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I'm adding the fragment using android.R.id.content in order to fill up Activity's space using the following code.
private void doFragmentTransaction(Fragment fragment, String tag) {
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.setCustomAnimations(R.anim.slide_in_bottom_y, R.anim.slide_out_bottom_y,
R.anim.slide_in_bottom_y, R.anim.slide_out_bottom_y);
transaction.add(android.R.id.content, fragment, tag);
transaction.addToBackStack(tag);
transaction.commitAllowingStateLoss();
}
And I have got a problem to catch the moment that the fragment is closed by pressing back button. The lifecycle method onStop is not called.
What I should do in order to make it working properly that all lifecycle methods are called?
Hello you can work on activity onBackPressed() like below
#Override
public void onBackPressed() {
if (getSupportFragmentManager().getBackStackEntryCount() > 1) {
val frag = getSupportFragmentManager().findFragmentById(android.R.id.container);
if (frag is HomeFragment) {
Fragment currentFragment = (HomeFragment) frag;
//do your code
return
}
}
super.onBackPressed();
}
I am pretty new to android development so I am curious how to work properly with Fragments.
My application contains a BottomNavigationActivity which switches between 3 fragments with this code:
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_montage_order_detail, fragment).commit();
I am storing the Fragments in a List<Fragment> to avoid loosing the current state. But everytime I replace the fragment with another the method onDestroy() is called.
I know, I know I could add and remove the fragment in the fragmentmanager instead of replacing it. I googled alot and most of the tutorials tell me to replace the fragment.
Whats the common way to keep a fragments state without recreating it on every call?
Find the solution
It will not recreate fragment anytime
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().add(R.id.content_montage_order_detail, fragment).commit();
Use fragment TAG at time of creation of fragment then when you want to get it again use findFragmentByTag. if fragment already created then old one will be find by fragment manager.
Fragment previousFragment = fragmentManager.findFragmentByTag("TAG");
I suggest you use show,not forreplace
protected void addFragmentStack(Fragment fragment) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if (this.mContent != fragment) {
if (fragment.isAdded()) {
ft.hide(this.mContent).show(fragment);
} else {
ft.hide(this.mContent).add(getFragmentViewId(), fragment);
}
this.mContent = fragment;
}
ft.commit();
}
Try using switchFragment to switch fragment, it will show fragment if it is already added.
Use fragmentTransaction.show method to re-use existing fragment i.e. saved instance.
public void switchFragment (Fragment oldFragment, Fragment newFragment, int frameId) {
boolean addFragment = true;
FragmentManager fragmentManager = getFragmentManager ();
String tag = newFragment.getArguments ().getString (BaseFragment.TAG);
Fragment fragment = fragmentManager.findFragmentByTag (tag);
// Check if fragment is already added
if (fragment != null && fragment.isAdded ()) {
addFragment = false;
}
// Hide previous fragment
String oldFragmentTag = oldFragment.getArguments ().getString (BaseFragment.TAG);
if (!tag.equals (oldFragmentTag)) {
FragmentTransaction hideTransaction = fragmentManager.beginTransaction ();
Fragment fragment1 = fragmentManager.findFragmentByTag (oldFragmentTag);
hideTransaction.hide (fragment1);
hideTransaction.commit ();
}
// Add new fragment and show it
FragmentTransaction addTransaction = fragmentManager.beginTransaction ();
if (addFragment) {
addTransaction.add (frameId, newFragment, tag);
addTransaction.addToBackStack (tag);
}
else {
newFragment = fragmentManager.findFragmentByTag (tag);
}
addTransaction.show (newFragment);
addTransaction.commit ();
}
Ya, you can also manage the state by managing the backstack.
I have a fragment inside a group activity and I want to replace it with another fragment:
FragmentTransaction ft = getActivity().getFragmentManager().beginTransaction();
SectionDescriptionFragment bdf = new SectionDescriptionFragment();
ft.replace(R.id.book_description_fragment, bdf);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
It works fine when it is done as a seperate project without using activity group, every thing works fine in log cat as control goes inside getview(), but no view is visible, not even any exception arises, I want the book detail fragment to be replaced by section detail fragment.
Xml of book detail fragment has id book_description_fragment and xml for section description fragment has id section_description_fragment.
The above code is in onClick method of an item, I want that when user taps on an item in horizontal scroll view, then the fragment changes.
