Develop Reference

Xamarin; Android 11.0 SDK is not available in Visual Studio; Target Framework

In a computer, I have installed Android 11.0 SDK for a Visual Studio 2019 Community installation and my Xamarin Android app is compiled correctly using this SDK. The SDK was installed automatically:
Then I installed Visual Studio 2019 Community in another computer to compile my app there. But it seems the Android 11.0 SDK is no longer available:
It is not installed automatically and I cannot find anywhere to install it manually. What's wrong and how can I install Android 11.0 SDK on Visual Studio?

After long searching and none of the solutions were working for me, i've found that the SDK can also be installed with the VS Installer.
The API level 30 (Android 11) was nowhere to be found to install, nor VS SDK Manager nor Android Studio SDK Manager (the AS SDK Manager didn't even work, could not load any SDK's)
(See screenshots)
Go to VS Installer -> Modify VS version
-> Go to tab 'Individual Components' -> Search for SDK API level 30 -> Select and install
After the first login you'll probably need to accept SDK licenses again as I had to.
Hope this helps anyone who, like me, did not find any other solution working
PS: I did update VS to its latest version before doing this, not sure if this is mandatory or not since I was on 16.10 before but if this doesn't work, try updating VS itself first.

As of now Android 11 is not officially supported in Visual Studio.
So you have two options:
Select to use unofficial repositories in that dialog
Wait for the version 16.9 where it is supposed to be supported.

Livecode android sdk setup fails

https://livecode.com/app-in-a-day/installation/android/
http://lessons.livecode.com/m/2571/l/27389-how-do-i-become-an-android-developer-on-a-mac
explain how to setup the android sdk with LiveStudio on MacOs. I am using Android Studio Version 2.3.1 succesfully on Mac OS Sierra using the path Library/Android/sdk (relative to my home directory).
When I try to select that path for LiveCode Version 9.0.0 dp-6 in Mobile Support/Location of Android development SDK root
i get the message
"The chosen folder is not a valid Android SDK. Please ensure you have installed it correctly, and enabled support for Android 4.0.3 (API15)".
So i checked the installed SDKs platforms and Android 4.0.3 IceCreamSandwich API Level 15 Revision 5 is indeed installed.
The problem seems to haven been common in the past see e.g.
http://forums.livecode.com/viewtopic.php?t=15215
Which folder needs to be specified when selecting the location of the Android development SDK?
What can I do about this with the current state of LiveCode and Android SDK versions?
Will this happen again on Android SDK changes?

You must use absolute path, not relative path.
It's a folder containing:
add-ons
docs
platforms
samples
sources
temp
build-tools
extras
platform-tools
SDK
Readme.txt
system-images
tools

Can’t open Xamarin Android .axml file: The installed Android SDK is too old. Version 25.1.3 or newer is required. Please update to the latest version

I'm using Visual Studio and am unable to open layout files in the Xamarin Android Designer. I get this error when I try:
Something went wrong
The installed Android SDK is too old. Version 25.1.3 or newer is required. Please update to the latest
version.
I’ve already updated Xamarin, and am still stuck. How can this be fixed?

