I'm getting user reports from my app in the market, delivering the following exception:
java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState
at android.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1109)
at android.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:399)
at android.app.Activity.onBackPressed(Activity.java:2066)
at android.app.Activity.onKeyUp(Activity.java:2044)
at android.view.KeyEvent.dispatch(KeyEvent.java:2529)
at android.app.Activity.dispatchKeyEvent(Activity.java:2274)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1803)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1855)
at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1277)
at android.app.Activity.dispatchKeyEvent(Activity.java:2269)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1803)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.widget.TabHost.dispatchKeyEvent(TabHost.java:297)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1112)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1855)
at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1277)
at android.app.Activity.dispatchKeyEvent(Activity.java:2269)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1803)
at android.view.ViewRoot.deliverKeyEventPostIme(ViewRoot.java:2880)
at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2853)
at android.view.ViewRoot.handleMessage(ViewRoot.java:2028)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4028)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
at dalvik.system.NativeStart.main(Native Method)
Apparently it has something to do with a FragmentManager, which I don't use. The stacktrace doesn't show any of my own classes, so I have no idea where this exception occurs and how to prevent it.
For the record: I have a tabhost, and in each tab there is a ActivityGroup switching between Activities.
Please check my answer here. Basically I just had to :
#Override
protected void onSaveInstanceState(Bundle outState) {
//No call for super(). Bug on API Level > 11.
}
Don't make the call to super() on the saveInstanceState method. This was messing things up...
This is a known bug in the support package.
If you need to save the instance and add something to your outState Bundle you can use the following:
#Override
protected void onSaveInstanceState(Bundle outState) {
outState.putString("WORKAROUND_FOR_BUG_19917_KEY", "WORKAROUND_FOR_BUG_19917_VALUE");
super.onSaveInstanceState(outState);
}
In the end the proper solution was (as seen in the comments) to use :
transaction.commitAllowingStateLoss();
when adding or performing the FragmentTransaction that was causing the Exception.
There are many related problems with a similar error message. Check the second line of this particular stack trace. This exception is specifically related to the call to FragmentManagerImpl.popBackStackImmediate.
This method call, like popBackStack, will always fail with IllegalStateException if the session state has already been saved. Check the source. There is nothing you can do to stop this exception being thrown.
Removing the call to super.onSaveInstanceState will not help.
Creating the Fragment with commitAllowingStateLoss will not help.
Here's how I observed the problem:
There's a form with a submit button.
When the button is clicked a dialog is created and an async process starts.
The user clicks the home key before the process is finished - onSaveInstanceState is called.
The process completes, a callback is made and popBackStackImmediate is attempted.
IllegalStateException is thrown.
Here's what I did to solve it:
As it is not possible to avoid the IllegalStateException in the callback, catch & ignore it.
try {
activity.getSupportFragmentManager().popBackStackImmediate(name);
} catch (IllegalStateException ignored) {
// There's no way to avoid getting this if saveInstanceState has already been called.
}
This is enough to stop the app from crashing. But now the user will restore the app and see that the button they thought they'd pressed hasn't been pressed at all (they think). The form fragment is still showing!
To fix this, when the dialog is created, make some state to indicate the process has started.
progressDialog.show(fragmentManager, TAG);
submitPressed = true;
And save this state in the bundle.
#Override
public void onSaveInstanceState(Bundle outState) {
...
outState.putBoolean(SUBMIT_PRESSED, submitPressed);
}
Don't forget to load it back again in onViewCreated
Then, when resuming, rollback the fragments if submit was previously attempted. This prevents the user from coming back to what seems like an un-submitted form.
#Override
public void onResume() {
super.onResume();
if (submitPressed) {
// no need to try-catch this, because we are not in a callback
activity.getSupportFragmentManager().popBackStackImmediate(name);
submitPressed = false;
}
}
Check if the activity isFinishing() before showing the fragment and pay attention to commitAllowingStateLoss().
Example:
if(!isFinishing()) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
DummyFragment dummyFragment = DummyFragment.newInstance();
ft.add(R.id.dummy_fragment_layout, dummyFragment);
ft.commitAllowingStateLoss();
}
It's October 2017, and Google makes Android Support Library with the new things call Lifecycle component. It provides some new idea for this 'Can not perform this action after onSaveInstanceState' problem.
In short:
Use lifecycle component to determine if it's correct time for popping up your fragment.