Fragments that are hard coded in XML, cannot be replaced. If you need to replace a fragment with another, you should have added them dynamically, first of all.
Note: R.id.fragment_container is a layout or container of your choice in the activity you are bringing the fragment to.
// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack if needed
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();
Please see this Question
You can only replace a "dynamically added fragment".
So, if you want to add a dynamic fragment, see this example.
I've made a gist with THE perfect method to manage fragment replacement and lifecycle.
It only replace the current fragment by a new one, if it's not the same and if it's not in backstack (in this case it will pop it).
It contain several option as if you want the fragment to be saved in backstack.
=> See Gist here
Using this and a single Activity, you may want to add this to your activity:
#Override
public void onBackPressed() {
int fragments = getSupportFragmentManager().getBackStackEntryCount();
if (fragments == 1) {
finish();
return;
}
super.onBackPressed();
}
Use the below code in android.support.v4
FragmentTransaction ft1 = getFragmentManager().beginTransaction();
WebViewFragment w1 = new WebViewFragment();
w1.init(linkData.getLink());
ft1.addToBackStack(linkData.getName());
ft1.replace(R.id.listFragment, w1);
ft1.commit();
Use ViewPager. It's work for me.
final ViewPager viewPager = (ViewPager) getActivity().findViewById(R.id.vp_pager);
button = (Button)result.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
viewPager.setCurrentItem(1);
}
});
hope you are doing well.when I started work with Android Fragments then I was also having the same problem then I read about
1- How to switch fragment with other.
2- How to add fragment if Fragment container does not have any fragment.
then after some R&D, I created a function which helps me in many Projects till now and I am still using this simple function.
public void switchFragment(BaseFragment baseFragment) {
try {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.setCustomAnimations(android.R.anim.slide_in_left, android.R.anim.slide_out_right);
if (getSupportFragmentManager().findFragmentById(R.id.home_frame) == null) {
ft.add(R.id.home_frame, baseFragment);
} else {
ft.replace(R.id.home_frame, baseFragment);
}
ft.addToBackStack(null);
ft.commit();
} catch (Exception e) {
e.printStackTrace();
}
}
enjoy your code time :)
you can use simple code its work for transaction
Fragment newFragment = new MainCategoryFragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame_NavButtom, newFragment);
ft.commit();
You Can Use This code
((AppCompatActivity) getActivity()).getSupportFragmentManager().beginTransaction().replace(R.id.YourFrameLayout, new YourFragment()).commit();
or You Can This Use Code
YourFragment fragments=(YourFragment) getSupportFragmentManager().findFragmentById(R.id.FrameLayout);
if (fragments==null) {
getSupportFragmentManager().beginTransaction().replace(R.id.FrameLayout, new Fragment_News()).commit();
}
I change fragment dynamically in single line code
It is work in any SDK version and androidx
I use navigation as BottomNavigationView
BottomNavigationView btn_nav;
FragmentFirst fragmentFirst;
FragmentSecond fragmentSecond;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
fragmentFirst = new FragmentFirst();
fragmentSecond = new FragmentSecond ();
changeFragment(fragmentFirst); // at first time load the fragmentFirst
btn_nav = findViewById(R.id.bottomNav);
btn_nav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem menuItem) {
switch(menuItem.getItemId()){
case R.id.menu_first_frag:
changeFragment(fragmentFirst); // change fragmentFirst
break;
case R.id.menu_second_frag:
changeFragment(fragmentSecond); // change fragmentSecond
break;
default:
Toast.makeText(SearchActivity.this, "Click on wrong bottom SORRY!", Toast.LENGTH_SHORT).show();
}
return true;
}
});
}
public void changeFragment(Fragment fragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_layout_changer, fragment).commit();
}
In kotlin you can do:
// instantiate the new fragment
val fragment: Fragment = ExampleFragment()
val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.book_description_fragment, fragment)
transaction.addToBackStack("transaction_name")
// Commit the transaction
transaction.commit()
This will work if you're trying to change the fragment from another fragment.
Objects.requireNonNull(getActivity()).getSupportFragmentManager()
.beginTransaction()
.replace(R.id.home_fragment_container,new NewFragment())
NOTE As stated in the above answers, You need to have dynamic fragments.
