I am working on a project and I need to be able to use the back button in each fragment to navigate between previous fragments, I have methods written to do so by using a back arrow in the action bar, however, I want to be able to use the same functionality on the back button pressed. I don't want to use the back stack. Is there a way to do this?
EDIT
Rather than using the back stack I want to be able to call the go back to previous method below when the user clicks the back button. I need to used the gobackpressed method within fragments. Is this possible? I hope this is clear and concise. Apologies for any confusion caused above.
Go Back to Previous
public void gobackToPreviousFragment(String preFragmentTag, Fragment preFragment){
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.setCustomAnimations(R.animator.close_slide_in,R.animator.close_slide_out);
ft.show(preFragment);
//**BY REMOVING FRAGMENT, WHEN USER TRIES TO REVISIT, FRAGMENT IS BLACK**
ft.remove(fm.findFragmentByTag(Misc.currentContentFragmentTag));
ft.addToBackStack(null);
ft.commit();
Misc.currentContentFragmentTag = preFragmentTag;
createBar(preFragment);
}
Go Forward
public void gotoNextFragment(String nextTag, Fragment nextFragment){
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.setCustomAnimations(R.animator.enter_slide_in, R.animator.enter_slide_out);
boolean newlyCreated = false;
if(nextFragment == null){
nextFragment = Fragment.instantiate(this, nextTag);
newlyCreated = true;
}
//hide current fragment
ft.hide(fm.findFragmentByTag(Misc.currentContentFragmentTag));
if(newlyCreated){
ft.add(R.id.content_frame, nextFragment, nextTag);
}
else{
ft.show(nextFragment);
}
ft.addToBackStack(null);
ft.commit();
Misc.currentContentFragmentTag = nextTag;
createBar(nextFragment);
}
These are how I navigate back and forth, and I'd like to be able to implement the go back method on the onBackPressed(). Does this make sense?
This works for me :D
@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 v, int keyCode, KeyEvent event) {
if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){
// handle back button's click listener
return true;
}
return false;
}
});}
For a Fragment you can simply add
getActivity().onBackPressed();
to your code
I didn't find any good answer about this problem, so this is my solution.
If you want to get backPress in each fragment do the following.
create interface OnBackPressedListener
public interface OnBackPressedListener {
void onBackPressed();
}
That each fragment that wants to be informed of backPress
implements this interface.
In parent activity , you can override onBackPressed()
@Override
public void onBackPressed() {
List<Fragment> fragmentList = getSupportFragmentManager().getFragments();
if (fragmentList != null) {
//TODO: Perform your logic to pass back press here
for(Fragment fragment : fragmentList){
if(fragment instanceof OnBackPressedListener){
((OnBackPressedListener)fragment).onBackPressed();
}
}
}
}
I found a new way to do it without interfaces. You only need to add the below code to the Fragment’s onCreate() method:
//overriding the fragment's oncreate
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//calling onBackPressedDispatcher and adding call back
requireActivity().onBackPressedDispatcher.addCallback(this) {
//do stuff here
}
}
requireActivity().onBackPressedDispatcher.addCallback(viewLifecycleOwner, object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
Log.w("a","")
}
})
You can try to override onCreateAnimation
, parameter and catch enter==false
. This will fire before every back press.
@Override
public Animation onCreateAnimation(int transit, boolean enter, int nextAnim) {
if(!enter){
//leaving fragment
Log.d(TAG,"leaving fragment");
}
return super.onCreateAnimation(transit, enter, nextAnim);
}
In the fragment where you would like to handle your back button you should attach stuff to your view in the oncreateview
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.second_fragment, container, false);
v.setOnKeyListener(pressed);
return v;
}
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
// TODO Auto-generated method stub
if( keyCode == KeyEvent.KEYCODE_BACK ){
// back to previous fragment by tag
myfragmentclass fragment = (myfragmentclass) getActivity().getSupportFragmentManager().findFragmentByTag(TAG);
if(fragment != null){
(getActivity().getSupportFragmentManager().beginTransaction()).replace(R.id.cf_g1_mainframe_fm, fragment).commit();
}
return true;
}
return false;
}
};
Use this:
@Override
public void onBackPressed() {
int fragments = getFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
finish();
}
super.onBackPressed();
}
Source: Stackoverflow.com