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java.lang.IllegalStateException: Fragment not attached to Activity

I am rarely getting this error while making an API call.
java.lang.IllegalStateException: Fragment not attached to Activity
I tried putting the code inside isAdded() method to check whether fragment is currently added to its activity but still i rarely gets this error. I fail to understand why I am still getting this error. How can i prevent it?
Its showing error on the line-
cameraInfo.setId(getResources().getString(R.string.camera_id));
Below is the sample api call that i am making.
SAPI.getInfo(getActivity(),
new APIResponseListener() {
#Override
public void onResponse(Object response) {
cameraInfo = new SInfo();
if(isAdded()) {
cameraInfo.setId(getResources().getString(R.string.camera_id));
cameraInfo.setName(getResources().getString(R.string.camera_name));
cameraInfo.setColor(getResources().getString(R.string.camera_color));
cameraInfo.setEnabled(true);
}
}
#Override
public void onError(VolleyError error) {
mProgressDialog.setVisibility(View.GONE);
if (error instanceof NoConnectionError) {
String errormsg = getResources().getString(R.string.no_internet_error_msg);
Toast.makeText(getActivity(), errormsg, Toast.LENGTH_LONG).show();
}
}
});

This error happens due to the combined effect of two factors:
The HTTP request, when complete, invokes either onResponse() or onError() (which work on the main thread) without knowing whether the Activity is still in the foreground or not. If the Activity is gone (the user navigated elsewhere), getActivity() returns null.
The Volley Response is expressed as an anonymous inner class, which implicitly holds a strong reference to the outer Activity class. This results in a classic memory leak.
To solve this problem, you should always do:
Activity activity = getActivity();
if(activity != null){
// etc ...
}
and also, use isAdded() in the onError() method as well:
#Override
public void onError(VolleyError error) {
Activity activity = getActivity();
if(activity != null && isAdded())
mProgressDialog.setVisibility(View.GONE);
if (error instanceof NoConnectionError) {
String errormsg = getResources().getString(R.string.no_internet_error_msg);
Toast.makeText(activity, errormsg, Toast.LENGTH_LONG).show();
}
}
}

Fragment lifecycle is very complex and full of bugs, try to add:
Activity activity = getActivity();
if (isAdded() && activity != null) {
...
}

I Found Very Simple Solution isAdded() method which is one of the fragment method to identify that this current fragment is attached to its Activity or not.
we can use this like everywhere in fragment class like:
if(isAdded())
{
// using this method, we can do whatever we want which will prevent **java.lang.IllegalStateException: Fragment not attached to Activity** exception.
}

Exception: java.lang.IllegalStateException: Fragment
DeadlineListFragment{ad2ef970} not attached to Activity
Category: Lifecycle
Description: When doing time-consuming operation in background thread(e.g, AsyncTask), a new Fragment has been created in the meantime, and was detached to the Activity before the background thread finished. The code in UI thread(e.g.,onPostExecute) calls upon a detached Fragment, throwing such exception.
Fix solution:
Cancel the background thread when pausing or stopping the
Fragment
Use isAdded() to check whether the fragment is attached
and then to getResources() from activity.

i may be late but may help someone .....
The best solution for this is to create a global application class instance and call it in the particular fragment where your activity is not being attached
as like below
icon = MyApplication.getInstance().getString(R.string.weather_thunder);
Here is application class
public class MyApplication extends Application {
private static MyApplication mInstance;
private RequestQueue mRequestQueue;
#Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized MyApplication getInstance() {
return mInstance;
}
}

In Fragment use isAdded()
It will return true if the fragment is currently attached to Activity.
If you want to check inside the Activity
Fragment fragment = new MyFragment();
if(fragment.getActivity()!=null)
{ // your code here}
else{
//do something
}
Hope it will help someone

This error can happen if you are instantiating a fragment that somehow can't be instantiated:
Fragment myFragment = MyFragment.NewInstance();
public classs MyFragment extends Fragment {
public void onCreate() {
// Some error here, or anywhere inside the class is preventing it from being instantiated
}
}
In my case, i have met this when i tried to use:
private String loading = getString(R.string.loading);

So the base idea is that you are running a UI operation on a fragment that is getting in the onDetach lifecycle.
When this is happening the fragment is getting off the stack and losing the context of the Activity.
So when you call UI related functions for example calling the progress spinner and you want to leave the fragment check if the Fragment is added to the stack, like this:
if(isAdded){ progressBar.visibility=View.VISIBLE }