I recently ran into The installed Android SDK is too old. Version 25.1.3 or newer is required. Please update to the latest version. myself and found that I had to update the Android SDK in two stages to get things working.
As other users have mentioned, only updates for version 24.x.x were showing, while version 25.x.x was nowhere to be found. I installed the available updates for Tools, Platform-Tools, and Build-Tools, then exited and reopened the Android SDK Manager. This worked; version 25.x.x was now available for installation.
tl, dr;
Install 64-bit JDK 1.8
Update Android SDK Tools, Platform-tools, and Build-tools. Close SDK Manager and repeat if the version required in the warning isn’t
shown. You may need to exit Visual Studio if you get "Warning! A
folder failed to be moved"
Make sure the Android settings in Visual Studio are pointing to the
right locations: Tools > Options > Xamarin > Android Settings
Keep the Xamarin installation up to date! Tools > Options > Xamarin > Other > “Check Now”
Unsure if that was a one-off, I decided to do a fresh Xamarin installation with Visual Studio 2015 on Windows 10. Here is how I reproduced the issue and got back to working with layout files. This is long and these steps can probably be streamlined, but I wanted to give a clear picture of what I did.
Here is my step-by-step process:
Download Xamarin for Windows
Update to Xamarin latest Stable: Tools > Options > Xamarin > Other > “Check Now”
Open Android SDK Manager, update Build-tools from v23.0.3 to v24.0.3
Uninstall Build-tools v23.0.3, close SDK Manager
Close & reopen layout file, get "too old" message
Open SDK Manager, update to Build-tools v25, uninstall Build-tools v24.0.3
Close SDK manager & layout file
Reopen open layout file, get same message
Open SDK Manager, update to Platform-tools v25
Close SDK Manager & layout file
Reopen layout file, still too old
Open SDK Manager, update SDK Tools from v25.1.2 to v25.2.2
Here, I got the same warning mentioned in another SO post
Carrying on:
Exit Visual Studio; dismiss warning and process continues fine
The warning came back; dismissing again allows process to complete
Close SDK Manager, open Visual Studio, load Android project, open and layout file. Success! I can view layout files again.
There are a few additional things I’d like to mention to minimize potential snags/confusion:
Android Studio is not required. In addition to the prompt in the “SDK is too old” message, the Android SDK Manager can be opened via Tools > Android > Android SDK Manager or the SDK Manager toolbar icon.
My personal practice is to have only one version of the Build-tools installed to help minimize potential conflict or upstream issues, such as a couple that came up while using “version 24”.
Xamarin.Android 7.0 requires JDK 1.8. If you have not already done so, consider installing 64-bit JDK 1.8. This is the simplest option since it is backwards compatible with all previous API levels, it supports the new Android designer features, and the 64-bit version is required to use custom controls in the Android designer.
After updating, go to Tools > Options > Xamarin > Android Settings to verify that the correct locations are pointed to for the JDK, Android SDK, and Android NDK.
I’d also like to note that Android SDK updates are not specific to Xamarin. If we’re developing for Android, we need these tools for things like emulators, debugging, signing APKs, and accessing the newest platform features, whether using Xamarin or not.
For the curious, more details can be found here:
- Android Studio Command Line Tools doc
- What are the Android SDK build-tools, platform-tools and tools? And which version should be used?

I've solved this problem. First, download Android SDK tool 25.1.3 from Google here and extract it.
Then, remove the existing 'tools' folder under SDK like D:\\android-sdk\tools.
After removing it, put the 'tools' folder you recently extracted under the android-sdk path.
Finally, restart your vs. This is working sucessfully for me. I'm running on Windows 7 32-bit.

What packages are really required for Android Applications Development

I've a 40kb/s Internet. The Android SDK took me 1 and half hour to download(at first I thought it is packaged with all required packages). I am using Ubuntu 14.10(yea, it took me 11 hours to download).
I downloaded and installed Android SDK Tools, Android SDK Platform-tools and Android SDK Build-tools. In Android 5.0.1(API 21), I unticked both Android TV whatever System Image and both Android Wear whatever System Image because I am sure that I'm not going to use it.
My questions is what things are really required for Android applications development? Can anyone explain what are those packages for?
EDIT: I am not new to Java development. I have Java JDK 7, Eclipse(without the ADT plugin) and IntelliJ installed. I'm going to use IntelliJ as it is came with "Android Support" plugin)

Downloading this packages will be enough for you
SDK Platform in Android 5.0.1 (API 21)
Android SDK Tools 24.0.2 in Tools
Android SDK Platform Tools 21 in Tools
Android SDK Build-tools 21.1.2 in Tools

You need eclipse,adt bundle and android sdk tool that's it. No other thing is required for it.

Basically you need:
Eclipse IDE integrated with Android
Select Android version on which you're going to develop your application (Lolipop/KitKat etc) through SDk Manager
Java SDK (with JRE)

Updating SDK 2.3 - what exactly are the SDK Platform tools?

I wish to update my SDK 2.3 to the latest revision of 2.3. I don't want to update to 3.0 preview and lose the GPS emulation and have a slow emulator. 2.3 is just fine for me. I've updated the ADT plugin to 9.0.0 by the Eclipse 'check for updates'.
If I run the AVD manager from Eclipse and look at my installed packages, I have installed :
and the available packages with the ones that I think I want checked are:
My question is: what do I get with the platform tools? Is it just what goes in the platform-tools folder (i.e. the aapt.exe, adb.exe etc)? I don't want to overwrite the tools folder and end up with the slow emulator.

Yes, platform-tools are adb.exe and friends. You will also want Android SDK Tools, revision 9 as well, and don't worry about Honeycomb stuff - even if you do install them, they won't interfere with you (for example you can filter on platform version within the developer docs).