I am using a BottomNavigationView for a Tab-Interface in my main activity. in onCreate(), the switchTab method is called with the initial fragment. Tapping the the bottom navigation calls switchTab() for the respective tabs and should hide the current and display the new one. If the fragment was not added to the SupportFragmentManager, it gets added, otherwise it will be shown. Here's my code snippet:
private fun switchTab(fragment: Fragment, tag: String): Boolean {
val currentFragment = supportFragmentManager.fragments.find { it.tag == tag }
val ta = supportFragmentManager.beginTransaction()
if (currentFragment != null) {
ta.hide(currentFragment)
}
if (supportFragmentManager.fragments.contains(fragment)) {
ta.show(fragment)
} else {
ta.add(R.id.contentContainer, fragment, tag)
}
ta.commit()
return true
}
Now the problem is that sometimes two fragments are visible and overlay each other, making the userinterface unusable. How can this happen?
Related
I have some custom DialogFragments in my Android application. I would prevent the user from opening multiple dialogs, and I would also avoid disabling the button which shows the dialog once it's pressed or using a variable or it.
So I was trying to make an extension for the fragment which checks for shown fragments via their tags like this:
fun Fragment.isFragmentVisible(tag: String): Boolean {
val fragment = childFragmentManager.findFragmentByTag(tag)
if (fragment != null && fragment.isVisible) {
return true
}
return false
}
And before showing the dialog to check it like this:
binding.destination.editText?.setOnClickListener {
if (!isFragmentVisible(ShopsDialog.TAG)) {
ShopsDialog.newInstance(this, "Destinazione") { bundle ->
val shopId = bundle.getString("shopId")
viewModel.setDestination(shopId)
}
}
}
While the newInstance is:
fun newInstance(fragment: Fragment, title: String, bundle: (Bundle) -> Unit) = ShopsDialog().apply {
arguments = Bundle().apply {
putString(ARG_TITLE, title)
}
fragment.setFragmentResultListener(KEY_CALLBACK_BUNDLE) { requestKey: String, bundle: Bundle ->
if (requestKey == KEY_CALLBACK_BUNDLE) {
bundle(bundle)
}
}
show(fragment.childFragmentManager, TAG)
}
But this seems not to work, I've tried even to use requireActivity().supportFragmentManager instead childFragmentManager but still nothing...
Before showing bottomsheetdialogfragment , i think you can check it like this
if(childFragmentManager.findFragmentByTag(ShopsDialog::class.java.simpleName) == null){
// show your bottom sheet dialog fragment
}
If you are going to show bottomSheetDialogFragment in Fragment then use childFragmentManager and if it is activity then use supportFragmentManager
Let's assume a fragment has this ActivityResultLauncher:
class MyFragment : Fragment(R.layout.my_fragment_layout) {
companion object {
private const val EXTRA_ID = "ExtraId"
fun newInstance(id: String) = MyFragment().apply {
arguments = putString(EXTRA_ID, id)
}
}
private val launcher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {
if (it.resultCode == Activity.RESULT_OK) {
Timber.i("Callback successful")
}
}
...
This Fragment a wrapped in an Activity for temporary architectural reasons, it will eventually be moved into an existing coordinator pattern.
class FragmentWrapperActivity : AppCompatActivity() {
private lateinit var fragment: MyFragment
private lateinit var binding: ActivityFragmentWrapperBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityFragmentWrapperBinding.inflate(this)
setContentView(binding.root)
fragment = MyFragment.newInstance("blah")
supportFragmentManager.transact {
replace(R.id.fragment_container, fragment)
}
}
}
And we use that launcher to start an Activity, expecting a result:
fun launchMe() {
val intent = Intent(requireContext(), MyResultActivity::class.java)
launcher.launch(intent)
}
On a normal device with plenty of available memory, this works fine. MyResultActivity finishes with RESULT_OK, the callback is called and I see the log line.
However, where memory is an issue and the calling fragment is destroyed, the launcher (and its callback) is destroyed along with it. Therefore when MyResultActivity finishes, a new instance of my fragment is created which is completely unaware of what's just happened. This can be reproduced by destroying activities as soon as they no longer have focus (System -> Developer options -> Don't keep activities).
My question is, if my fragment is reliant on the status of a launched activity in order to process some information, if that fragment is destroyed then how will the new instance of this fragment know where to pick up where the old fragment left off?
Your minimal fragment is unconditionally replacing the existing fragment with a brand new fragment everytime it is created, thus causing the previous fragment, which has had its state restored, to be removed.