This will solve your problem.
Add This on your Fragemnt
Activity activity;
#Override
public void onAttach(#NonNull Context context) {
super.onAttach(context);
activity = context instanceof Activity ? (Activity) context : null;
}
Then change getContext() , getActivity() , requireActivity() or requireContext() with activity

I adopted the following approach for handling this issue. Created a new class which act as a wrapper for activity methods like this
public class ContextWrapper {
public static String getString(Activity activity, int resourceId, String defaultValue) {
if (activity != null) {
return activity.getString(resourceId);
} else {
return defaultValue;
}
}
//similar methods like getDrawable(), getResources() etc
}
Now wherever I need to access resources from fragments or activities, instead of directly calling the method, I use this class. In case the activity context is not null it returns the value of the asset and in case the context is null, it passes a default value (which is also specified by the caller of the function).
Important This is not a solution, this is an effective way where you can handle this crash gracefully. You would want to add some logs in cases where you are getting activity instance as null and try to fix that, if possible.

this happen when the fragment does not have a context ,thus the getActivity()method return null.
check if you use the context before you get it，or if the Activity is not exist anymore . use context in fragment.onCreate and after api response usually case this problem

Sometimes this exception is caused by a bug in the support library implementation. Recently I had to downgrade from 26.1.0 to 25.4.0 to get rid of it.

This issue occurs whenever you call a context which is unavailable or null when you call it. This can be a situation when you are calling main activity thread's context on a background thread or background thread's context on main activity thread.
For instance , I updated my shared preference string like following.
editor.putString("penname",penNameEditeText.getText().toString());
editor.commit();
finish();
And called finish() right after it. Now what it does is that as commit runs on main thread and stops any other Async commits if coming until it finishes. So its context is alive until the write is completed. Hence previous context is live , causing the error to occur.
So make sure to have your code rechecked if there is some code having this context issue.

Call fragment method from activity but view is null

I am checking internet connection in my main activity.If connection is lost,I want to show reconnecting message in fragment.Example:If I run following code in main activity my app is crashing.
ConversationFragment conv1 = new ConversationFragment();
conv1.showReconnecting();
And this is the showReconnecting method in fragment:
public void showReconnecting() {
final RelativeLayout rel=(RelativeLayout)rootView.findViewById(R.id.reconnecting);
rel.setVisibility(View.VISIBLE);
}
I know why my app is crashing because rootView is setting in onCreateView and when I call this method from activity rootView is returning null.
What can I do for resolve this problem ?

Try this (Assuming reconnecting view is in fragment and your fragment is visible on screen),
public void showReconnecting() {
if (conv1 != null && conv1.getView()!=null) {
final RelativeLayout rel=(RelativeLayout)conv1.getView().findViewById(R.id.reconnecting);
rel.setVisibility(View.VISIBLE);
}
}
If conv1 is not available then please make it class variable.

According to what you want to do, a simple ProgressDialog will do the job. You can lauch it from your ChatFragment, like this:
First, declare it on your Fragment:
private ProgressDialog connectiongProgressDialog;
Then, when you want to show it, use:
connectiongProgressDialog = ProgressDialog.show(getActivity(), "My title", "Reconnecting");
When you want to dismiss it, use:
if (connectiongProgressDialog != null){
connectiongProgressDialog .dismiss();
}
It will display a simple dialog with the message you want.

Well, just looking at this and your explanation, I would think you can't call methods relating to a view (such as a fragment) without creating said fragment. An option, if the fragment is only used for showing the reconnecting, would be just to put some code in the activity and use a Toast.makeText(....).show();
which notifies the user that you are attempting to reconnect. So instead of conv1.showReconnecting(); maybe rather put, Toast.makeText(context,"Reconnecting", Toast.LONG).show(); and then do the necessary background work in an AsyncTask.
I hope this helps.

