How do I get context from Activity in a fragment in Kotlin. I know, in Java you can call getActivity()
To get the Context in the Fragment from AndroidX support library you can use method requireContext()
If you need an Activity instance to which your Fragment is attached, use the requireActivity() method.
Note: These methods will only work when the fragment is attached to some activity. Otherwise they will throw an error.
Related
In Alfresco APS 2.3 version, we have one upgrade i.e., Changing ActivitiExecution class to Delegate Execution class.
Both the classes has execute() method.
Inside the execute() method of ActivitiExecution, we have method called "getCurrentActivitiName()"
But inside the execute() method of DelegateExecution,we don't have this method called "getCurrentActivitiName()".
How to get the Current activitiName in Alfresco Process services (Activti 7)without this method in DelegateExecution class?
Try by casting this way.
ActivityExecution activityExecution =(ActivityExecution) delegateExecution;
I'm running into an interesting issue when using OCMock 3 when partially mocking an object that defines class methods. I'm not sure if this is an issue with the dynamic subclassing that takes part as partial mocking or my misunderstanding of the objc runtime. Any help would be greatly appreciated.
As part of running tests and other debug builds we do some runtime verification of method declarations using OmniFoundations' OBRuntimeCheck. One of these checks, in short, attempts to use the runtime to verify that type signatures match for class methods across inheritance and protocol conformance. This happens by listing the classes registered in the runtime and for each class the instance methods of the metaClass are copied. For each Method from the metaClass if it exists on the metaClass's superclass the type signatures are compared.
The problem comes when calling class_getInstanceMethod on the metaClass's superclass for one of the ocmock replacement selectors, ocmock_replaced_*. The test crashes EXC_BAD_INSTRUCTION code=EXC_i386_INVOP subcode=0x0 and no class for metaclass is logged in the console. Example given:
class_getInstanceMethod(metaSuperClass, NSSelectorFromString(#"ocmock_replaced_classMessage"))
When partial mocking an object that defines a class method, it appears that the OCMock 3 framework generates a dynamic subclass, does some isa swizzling of the mocked object and also some isa swizzling of the dynamically generated class' metaClass.
This behavior and crash is new in OCMock 3 and I'm really at a loss of where to look next. Any runtime gurus have any idea what may be going on here? When looking through the code it did surprise me that the dynamically generated class used for the mock was having it's meta class swizzled out, but I don't necessarily think that is wrong. For ease in debugging I have created a simplified test case in a fresh fork of OCMock. The crashing test can be found here. Any help for guidance would be greatly appreciated.
I may be way off here, but I thought the superclass of a metaClass is NSObject (which is why you can normally call NSObject instance methods on class objects). I'm not sure you should be doing anything, normally, with the superclass of a metaClass.
In general, the metaClass stores all of the information about class methods. Therefore, getting an "instance" method on a metaClass is the same as getting a class method on the associated regular Class. The runtime can simply dereference the "isa" pointer of an instance to find a method list to find instance methods; doing the same on a Class object gets the meta class (of the same structure) and therefore the same process results in finding the class methods.
OCMock will create a magic subclass for any partial mock, and change the class on that instance to the new subclass, so all the instance method swizzling will be specific to that instance. For class methods though, I thought it had to modify the original class itself -- otherwise, calls to the regular class method in regular code would not be intercepted. It keeps a copy of the original implementation so that when you call -stopMocking on the mock it can restore the original implementation (the added ocmock_replaced* impl will still be there but should no longer be called).
You could simply ignore any selector which starts with "ocmock_replaced" since that really is not related to your actual code you are presumably checking. You might also have better luck changing "class_getInstanceMethod(metaSuperClass, ..." to "class_getClassMethod(regularSuperClass, ..."). I'm not sure why you would be getting a crash though -- I would expect class_getInstanceMethod(metaSuperClass, ...) to just return NULL in most situations.
I am creating some hack kind of thing in existing android code to verify database creation and its accessibility across layers in application.
For this I have modified an existing function of .java file but I am facing an issue while calling constructor of SQLiteOpenHelper.
The signature is SQLiteOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version)
And I don't know how to create this Context instance. From googling I am seeing it is being some kind of activity class instance.
