I'm new to android programming pls help. It's just that I have this application modules created in Activities form. Now that I wanted to use the Android navigation bar to navigate between them, I can't do so, it seems that theres alot of things I would have to change such as the imports, the declarations, and omit certain methods etc. Is there a comprehensive manual for such task?. I just can't seem to find one. If there is, it's just limited to a few things. BTW, I just want to know how I would be able to do such task. If there is a for Dummies of it,would be the best.
Be better if it would also include the AppCompatActivity thing, I can't seem to combine it too with Fragments and Activities, :(.
You need to understand your app's architecture first. You need to analyse the flow of UI screens and the underlying logic they perform. If you want to navigate through your activities using Navigation Drawer, well, then converting all of them them into fragments isn't a solution! First find out which screens can perform flawlessly if you replace them with fragments and then go ahead with it. If you are new to android programming then visit Udacity online and watch all of their android tutorial videos! They have a bunch of comprehensive ones and the best part - it's free.
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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
In the last year I have taken over two existing projects, each of which was structured very differently.
Project A had one Activity, and then each area of functionality was contained as a Fragment within that activity. The areas of functionality were not related - there were the usual type of screens such as account, settings, help, etc. Overall there were probably around 25 fragments. The fragment management code was rather complex and tricky to debug.
Project B had one Activity per each Fragment. It was a complex project with many areas of functionality and the manifest listed almost 30 activities.
I was wondering which was the 'correct' solution? What are the pros and cons of each? If I were starting a new project from scratch which model should I follow?
There really is no "correct" solution. Whichever architecture makes the most sense to you is probably the one that you should choose for your projects.
Think of Activities as a collection of zero or more Fragments, and Fragments as a way to separate pieces of an Activity into smaller logical or functional pieces. From there, decide how you personally want to organize these pieces and go with it.
Dianne Hackborn and Adam Powell addressed this question at the 2014 Google I/O Android Fireside Chat as well, and I think they did a good job of explaining how the two are just different levels of abstraction for the same concepts.
My doubt here is how to achieve a clean and easy code to maintain over time in an Android app?, I'm trying to apply Uncle bob - clean code rules but as I keep going with development sometimes some rules must be broken, and I end with an Activity of 700 lines (I'm not using Fragment, and 700 lines seems to be a Class that "does too much things") so I want to know if someone has try an Android app with proper use of Fragment and could answer these questions:
1- does it really impact on Activity lines length (at least less than 300-500 [not strictly this numbers but a "reasonable" Class length] lines)?
2- does code keep clean and easy over the time?, not necessary with Uncle bob rules but considering best practice in OO while coding.
3- does it have a considerable impact in terms of "Performance"?
4- does Fragment help to support in a more simple way a wide fan of Screens?"
5- ignoring developer skills, what "should" be the way to go non-Fragment activities or activities with rich Fragment use?
Note: this is not an attemp of Duplication to Android - Activity vs FragmentActivity? since the topic here is not about tab format but best practice for android development.
sorry for my english ;).
You are conflating the use of fragments with the use of FragmentActivity.
FragmentActivity is a subclass of Activity designed for use with the backport of fragments from the Android Support package. You usually only use FragmentActivity if you are using the backport. If you are using fragments, but your android:minSdkVersion is set to 11 or higher, you can usually skip FragmentActivity.
With that in mind:
does it really impact on Activity lines length (at least less than 300 lines)?
That is impossible to say. It is equivalent to asking whether a Restaurant that subclasses Business will be longer or shorter than a Restaurant that subclasses FoodSupplier. It all depends on your code.
That being said, it is certainly possible that the use of fragments will reduce the lines of code in the activity. IMHO, that's not a good reason to use fragments.
does code keep clean and easy over the time?, not necessary with Uncle bob rules but considering best practice in OO while coding.
That is impossible to say. It is equivalent to asking whether a Restaurant that subclasses Business will be "clean and easy" compared to a Restaurant that subclasses FoodSupplier. It all depends on your code.
does it have a considerable impact in terms of "Performance"?
Not usually.
does Fragment help to support in a more simple way a wide fan of Screens?"
If by "wide fan of screens", you mean "a wide range of screen sizes", then yes, fragments can help with that. In fact, that's the #1 reason for using fragments, IMHO. However, fragments alone do not magically help with screen sizes, any more than having capital letters in method names magically helps with screen sizes.
ignoring developer skills, what "should" be the way to go FragmentActivity or Activity?
As stated previously, you usually only use FragmentActivity if you are using the backport of fragments. If you are using fragments, but your android:minSdkVersion is set to 11 or higher, you can usually skip FragmentActivity.
If your question really is "should I be using fragments in my app?", the answer is "probably, but it depends upon the app".
Yes, fragments are the way to go. They help spread your code around in a logical way so you don't have a 700 line activity, they keep your code easy because each fragment will have its own class usually, and they do, to answer your 4th question, make it easy to have "A wide fan of Screens".
I recommend this video to help get you started. For any beginners, this video is a great explanation of how to use fragments ( I know because I had a hard time figuring out how to use them until I watched this video). It is called "Programming Android with Fragments" by Andrew Ruffolo:
http://www.youtube.com/watch?v=KyXvq_kwfzg
This video demonstrates the power of fragments. You still need a main activity of some kind, but this main activity acts kind of like a container for the fragments, and most of the functionality of your app is handled by the fragments and their corresponding classes.
I have never used activities because I started app development after fragments were added to android, but it seems like fragments help break down your app in the same way that methods and inner classes help break down your classes, and the same way that classes help break down a project or program. I am not sure if this was possible or as simple using only activities before fragments were added.
I know how to change the activity, without use of Master Detail Flow Template but I need to make an app with multiple Master Detail Flow layouts.
I think that a single Master Detail Flow Layout is already a little bit complex and confuse alone, but it must be more confuse when there's necessity of multiple app screens.
Someone knows a good tutorial on this?
I have the same need, did you ever get any response or found the solution? I have a List that is a Menu, with around 10 entries and each entry requires a different activity/screenlayout.
EDIT:
I have found this very good tutorial: http://www.michenux.net/android-fragment-swapping-325.html. After making the needed adjustments for my app, change until 10 different layouts in the detailFragment, based on item selected in masterFragment, it works perfect for me.
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.