Callback When DialogFragment is Dismissed

I want to launch a dialog with a custom layout, which I've implemented via a DialogFragment. (I basically just changed onCreateView() and added button handlers). The dialog lets the user quickly change an important setting.
This dialog will be launched from several different activities. The different activities don't have much in common, except that they need to refresh after the user makes a change to the setting. They don't need to get any information from the dialog; they merely need to know when it's closed (dismissed).
What I've Tried
I tried having the activity refresh in onResume(), but launching and dismissing a dialog never seems to call this method. (So I'm not sure why it even exists, but that's probably a topic for another question.)
Next, I tried adding a DialogInterface.OnDismissListener to the dialog:
public static void showMyDialog(OnDismissListener listener, Activity activity)
{
DialogFragment fragment = new MyDialogFragment();
fragment.show(activity.getFragmentManager(), "date");
activity.getFragmentManager().executePendingTransactions();//A
fragment.getDialog().setOnDismissListener(listener);//B
}
When I originally left out the line A, I got a NullPointerException on line B because the dialog is null at that point. Following the advice of this SO answer, I put in the call to executePendingTransaction(). This causes an IllegalStateException on line B, with the message "OnDismissListener is already taken by DialogFragment and cannot be replaced." I also tried putting setOnDismissListener() before the call to show(), but that always caused a NullPointerException.
I then read this other SO answer, which says the original asker was "calling getDialog() too early in the DialogFragment's life cycle." So I tried adding a constructor to my DialogFragment:
public MyDialogFragment(SomeCallback illTakeAnythingICanGet)
{
//I'll store the callback here and call it later
}
Unfortunately, adding a constructor made Android Lint freak out with a fatal warning, and when I looked it up, I found a comment in this question that seems to say this approach will make it impossible to deal with the user rotating the screen while the dialog is open.
The Question
How can an activity figure out when a DialogFragment has closed (been dismissed) in a way that won't break my app if the user rotates the screen? Should I be using something else besides a DialogFragment?

This is just a longer explanation of harism's comment in case anyone else has the same problem I did.
You can accomplish what I wanted by creating an interface like this:
public interface MyDialogCloseListener
{
public void handleDialogClose(DialogInterface dialog);//or whatever args you want
}
Have the activity that launches your dialog (DialogFragment) implement this interface. Then give that DialogFragment the following method:
public void onDismiss(DialogInterface dialog)
{
Activity activity = getActivity();
if(activity instanceof MyDialogCloseListener)
((MyDialogCloseListener)activity).handleDialogClose(dialog);
}

More explanatory code for someone to do the same.
Create the interface as:
package com.example.dialoglistener;
import android.content.DialogInterface;
public interface MyDialogCloseListener {
public void handleDialogClose(DialogInterface dialog);
}
Implement the interface in activity as:
MyDialogCloseListener closeListener = new MyDialogCloseListener() {
#Override
public void handleDialogClose(DialogInterface dialog) {
//do here whatever you want to do on Dialog dismiss
}
};
Write a DismissListener in DialogFragement as
public void DismissListener(MyDialogCloseListener closeListener) {
this.closeListener = closeListener;
}
call DismissListener from your activity as:
dialogFragementObject.DismissListener(closeListener);
and finally write onDismiss method
#Override
public void onDismiss(DialogInterface dialog) {
super.onDismiss(dialog);
if(closeListener != null) {
closeListener.handleDialogClose(null);
}
}

Tyler's example was the only example I could find that actually worked. The only thing that needs changed for the example to work is the call to the DismissListner method in the DialogFragment class. He has it as:
dialogFragementObject.DismissListner(closeListener);
This just needs to be a cast to whatever your class name of that DialogFragment is. For example:
((MyDialogFragment)dialogFragementObject).DismissListner(closeListener);

Android RuntimeException onCreateDialog did not create a dialog for id

I've an application that you can show and close several Dialogs with:
showDialog(...)
removeDialog(...)
I play a little bit with the application and when there is no any Dialog on the screen, I press the menu button and I go to the main android screen.
After a while, I enter again into my application and sometimes, I get this RuntimeException:
java.lang.IllegalArgumentException: Activity#onCreateDialog did not create a dialog for id 4
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)
at android.app.ActivityThread.access$2200(ActivityThread.java:126)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1932)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4595)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: Activity#onCreateDialog did not create a dialog for id 4
at android.app.Activity.createDialog(Activity.java:878)
at android.app.Activity.restoreManagedDialogs(Activity.java:867)
at android.app.Activity.performRestoreInstanceState(Activity.java:815)
at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1096)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2565)
... 11 more
Any idea?
Thank you very much.
UPDATE, more information:
The current onCreateDialog implementation is:
protected Dialog onCreateDialog(int id){
Builder b = new AlertDialog.Builder(this);
if(id == 4){
b.setMessage(...);
b.setItems(items, new DialogInterface.OnClickListener(){
public void onClick(DialogInterface dialog, int which){
Intent i = new Intent(Current.this, Another.class);
startActivity(i);
}
});
return b.create();
}
return null;
}
In order to call this function I do:
removeDialog(4);
showDialog(4);

In API level 8, onCreateDialog(int) was deprecated in favor of onCreateDialog(int,Bundle). If you implement only the latter method and run the app on a device with an API level lower than 8, you get the described error message.
The solution is to implement onCreateDialog(int)

For SDK version < 8, if you return null in onCreateDialog you get Exception java.lang.IllegalArgumentException.