What ways are there to create this Context instance? Do we have to have activity class implemented?
Have a look at this question. It shows how to obtain a reference to the current Context object statically.
The gist of it is that you have to store a reference to the context that can be accessed statically from other sections of code.
P.S. You can't really "create" a context. That is something that is provided to you by the Android platform.
Just call:
this.getApplicationContext()
from wherever you are trying to create the instance of SQLiteOpenHelper.
I have a class called CommunicationManager which is responsible for communication with server.
It includes methods login() and onLoginResponse(). In case of user login the method login() has to be called and when the server responds the method onLoginResponse() is executed.
What I want to do is to bind actions with user interface. In the GUI class I created an instance of CommunicationManager called mCommunicationManager. From GUI class the login() method is simply called by the line
mCommunicationManager.login();
What I don't know how to do is binding the method from GUI class to onLoginResponse(). For example if the GUI class includes the method notifyUser() which displays the message received from theserver.
I would really appreciate if anyone could show how to bind methods in order to execute the method from GUI class (ex. GUI.notifyUser()) when the instance of the class mCommunicationManager receives the message from the server and the method CommunicationManager.onLoginResponse() is executed.
Thanks!
There's two patterns here I can see you using. One is the publish/subscribe or observer pattern mentioned by Pete. I think this is probably what you want, but seeing as the question mentions binding a method for later execution, I thought I should mention the Command pattern.
The Command pattern is basically a work-around for the fact that java does not treat methods (functions) as first class objects and it's thus impossible to pass them around. Instead, you create an interface that can be passed around and that encapsulates the necessary information about how to call the original method.
So for your example:
interface Command {
public void execute();
}
and you then pass in an instance of this command when you execute the login() function (untested, I always forget how to get anonymous classes right):
final GUI target = this;
command = new Command() {
#Override
public void execute() {
target.notifyUser();
}
};
mCommunicationManager.login(command);
And in the login() function (manager saves reference to command):
public void login() {
command.execute();
}
edit:
I should probably mention that, while this is the general explanation of how it works, in Java there is already some plumbing for this purpose, namely the ActionListener and related classes (actionPerformed() is basically the execute() in Command). These are mostly intended to be used with the AWT and/or Swing classes though, and thus have features specific to that use case.
The idiom used in Java to achieve callback behaviour is Listeners. Construct an interface with methods for the events you want, have a mechanism for registering listener object with the source of the events. When an event occurs, call the corresponding method on each registered listener. This is a common pattern for AWT and Swing events; for a randomly chosen example see FocusListener and the corresponding FocusEvent object.
Note that all the events in Java AWT and Swing inherit ultimately from EventObject, and the convention is to call the listener SomethingListener and the event SomethingEvent. Although you can get away with naming your code whatever you like, it's easier to maintain code which sticks with the conventions of the platform.
As far as I know Java does not support method binding or delegates like C# does.
You may have to implement this via Interfaces (e.g. like Command listener.).
Maybe this website will be helpful:
http://www.javaworld.com/javaworld/javatips/jw-javatip10.html
You can look at the swt-snippets (look at the listeners)
http://www.eclipse.org/swt/snippets/
or you use the runnable class , by overwritting the run method with your 'callback'-code when you create an instance
I've got a number of modules in a Prism application which load data that takes 3-8 seconds to get from a service.
I would like to be able to say in my bootstrapper something like this:
PSEUDO-CODE:
Customers allCustomers = Preloader(Models.GetAllCustomers);
And this would run in a background thread and when the user actually needs the variable "allCustomers" it would be fully loaded.
Is there an automatic service in Prism/Unity which does this type of preloading?
No, there is not.
However...
What you can consider is adding your ViewModel with a ContainerControlledLifetime to the container in your ConfigureContainer method that the views can use. You'd kickoff your threaded request in the constructor of your ViewModel and allow Views to pull this ViewModel out of the Container.
Even if they grab the ViewModel out of the container before the GetAllCustomers method is done firing, they will be notified correctly if the property you store the customers in implements INotifyPropertyChanged correctly.
If it was more appropriate, you could also do this from the Modules (in the Initialize method), rather than in the bootstrapper (for instance, if your Module was what actually knew about your Customer's Model).