I need some best practices ideas for my app. I think there is too much boilerplate code right now and I don't know if I'm using activities and fragments the right way.
There are 3 activities (A,B,C). The app starts at A. I can navigate to B which is a simple list and each of the items are clickable to show the item more detailed in activity C. A should be the "root" activity, so I set the parent activities in the manifest file.
Now I want to have a DrawerLayout navigation on B and C, which actually represents A in a smaller way.
I created an abstract NavigationActivity class for taking the view of the activity and set is as the first child of the DrawerLayout and add the navigation as second child. This works very well, but since the navigation has a state I embed the navigation as fragment, because I thought that the state is shared then, but it isn't and I don't know why I should use fragments at all.
Should I use one activity and load different fragments as main content? Then my app consists of 2 activities and maybe 50 fragments, when I finished it. I think that the way I try to implement it is not correct.
As an example: When you enter the PlayStore, there is the navigation on the left. You can browse the app and so on. Do you thing/know that it's the same activity with different main content or are there more activities?
Can you help me? Thanks :)
Single Activity applications are possible, but are not necessarily a best practice. IMHO, fragments have a very complicated lifecycle, so use Activituies when you don't HAVE to use fragments.
If your problem is to share the state of your drawer fragment through activities, you could pass it as an extra to each activity, or keep it in a static class/variable to retrieve it at every start.
Don't forget to also save this state during the destruction of one of your activity.
Related
I am trying to find a way to show two activities on the same screen, I have two activities main and content activity, the main activity has a mini-player that's implemented and only works in an activity and the content activity has some implementations that also only work in an activity so the solution of converting them into a fragment does not work for me. I need to find a way to show the mini-player in the main activity inside of the content activity. I have looked online and none of the solutions so far have been working for me!
You have 2 ways to complete task.
Fragments, They can do same things as activity. Its lite weight activity class with more flexible to attach and detach from the screen.
Views, If you think your task can be done by only activity then use views for it. you can apply different animations and show/hide feature to display content on the screen within single activity.
Fragment is a part of an activity, which contributes its own UI to that activity. Fragment can be thought like a sub activity. Where as the complete screen with which user interacts is called as activity. An activity can contain multiple fragments.Fragments are mostly a sub part of an activity.
From document
For example, a news application can use one fragment to show a list of
articles on the left and another fragment to display an article on the
right—both fragments appear in one activity, side by side, and each
fragment has its own set of lifecycle callback methods and handle
their own user input events. Thus, instead of using one activity to
select an article and another activity to read the article, the user
can select an article and read it all within the same activity
Use Fragment.Fragment are Runs inside the Activity.
you can display multiple fragment in same time.
Refer Fragments
Create a fragment
At first, Android system can show only one activity on the screen.
You should not use Activity.
Please use Fragment. You can use multiple fragment on the same screen.
I set up my application in the following way and am curious if it's considered "best practice." I have two activities and two fragments. Activity 1 launches and immediately uses Fragment 1 to display a RecyclerView of items. An Item is clicked in the Fragment, it's communicated back to the Activity through an interface, some logic occurs and Activity 2 is launched, which immediately uses Fragment 2 to display the detail of the selected item.
I did this because A)I like the logical flow of Activities within an application and 2) I needed to create tablet layouts in which I could use both the Fragments to fill the screen.
The more I'm looking at this thing, I'm thinking why not simply have 1 Activity that manages both of these Fragments? Activity 1 launches Fragment 1, item is clicked, info goes back to Activity, FragmentManager replaces Fragment 1 with Fragment 2.
My question does one of these ways adhere more to "best practices" or are they both fine and it's a matter of choice?
You've not described your problem clear enough to use more than one Activity, other than unrelated data to the list and what happens when you click there.
What you described is a "master-detail" flow, and that is a good use case for one Activity and two (or more) Fragments - a list + some detail page. This especially makes sense on larger screens when you can show those Fragments side-by-side.
For example, you can have an Activity that holds a navigation screen (whether that be tabs, a drawer, or a bottom view), then everything you navigate to within there is a Fragment.
Otherwise, you redirect to some "settings" page, for example, that is a new Activity, which demonstrates the "Single responsibility principle" in your UI.
Well you can go with the single activity - multiple fragments. You can pass data between fragments using bundle as well. Matter of choice also depends on the use case. But fragments are made to use as light weight activity that requires less resources then activity. Most of the things are possible with fragments. So unless it is not required to use activity my choice goes with single activity - multiple fragments.
I used to have 3 activities with 3 layouts.
1. HomeActivity.java (activity_home.xml)
2. HelpActivity.java (activity_help.xml)
3. SettingsActivity.java (activity_settings.xml)
Whenever i had to open other activities, i used animated slide-in-out intents using overridePendingIntent. In this way, all the variables of HomeActivity stayed in itself and HelpActivity's variables/methods were in itself and same for SettingsActivity. I used onCreate() in these to perform some activity specific code. and, android:onClick="fetchSarcasm" from activity_home.xml was calling specified method in HomeActivity.java. So, there were no conflicts. All the normal things, that happen in an AndroidProject with 3 activities and used intents to switch to one another, were happening as i wanted.