After experiencing this same issue (and finding that calling removeDialog from within onPause doesn't work reliably), I developed a workaround that seems to function (although it's admittedly a hack).
As seen in the grepcode link posted by antslava, in method performRestoreInstanceState, onRestoreInstanceState is called right before restoreManagedDialogs and is passed the same instance of Bundle savedInstanceState.
final void performRestoreInstanceState(Bundle savedInstanceState) {
onRestoreInstanceState(savedInstanceState);
restoreManagedDialogs(savedInstanceState);
}
Thus, there is opportunity to modify the Bundle savedInstanceState that is passed to restoreManagedDialogs from within the onRestoreInstanceState method.
To prevent any and all managed dialogs from being restored, one could implement onRestoreInstanceState in the following way:
// This same variable is defined as private in the Activity class. I need
// access to it, so I redefine it here.
private static final String SAVED_DIALOGS_TAG = "android:savedDialogs";
#Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
final Bundle b = savedInstanceState.getBundle(SAVED_DIALOGS_TAG);
if (null != b) {
savedInstanceState.remove(SAVED_DIALOGS_TAG);
}
}
This causes the Bundle referenced by key "android:savedDialogs" to be removed from Bundle savedInstanceState, which subsequently causes the call to restoreManagedDialogs to immediately return when it finds that this key cannot be found:
private void restoreManagedDialogs(Bundle savedInstanceState) {
final Bundle b = savedInstanceState.getBundle(SAVED_DIALOGS_TAG);
if (b == null) {
return;
}
...
}
This will cause onCreateDialog to not be called while restoring the Activity, effectively "hiding" any dialogs, thus preventing the scenario where one must return null from onCreateDialog from occurring.
This isn't a 'one size fits all' solution, but given my requirements it seems to fit the bill. By reviewing the code in grepcode for several platform versions (1.6, 2.1, 2.2, 2.2.2, and 4.0.3), it appears that this solution should work consistently given these existing implementations.

Have you implemented OnCreateDialog as presented here? When you call showDialog(4) for the first time, OnCreateDialog(4) will be called and you need to create the dialog and return it from this method.

Are you properly returning the dialog in onCreateDialog? If you were to do dialog.show() in dialog create but return some other dialog you could perhaps get a result like that.
Or are you doing any sort of manipulation in of the dialog object in onPrepareDialog

Gettring a reference to a managed ProgressDialog

In my activity I need a ProgressDialog with a horizontal progress bar to visualise the progress of a background task. To make the activity care for the dialog e.g. in case of screen rotation, I would like to use a managed dialog created in onCreateDialog. The problem is that I need to update the progress bar of the dialog after it has been created and therefor I need a reference to the managed progress dialog: Does anyone know how to retrieve a reference to a dialog created by onCreateDialog?
At the moment I am storing a reference to the dialog created in onCreateDialog, but that my fail with a InvalidArgumentException in the onFinished() method after the screen has been rotated (and the activity has been recreated):
public final class MyActivity extends Activity {
private static final int DIALOG_PROGRESS = 0;
private ProgressDialog progressDialog = null;
// [...]
#Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case DIALOG_PROGRESS:
progressDialog = createProgressDialog();
return progressDialog;
default:
return super.onCreateDialog(id);
}
}
// [...]
public void updateProgress(int progress) {
progressDialog.setProgress(0);
}
public void onFinished() {
progressDialog.dismiss();
}
// [...]
}
I would have expected something like a getDialog(int) method in the Activity class to get a reference to a managed dialog, but this doesn't seem to exist. Any ideas?

I answer myself:
There really is no getDialog(int) method available in the Activity class.
Storing the reference like shown above works correctly -- the bug was something else...
The problem was, that the parallel thread, that called the onFinished() method called this method on the already destroyed activity, thus the accessed ProgressDialog instance is still existing but no longer a valid dialog. Instead another activity with another ProgressDialog has already been created by Android.
So all I needed to do was to make the background thread call the onFinished() method of the new activity and everything works fine. To switch the reference I override the onRetainNonConfigurationInstance() and getLastNonConfigurationInstance() methods of the Activity class.
The good thing of the shown example: Android really cares about recreating the new dialog after the screen orientation changed. So constructing the ProgressDialog that way is definitely easier than using ProgressDialog.show() where I would need to handle the dialog recreation on my own (the two methods described above would be a good place to do this.