You can use fragment-ktx
// If you are in fragmet
childFragmentManager.beginTransaction()
// or if you are in activiry
supportFragmentManager.beginTransaction()
// Create and commit a new transaction
supportFragmentManager.commit {
setReorderingAllowed(true)
// Replace whatever is in the fragment_container view with this fragment
replace<ExampleFragment>(R.id.fragment_container)
}
To replace a fragment with another one do this, Note that R.id.fragment comes from the id that you give to the first tag of the fragment in the XML.
barAudioPlaying.setOnClickListener(view -> {
getActivity().getSupportFragmentManager()
.beginTransaction()
.replace(R.id.fragment,new HomeFragment())
.commit();
My activity is composed of 3 nested Fragments. There is my MainFragment that is displayed by default, ProductFragment that can be called from it, then DetailFragment can be called from ProductFragment.
I can go back and forth between my ProductFragment and DetailFragment. By doing so, the popStackBack method is accumulating similar fragments. Then, if I click on the back button, It will go back through all the Fragments as many time I called them.
What is the proper way to avoid the same Fragment to be kept in the back stack ?
EDIT :
I firstly call my main fragment :
if (savedInstanceState == null) {
getFragmentManager()
.beginTransaction()
.add(R.id.container, new SearchFragment(), "SEARCH_TAG")
.commit();
}
Here is the code that calls the fragments from the activity :
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.setCustomAnimations(R.animator.enter_from_bottom, R.animator.exit_to_top, R.animator.enter_from_bottom, R.animator.exit_to_top);
ft.replace(R.id.container, new FactFragment(), "FACT_TAG");
ft.addToBackStack("FACT_TAG");
ft.commit();
Then, on back click :
#Override
public void onBackPressed() {
getFragmentManager().popBackStack();
}
I tried to get the tag of my current fragment and execute some specific code related to it but it doesn't work well. I also tried to addToBackStack() only when current Fragment wasn't already added to the backStack but it messed up my fragment view.
Use fragment's method isAdded() to evaluate the insertion. For example:
if(!frag.isAdded()){
//do fragment transaction and add frag
}
Here is my solution. Maybe dirty but it works. I implemented a method that returns the tag of the fragment that is displayed before clicking the on back button :
public String getActiveFragment() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
return null;
}
String tag = getFragmentManager()
.getBackStackEntryAt(getFragmentManager()
.getBackStackEntryCount() - 1)
.getName();
return tag;
}
Then, on my onBackPressed() method :
// Get current Fragment tag
String currentFrag = getActiveFragment();
if(currentFrag.equals("PRODUCT_TAG")) {
// New transaction to first Fragment
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.setCustomAnimations(R.animator.enter_from_right, R.animator.exit_to_left, R.animator.enter_from_right, R.animator.exit_to_left);
ft.replace(R.id.container, new SearchFragment(), "MAIN_TAG");
ft.commit();
} else {
// Go to Fragment-1
getFragmentManager().popBackStack();
}
Here is my handy and simple solution to check for duplicate insertion through fragment manager
at first, I check if it is first time intention for adding fragment and then I check if the fragment is presented using fragment manager
Fragment fragment = getSupportFragmentManager().findFragmentByTag("firstFragment");
if (fragment == null) {
getSupportFragmentManager().beginTransaction().add(R.id.frameLayout, new FirstFragment(), "firstFragment")
.addToBackStack(null)
.commit();
}else if(!fragment.isAdded()){
getSupportFragmentManager().beginTransaction().add(R.id.frameLayout, new FirstFragment(), "firstFragment")
.addToBackStack(null)
.commit();
}
Here is my solution:
Fragment curFragment = fragmentManager.findFragmentById(R.id.frameLayout);
if(curFragment != null
&& curFragment.getClass().equals(fragment.getClass())) return;
// add the fragment to BackStack here
Xamarin.Android (C#) version:
var curFragment = fragmentManager.FindFragmentById(Resource.Id.frameLayout);
if (curFragment != null
&& curFragment.GetType().Name == fragment.GetType().Name) return;
// add the fragment to BackStack here
I'm working on an android application, that uses a navigation drawer to switch between two fragments. However, each time I switch, the fragment is completely recreated.
Here is the code from my main activity.
