I have Activity A which defines a dialog using AlertBuilder.create etc. This Activity invokes the dialog using showDialog(dialogID). dialogID is declared and recognized in all classes/activities. Everything works perfectly in Activity A.
My question is when trying to invoke this same dialog -- showDialog(dialogID) -- from another Activity (Activity B) the application crashes. Can anyone help?
How to invoke a dialog from multiple activities?
Thanks in advance.
Andy
My question is when trying to invoke
this same dialog --
showDialog(dialogID) -- from another
Activity (Activity B) the application
crashes.
How do you invoke the dialog from Activity B? Just to let you know, you do not instiante activities (so no new ActivityA().showDialog(id).
What you can do is
Create a class that extends AlertDialog.Builder and accept a Context parameter in the constructor. You can customize the text, buttons and other things.
From your activity, in your onCreateDialog, you can just instantiate your class and call create() on it. And your class will be accessible from any activities.
I don't think you can accomplish what you want without hooking up a similar entry point in your new activity.
showDialog(int id)
The id is unique within the activity that launches it. So if two activties A and B both call showDialog(1); That will do something different in each unless someone has coded the same code path for them in their onDialogCreate() and onPrepareDialog methods. So in your onDialogCreate of the original activity, that code will have to exist in both activities. You can sometimes get way with creating a new Dialog type that does all the initialization internally based on a given context and just call show() on it. The problem with this solution usually arises when the context is no longer valid and you need to dismiss or show it. Basically though when using showDialog() it's on a per activity basis.
I don't think that's possible.
Dialog built in Activity A, belongs to Activity A.
No matter if you store its ID in a global data space. It won't be available to be used in Activity B.
You'll have to create another Dialog in Activity B
Related
I'm badly confused and hope to get your help understanding this concept.
I have an app with 3 activities, splash, login and main and the main activity is a multi fragment drawer activity that uses sqlite.
In my fragments i need to use context many places. I used to have a static context in my main activity defined and passed that around but in another questions someone suggested not to use static context to avoid leaks and i took the advice.
I had to change a few things and got things working. I use getapplicationcontext() but now my application now consistently crashes. The crashes are more prominent when the app is put in background.
My question is, which activity's context should i be using to start with? Splash? Login or main? How would you get access to the context in resume?
Thanks
If you are in A fragment you can use getActivity() to access its container activity context.
If you are try to access activity context from an adapter class or dialog, you must pass the activity context to the constructor of the adapter class or dialog
If you are in an activity you can use this or yourActivity.this as per the situation.
For example
1)If you want to access activity context from onResume() or onCreate() you can simply use this.
2)If you are try to access activity context from an inner class like retrofit call then you must use yourActivity.this for activiy context
In android app, having a few activities with multiple fragments.
Those activities or fragment could be running alive even if it's not on the top of the backStack, and receiving notifications from different services.
When some event happens it is required to show a dialog to communicate with user. The activity or fragment on top of the stack may not have the handler for that event. Any other activity or fragment who is interested should react to open one dialog to the user.
The problem is the listeners in the activities and fragments to handle the events independently don't know if there has been already the same dialog displayed.
What is best way to tell whether the handler should open the dialog or not?
Since this dialog is same for the same event so it may help if could have it as a singleton.
Anyone have suggestion how to make the dialog a singleton for this type of situation?
You can't make Dialog singletone, because Dialogs are linked with current view. And your current view may change - dialog may be sown from different instances of the activities (one or many).
But you can implement a simple singletone class to store all dialog data - save data into onPause and retrieve it in Dialog's onCreateView.
So you will get singleton instance with all data, but Dialogs may vary according to current view.
Also you can store a weak link to the shown dialog in that singletone class. Using such method, you can detect is your dialog currently shown or not.
Assume i has activity A and B and external class C.
class C contains code to create dialog but requires contex.
class B is like this one
activity A is in focus(active).
Activity A call C to create dialog.
In first case, A send's it's ActivityContext to C.
In second case, C get application activity from B.
Are those two cases leads to same result? E.G dialog will pop up on a screen (on a screen of activity A)
Yes,
In android there's only 1 "Context" per application, is what documentation calls as Application Context, is where pretty much every single component related to your activity lives, so it doesn't matter what activity context reference you are using, in the end is the same since all the activities live within it, and taking on count that this app context follows the singleton design pattern be sure that is the very same instance object within the virtual machine...
Regards!
From my activity I call showDialog(0) and then in the switch of the method onCreateDialog I would like to access a variable from the parent activity. It doesn't seem to work though. I've tried
this.neededVariable
or
((MyActivity)dialog.getOwnerActivity()).neededVariable
but they don't seem to work. Any ideas? It might be something simple which I'm not getting cause I'm very tired :)
you can pass the value of that variable to your dialog in setArgumenet, or you can use Fragment Callback to communicate the Activity, here is the example of callback
When you are in dialog you should use dialog context to interact with your dialog and when you want your Activity context you can use your activity name like :
YourActivityName.this
here is a sample that i've used in dialog code to access a TextView inside of the parent activity :
((TextView)DayReportActivity.this.findViewById(R.id.edtDailyCPCode)).setText(CPCodeText);
My launch activity starts up another activity whose launch is set to single instance. In this 2nd activity, I have a public method. I then start up a 3rd activity and that activity needs to access the public method in the 2nd activity. I don't want to use startActivity and pass it extras because I assume the onCreate will get called (or am I wrong?) and I need to avoid the 2nd activity from reinitializing itself.
When an activity is started using startActivity, is it possible to gain access to the underlying class instance itself and simply call the method?
I actually came up with a simple solution. As a matter of fact you can access the underlying class of an activity. First, you create a class that is used to hold a public static reference to activity 2. When activity 2 is created, in its onCreate method you store "this" in the static reference. Activity 2 implements an interface with the methods that you want available to any other activity or object. The static reference you hold would be of a data type of this interface. When another activity wants to call a method in this activity, it simply accesses the public static reference and calls the method. This is no hack but is intrinsic to how Java operates and is totally legitimate.
It is not a good idea.
As I can understand method from second activity is actually not connected to particular activity while you want to call it from another one. So carry the method out to other (non-activity) class (maybe static method) and use it from both activities.
It's not directly possible to gain access to activity object started using startActivity (without using some hacks). And frankly you shouldn't even trying to accomplish this.
One Activity component can cycle through several Activity java object while its alive. For example, when user rotates the screen, old object is discarded and new activity object is created. But this is still one Activity component.
From my experience, when you need to do things you described, there is something wrong with your architecture. You either should move part of activity's responsibilities to Service or to ContentProvider, or use Intents, etc. Its hard to recommend anything more specific without knowing more details.
No there is no way to pass a reference via startActivity() however you can use some sort of shared memory to keep reference to your Activity. This is probably a bad design. However passing an extra with your Intent will not cause onCreate, that is completely related to the lifecycle.