Longer version with explain:
why this problem come out?
It's because you are trying to use FragmentManager from your activity(which is going to hold your fragment I suppose?) to commit a transaction for you fragment. Usually this would look like you are trying to do some transaction for an up coming fragment, meanwhile the host activity already call savedInstanceState method(user may happen to touch the home button so the activity calls onStop(), in my case it's the reason)
Usually this problem shouldn't happen -- we always try to load fragment into activity at the very beginning, like the onCreate() method is a perfect place for this. But sometimes this do happen, especially when you can't decide what fragment you will load to that activity, or you are trying to load fragment from an AsyncTask block(or anything will take a little time). The time, before the fragment transaction really happens, but after the activity's onCreate() method, user can do anything. If user press the home button, which triggers the activity's onSavedInstanceState() method, there would be a can not perform this action crash.
If anyone want to see deeper in this issue, I suggest them to take a look at this blog post. It looks deep inside the source code layer and explain a lot about it. Also, it gives the reason that you shouldn't use the commitAllowingStateLoss() method to workaround this crash(trust me it offers nothing good for your code)
How to fix this?
Should I use commitAllowingStateLoss() method to load fragment? Nope you shouldn't;
Should I override onSaveInstanceState method, ignore super method inside it? Nope you shouldn't;
Should I use the magical isFinishing inside activity, to check if the host activity is at the right moment for fragment transaction? Yeah this looks like the right way to do.
Take a look at what Lifecycle component can do.
Basically, Google makes some implementation inside the AppCompatActivity class(and several other base class you should use in your project), which makes it a easier to determine current lifecycle state. Take a look back to our problem: why would this problem happen? It's because we do something at the wrong timing. So we try not to do it, and this problem will be gone.
I code a little for my own project, here is what I do using LifeCycle. I code in Kotlin.
val hostActivity: AppCompatActivity? = null // the activity to host fragments. It's value should be properly initialized.
fun dispatchFragment(frag: Fragment) {
hostActivity?.let {
if(it.lifecyclecurrentState.isAtLeast(Lifecycle.State.RESUMED)){
showFragment(frag)
}
}
}
private fun showFragment(frag: Fragment) {
hostActivity?.let {
Transaction.begin(it, R.id.frag_container)
.show(frag)
.commit()
}
As I show above. I will check the lifecycle state of the host activity. With Lifecycle component within support library, this could be more specific. The code lifecyclecurrentState.isAtLeast(Lifecycle.State.RESUMED) means, if current state is at least onResume, not later than it? Which makes sure my method won't be execute during some other life state(like onStop).
Is it all done?
Of course not. The code I have shown tells some new way to prevent application from crashing. But if it do go to the state of onStop, that line of code wont do things and thus show nothing on your screen. When users come back to the application, they will see an empty screen, that's the empty host activity showing no fragments at all. It's bad experience(yeah a little bit better than a crash).
So here I wish there could be something nicer: app won't crash if it comes to life state later than onResume, the transaction method is life state aware; besides, the activity will try continue to finished that fragment transaction action, after the user come back to our app.
I add something more to this method:
class FragmentDispatcher(_host: FragmentActivity) : LifecycleObserver {
private val hostActivity: FragmentActivity? = _host
private val lifeCycle: Lifecycle? = _host.lifecycle
private val profilePendingList = mutableListOf<BaseFragment>()
#OnLifecycleEvent(Lifecycle.Event.ON_RESUME)
fun resume() {
if (profilePendingList.isNotEmpty()) {
showFragment(profilePendingList.last())
}
}
fun dispatcherFragment(frag: BaseFragment) {
if (lifeCycle?.currentState?.isAtLeast(Lifecycle.State.RESUMED) == true) {
showFragment(frag)
} else {
profilePendingList.clear()
profilePendingList.add(frag)
}
}
private fun showFragment(frag: BaseFragment) {
hostActivity?.let {
Transaction.begin(it, R.id.frag_container)
.show(frag)
.commit()
}
}
}
I maintain a list inside this dispatcher class, to store those fragment don't have chance to finish the transaction action. And when user come back from home screen and found there is still fragment waiting to be launched, it will go to the resume() method under the #OnLifecycleEvent(Lifecycle.Event.ON_RESUME) annotation. Now I think it should be working like I expected.
Here is a different solution to this problem.
