I have a app on Google App Engine and I'm using GWT, and when the user goes to www.myapp.com/#show I need to show a graph, and in that page there is a button to search and add nodes to that graph, when the search Button is clicked I need to show a popup with the search form (it has several functions and dialogs).
Can I create a view for that page and another view for the popup and use the same presenter for both?
or What is the best way to implement that based on the pattern MVP?
MVC(Model View Controller) style tells that you have this three packages for Entities, UI, Controller classes. This help you organize your code and break it to plugins.
As for your question it is better if you can implement a CustomPopUp class in the View(UI) package and make it abstact. So PopUp could have as parameters the message the context or everything it needs to show the approprate message.
And you can pass CustomPopUp as private delegator to your UI classes who need to show popup messages.
Related
In my Vaadin 8 application, I have a TabSheet, that contains several views. When I override the enter method in the first view of my TabSheet, and then I proceed to enter the view on my application, the method doesn't get called.
Do you have a Navigator, and have you registered the views for it? Navigator's navigateTo is what calls the enter. Registering views happens along these lines:
navigator.addView("", new InitialView());
navigator.addView("second", new SecondView());
Navigation also updates the URI fragment in your browser, and makes it possible to bookmark specific views and enter them via direct URL. See e.g. https://vaadin.com/docs/v8/framework/advanced/advanced-navigator for more information about Navigator.
TabSheet isn't the most trivial thing to use with Navigator and I'm afraid I don't have a ready-made example at hand, but I think it should be doable with a custom ViewDisplay and maybe SelectedTabChangeListener.
If you aren't interested in the Navigator approach, I suppose you could replace the View+enter with something along these lines, although if you need to know the previously selected tab you'll need to keep track of it yourself since this particular event isn't very informative:
tabSheet.addSelectedTabChangeListener(e -> {
((MyClass) tabSheet.getSelectedTab()).myMethod());
});
Attached screenshot of netflix app with left side menu I am able to develop a side menu with customized icon and header in it. I want, when the focus comes on header fragment it should expand on top of row fragment, that is not collapsing the row fragment, the same as Netflix and hotstar are doing. How can I achieve it?
unfortunately, the HeaderSupportFragment used in the BrowseSupportFragment is not configurable enough to achieve this kind of design. Leanback is great to build quickly and easily media browser app but when it comes to "complex" design, it's easier to use custom component.
The major difference also here, is that the left menu of the BrowseSupportFragment show each rows header name displayed in the screen (that's why it's called HeaderSupportFragment). Here you want to show different entries like search, home, settings, etc.
To make this kind of view, I would suggest creating your own custom view and use a basic Fragment. I followed this tutorial which can be useful to handle menu open/close animation (I mixed it with a ConstraintLayout to simplify the animation and I made the menu overlap the rest of the screen instead of moving everything.)
See the tutorial: https://medium.com/building-for-android-tv/building-for-android-tv-episode-3-381e041dfec7
Despite its not best UX. I wonder what is the best solution to start several different Activity(Dialog) with different callback implementation. I assume starting each dialog needs to be from static fabric method with context.startactivity(dialog1). Each dialog looks exactly the same besides some title and message but callback for ok and cancel buttons are different. I want to separate implementation of dialog callbacks(ok, cancel) from generic dialog behavior. What if I can't pass actions while starting activity from static method, I don't find Bundle to fit this case.
How about this, create an enum for the dialogs.
Based on the enum you can either have the values for everything be in the enum itself or switch on the enum in your code at the appropriate places.
recommend creating different click listeners for the yes and no buttons.
In those click listeners you can switch(enum) and for each case have the specific business logic. OR create different click listeners and use a factory that will allocate the listeners based on the enum.
either solution works depending on how you want to code it. They both have their own pros and cons.
There is an AlertDialog.Builder class that you may be able to use depending on what your dialogs look like. There is also the dialogfragment class that you can extend to help out with the dialogs.
if you want to show the users several dialogs you will need some sort of queue that you populate with all the dialogs that you want to show and then show them one after another, IMHO, use different views and just replace the view in an activity so you can slide it in or animate it in somehow.
You can make them look like cards and then just change the text inbetween that way switching on the clicklisteners based on the type of the current view will be easy and you can even have the enums provide the views using the R.layout.layout_name as a value in the enum.
I know that is a lot and maybe some of it is unclear, Please ask questions and i will do my best to respond in a timely manner.
So I have read a lot about MVC online and have learned about it in class, but I am still lost on one aspect - changing and showing Views. I know Views are GUI, they pass user input to the Controller, but I'm having a hard time wrapping my mind around how the following would work:
View A displayed
user clicks button on View A
Controller notified, tells Model
Model tells Controller to display View B
Controller displays View B?!?
The last 2 lines here is what I don't understand how to implement. If the View did not change to another View, I know to use the Observer/Observable interface to update the View. But in my case there is a Home Screen and a Game Screen and when the user clicks Play button on the Home Screen, I want the "view" and the GUI to change to the GameScreen. I want to use 2 distinct Views (I think).
I'm having trouble structuring my code to achieve this, and I don't know where to put the ActionEventListeners
Assuming you're just switching the view, this is the sequence.
View A displayed
User clicks button on View A
Button controller tells view to display View B
View displays View B
The model is not involved at all. Other controllers can change the model.
When coding a Java Swing application, here's what I do.
The view may read values from the model.
The view may not update the model.
The controller(s) will update the model.
The controller(s) may revalidate / repaint the view.
To see an example of the model / view / controller pattern in a realistic Swing application, take a look at my article, Retro Snake Game.
First time posting a question on StackOverflow, so please go easy on me :)
From what I understand, proper use of the model-view-controller pattern requires that we decouple the view and controller such that the view knows nothing about the controller. I'm having a bit of a problem understanding how to do this using Java Swing.
Say I have a view (some class that would extend JFrame), and this view has a button. Is it safe to say that I would want to register the controller as an ActionListener of the button? Or do I make it a listener of the entire view itself.
And how do I go about doing this without doing something like:
button.addActionListener(myController)
in the view, because if I were to do this in the view code, wouldn't it now have a dependency on the controller?
I didn't post any code because, frankly I don't have much to go on at the moment.
any help is appreicated!
It might help to not think of the view in terms of buttons etc. so much as an interface. The interface makes it possible for web ui's, command line consoles, etc. to be written and fulfill the role of the view.
In the case of your button event, the button represents a call to some command carried out by the controller.
So, you could have an interface like this:
public interface MyViewIf {
// used by the controller to register its self as a listener of the view
public addViewListener(ViewListener vl);
...
}
and:
public interface ViewListenerIf {
// used by the View to notify any listeners of control events etc.
public onViewEvent(ViewEvent ve);
}
Then your controller would implement ViewListenerIf and register it's self with a factory generated instance of MyViewIf. That way the controller doesnt need to know any specifics about your view class(es).
Your view class would then internally handle it's own button events, turn them into ViewEvent objects and call onViewEvent() on the controller that registered it's self with the view, leaving the View 100% oblivious to the existence of the Controller.
Make an actionlistener in your view class. From your actionlistener you call your controller.
Code for actionlistener:
controller.doButtonClick();
This means you need to inject your model and controller to the view. That is how I do it.
Take a look at the Spring Framework to get an insight in implementing the MVC pattern.
Brief Spring tutorial Tutorial