In the modern Android development, is it advised to completely move onto fragment-like development?
To build both mobile phones and tablets apps using fragments and not do differentiate between activity-solely and activity+fragment apps?
Are there any Google Android Team's official recommendation to completely move to "fragments" or not to completely move?
You don't have to develop using fragments but if you want to provide the maximum number of consumers/devices with the best possible environment then you should switch to fragments. However if you really think fragments are the devils work you can stick to just Activity-based development and provide a sloppy looking UI.
As far as Googles' feelings go, I think this sums it up-
Embedded Activities via ActivityGroup were a nice idea, but have always been difficult to deal with since Activity is designed to be an independent self-contained component instead of closely interacting with other activities. The Fragment API is a much better solution for this, and should be considered as a replacement for embedded activities.
For more info about fragment usage check it out here and for more of the design philosophy check out this post.
Related
I've developed an android phone app in which the navigation is mostly activities and starting activities for results. I've read that in order to make the tablet layout look like 2 screens of my phone app one next to the other I should have made it with fragments. Is there another way to migrate my functionality to the tablet app? Meaning to keep the start activity for result but just concatenate two activities on screen? (it may sound stupid, I know). Thanks
In order to keep the software design simple and modular, fragments come in really handy. You can use the same fragment's UI design + working code in multiple places without changing much functionality.
Since you have the code built and running in terms of activities, it won't take much time to migrate/port it to a Fragment since the life cycle methods are pretty similar. All you need to do is study the life cycle of a Fragment and move code chunks from the Activity to the Fragment class.
You can study all about Fragments here - http://developer.android.com/guide/components/fragments.html
or maybe a training session here will help you more -
http://developer.android.com/training/basics/fragments/index.html
You will learn a lot and once you have tried it you will be able to comprehend the advantages in a much better way. In future always make it a point to design in terms of Fragments to have a much modular design.
Along with that I think you will also need to learn to design layout for multiple screen sizes. This link over here will help you understand how to support multiple screen sizes -
http://developer.android.com/guide/practices/screens_support.html
If a tutorial to do this very quickly is what you seek then this should help -
http://www.101apps.co.za/index.php/articles/converting-android-activities-to-fragments.html
All the best :)
It very depends on your app GUI structure. Sometimes, you even not need to adapt your GUI for tablet (if you build interface dynamically basing on screen dimension). As rule, if you have two screens where one screen is advanced or logical extension of other then you can union it into one screen on tablets for better informativeness. Secondary way, as rule, based on fragments.
You can achieve it with help of Activity group but it is deprecated in Api level 13, for more details please visit http://developer.android.com/reference/android/app/ActivityGroup.html, but I will suggest to go with Fragment as Fragment having nearly similar life cycle like as Activity with extra methods and features. Please refer link for more details http://developer.android.com/guide/components/fragments.html
I would like to know if someone know some Android Framework to conventional applications. For example, a framework like rails which we can see easily the MVC pattern.
See answer here for an overview of Android's limitations, which will give you an idea of why an MVC pattern on Android has not yet emerged: http://www.quora.com/Is-there-any-standard-MVC-framework-in-Android-application-development-If-not-is-it-worth-developing-one
After having posted that answer I have gone ahead and built a fully-featured app using a single-Activity architecture. It allowed us to get past all the major UX limitations that were mentioned while being able to have arbitrary complexity in controller hierarchies (parents with children with sub-children etc.). Overall it worked out great, however you WILL have to build out specialized components (ie: custom back stack mechanism) as well as to store/restore state in a way that plays nicely with Android's own Activity/Fragment lifecycle patterns. There are also certain limitations around Fragment animations which had us pull our hair out at times, which required more custom component workarounds. ie: animations that show both an outgoing and incoming Fragment on-screen at the same time aren't supported on Android, so you will have to resort to taking screenshots of views and placing them into temporary ImageViews so that you create the appearance of transitions that show two fragments at the same time. In the end it's all possible, but you will have to be ready to work around annoying Android limitations while keeping an overall MVC architecture intact.