Using a private member variable you are able to set the returned data as an intent that can then be processed after super.onResume();
Like so:
private Intent mOnActivityResultIntent = null;
#Override
protected void onResume() {
super.onResume();
if(mOnActivityResultIntent != null){
... do things ...
mOnActivityResultIntent = null;
}
}
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data){
if(data != null){
mOnActivityResultIntent = data;
}
}
Short And working Solution :
Follow Simple Steps
Steps
Step 1 : Override onSaveInstanceState state in respective fragment. And remove super method from it.
#Override
public void onSaveInstanceState( Bundle outState ) {
}
Step 2 : Use
fragmentTransaction.commitAllowingStateLoss( );
instead of fragmentTransaction.commit( ); while fragment operations.
BEWARE, using transaction.commitAllowingStateLoss() could result in a bad experience for the user. For more information on why this exception is thrown, see this post.
I found a dirty solution for this kind of problem. If you still want to keep your ActivityGroups for whatever reason (I had time limitation reasons), you just implement
public void onBackPressed() {}
in your Activity and do some back code in there. even if there is no such Method on older Devices, this Method gets called by newer ones.
Do not use commitAllowingStateLoss(), it should only be used for cases where it is okay for the UI state to change unexpectedly on the user.
https://developer.android.com/reference/android/app/FragmentTransaction.html#commitAllowingStateLoss()
If the transaction happens in ChildFragmentManager of parentFragment, use
parentFragment.isResume() outside to check instead.
if (parentFragment.isResume()) {
DummyFragment dummyFragment = DummyFragment.newInstance();
transaction = childFragmentManager.BeginTransaction();
trans.Replace(Resource.Id.fragmentContainer, startFragment);
}
I had a similar problem, the scenario was like this:
My Activity is adding/replacing list fragments.
Each list fragment has a reference to the activity, to notify the activity when a list item is clicked (observer pattern).
Each list fragment calls setRetainInstance(true); in its onCreate method.
The onCreate method of the activity was like this:
mMainFragment = (SelectionFragment) getSupportFragmentManager()
.findFragmentByTag(MAIN_FRAGMENT_TAG);
if (mMainFragment == null) {
mMainFragment = new SelectionFragment();
mMainFragment.setListAdapter(new ArrayAdapter<String>(this,
R.layout.item_main_menu, getResources().getStringArray(
R.array.main_menu)));
mMainFragment.setOnSelectionChangedListener(this);
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.add(R.id.content, mMainFragment, MAIN_FRAGMENT_TAG);
transaction.commit();
}
The exception was thrown because the when configuration changes (device rotated), the activity is created, the main fragment is retrieved from the history of the fragment manager and at the same time the fragment already has an OLD reference to the destroyed activity
changing the implementation to this solved the problem:
mMainFragment = (SelectionFragment) getSupportFragmentManager()
.findFragmentByTag(MAIN_FRAGMENT_TAG);
if (mMainFragment == null) {
mMainFragment = new SelectionFragment();
mMainFragment.setListAdapter(new ArrayAdapter<String>(this,
R.layout.item_main_menu, getResources().getStringArray(
R.array.main_menu)));
FragmentTransaction transaction = getSupportFragmentManager()
.beginTransaction();
transaction.add(R.id.content, mMainFragment, MAIN_FRAGMENT_TAG);
transaction.commit();
}
mMainFragment.setOnSelectionChangedListener(this);
you need to set your listeners each time the activity is created to avoid the situation where the fragments have references to old destroyed instances of the activity.
If you inherit from FragmentActivity, you must call the superclass in onActivityResult():
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
...
}
If you don't do this and try to show a fragment dialog box in that method, you may get OP's IllegalStateException. (To be honest, I don't quite understand why the super call fixes the problem. onActivityResult() is called before onResume(), so it should still not be allowed to show a fragment dialog box.)
Fragment transactions should not be executed after Activity.onStop() !
Check that you do not have any callbacks that could execute transaction after onStop(). It is better to fix the reason instead of trying to walk around the problem with approaches like .commitAllowingStateLoss()
Possibly the smoothest and the simplest solution I found in my case was to avoid popping the offending fragment off the stack in response to activity result. So changing this call in my onActivityResult():
popMyFragmentAndMoveOn();
to this:
new Handler(Looper.getMainLooper()).post(new Runnable() {
public void run() {
popMyFragmentAndMoveOn();
}
}
helped in my case.
I was getting this exception when i was pressing back button to cancel intent chooser on my map fragment activity.
