Develop Reference

Linking an Android library that is on local machine

I have a set of utils and custom widgets that I want to pull out of my project as an Android library so that I can use them in other projects (and possibly share in the future). I created a new Android Studio project and changed the build.gradle file so that 'com.android.application' was 'com.android.library' and deleted the applicationId. It all compiles fine and I have a .aar file created.
I now want to use this new library as a module in my original project. When I do an Import Project, all the files from the library project are copied into my original project. But I don't want that because if I change the imported library code, it isn't reflected in the library project or vice versa.
I also tried adding this to settings.gradle:
include ':myutils'
project(':myutils').projectDir = new File(settingsDir, '../../../../Development/MyUtils/')
and in the original project app build.gradle:
dependencies {
implementation project(':myutils')
...
But I get this error:
ERROR: Unable to resolve dependency for ':app#debugUnitTest/compileClasspath': Could not resolve project :myutils.
Show Details
Affected Modules: app
How can I link the library to my project without importing it? I would prefer not to go through an external maven repo yet. I'm happy to (and would expect to) recompile my library whenever there is a change there and then rebuild my original project.
Thank you in advance.

I think I just had the same problem - I wanted to put the library .aar file somewhere on my local drive and then use it in a new app as a dependency. I didn't want to have to go through a repo or to include it in the libs folder in the new app. Hopefully that is what the OP asked and the following might be of help to others.
Searching on SO (Aug 2021), majority of answers seemed much more involved than what Android Studio offers (tested on version 4.2). That is, an .aar file that lives outside the app project can now be added as an implementation file in the gradle dependencies. So, it doesn't have to go through a repo, and it doesn't have to be included in the libs folder in the project.
The current documentation (Aug 2021) gives a fairly straightforward answer how to do it:
https://developer.android.com/studio/projects/android-library#psd-add-aar-jar-dependency
In short, if you have put your .aar file somewhere on your local drive, this is how to add it as an implementation file in another app project:
In Android Studio, in your new app project, go to: File > Project Structure > Dependencies.
In: Modules > app > Declared Dependencies, click '+' and select 'Jar Dependency'. (Even though you are trying to use an .aar file, you still select 'Jar Dependency').
In the 'Add Jar/Aar Dependency' popup dialog:
in step 1 enter the path to your .aar file on your local drive, and
in step 2 select 'implementation'.
If everything worked out, your build.gradle(Module) should have a line in the dependencies that looks like:
dependencies {
implementation files('../../../MyFolder/MyLibraryFile.aar')
A few notes:
You can actually just add the dependency manually, by typing it into the build.gradle(Module) dependencies, so you don't actually have to go through the Android Studio dialog outlined above.
you can either use a relative path (as the example above), or an absolute path.
the Android Studio dialog is somewhat limited in that you cannot just browse to your file (in point 3, step 1), but you have to actually enter the path manually.
Probably the most important: Whenever you make a change in the library and assemble a new .aar file, then remember to do the following in your app project that uses the .aar file as a dependency: Clean Project, then Sync Project with Gradle Files, and only then run the app, so that the changes in the library could take effect in your app.

I have been using Phgr's above technique for four years. I have three comments -
First, I don't clean the app project each time I change the library - I just do a Sync Project before building and testing the app.
Second, I changed the File-Settings-Keymap-Main Menu-File-Sync to Alt-S for easy of syncing - I hate wasting time using the mouse for selecting the Sync icon.
Third, I have an implementation line in the app's build module file for each app variant such as the following -
debugImplementation files('c:/Android Studio Projects/PciLibrary/app/build/outputs/aar/PciLibrary-debug.aar')
releaseImplementation files('c:/Android Studio Projects/PciLibrary/app/build/outputs/aar/PciLibrary-release.aar')
All of this is working fine with Android Studio 4.2.2 and sdk version 30.
Hope this helps others with this problem

Editing external libraries in Android Studio

I am using an image carousel library that I snagged off of github, but there are a few things I would like to change in the code. I have imported it using the compile 'com.theartofdev.edmodo:android-image-cropper:2.6.+' command. Is that code available for me to edit somehow? Or is it downloaded from github every time I run my code?

For this you need to import it as lib and modify as you like:
To import the library to Android Studio, there are two methods that can work.
Method 1:
Open your project in Android Studio
Download the library (using Git, or a zip archive to unzip)
Create a folder "subProject" in your project
Copy and paste the FreemiumLibrary folder to your subProject folder
On the root of your project directory create/modify the settings.gradle file. It should contain something like the following:
include 'MyApp', ':subProject:FreemiumLibrary'
gradle clean & build/close the project and reopen/re-import it.
Edit your project's build.gradle to add this in the "dependencies" section:
dependencies {
//...
compile project(':subProject:FreemiumLibrary')
}
Edit your App Activities to extend AdsFragmentActivity instead of Activity.
Edit the library if you want to use it with ActionBarCompat
Method 2:
Open your project in Android Studio
Download the library (using Git, or a zip archive to unzip)
Go to File > New > Import-Module and import the library as a module
Right-click your app in project view and select "Open Module Settings"
Click the "Dependencies" tab and then the '+' button
Select "Module Dependency"
Select "Freemium Library" (not Freemium Library Project)
Modify your App Activities to extend AdsFragmentActivity instead of Activity.
Modify the library if you want to use it with ActionBarCompat

I solved this way. Fork library project. Then clone it (In Android Studio, File -> New -> Project from Version Control -> put the link of your repository that you forked and open it). Edit it and commit it to your master branch. Then push it to your master branch. And finally find snapshot version of that library. For example if you use JitPack. Go to jitpack.io website and search for your repository (forked version with your username). And there go to commits section and get latest version that you committed. And use that library dependency in your project instead of original repo.

