What exactly is it Xamarin.android.support.v7.appcompat - android

I'm working with Xamarin.Android.
Appcompat is actually necessary for use material design because the nougat package (Android.support.design) requires it.
But why, for example, if I work only with API 27, I must add the AppCompat package? In my toolBox i've not the floatingActionButton, NavigationDrawer etc.. so I must add this packet to unlock them.
What is exactly this package? I've read on the web that this package works with backward compatibility but I only work with new APIs, so why I must install it?
Thanks.

AppCompat should add the functionality of the latest API to older APIs when needed. For instance, lollipop added the CardView class, which can be used in older Android APIs when AppCompat is used, with some minor differences (some of the Android L animations may not apply on older versions of Android for example). It is recommended to use AppCompat in most cases since more users will be able to run your app when you do (depending on your MinSdkVersion). If you want to know what classes you can access in AppCompat, you can take a look at the features here:
https://developer.android.com/topic/libraries/support-library/features.html

The Xamarin.Android.AppCompat is just what it says. Its a library for App Compatibility for backward compatibility for previous versions of Android and more specifically this version (v7) brings support for Action Bar support. Read more here :
AppCompat

They are libraries used for accessing the latest features of an Android OS version. It is backward compatible by the way.

Related

Purpose of Android Support Library

I am getting started with Android. I am quite confused with what support library actually does . I am following a book and in the book it is mentioned that :
If an app is installed on a minimum SDK system, and our Java code
contains any calls to classes that are not present in minimum SDK ,
our app will crash
I read an article about support libraries here:
Tutorials Point
If Support libraries provide backward compatibility, doesn't it mean when they should prevent app crash?(may be by wrapping up those newer classes and making them backward compatible). What does support library actually do? Please explain.
When should I use the Android Support Library?
As new versions of Android are released, some style and behaviors may change. You should use one of the support libraries when you need specific framework features that are newer than the minSdkVersion of your app or that are not available in the standard framework.
What does support library actually do?
There are many devices still running in Jelly bean and below versions. So you need to give the same importance for old and new devices While making an app. Otherwise, the App in old devices looks dull when compared to new ones. That may affect the app’s market. To avoid this trouble, Android introduced the Support library. These are set of code libraries provides backward compatibility
Example:
Fragment API was introduced in API 11 HONEYCOMB .android.app.Fragment is the Fragment class introduced in API 11 and android.support.v4.app.Fragment is the Fragment class in the android support library,
If you want to make your app use fragments, and want to target devices before API 11, you must use android.support.v4.app.Fragment. However, if you want only targeting devices >=API 11 ,you can use android.app.Fragment.Therefore, android.support.v4.app.FragmentManager is used to deliver newer features to older platforms.
For more info about android support library:doc
1.Suppose you want to create an app which runs on platform comes after marshmallow.
then minimum sdk of your app will be marshmallow.
2.While creating your app you call a method which is present in oreo or later version then you app will have chances to crash on marshmallow and nougat.

Will Android Auto Work With MediaBrowserService?

The documentation for getting your app to work with Android auto direct users to use MediaBrowserServiceCompat. Because my app doesn't support pre-APIv21 I didn't use the compat version I used MediaBrowserService.
My main question is: can not using MediaBrowserServiceCompat (over using the MediaBrowserService) cause problems getting apps to work with Android auto?
My other question is: is there a reason to use the compat libraries other than supporting legacy devices (pre APIv21)?
No, it should not be a problem. But one thing to be noted here is Compat library is not a way to support exactly pre APIv21 devices, instead according to android documentation: "it is a standard way to provide newer features on earlier versions of Android or gracefully fall back to equivalent functionality".
To understand it, suppose after some years when android P/Q/R gets released with some new features that previous android versions didn't had, so to have support for these features on those api devices an equivalent compat class in compat library will be provided. So you can't say that compat libraries are for exactly pre APIv21.
Any way if you are not targeting older devices then you can ignore compat library.

