I am trying to create a layout in an activity that will look different in landscape and portrait, however it will contain the same sections, just in different places on the screen.
Most examples I find on fragments is always the list and detail, which is not what I'm looking at.
In my example I have, amongst others,
a scrolling image section (carousel)
a page title with some brief details
a carousel of thumbnails
two buttons
full details of the page
Now in the landscape layout, the image section will always be on the left side with down the right side, the page title, carousel of thumbs, two buttons and full details.
In the Portrait the title will appear at top, with image carousel beneath, then thumbs, then buttons etc.
The way it works in my head, is that each section should be a fragment, and then depending on the layout file in the respective res/layout folder corresponding to land/port, the fragments are arranged accordingly. But I'm also thinking is each section a whole fragment? Or could it be a separate view that get's loaded in, but just in a different order depending on the screen orientation.
I hope that made sense?
Does anyone have any good tutorials that explain exactly when you should and shouldn't use fragments. All the usual suspects just list the list/detail example, which is not applicable in my case.
tl;dr Can I use fragments as modules/blocks in various layouts or should I just create other layouts and display them inside the main layouts.
Fragments can be used to have split screen and to store previous state unlike views. It is difficult to manage back button with views
If you just want to change how the screen is laid out, the answer is neither. You can define orientation-specific resources (either a separate layout file for each orientation or different dimensions/constraints for each orientation) and the system will just provide you with the correct resource set for the current orientation.
That said, it sounds like you may be describing a modified version of master/detail flow. If this is the case, fragments are a good way to go since the landscape view is actually several separate screens in the portrait version of the app, so each section needs it's own state and lifecycle, which fragments provide.
Now, I know you said you wanted an example beyond a list and detail view, so here's some more details on when to use fragments:
Fragment, like activities, have state and lifecycle. Custom views do not have lifecycle and are completely dependent on the activity or fragment containing them.
You might use a custom view when you have a widget on screen that is used in multiple places and is just like any other view – bound to the activity when the layout is inflated and controlled from there. It's a way to either reduce duplicating combinations of views in your layout or to draw a custom view that doesn't exist yet.
Fragments are good when you need some state or lifecycle for a section of the app that might get used in multiple places or shouldn't be logically connected to the activity it is contained in. If you use the new Navigation Component, you actually just define one activity and then each screen in the navigation tree is a fragment that gets swapped out as the user navigates around the app. Here each child component on the screen (each "screen" that the user navigates to) has it's own lifecycle, business logic, etc, so mixing the code for all of that in the activity wouldn't make sense.
So the question comes down to what you are trying to build, and this may be a case where the best way to learn the difference is to try each option out as bit. The differences become more clear with practice using them. As a general rule of thumb, personally, I only really use custom views when I am trying to make a new view that doesn't exist elsewhere. If what I'm trying to do is simply a matter of laying out existing views in a new way, the answer is probably some trick in the layout file or layout code inside the activity. If I'm trying to make a stand-alone piece of the app that does stuff, especially if it also appears in multiple places in the app, I'll probably be building a fragment.
Related
Is it advisable to stack up multiple views and depending on the preceding activity, show the appropriate widgets/views to user? e.g. To have 2 or 3 forms in 1 layout file(xml),and show one view depending on what the user wants to see.
you can use Fragments... Add the right fragment to activity based on the preceding activity.
Fragments do this. Stacked views are nice for collapsed elements. There are uses for them as well. The choice is based on your particular use case. From what you've said, I would recommend Fragments.
The nice thing about fragments is that they handle life cycle events (like activities) but without the need for serializing and parceling data to communicate among your fragments.
As for your question "Is it advisable to layer views?" I would advise against layering different forms UI. The xml design and maintenance can grow hair real quick.
Fragment is the solution in android when you want to show some specific layout to the user create 2,3 fragments android depending on the condition load the appropriate fragment.
You can go through this to get started on fragments.
https://developer.android.com/guide/components/fragments.html
im developing an application with multiple screens using activities and fragments. The principle behind my decisions to use one or the other are based on the interaction in the application.
I have come to the conclusion that you should use an activity whenever major UI elements remain present after an event has occurred that forces the views inside the UI to change (An example of this can be a tabhost nested in the toolbar styled as the Google Play store android App with multiple fragments as childs. Another example is fragments representing the different rows or clickable elements on a navigation drawer).
So right now im presented with the dilemma of choosing once again between the two (fragment or activity) for a UI element that is going to be present across my whole application. Its triggered by a floating action button that launches a creation tool for an element inside my application and i needed to be accesible across all of my apps screens.
So to sum things up, what i need to know if its better to use a fragment or an activity for an element that is ever present across my whole application.
Thanks in advance
Use Fragments or a compound Views. But both in the right way.
Fragments are thought for reusable combinations of views. Compound Views are Layouts containing views. They are the right way if you want to create views from more primitive views, for example a View containing TextView and a increment- and decrement-button.
Fragments are more Activity-like. They have a real lifecycle. Your description looks like you want to create acitivity-parts. And thats exactly what fragments do.
A Fragment represents a behavior or a portion of user interface in an
Activity. You can combine multiple fragments in a single activity to
build a multi-pane UI and reuse a fragment in multiple activities.