But now, I wanted to migrate to ViewPager instead of slide-in-out intent transitions. In this way, there will be only one Activity with an XML of ViewPager. This ViewPager and its FragmentPagerAdapter gets the Pages from 3 classes extending Fragment with relative XML layouts.
I want to ask: Where do i write my Page Specific Code for onCreate(), layoutView's onClick="" and for onChangeListeners. Because, 3 classes extending Fragment do not have any Context or findViewById() and they do not respond to android:onClick="method" in different layouts.
Do i need to mix all that code of three activities into one containing ViewPager? If so, this makes ViewPager activity pretty heavy. and, writing if(page=2){ dothis(); } seems absurd for all pages at every code point. Any checkbox(view) that is in page 3, becomes null in other pages.
I know this might be a stupid question. I have spent almost 4 days trying to achieve something but i can't. Also, this is just my 2nd month in android, so i am new. I do not use Action Bars, Tabbed Bars or Navigation Drawers.
I am available on SO Chat too if you want to ask something more.
I just want to know how do i merge all the work i did when I was not using ViewPager.
If you're only reading the Preferences once for each Fragment, you can move your previous Activity.onCreate() logic to each Fragments onViewCreated() or onCreateView(). Read your shared Preferences there and set your Checkboxes accordingly.
Fragments inside a ViewPager aren't necessarily recreated on each page change. You can change how many Fragments are instantiated at a time with ViewPager.setOffscreenPageLimit(int).
Fragment Lifecycles explained
What scenarios using fragments what scenario using the activity , How can I make sure you when to use the activity when using fragments ！
Basically, when you want a fixed portion of the screen and the rest will be changing, you want to use fragments.
If all your app is going to be on different screens, you want to use Activities.
Anyway, at least you will need one activity to hold your fragments.
Hope this helps.
As i know,You need to extend the fragment when you are displaying the view into tabs.
Otherwise you can extend activity.
It depends on your requirement. if u want to expose your toolbar throughout your application you can use fragment both activity and fragment are quite similar . You can also use only one activity remaining things may be your fragment
It depends on UI which you are creating.
If you are creating Multi-Pane UI then you should use Fragment.
And if you are creating some part of screen which can be reused then for that part you should create Fragment as Fragment is meant for re-usability.
If you are creating stand-alone screen then you should use Activity
For more info please refer this link How to choose Activity or Fragment if both scenarios are possible?
I've been struggling with this for a while now, I want to start off with a diagram of my problem:
The three navigation drawer buttons are part of my Base Activity. Each purple block below the three buttons are fragments, and the descendants of each of those blocks are in turn fragments. I'll use the master and detail fragments as a demonstration of the issue I am having...The user clicks the nav drawer button, which opens the master fragment that hosts a list of articles. Once a user clicks one of those articles, I then open the detail fragment inside of the master fragment. So If I find myself at the detail, and I decide to open the nav drawer and click the third button for instance, then click the second button again, I want the detail to be open still, and if I hit the phone's back button I want it to move back to the master fragment, and end there. Any tips will be helpful, as I am probably going to use a similar pattern for the first button, it's main fragment and it's children fragments as well.
In my opinion, the cleanest way to handle what you are describing would be to have three separate FragmentActivity classes that implement the DrawerLayout instead of one monolithic BaseActivity.
Each button in the drawer should start it's respective FragmentActivity using launchMode singleTask. This ensures that you launch the same activity instance each time, instead of a new one, which will maintain your back stack for each activity as you switch between them using the drawer buttons. See Android Developer Guide Activity:launchMode for more details.
Each of the three FragmentActivity instances should be responsible for starting and managing it's fragments using listener interfaces. For example, where you have your Master fragment opening a Detail fragment directly, you should instead have your Master fragment tell it's FragmentActivity that it needs to open the Detail fragment. See Android Developer Guide: Communicating with Other Fragments for recommended practices in implementing this type of decoupled communication between FragmentActivity and Fragment. It will make your life much easier down the road when you want different layouts for tablets, etc.
Each of the three main drawer "tasks" seem to be unique enough that isolating each within it's own FragmentActivity seems the best way to implement what you are trying to do. You can apply this same approach for each of your main sections.
I had the same problem and didn't want to go to multiple activities since that would complicate the back navigation of my application. Your fragments won't save their state automatically unless the activity lifecycle events are being called.
In our case those don't happen since we're not leaving the activity. You can use FragmentManager's saveFragmentState on the fragment you are replacing to manually trigger the state saving and get a Fragment.SavedState object. You can keep a list of your SavedState objects and when pushing a fragment check if you have a saved state for it. If so you can call Fragment setInitialSavedState which will cause your fragment to load the previous state.
Now in my app as a user toggles between fragments with their own child fragments the state is retained when they come back.