I'm new to Android and a confused about the options to group Views together.
Let's say I want to create a UI where I have 2 sections of controls (one with Buttons and one with text + Spinners) that are above each other in portrait mode and next to each other in landscape mode, and the same goes for the stuff within those sections. Obviously I would like to dynamically change this when the user changes from one mode to another.
So, do I use Fragments within Fragments or use them only the outer section and then a Compound Control for the inner elements? Or are Fragments even necessary and I should better stick to something else? What is the best practice here?
Thank you in advance!
In your example you would create two layout files. One that contained your buttons and the other that contained your spinners.
You would create a 3rd layout file for the portrait orientation and use the include tag to include your other layouts within the 3rd layout. Similarly for your landscape layout, you would include your inner UI layouts in that.
You could then use an Activity or a Fragment which would use only the main layouts and assuming they were placed into the correct layout folders, the fragment/activity would load the correct one based on your orientation.
Fragments within Fragments should be avoided unless you have a specific need for it. It works but in practice managing the lifecycle becomes tiresome.
Related
I have an Activity and two Fragment layouts and classes.
All I need to do is that when I change the screen orientation, reorganize the same content differently.
My question is where should I put my code?
Which class Activity class or Fragment class?
If I code in Fragment class, should I put code in both classes, or if I use main Activity, how would I find objects (like TextViews) from each layout?
You put the code where the views are... It's really that simple.
res/layout-land should keep the exact same view IDs.
For example, MainActivity would load both res/layout/activity_main.xml and res/layout-land/activity_main.xml automatically for you depending on orientation.
findViewById will work appropriately if you don't change any ID values
There is a whole documentation page on this. Notice they use retained Fragments, but that is not necessary.
Also Android Studio: Creating landscape layouts
Based on Comments what i have understood so far.
You have an activity and you have two fragments. These two fragments have different layouts and you want to show these layouts based on the orientation of the device.
Well there are two approach for this problem
1) You want to achieve this using fragments
Create an abstract class for Fragment put common functionality in base class and provide different implementation in different Fragment child class
You can refer this
2) Second approach
It can be achieved in a much simpler way without using fragment.
Create a layout-land directory and put the landscape version of your layout XML file in that directory.
See this thread in stackoverflow
Hope it helps.
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.
After having been introduced to Android development and creating a few basic applications, I have begun splitting activities into fragments for reusability. However one thing that I'm still slightly confused about is how the layout of the main activity(which holds the fragments), is affected by the layouts defined for fragment activities and vice versa.
While I believe that the layouts would affect each other based on definitions of height and width for each fragment, the number of fragments in an activity, etc. However Im not sure if there are other rules I am unaware of and I want to know if the layouts specified for the fragments directly affect the way the way the layout of the main activity displays.
For example, the main activity has a RelativeLayout and contains two fragments which have LinearLayout defined in their own separate layout xml files. Do the LinearLayouts affect the way in which the RelativeLayout would normally display and vice versa?
Fragments are basically similar to other view like RelativeLayout or LinearLayout in some ways. For Example they can also have width and height; Fragments can expand on the basis of size of its children. Rest is up on you, how you design layouts (fragments). Fragment is also similar to Activity in a sense that it has its own xml layout and corresponding java class. Primarily, we use fragments in two ways:
i) One or more fragments capturing separate parts (space) of activity at a time.
ii) A particular fragment in activity which is replaced (add,remove,replace) by many other fragments programmatically
You can use fragments statically in the layout files of your activities and dynamically by adding them in containers which you also define in the layout files of your activities.
The fragment view, will be inflated and be displayed in its container. It all depends on how you define your container. If you make it so it match the width of its parent, the layout of the fragment can have a width as much as the parent of the container. It is like putting views into that container.
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.
I am thinking of an app in which I will be programatically able to display some fragments according to metadata I have stored somewhere. Up to know, I have been able to find out, that each fragments lies in corresponding FrameLayout, or especially, when I create activity with one FrameLayout, I am able to store there only one Fragment at a time, no matter what kind is it. Problem is, however, with situation, when my metadata declares I have to put 3 fragments into my activity, while there is only one FrameLayout.
I see two possible solutions:
1) making several FrameLayout and in final stage, some of them will be used or not
2) somehow join multiple fragments to fit into one available FrameLayout
I don't like solutuion 1) and I don't know how to achieve 2). How to you see it? Is it possible to dynamically add multiple Fragments into activity with one Frame Layout?
In your situation where you require more number of Fragments to be added to your screen avoid using the FrameLayout, you will not be able to achive it. There are several factors that define how you layout multiple Fragments
Are all the fragments of the same size?
Should the fragments be place in a particular order?
First Create an empty parent layout (Layout class is left to your choice except FrameLayout). Next define your child view for your parent layout using a seperate xml file this file must contain your fragment place holder. Using the inflator inflate your child view and assign a Fragment to the inflated layout and eventually add it to your parent layout, through this way you can active what you are looking for. Just remember as you inflate your layout do mention its layout size so that you achive the kindly of layout you want.