/* The click listener for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
android.support.v4.app.Fragment fragment;
String tag;
android.support.v4.app.FragmentManager; fragmentManager = getSupportFragmentManager();
switch(position) {
case 0:
if(fragmentManager.findFragmentByTag("one") != null) {
fragment = fragmentManager.findFragmentByTag("one");
} else {
fragment = new OneFragment();
}
tag = "one";
break;
case 1:
if(fragmentManager.findFragmentByTag("two") != null) {
fragment = fragmentManager.findFragmentByTag("two");
} else {
fragment = new TwoFragment();
}
tag = "two";
break;
}
fragment.setRetainInstance(true);
fragmentManager.beginTransaction().replace(R.id.container, fragment, tag).commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mNavTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
I've set up some debug logging, and every time selectItem is called, one fragment is destroyed, while the other is created.
Is there any way to prevent the fragments from being recreated, and just reuse them instead?
After #meredrica pointed out that replace() destroys the fragments, I went back through the FragmentManager documentation. This is the solution I've come up with, that seems to be working.
/* The click listener for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
android.support.v4.app.FragmentManager; fragmentManager = getSupportFragmentManager();
switch(position) {
case 0:
if(fragmentManager.findFragmentByTag("one") != null) {
//if the fragment exists, show it.
fragmentManager.beginTransaction().show(fragmentManager.findFragmentByTag("one")).commit();
} else {
//if the fragment does not exist, add it to fragment manager.
fragmentManager.beginTransaction().add(R.id.container, new OneFragment(), "one").commit();
}
if(fragmentManager.findFragmentByTag("two") != null){
//if the other fragment is visible, hide it.
fragmentManager.beginTransaction().hide(fragmentManager.findFragmentByTag("two")).commit();
}
break;
case 1:
if(fragmentManager.findFragmentByTag("two") != null) {
//if the fragment exists, show it.
fragmentManager.beginTransaction().show(fragmentManager.findFragmentByTag("two")).commit();
} else {
//if the fragment does not exist, add it to fragment manager.
fragmentManager.beginTransaction().add(R.id.container, new TwoFragment(), "two").commit();
}
if(fragmentManager.findFragmentByTag("one") != null){
//if the other fragment is visible, hide it.
fragmentManager.beginTransaction().hide(fragmentManager.findFragmentByTag("one")).commit();
}
break;
}
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mNavTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
I also added this bit, but I'm not sure if it's necessary or not.
#Override
public void onDestroy() {
super.onDestroy();
FragmentManager fragmentManager = getSupportFragmentManager();
if(fragmentManager.findFragmentByTag("one") != null){
fragmentManager.beginTransaction().remove(fragmentManager.findFragmentByTag("one")).commit();
}
if(fragmentManager.findFragmentByTag("two") != null){
fragmentManager.beginTransaction().remove(fragmentManager.findFragmentByTag("two")).commit();
}
}
Use the attach/detach method with tags:
Detach will destroy the view hirachy but keeps the state, like if on the backstack; this will let the "not-visible" fragment have a smaller memory footprint. But mind you that you need to correctly implement the fragment lifecycle (which you should do in the first place)
Detach the given fragment from the UI. This is the same state as when it is put on the back stack: the fragment is removed from the UI, however its state is still being actively managed by the fragment manager. When going into this state its view hierarchy is destroyed.
The first time you add the fragment
FragmentTransaction t = getSupportFragmentManager().beginTransaction();
t.add(android.R.id.content, new MyFragment(),MyFragment.class.getSimpleName());
t.commit();
then you detach it
FragmentTransaction t = getSupportFragmentManager().beginTransaction();
t.detach(MyFragment.class.getSimpleName());
t.commit();
and attach it again if switched back, state will be kept
FragmentTransaction t = getSupportFragmentManager().beginTransaction();
t.attach(getSupportFragmentManager().findFragmentByTag(MyFragment.class.getSimpleName()));
t.commit();
But you always have to check if the fragment was added yet, if not then add it, else just attach it:
if (getSupportFragmentManager().findFragmentByTag(MyFragment.class.getSimpleName()) == null) {
FragmentTransaction t = getSupportFragmentManager().beginTransaction();
t.add(android.R.id.content, new MyFragment(), MyFragment.class.getSimpleName());
t.commit();
} else {
FragmentTransaction t = getSupportFragmentManager().beginTransaction();
t.attach(getSupportFragmentManager().findFragmentByTag(MyFragment.class.getSimpleName()));
t.commit();
}
The replace method destroys your fragments. One workaround is to set them to Visibility.GONE, another (less easy) method is to hold them in a variable. If you do that, make sure you don't leak memory left and right.