In summary: make your top-level component an Activity which is primarily responsible for top-level navigation (tab-based, menu-based, etc., as well as back stack and state preservation). The top-level component should not govern any particular screen of your app, instead it manages controllers for every top-level screen. The controllers are all Fragments, and can contain sub-controllers which are also Fragments. All screen transitions are performed using fragment transactions as opposed to Intents/Activities. Passing around data between Fragments is another point of contention as Android generally only supports data-passing through an Activity (ie: Fragment uses its parent Activity). But in this architecture you have need to have Fragments passing data to each other (either parent/child or sibling-sibling relationships).
I don't have this wrapped up into a framework or anything, but if your dev/arch team is sufficiently proficient the architecture is definitely worthwhile shooting for. You will come out with an app that is not subject to the traditional UX limitations of Android... something that very few Android apps can say they've achieved. Also... it generally feels awesome showing you can achieve the same level of UX that iOS apps have for years. It's about time isn't it??
Don't know about the "conventional" part - Android does not play well with MVC architecture natively (mostly because Activities and Fragments take on responsibilities of both views and controllers), and I don't know if there is a standard framework for implementing MVC in Android.
I described some of my insights in more details in this answer.
That said, I created MVC (in fact MVP) template/tutorial application which demonstrates the approach I take to enforce MVP in my apps. You can use this app as tutorial, or clone/fork it and use as Android Studio template for your own apps. The source code is here: https://github.com/techyourchance/android_mvc_template
basically android has MVC pattern, but if you need more features like .net mvc you can use com.divankits.mvc module. Just see one of samples to find out how to use it.
here is more details about module:
bind properties to view(layout) objects
you are able to create field validators
convert model to json
In an Android app, I have two screens* the user sees, one for preparing a query and the other for displaying the results. The right UI here is to have the query preparation in one screen, and then see the result on the second screen. Since this app is aimed at phone users, there's no need to display the two at once.
The traditional Android way is to use two activities, a QueryPreparationActivity and a DisplayResultActivity, and switch between the two. However, I've been hearing more and more about how the Android UI is switching to fragments. I can implement the two screens as two fragments and have the activity switch them, but is it worth the trouble? I will essentially be reproducing the Activity management code Android already has.
Is there a reason to use two fragments here?
*I'm using the term screen, because it isn't necessarily an activity...
Personally, I always develop using Fragments.
But the best reason I can give you for using Fragments is when you develop for handset and tablet devices you get a lot of reusability.
I know you already mentioned that there is no need to show both screens at once. But say later you were to develop the same "screen" for a tablet device and realize that the preparation screen is too barren and want to have both queryprep and display result show at the same time, you would have to write a totally new 3rd activity.
If you used fragments, you would reuse your 1 activity and 2 fragments, and that activity should be coded smart enough to determine the size of the screen and show the proper layout.
Code Reusability & Flexibility are the buzz words here.
If you have any questions please leave a comment and I will expand my answer. If you like my answer, please upvote and accept.
Fragments were introduced encapsulate UI elements and related behaviour into a single, reusable module. Before fragments you had to re-write the much of the same code that 2 or more activities had in common especially if you couldn't find a good approach to abstract the UI/control code into a super class. This was further complicated by the limitations that activities only call setContentView once. So sharing some code between activities wasn't all that nice.
Now, to answer your question, it all depends on you. If you think that further down the road you could use the QueryPreparation or DisplayResult ui as a module (layout and logic behind it) then go for the fragment implementation. It could be a different layout for landscape view on phone or if you decide to support smaller tablets like the nexus 7. If you are sure that it will never happen then stick with activities. Personally, I use fragments everywhere and they are a sure way to "future proof" your implementation for reuse down the road.
In short Fragments were introduced to accommodate the emergence of tablet/large screen devices and allow developers to create applications that will run across a wide range of screen sizes with very little change to code.