I resolved this by replacing the code of onResume(where i was initializing the fragment) to onstart() and the app is working fine.Hope it helps.
Courtesy: Solution for IllegalStateException
This issue had annoyed me for a lot of time but fortunately I came with a concrete solution for it. A detailed explanation of it is here.
Using commitAllowStateloss() might prevent this exception but would lead to UI irregularities.So far we have understood that IllegalStateException is encountered when we try to commit a fragment after the Activity state is lost- so we should just delay the transaction until the state is restored.It can be simply done like this
Declare two private boolean variables
public class MainActivity extends AppCompatActivity {
//Boolean variable to mark if the transaction is safe
private boolean isTransactionSafe;
//Boolean variable to mark if there is any transaction pending
private boolean isTransactionPending;
Now in onPostResume() and onPause we set and unset our boolean variable isTransactionSafe. Idea is to mark trasnsaction safe only when the activity is in foreground so there is no chance of stateloss.
/*
onPostResume is called only when the activity's state is completely restored. In this we will
set our boolean variable to true. Indicating that transaction is safe now
*/
public void onPostResume(){
super.onPostResume();
isTransactionSafe=true;
}
/*
onPause is called just before the activity moves to background and also before onSaveInstanceState. In this
we will mark the transaction as unsafe
*/
public void onPause(){
super.onPause();
isTransactionSafe=false;
}
private void commitFragment(){
if(isTransactionSafe) {
MyFragment myFragment = new MyFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.frame, myFragment);
fragmentTransaction.commit();
}
}
-What we have done so far will save from IllegalStateException but our transactions will be lost if they are done after the activity moves to background, kind of like commitAllowStateloss(). To help with that we have isTransactionPending boolean variable
public void onPostResume(){
super.onPostResume();
isTransactionSafe=true;
/* Here after the activity is restored we check if there is any transaction pending from
the last restoration
*/
if (isTransactionPending) {
commitFragment();
}
}
private void commitFragment(){
if(isTransactionSafe) {
MyFragment myFragment = new MyFragment();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.frame, myFragment);
fragmentTransaction.commit();
isTransactionPending=false;
}else {
/*
If any transaction is not done because the activity is in background. We set the
isTransactionPending variable to true so that we can pick this up when we come back to
foreground
*/
isTransactionPending=true;
}
}
I think using transaction.commitAllowingStateLoss(); is not best solution.
This exception will be thrown when activity's configuration changed and fragment onSavedInstanceState() is called and thereafter your async callback method tries to commit fragment.
Simple solution could be check whether activity is changing configuration or not
e.g. check isChangingConfigurations()
i.e.
if(!isChangingConfigurations()) {
//commit transaction.
}
Checkout this link as well
Whenever you are trying to load a fragment in your activity make sure that activity is in resume and not going to pause state.In pause state you may end up losing commit operation that is done.
You can use transaction.commitAllowingStateLoss() instead of transaction.commit() to load fragment
or
Create a boolean and check if activity is not going to onpause
#Override
public void onResume() {
super.onResume();
mIsResumed = true;
}
#Override
public void onPause() {
mIsResumed = false;
super.onPause();
}
then while loading fragment check
if(mIsResumed){
//load the your fragment
}
If you are doing some FragmentTransaction in onActivityResult what you can do you can set some boolean value inside onActivityResult then in onResume you can do your FragmentTransaction on the basis of the boolean value. Please refer the code below.
#Override
protected void onResume() {
super.onResume;
if(isSwitchFragment){
isSwitchFragment=false;
bottomNavigationView.getTabAt(POS_FEED).select();
}
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == FilterActivity.FILTER_REQUEST_EVENT && data != null) {
isSwitchFragment=true;
}
}
In regards to #Anthonyeef great answer, here is a sample code in Java:
private boolean shouldShowFragmentInOnResume;
private void someMethodThatShowsTheFragment() {
if (this.getLifecycle().getCurrentState().isAtLeast(Lifecycle.State.RESUMED)) {
showFragment();
} else {
shouldShowFragmentInOnResume = true;
}
}
private void showFragment() {
//Your code here
}
#Override
protected void onResume() {
super.onResume();
if (shouldShowFragmentInOnResume) {
shouldShowFragmentInOnResume = false;
showFragment();
}
}
The exception is threw here (In FragmentActivity):
#Override
public void onBackPressed() {
if (!mFragments.getSupportFragmentManager().popBackStackImmediate()) {
super.onBackPressed();
}
}
In FragmentManager.popBackStatckImmediate()，FragmentManager.checkStateLoss() is called firstly. That's the cause of IllegalStateException. See the implementation below:
private void checkStateLoss() {
if (mStateSaved) { // Boom!