Taken from Android SDK Documentation: Fragments.
With the NavigationDrawer and the recommended way to implement it according to google it should be with fragments. Which creates a lot of nesting which does not seem to be too supported. And kind of messes up the idea of having activities with fragments for supporting different layouts.
So I wonder what the best suggestion would be if you have have a layout, that on a phone will be a list on the whole display, and on tablet you will have a list on the left side and detailed information about the item clicked on the right side? Ses images attached as links. It would have felt more natural to have activities instead of Fragment A, different for each layout.
Fragment A is the fragment that your navigating to. Fragment B in both variants should be the same except for what's gonna happen when you click on an item. In the phone example the Fragment B should be an expandable list and on the tablet it should show the details in Fragment C.
What do you mean by "Which creates a lot of nesting which does not seem to be too supported."? Nested Fragments do have some different behaviour (e.g. the "for result" stuff is a bit trickier to do), but it's not that much different from an Activity with Fragments. Just always make sure that your Fragments are correctly attached and detached, then you can use them however you want.
Some people don't like Fragments, because of their "lazy loadingness" and they're sometimes harder to see through, but that's just the cost for having a more flexible way to structure your components. It really depends what you want to do and how fit you are with the Android Framework.
I'm writing an app for phones and tablets. Like the Contacts app, there are multiple tabs (2 in my case). For the phone UI, they're managed by a ViewPager, with a fragment for each tab.
But for the tablet UI, each tab is an activity, rather than a fragment. They have to be, because you can't put fragments inside fragments. (Right?)
I realize I could just call setContentView() on the tab listener, but wouldn't that destroy the activity every time it was changed? I'm confused by a lot of this.
What's the best way to do this without breaking my phone UI?
A well designed tabbed UI never uses Activities for tab content.
You're correct in that you cannot nest Fragments in the current implementation, but that doesn't mean your only alternative is Activities. Tabs should always act as a view switch; a tab switch never creates navigation history and tab navigation should always happen within the same Activity.
Remember that Activities and Fragments are just controllers from an MVC point of view. They exist to respond to lifecycle events and manage elements of your application in response to those events, including views within your UI. The content of your UI is wholly determined by the view hierarchy of the current window and you can manipulate the view hierarchy in whatever way makes sense for your app. (While preferably still following the design guidelines!)
Since Fragments have a built-in mechanism for managing a view sub-hierarchy they're often a natural choice for factoring your UI but they're not the only way. ViewPager PagerAdapters can manipulate view sub-hierarchies by inflating them from the resource system, recycling views the way a ListView does, or any other mechanism you can come up with and not use Fragments at all if the lifecycle events they provide aren't needed. Different layout resources may include or exclude certain elements based on screen size using different layout variants for different resource qualifiers.
In short, don't get stuck on the idea that Fragments are the only way to do multi-pane UIs, or the only way to implement each page of a ViewPager. They're powerful options for both, but depending on the information architecture of your Activity you may find yourself using them in a different way than another app and that's OK.
Overall, if you're having trouble determining where the logical cut points are when factoring your Activity's UI, you may be building an overall UI for your app that is going to be as awkward to use as it is to implement. Let the UI design guide your implementation. If each tab is naturally switching out the entire content of the Activity window, then each tab might be well suited to a Fragment. Perhaps those Fragments in tablet mode expand their capabilities and present more than one pane in their respective layouts using different layout resources.
I've recently decided to update my app to support the new fragments feature in honeycomb 3.0.
My Application currently works on a list view that opens different activities depending on which list item is clicked.
Using an adaptation of the code in this tutorial I have created an app that consists of only two activities, but depending on which list item is clicked the second "viewer" activity launches using a different layout xml.
Unfortunately I haven't been able to figure out how to call the old methods that had all the functionality. Should I Import all of my old activities and then call the methods into the viewer activity (I may need some advice on how exactly to do this) or should I just put all the methods directly into the same viewer activity (please consider the size of these methods(which is very large by the way)).
Once everything is working with two activities upfront then it will be a pretty simple task of "fragmenting" the app as demonstrated here
Although I haven't considered that there might be a way to allow multiple fragments to occupy the same space in an activity(If this is the case then please let me know how it's done)
Thanks
As James has pointed out you will have to move the business logic from your Activities to your Fragments.
To handle events you can create a listener Interface. The CONTAINER activity/ies will implement this interface. As fragments has access to the container activity you will be able to delegate to the container Activity the "logic" for the desired events. For this events the activity will decide whether to launch a new activity, show/hide new fragments or whatever.
I had a similar question, take a look to the question and answer: here
Although I haven't considered that there might be a way to allow multiple fragments to occupy the same space in an activity(If this is the case then please let me know how it's done)
I think its possible to allow multiple fragments to occupy the same space in an activity. Again, take a look to the answer here ... I think the concept/scope of Activity has change a bit and now an Activity can contain different Fragments which every one will allow user to do a single focused thing.
I'm not sure what you mean by "call the old methods that had all the functionality". You'll want to rewrite all of your activity classes as fragments. Check out this tutorial here (it's very concise). Basically, you'll want an activity that consists of a ListFragment and a FrameLayout. Your ListFragment will update the FrameLayout by changing to the appropriate Fragment based on which row was selected.