As per the Create a Fragment guide, you always need to wrap your code to create a fragment in onCreate in a check for if (savedInstanceState == null):
In the previous example, note that the fragment transaction is only created when savedInstanceState is null. This is to ensure that the fragment is added only once, when the activity is first created. When a configuration change occurs and the activity is recreated, savedInstanceState is no longer null, and the fragment does not need to be added a second time, as the fragment is automatically restored from the savedInstanceState.
So your code should actually look like:
fragment = if (savedInstanceState == null) {
// Create a new Fragment and add it to
// the FragmentManager
MyFragment.newInstance("blah").also { newFragment ->
supportFragmentManager.transact {
replace(R.id.fragment_container, newFragment)
}
}
} else {
// The fragment already exists, so
// get it from the FragmentManager
supportFragmentManager.findFragmentById(R.id.fragment_container) as MyFragment
}
I have a small app with on activity and two fragments inside. The fragments are loaded with the BottomNavitationView.
MonitoringFragment gets loaded on the OnCreate in the activity.
I want to add this one to the backstack so when I'm inside the second fragment (ConnectionFragment) and i press back I get to the first fragment. This works fine. However the BotttonNavigationView doesn't get updated (doesn't set the first item as selected when returning from second fragment. picture 3). I assume it doesn't handle this behavior by itself and I have to implement it myself but every attempt I made was unsuccessfull.
Activity code:
Fragment activeFragment = null;
BottomNavigationView bottomNavigationView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bottomNavigationView = findViewById(R.id.bottom_navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(item -> {
switch (item.getItemId()) {
case R.id.monitoring:
setCurrentFragment(new MonitoringFragment(), false);
break;
case R.id.connection:
setCurrentFragment(new ConnectionFragment(), true);
break;
}
return true;
});
setCurrentFragment(new MonitoringFragment(), true);
}
private void setCurrentFragment(Fragment fragment, boolean addToBackStack) {
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.fragment_container, fragment);
if (addToBackStack) {
fragmentTransaction.addToBackStack(null);
}
fragmentTransaction.commit();
activeFragment = fragment;
}
Thanks!
Yes, BottomNavigationView is not setup with fragmentManager. You might set prop select tab by yourself, when a fragment gets resumed.
Or you can use navigation component with BottomNavigationView, those working ok together.
With the second approach when pressing back button will not return you from 2nd fragment to 1st one.
Faced a similar problem, here is how I solved it
I added OnDestinationChangedListener to my navcontroller, and created several arraylists with destination label of fragments in my progect.
When current destination is in one of these fragments, bottom menu button is checked
I hope the code example is clearer than my explanation)
val destListNews = arrayListOf(
"news_fragment",
"NewsViewingFragment"
)
val destListAds = arrayListOf(
"ads_view_fragment",
"ads_fragment",
"AdsAddFragment"
)
val destListPass = arrayListOf(
"pass_fragment",
"pass_creation_fragment",
"PassViewFragment"
)
val destListVotes = arrayListOf(
"VotesListFragment",
"VotesAddFragment",
"ChooseVoteTypeFragment"
)
navController.addOnDestinationChangedListener { controller, destination, arguments ->
when (destination.label) {
in destListNews -> {
bottom_nav.menu.getItem(0).isChecked = true
}
in destListAds -> {
bottom_nav.menu.getItem(1).isChecked = true
}
in destListPass -> {
bottom_nav.menu.getItem(2).isChecked = true
}
in destListVotes -> {
bottom_nav.menu.getItem(3).isChecked = true
}
else -> {
bottom_nav.menu.getItem(4).isChecked = true
}
}
}
I face problem with changing fragment in my container. I have three navigation: Home, Special offers, Profile. In Home navigation it could be fragment1_1 or fragment2_2 depending on situation. My problem is getting showed fragment from my container. I try to get using findFragmentById, but when I in Profile navigation and try to go to Home my code do not hide() fragment from Pofile. I tried to see the logs and I see that it hides Home and shows Home. My code for navigation:
botNav.setOnNavigationItemSelectedListener {
when(it.itemId){
R.id.act_home -> {
if (!it.isChecked){
val homeFragment = supportFragmentManager.findFragmentByTag("Home")
activeFragment = supportFragmentManager.findFragmentById(R.id.fragment_container)
activeFragment?.let { hideFragment(it) }
showFragment(homeFragment!!)
}
}
R.id.act_profile_info -> {
if (!it.isChecked) {
activeFragment = supportFragmentManager.findFragmentById(R.id.fragment_container)
activeFragment?.let { hideFragment(it) }
showFragment(profileFragment)
}
}
R.id.act_special_offer -> {
if (!it.isChecked) {
activeFragment = supportFragmentManager.findFragmentById(R.id.fragment_container)
activeFragment?.let { hideFragment(it) }
showFragment(specialFragment)
}
}
}
return#setOnNavigationItemSelectedListener true
}
So now I want to understand why it is acting so and how can I get shown fragment from FrameLayout container.