throw new IllegalStateException(
"Can not perform this action after onSaveInstanceState");
}
if (mNoTransactionsBecause != null) {
throw new IllegalStateException(
"Can not perform this action inside of " + mNoTransactionsBecause);
}
}
I solve this problem simply by using a flag to mark Activity's current status. Here's my solution:
public class MainActivity extends AppCompatActivity {
/**
* A flag that marks whether current Activity has saved its instance state
*/
private boolean mHasSaveInstanceState;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#Override
protected void onSaveInstanceState(Bundle outState) {
mHasSaveInstanceState = true;
super.onSaveInstanceState(outState);
}
#Override
protected void onResume() {
super.onResume();
mHasSaveInstanceState = false;
}
#Override
public void onBackPressed() {
if (!mHasSaveInstanceState) {
// avoid FragmentManager.checkStateLoss()'s throwing IllegalStateException
super.onBackPressed();
}
}
}
If you have crash with popBackStack() or popBackStackImmediate() method please try fixt with:
if (!fragmentManager.isStateSaved()) {
fragmentManager.popBackStackImmediate();
}
This is worked for me as well.
In my case I got this error in an override method called onActivityResult. After digging I just figure out maybe I needed to call 'super' before.
I added it and it just worked
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
super.onActivityResult(requestCode, resultCode, data); //<--- THIS IS THE SUPPER CALL
if (resultCode == Activity.RESULT_OK && requestCode == 0) {
mostrarFragment(FiltroFragment.newInstance())
}
}
Maybe you just need to add a 'super' on any override you are doing before your code.
Kotlin extension
fun FragmentManager?.replaceAndAddToBackStack(
#IdRes containerViewId: Int,
fragment: () -> Fragment,
tag: String
) {
// Find and synchronously remove a fragment with the same tag.
// The second transaction must start after the first has finished.
this?.findFragmentByTag(tag)?.let {
beginTransaction().remove(it).commitNow()
}
// Add a fragment.
this?.beginTransaction()?.run {
replace(containerViewId, fragment, tag)
// The next line will add the fragment to a back stack.
// Remove if not needed.
// You can use null instead of tag, but tag is needed for popBackStack(),
// see https://stackoverflow.com/a/59158254/2914140
addToBackStack(tag)
}?.commitAllowingStateLoss()
}
Usage:
val fragment = { SomeFragment.newInstance(data) }
fragmentManager?.replaceAndAddToBackStack(R.id.container, fragment, SomeFragment.TAG)
Starting from support library version 24.0.0 you can call FragmentTransaction.commitNow() method which commits this transaction synchronously instead of calling commit() followed by executePendingTransactions(). As documentation says this approach even better:
Calling commitNow is preferable to calling commit() followed by executePendingTransactions() as the latter will have the side effect of attempting to commit all currently pending transactions whether that is the desired behavior or not.
I know there is an accepted answer by #Ovidiu Latcu but after some while, error still persist.
#Override
protected void onSaveInstanceState(Bundle outState) {
//No call for super(). Bug on API Level > 11.
}
Crashlytics still sending me this weird error message.
However error now occurring only on version 7+ (Nougat)
My fix was to use commitAllowingStateLoss() instead of commit() at the fragmentTransaction.
This post is helpful for commitAllowingStateLoss() and never had a fragment issue ever again.
To sum it up, the accepted answer here might work on pre Nougat android versions.
This might save someone a few hours of searching.
happy codings. <3 cheers
To bypass this issue, we can use The Navigation Architecture Component , which was introduced in Google I/O 2018.
The Navigation Architecture Component simplifies the implementation of navigation in an Android app.
change getFragmentManager() to getChildFragmentManager(). Don't use parent FragmentManager, try to use self.
Add this in your activity
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (outState.isEmpty()) {
// Work-around for a pre-Android 4.2 bug
outState.putBoolean("bug:fix", true);
}
}
I have also experienced this issue and problem occurs every time when context of your FragmentActivity gets changed (e.g. Screen orientation is changed, etc.). So the best fix for it is to update context from your FragmentActivity.