More can be read here at the Android Blog. That blog also details some of the finer technical details for the reasons for the move toward Fragments. Also introduced at Goolge IO 2012 were DialogFragments which you should consider using instead of Dialogs. Another blog post here describes them.
You're better off getting used to using Fragments and DialogFragments from the get go as this is the way Android is moving. Only use individual Activities if you really really need to do a quick-and-dirty app for say testing purposes. Fragments, in my opinion, do require a bit more code-work to incorporate and to initially get your head round but it's worth the effort.
I have a full-fledged app which is NOT developed using Fragments. My confusion is that should I change it to have Fragments instead of Activities. The thing that I would like to tell is that I'm using only portrait orientation in my application and it is built, keeping in mind only phones, not tablets. So my question is, will it do any good if I change the whole structure of app and use Fragments.
As far as I know, Fragments should be used only If we want to reuse something. Any suggestion is appreciated.
Fragments can be used to create a dynamic and multi-pane user interface, and as such are ideally suited for tablets which have a lot more screen real estate to use up. Of course, on a phone the situation is a little different, you have a much smaller space to play with and sometimes it can be a struggle just to get one Activity fitting onto the screen without worrying about including multiple Fragments.
Fragments are very good for dynamic interfaces, and for helping with compatibility between Tablet and Phone. They are also able to communicate with each other much better than Activities can, so there are certainly advantages to using them even on a phone-only setup. (See FragmentsManager for some functionality they can be used for)
One example of use is illustrated in the diagram below (taken from Android Developer site)
This illustrates the flexibility of the Fragments, which on tablet can occupy the same screen, switching to a more Activity-like format on a phone. It is this kind of power that gives the Fragment such an advantage over an Activity.
So clearly there are advantages to switching to a Fragment orientated solution in terms of flexibility, but your original question states that you are targeting phones only, and only in portrait orientation.
Having an application that is already in existence with Activities, providing that it is a solution that you are happy with, and has good usability I would say there was no reason to switch to Fragments (unless you are looking for a challenge or have some spare time and fancy a tinker). While advantages exist, a drastic change such as adding Fragments could introduce bugs into your application and impact the user experience (at least for the short term).
Long term, if you are ever considering bringing tablet support into the fold or would like to use the landscape orientation, then it might be a good idea to start looking at what you can do with Fragments to improve the experience, and integrate this with the current flow of your phone application.
Otherwise, the current solution you have created will more than suffice, and as long as it is well received by your customer base I see no reason to change.
Of course, there is no harm familiarising yourself with the Fragment APIs for future projects, or in the event that it is time for a refresh of your current project's UI.
It is worth pointing out that Fragments are only supported natively from Android 3.0 (API level 11), and to support earlier devices you will require the Android Support package found in your installation. As such, if your current application targets 2.x devices, I would stick with an Activity based approach, for simplicity and .apk size, unless moving to a native API Level (like Android 3.0+). This is personal preference though and ultimately the answer to your original question will boil down to your personal preference.
Think of fragments as a way to modularize your code into manageable pieces. Each fragment represents a small piece of functionality and UI. This allows your to easily adjust your code to fit different scenarios.
Sure you don't plan on supporting tablets now (regardless of how you feel tablet users will install the app), think of larger size 5-6" devices and the potential of extending your app over to them. It is best to provide your app to as many devices as possible and the best apps will tailor the experience to the device.
The transition to Fragments doesn't have to be difficult. Take a small piece of functionality and move it over to a Fragment. Then you will see how easy and flexible the new pattern is. You don't need to rewrite the entire application as Activities and Fragments can work together.
I believe by skipping out on Fragments you are really making your development tasks much more difficult in the long run.
If you don't plan to support tablets in the future than leave it as it is. You won't gain anything when you convert your app to fragments.
The situation is different if you start a new application. I would use fragments from the beginning in order to be more flexible should the need arise to support other form factors in the future. Note that the functionality is available in the support library so you can use it also on older devices.
It is easier to set interaction between fragments than between activities.
