscreen devices, cell phones, and tablets.

onKey method never execute - android

Try this: public class MyClass implements OnKeyListener { ... Then override the method onKey #Override public boolean onKey(View v, int keyCode, KeyEvent event) { //do what you want return false; }

What results do you get when you override onBackPressed() ?

Related

Hardware “back” button doesn't work after typing in edittext

Android: Back button OnKeyListener inside Fragment is not working

how to disable the back button in device by implement 1 function

Fragment pressing back button

Android Fragment handle back button press [duplicate]

Categories

Resources