I ended up with creating a base fragment and make all fragments in my app extend it
public class BaseFragment extends Fragment {
private boolean mStateSaved;
#CallSuper
#Override
public void onSaveInstanceState(Bundle outState) {
mStateSaved = true;
super.onSaveInstanceState(outState);
}
/**
* Version of {#link #show(FragmentManager, String)} that no-ops when an IllegalStateException
* would otherwise occur.
*/
public void showAllowingStateLoss(FragmentManager manager, String tag) {
// API 26 added this convenient method
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
if (manager.isStateSaved()) {
return;
}
}
if (mStateSaved) {
return;
}
show(manager, tag);
}
}
Then when I try to show a fragment I use showAllowingStateLoss instead of show
like this:
MyFragment.newInstance()
.showAllowingStateLoss(getFragmentManager(), MY_FRAGMENT.TAG);
I came up to this solution from this PR: https://github.com/googlesamples/easypermissions/pull/170/files
lately i have been researching about memory leaks in java/android and pretty much everywhere it says that instead of anonymous classes i should use static inner classes with weak references.
so, in my android app i started doing that but very quickly got tired of it because it's a lot of boilerplate code... i think have an alternative solution which i would prefer to use, but i'm juts not sure that it is a valid alternative to static inner classes in terms of preventing memory leaks. as i said before, i haven't seen this solution suggested anywhere else (all say to use static inner classes) so thats why im not sure my alternative will work.
ill use a simple example from my app:
i have a class called WebClient which handles asynchronous web requests and it accepts an interface called iCallback which returns the response from the server to the caller, and in my activity once i get this callback i need to dismiss a dialog, and maybe perform some activity related things (like trigger onBackPressed() and setResult()).
so here is my static inner class i have created:
private static class CallBack implements WebClient.ICallback
{
private WeakReference<ProgressDialog> mProgDiag;
private WeakReference<BaseActivity> mActivity;
public CallBack(BaseActivity activity, ProgressDialog progDiag)
{
this.mProgDiag = new WeakReference<>(progDiag);
this.mActivity = new WeakReference<>(activity);
}
#Override
public void onCallback(String data)
{
String responseAsString = Utils.extractStringFromResponse(...);
final BaseActivity parentActivity = mActivity.get();
ProgressDialog dialog = mProgDiag.get();
if(dialog != null)
{
dialog.dismiss();
}
if (responseAsString == null)
{
if(parentActivity != null)
{
Utils.makeServerErrorDialog(parentActivity,
new iDialogButtonClickedListener()
{
#Override
public void onDialogButtonClicked()
{
parentActivity.onBackPressed();
}
});
}
return;
}
//everything is ok
if (responseAsString.equals("1"))
{
if(parentActivity != null)
{
Intent result = new Intent();
result.putExtra(...);
parentActivity.setResult(Activity.RESULT_OK, result);
}
}
else
{
Utils.reportErrorToServer(...);
if(parentActivity != null)
{
parentActivity.setResult(Activity.RESULT_CANCELED);
}
}
if(parentActivity != null)
{
parentActivity.onBackPressed();
}
}
}
so for every variable i need in this static inner class i have to create a new weak reference, then retrieve the object itself, and then every time i want to access it i need to check whether it's null... that seems like a lot of code to me.
and here is my suggested alternative:
public abstract class BaseActivity extends AppCompatActivity
implements WebClient.ICallback
{
private static final String TAG = "BaseActivity";
WebClient.ICallback mCallBack;
ProgressDialog mProgDiag;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(...);
mCallBack = this;
//some code to invoke a server request on button click
//and passing mCallBack to the request
}
#Override
public void onCallback(String data)
{
String responseAsString = Utils.extractStringFromResponse(...);
mProgDiag.dismiss();
if (responseAsString == null)
{
Utils.makeServerErrorDialog(this,
new iDialogButtonClickedListener()
{
#Override
public void onDialogButtonClicked()
{
onBackPressed();
}
});
return;
}
//everything is ok
if (responseAsString.equals("1"))
{
Intent result = new Intent();
result.putExtra(...);
setResult(Activity.RESULT_OK, result);
}
else
{
Utils.reportErrorToServer(...);
setResult(Activity.RESULT_CANCELED);
}
onBackPressed();
}
#Override
protected void onPause()
{
mCallBack = null;
super.onPause();
}
#Override
protected void onResume()
{
super.onResume();
mCallBack = this;
}
}
to me this seems much cleaner: no creating and retrieving instances of weak references for every variable i need access to, i can directly invoke activity methods (e.g. onBackPressed()), and no checking for null everywhere.
the only place i would now have to check for null is inside WebClient class before invoking the callBack method.
so my question is, does this approach achieve the same result in terms of preventing memory leaks? is it a "worthy" alternative to static inner classes?