In case of activities:
You need to use startActivityForResult()/onActivityResult();
Your custom types must implement Parcelable interface in order to be passed between activities;
You have to free all resources when your activity is paused/stopped.
In case of fragments:
Passing data is as easy as getting an instance of fragment from FragmentManager and calling a method on it;
No need to implement Parcelable;
You can hold references to "heavy" resources in activity which contains all of your fragments and initialise/release them only once (no need for initialisation/release for each fragment).
Also, an instance of Fragment is more lightweight than instance of Activity and takes less time and resources to be initialised/resumed.
In general, interaction between the components of your UI is cleaner, more elegant, easier to implement when you use fragments.
As far as your application or any of the application is concerned , it's better to use fragments and it causes no harm to your application and it also ease your burden while further extending your application for tablets also.So, better to start with the use of fragments in your application.
I've just finished converting my application to use fragments, because:
Wanted a tablet version
Wanted to use ViewPageIndicator and ViewPager with advanced views
Those are the most compelling reasons to use fragments.
It might be a little more work, but with significantly more tablets appearing on the market and fast adoption rate, perhaps it's worth considering supporting tablets with a nicer UI?
If you really don't want to do this and have no requirement for view paging using advanced views then there is no point over-engineering your project to make it use fragments for using fragments sake. You could argue you might learn about them, but when you come to use them in your next project, you can learn then (that is what I did and it worked out fine).
I will try to keep this short, but I need some advice.
I work on a team that is developing applications for android, iphone, and wp7 in parallel.
We have a design team that comes up with a single design for all three platforms.
The latest application’s design is more marketing than productivity. The original POC for this app was done on the iphone. The design is very animation centric and most state changes are seamless (things will animate on and off the screen during state transitions).
If I keep developing against this design it means I will have to have everything in a single activity. So far, this has been a major headache. To my knowledge, dividing your application into activities is almost required. I could try to dynamically load and unload views as I change states but this doesn’t seem right.
I see where the design team is coming from where they want all these state changes to be seamless, but I don’t think this is right for android.
I would like to know what makes most sense. Should the design change to incorporate multiple activities or would it be worth trying to make this work.
We have a design team that comes up with a single design for all three platforms.
That's akin to coming up with a single floor plan to be applied to apartments, single family homes, and warehouses. The designers, or management, need to have their heads examined.
The latest application’s design is more marketing than productivity.
Did I mention that the designers, or management, need to have their heads examined?
If I keep developing against this design it means I will have to have everything in a single activity.
If I am interpreting your requirements correctly, that is probably accurate. While you can arrange for animations between activities, it is more of a "slide the old off, slide the new on", and I suspect that your requirements exceed that.
To my knowledge, dividing your application into activities is almost required.
It is certainly Android's intended development model for ordinary apps. However, games and the like may not follow this pattern, and you don't have to either.
I could try to dynamically load and unload views as I change states but this doesn’t seem right.
Depending on how many states there are, you might just hang onto all of them, recycling as you go.
I am surprised no one mentioned fragments which can be used instead of activities at many places.
Fragments can be seamlessly animated in and out or an activity.
You might want to take a look at subclassing ActivityGroup for your top-level activity. That can host multiple sub-activities. TabActivity, the only stock subclass of ActivityGroup, is perhaps not what you need because it includes a tab widget, but you can use it as inspiration for what you do need.
What specific headaches are you having with a single-activity architecture? Perhaps there are ways to make that less painful.
In general, if you are aiming to have native apps with a native look and feel, it is not reasonable to have a single UI design for all three platforms. The UI guidelines and user expectations for the systems are different, and those differences should be reflected in the UI designs.
If you really want to have a single UI for all platforms, just create a web app instead.
I'm not sure exactly what you mean by an "animation centric" design with seamless state changes. If you use multiple Activities, Android will animate between them in a way that Android users will expect. If you explain what exactly you are trying to accomplish, we can help you figure out if it makes sense in Android, and if so how to accomplish it.