For adding fragments for my navigation I used addFragment() function.
You can try this. Working fine for me tested.
Call this bellow method whenever want to add and show previous existing fragment
/**
* Method for add and replace and set fragment if exist in stack
*/
fun setAndReplaceFragment(fragmentWantToAdd: Fragment, tag: String) {
val manager = supportFragmentManager
val fragmentFind = manager.findFragmentByTag(tag)
if (fragmentFind != null) {
val ft = manager.beginTransaction()
ft.replace(R.id.mFrmContainer, fragmentFind, tag)
ft.addToBackStack(tag)
ft.commit()
} else {
val ft = manager.beginTransaction()
ft.replace(R.id.mFrmContainer, fragmentWantToAdd, tag)
ft.addToBackStack(tag)
ft.commit()
}
}
you can try this one :
//Fragment1 is your new fragment to be shown.
Fragment fragment=new Fragment1();
if (fragment != null) {
FragmentTransaction ft=getSupportFragmentManager().beginTransaction();
//frams is your backup fragment upon on your navigation/new black
fragment(thi will beshown if the Fragment1 is not working)
ft.replace(R.id.frams, fragment);
ft.commit();
I want to resume android fragments that are in the backstack. When switching between different tabs on bottomnavigation,i don't want the views of fragments to be recreated.
I read this, this,this and some other questions on stackoverflow related to this. Common suggestions are to use show and hide method of fragment transactions but it is not working. Here is my kotlin code:
bottomnavigation.setOnNavigationItemSelectedListener {
item ->
when(item.itemId){
R.id.first_fragment_item -> {
var fragment:Fragment = FirstFragment.newInstance()
replaceFragment(fragment)
return#setOnNavigationItemSelectedListener true
}
R.id.second_fragment_item -> {
var fragment:Fragment = SecondFragment.newInstance()
replaceFragment(fragment)
return#setOnNavigationItemSelectedListener true
}
}
return#setOnNavigationItemSelectedListener false
}
}
fun replaceFragment(fragment:Fragment) {
var fragmentName:String = fragment::class.simpleName!!
if(supportFragmentManager.findFragmentByTag(fragmentName)==null) {
val fragmentTransaction = supportFragmentManager.beginTransaction()
fragmentTransaction.replace(R.id.fragment_container, fragment, fragmentName)
fragmentTransaction.addToBackStack(fragmentName)
fragmentTransaction.commit()
}
else{
if(fragmentName == "FirstFragment") {
supportFragmentManager.beginTransaction().
hide(supportFragmentManager.findFragmentByTag("SecondFragment"))
.show(supportFragmentManager.findFragmentByTag("FirstFragment"))
.commit()
}
else{
supportFragmentManager.beginTransaction()
.hide(supportFragmentManager.findFragmentByTag("FirstFragment"))
.show(supportFragmentManager.findFragmentByTag("SecondFragment"))
.commit()
}
}
}
The last fragment of backstack is always shown. When i want to hide it and show
the other fragment, that fragment screen becomes white with nothing on it.
My bottomnavigation has four items but for testing purpose i am only using two. Two of fragments are FirstFragment and SecondFragment. I am using v4.app.fragments.
With the help of Kishan Viramgama comment's, i solved my problem. I used "add" method instead of "replace". This is my code for resuming fragments: `
fun replaceFragment(fragment: Fragment) {
var nameOfFragment: String? = fragment::class.simpleName
var fragmentTransaction = supportFragmentManager.beginTransaction()
var fm: FragmentManager = supportFragmentManager
if (supportFragmentManager.findFragmentByTag(nameOfFragment) == null) {
fragmentTransaction.add(R.id.root_fragments, fragment, nameOfFragment) //if fragment is not added to the backstack,add it/ don't use replace because it creates new fragment emptying fragment container
fragmentTransaction.addToBackStack(nameOfFragment)
fragmentTransaction.commit()
} else {
var fragmentToShow:Fragment = supportFragmentManager.findFragmentByTag(nameOfFragment) //if fragment is already in backstack,show it and hide all other fragments.
for (i in 0 until fm.backStackEntryCount) {
var fragmentToHide: Fragment = fm.findFragmentByTag(fm.getBackStackEntryAt(i).name)
if (fragmentToHide::class.simpleName != fragment::class.simpleName)
fragmentTransaction.hide(fragmentToHide)
}
fragmentTransaction.show(fragmentToShow)
fragmentTransaction.commit()
}
}
`