Unfortunately, your approach does not work. By implementing the WebClient.ICallback in your activity, rather than an inner class, you don't get rid of the leak. The leak happens not because the references to activity and dialog are implicit in an anonymous class, or in lambda, or in a non-static inner class instance; the happens when the WebClient keeps this reference while the activity is gone (it is not destroyed, because there is a strong reference to it).
The special mCallBack that you set to null when the activity is paused, gains nothing. Just as well, you can simply pass your activity instance to the WebClient. Now there is a strong reference to your activity, which is managed by someone (async handlers of the WebClient), who is not under your control. If you are unlucky, the async handler will get stuck somewhere and will never release this reference.
Please read this detailed explanation.
Note that WebView itself can cause a memory leak, if special measures are not undertaken!
In my test, after one action, there are two possible views which can appear and both of them are correct. How can I check if one of the view is displayed. For a single view I can check with is Displayed(). But that would fail if other view is visible instead. I want to pass the test if any one of those two views are displayed.
onMyButton.perform(click());
onMyPageOne.check(matches(isDisplayed())); //view 1
or
onMyPageTwo.check(matches(isDisplayed())); //view 2
After, perform click on MyButton, any one of the view (1 or 2) is expected to appear but not both. It is not fixed that which one would be displayed.
How can I check if any one of them is displayed?
It's possible to catch the exceptions raised by Espresso like this:
If you want to test if a view is in hierarchy:
try {
onView(withText("Button")).perform(click());
// View is in hierarchy
} catch (NoMatchingViewException e) {
// View is not in hierarchy
}
This exception will be thrown if the view is not in the hierarchy.
Sometimes the view can be in the hierarchy, but we need to test if it is displayed, so there is another exception for assertions, like this:
try {
onView(withText("Button")).check(matches(isDisplayed()));
// View is displayed
} catch (AssertionFailedError e) {
// View not displayed
}
There are two cases here that you could be trying to cover. The first is if you are checking if the view "is displayed on the screen to the user" in which case you would use isDisplayed()
onView(matcher).check(matches(isDisplayed()));
or the negation
onView(matcher).check(matches(not(isDisplayed())));
The other case is if you are checking if the view is visible but not necessarily displayed on the screen (ie. an item in a scrollview). For this you can use withEffectiveVisibility(Visibility)
onView(matcher).check(matches(withEffectiveVisibility(ViewMatchers.Visibility.VISIBLE)));
You can use Matchers.anyOf to check if any of the two views are displayed:
onView(
anyOf(withId(R.id.view_1), withId(R.id.view_2))
).check(matches(isDisplayed()));
For the ones looking to check the visibility status for a view; here are some utility functions I use.
fun ViewInteraction.isGone() = getViewAssertion(ViewMatchers.Visibility.GONE)
fun ViewInteraction.isVisible() = getViewAssertion(ViewMatchers.Visibility.VISIBLE)
fun ViewInteraction.isInvisible() = getViewAssertion(ViewMatchers.Visibility.INVISIBLE)
private fun getViewAssertion(visibility: ViewMatchers.Visibility): ViewAssertion? {
return ViewAssertions.matches(ViewMatchers.withEffectiveVisibility(visibility))
}
And can be used as follows
onView(withId(R.id.progressBar)).isVisible()
onView(withId(R.id.progressBar)).isGone()
I researched Espresso a bit, and I found this # Espresso Samples.
Search text "Asserting that a view is not displayed". It says "The above approach works if the view is still part of the hierarchy." So I think your code should work but you need to use ViewAssertions also. Using your code, perhaps do this:
if (ViewAssertions.doesNotExist()) == null) {
return;
}
onMyPageOne.check(matches(isDisplayed()));
Another technique is check for UI existence. Search for text "Asserting that a view is not present".
Using your code, my best suggestion is:
onMyPageOne.check(doesNotExist());
Note: This calls doesNotExist method.