I did this before like this:
if (mPrevFrag != fragment) {
// Change
FragmentTransaction ft = fragmentManager.beginTransaction();
if (mPrevFrag != null){
ft.hide(mPrevFrag);
}
ft.show(fragment);
ft.commit();
mPrevFrag = fragment;
}
(you will need to track your pervious fragment in this solution)
I guess you can not directly manipulate the lifecycle mechanisms of your Fragments. The very fact that you can findFragmentByTag is not very bad. It means that the Fragment object is not recreated fully, if it is already commited. The existing Fragment just passes all the lifecycle steps each Fragment has - that means that only UI is "recreated".
It is a very convenient and useful memory management strategy - and appropriate, in most cases. Fragment which is gone, has the resources which have to be utilized in order to de-allocate memory.
If you just cease using this strategy, the memory usage of your application could increase badly.
Nonetheless, there are retained fragments, which lifecycle is a bit different and do not correspond to the Activity they are attached to. Typically, they are used to retain some things you want to save, for example, to manage configuration changes
However, the fragment [re]creation strategy depends on the context - that is, what you would like to solve, and what are the trade-offs that you are willing to accept.
Just find the current fragment calling getFragmentById("id of your container") and then hide it and show needed fragment.
private void openFragment(Fragment fragment, String tag) {
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment existingFragment = fragmentManager.findFragmentByTag(tag);
if (existingFragment != null) {
Fragment currentFragment = fragmentManager.findFragmentById(R.id.container);
fragmentTransaction.hide(currentFragment);
fragmentTransaction.show(existingFragment);
}
else {
fragmentTransaction.add(R.id.container, fragment, tag);
}
fragmentTransaction.commit();
}
Same idea as Tester101 but this is what I ended up using.
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment oldFragment = fragmentManager.findFragmentByTag( "" + m_lastDrawerSelectPosition );
if ( oldFragment != null )
fragmentTransaction.hide( oldFragment );
Fragment newFragment = fragmentManager.findFragmentByTag( "" + position );
if ( newFragment == null )
{
newFragment = getFragment( position );
fragmentTransaction.add( R.id.home_content_frame, newFragment, "" + position );
}
fragmentTransaction.show( newFragment );
fragmentTransaction.commit();
Hide easily in kotlin using extensions:
fun FragmentManager.present(newFragment: Fragment, lastFragment: Fragment? = null, containerId: Int) {
if (lastFragment == newFragment) return
val transaction = beginTransaction()
if (lastFragment != null && findFragmentByTag(lastFragment.getTagg()) != null) {
transaction.hide(lastFragment)
}
val existingFragment = findFragmentByTag(newFragment.getTagg())
if (existingFragment != null) {
transaction.show(existingFragment).commit()
} else {
transaction.add(containerId, newFragment, newFragment.getTagg()).commit()
}
}
fun Fragment.getTagg(): String = this::class.java.simpleName
Usage
supportFragmentManager.present(fragment, lastFragment, R.id.fragmentPlaceHolder)
lastFragment = fragment
Here's what I'm using for a simple 2 fragment case in Kotlin:
private val advancedHome = HomeAdvancedFragment()
private val basicHome = HomeBasicFragment()
override fun onCreate(savedInstanceState: Bundle?) {
...
// Attach both fragments and hide one so we can swap out easily later
supportFragmentManager.commit {
setReorderingAllowed(true)
add(R.id.fragment_container_view, basicHome)
add(R.id.fragment_container_view, advancedHome)
hide(basicHome)
}
binding.displayModeToggle.onStateChanged {
when (it) {
0 -> swapFragments(advancedHome, basicHome)
1 -> swapFragments(basicHome, advancedHome)
}
}
...
}
With this FragmentActivity extension:
fun FragmentActivity.swapFragments(show: Fragment, hide: Fragment) {
supportFragmentManager.commit {
show(show)
hide(hide)
}
}
How about playing with the Visible attribute?
this is a little late response.
if you're using view pager for fragments, set the off screen page limit of the fragment to the number of fragments created.
mViewPager.setOffscreenPageLimit(3); // number of fragments here is 3