Programming for Android 5 without AppCompat

I understand that it is considered good practice to program for Android using the AppCompat support libraries for backwards compatibility. However, for this specific project, the minimum API level I am to support is Android 5.0 (level 22).
However all information I can find for new Lollipop features always points towards the AppCompat support libraries. Must I do this, or are there vanilla equivalents that do not require AppCompat themes, classes or attention to backwards compatibility (ie. a plain CoordinatorLayout in layout XML instead of android.support.design.widget.CoordinatorLayout)?
First, Andorid 5.0 is API 21. If you set the min SDK to 21, most features like material design theme comes by default, you don't need any libraries. But I think the CoordinatorLayout is only in the com.android.support:design library, you have to include the library to use it.
You will need to use various support libs for certain functionality.
The CoordinatorLayout exists in the design library, and not in the OS framework.
This can actually be quite useful. Use of the design library means you can use these components independently from the OS version of the user's device. Meaning you can get updated functionality without the user updating their OS.
And won't experience breaking API differences depending on what OS the user runs.

For what devices do I use this android.support.v4.os classes?

In Android support library docs about android.support.v4.os:
Support android.os classes to assist with development of applications for android API level 4 or later.
"Or later" means API 5,6,7 etc.? But a device running API 22(latest at the moment)
will automatically support older devices?
I don't quite understand it - it means, I should use this class to make old API 4 devices use my modern API 22 app? Or should I use it to make new phones support old devices
When should I use this numerous support.v17, support.v13 packages?
What is backward compatible?
Can you explain typical situation?
"Or later" means api5,6,7 etc?
It means that this code can be used in devices with a old version of Android (api7= Android 2.1, api=8 Android 2.2.... api14 = Android 4.0)
but a device running api22(latest at the moment) will already automatically support older devices?
A device can run only a version of Android. If it is running api22, it means that it has Android 5.1
I dont' quite understand it - it means, i should use this class to make old api 4 devices use my modern api22 app? or should I use it to make new phones support old devices
It means that you can use this library to backport some features introduced with the last api (for example 21) to old devices running a previous api level.
1.When should i use this numerous support.v17, support.v13 packages? 2. what is backward compatible?
You can use them, when you need them... If you would like to use the Google cards you can use the v7 cardview library for example.
As described in the official link:
Each Support Library is backward-compatible to a specific Android API level.
For example the
support v4 : minSdk=4
v7 appcompat library: minSdk=7
v7 recyclerview library: minSdk = 7
v7 CardView library: minSdk = 7
can you explain typical situation?
API21 introduced a new widget, the Toolbar. This widget can be used only in device with API >=21.
With the appcompat rel.21 (a v7 Support Libraries) you can use the Toolbar (pay attention to the package) to implement your Toolbar in old devices running API>=7.

AppCompat Library Disadvantages

I'm a new Android developer who is trying to find the best balance for API level support. I think my indecision stems from a lack of understanding of the benefits and disadvantages of using the AppCompat Library over newer Android features such as Holo themes and the action bar.
Of course, I know that Holo is unavailable before API Level 14 and the Action Bar is unavailable before API Level 11. If I want to make my apps available to the broader Android userbase, I will need to lower my minSdkVersion and use the AppCompat Library.
My question is, are there any significant recent features of the Android OS that just aren't supported or are unable to be implemented through the AppCompat Library? Adding on to that, if you set your minSdkVersion to say API Level 7 and build your app with support for AppCompat (say, with your app themes being Theme.AppCompat.Light), will devices running an API greater than 11 or 14 for example use default Holo or action bar features or be restricted to AppCompat? I'd like to know if supporting older APIs will disadvantage users with newer and more capable devices.
Anyway, regardless of the outcome, I'll probably still go for supporting say API 7-8. This is more of a curiosity question on my part. I hope it makes sense!
Thanks, Klep
AppCompat should add functionality of the latest API to older APIs when needed. For instance, lollipop added the CardView class, which can be used in older Android APIs when AppCompat is used, with some minor differences (some of the Android L animations may not apply on older versions of Android for example). It is recommended to use AppCompat in most cases, since more users will be able to run your app when you do (depending on your MinSdkVersion). If you want to know what classes you can access in AppCompat, you can take a look at the features here.
Regarding the Styles: through Platform.AppCompat style the Theme.Appcompat inherits, and then overrides some properties, from Holo (11+) or Material (21+) if these are native on the running device.

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