Their sample code is: onView(withId(R.id.bottom_left)).check(doesNotExist());
Utility class which allows to check if view is visible, gone or invisible:
public class ExtraAssertions {
public static ViewAssertion isVisible() {
return new ViewAssertion() {
public void check(View view, NoMatchingViewException noView) {
assertThat(view, new VisibilityMatcher(View.VISIBLE));
}
};
}
public static ViewAssertion isGone() {
return new ViewAssertion() {
public void check(View view, NoMatchingViewException noView) {
assertThat(view, new VisibilityMatcher(View.GONE));
}
};
}
public static ViewAssertion isInvisible() {
return new ViewAssertion() {
public void check(View view, NoMatchingViewException noView) {
assertThat(view, new VisibilityMatcher(View.INVISIBLE));
}
};
}
private static class VisibilityMatcher extends BaseMatcher<View> {
private int visibility;
public VisibilityMatcher(int visibility) {
this.visibility = visibility;
}
#Override public void describeTo(Description description) {
String visibilityName;
if (visibility == View.GONE) visibilityName = "GONE";
else if (visibility == View.VISIBLE) visibilityName = "VISIBLE";
else visibilityName = "INVISIBLE";
description.appendText("View visibility must has equals " + visibilityName);
}
#Override public boolean matches(Object o) {
if (o == null) {
if (visibility == View.GONE || visibility == View.INVISIBLE) return true;
else if (visibility == View.VISIBLE) return false;
}
if (!(o instanceof View))
throw new IllegalArgumentException("Object must be instance of View. Object is instance of " + o);
return ((View) o).getVisibility() == visibility;
}
}
}
And usage could look like this:
onView(withId(R.id.text_message)).check(isVisible());
Another view assertion which could help to check extra visibility properties of a view and its parents: it checks visibility, isAttachedToWindow, alpha:
class IsVisible : ViewAssertion {
override fun check(view: View, noViewFoundException: NoMatchingViewException?) {
ViewMatchers.assertThat(
"View is not visible. " +
"visibility: ${view.visibility}, " +
"isAttachedToWindow: ${view.isAttachedToWindow}, " +
"alpha: ${view.alpha}",
true, `is`(isViewTreeVisible(view)))
}
private fun isViewTreeVisible(view: View?): Boolean {
return if (view != null) {
val viewVisible = view.isAttachedToWindow && view.visibility == View.VISIBLE && view.alpha == 1.0f
if (view.parent !is View) viewVisible
else viewVisible && isViewTreeVisible(view.parent as View)
} else {
true
}
}
}
The problem is that all assertoin() and check() methods return Assertion that stops test flow if failed.
One simple way to check for a View or its subclass like a Button is to use method
getVisibility from View class. I must caution that visibility attribute is not clearly defined in the GUI world. A view may be considered visible but may be overlapped with another view, for one example, making it hidden.
Another way but more accurate (I have not tried) is to check for the rectangular bounds of the View. Not so simple.
Is that clear enough? cannot give you specific examples since you did not post code.
final AtomicBoolean view1Displayed = new AtomicBoolean(true);
Espresso.onView(ViewMatchers.withId(viewId1)).inRoot(RootMatchers.withDecorView(Matchers.is(intentsTestRule.getActivity().getWindow().getDecorView()))).withFailureHandler(new FailureHandler() {
#Override
public void handle(Throwable error, Matcher<View> viewMatcher) {
view1Displayed.set(false);
}
}).check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
if (view1Displayed.get()) {
try {
Espresso.onView(ViewMatchers.withId(viewId2)).inRoot(RootMatchers.withDecorView(Matchers.is(intentsTestRule.getActivity().getWindow().getDecorView()))).check(ViewAssertions.matches(Matchers.not(ViewMatchers.isDisplayed())));
} catch (NoMatchingViewException ignore) {
}
} else {
Espresso.onView(ViewMatchers.withId(viewId2)).inRoot(RootMatchers.withDecorView(Matchers.is(intentsTestRule.getActivity().getWindow().getDecorView()))).check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
}
When I face this situation I generally split into multiple tests. One test sets the conditions for view #1 to be displayed and the other test sets the conditions for view #2 to be displayed.
But let's say that you can't really control the conditions. For example, what if it depends on a random number or it depends on a third-party resource such as a calculation on a server? In that case, I usually solve the problem mocking. That way I can control the conditions so I know exactly which view to expect. I use Dependency Injection to set the mock I need for each test.