My approach was similar to #Shailendra Madda's with some minor differences.
At first I downloaded/cloned the project in my PC. Let's say the library's name is 'VideoPlayer'.
I ensured that the module level gradle of VideoPlayer did not contain applicationId. I also ensured that it contained
plugins {
id 'com.android.library'
}
instead of
plugins {
id 'com.android.application'
}
Now the library is ready for import.
In order to import this library into my project, I went to File -> New -> Import Module.
From there, I selected the directory of VideoPlayer. The VideoPlayer project that I downloaded had four modules. In cases like this you can simply select the modules you want to import. I selected the module named core and clicked finish. [Note: instead of selecting VideoPlayer folder from the explorer, you can also select the 'core' folder].
After importing the module, go to File -> Project Structure (or Ctrl+Alt+Shift+S) and select dependencies. From modules section, select app (here, app is the name of my project's module) and then select the + icon in 'declared dependencies' section and select Module Dependency. From the new window, select the module you wish to add as dependency (in my case, it is 'core').
After you click Apply and/or OK, android studio will modify relevant gradle files, so you don't have to worrry about it. And the project will be added as a dependency in your project.
Check this page to learn more: https://developer.android.com/studio/projects/android-library

How to update an imported module in Android Studio?

While I develop an Android App, I have a library which I have created as separate Android Studio project and can use it by inserting it into new projects. I insert the library by choosing 'File|New|Import Module...' option.
The thing is that after the import, Gradle creates a hard copy of my library. If I change the library code in main external project, the code inside the project which is using the library won't get updated.
How can I have a library and share it among many project? I need to change the library in one single place and then all other projects which are using it get the update.
I found this post also which has no answer:
How to update imported modules with code modification from the their external library project in Gradle/Android Studio

OK I found the answer by myself:
You must not add the external library as an existing module. It will make a copy of it under your project folder.
What you have to do is:
Delete the library folder in your current project. (You can also delete the ./idea/modules/[module_name] folder.)
Open the setting.gradle file and add these:
include ':your_external_library_module_name'
project (':your_external_library_module_name').projectDir = new File('../path/to/your/external/library')
include ':perhaps_second_external_library'
project (':perhaps_second_external_library').projectDir = new File('../path/to/your/second/external/library')
In your build.gradle (:app) file add dependency as:
dependencies {
implementation project(':your_external_library_module_name')
implementation project(':perhaps_second_external_library')
}
Sync the project and you are done.

Run Facebook SDK sample apps in Android Studio

Novice question.
What is the recommended way to run the sample apps, included in the Facebook SDK, in Android Studio (0.8.6)?
The ideal answer would include step-by-step instructions.

I'm using Android Studio version 0.8.0, and Facebook SDK 3.18.
When I tried to open a sample as a separate project, it can't find Gradle and wasn't able to run it. However, when I imported /samples folder as a root, all sample projects were imported and was able to run each samples.
File > Import Project > Select FACEBOOK_SDK_PATH/samples > OK > Create project from existing sources
and then, click next/ok as Android Studio's default setting.
Hope it helps!

Suposing you already downloaded and unzipped the SDK.
Create your android project. Gradle based.
File -> Import Module. Navigate to the unzipped folder and select the unzipped folder.
Add the library dependency in your main module (the one created with your project) adding this line in your build.gradle:
Synchonize project.
If you want to continue creating your own app, you might add the dependency module build.gradle file:
android {
dependencies {
compile project (':facebook')
}
}

Eclipse -> Android Studio migration: how to include v4 support library (also including the ant build script)

I have a setup of android project on eclipse and I want to migrate to Android Studio. So, I have android-support-v4.jar that I use for my main project and my Facebook lib-project.
I guess I have to exclude lib-projects as a folder in my main module (lets call the main module Jack). Jack has dependancy on the facebook lib-project.
How should I define the android-support-v4.jar as a separate library and use it in both projects? Or should I just use directly the jar files and leave them in both Jack's libs folder and Facebook libs folder?
If the first option should be done, will ant clean release still work (with the build.xml android generated file)?

In Android Studio, builds are done with Gradle now. Gradle is different. With gradle, you tell your project which jar's you need, and it will connect to a server and download them if it doesn't already have them when you compile your apk.
A few things to note:
When you install Android Studio, it has it's own Android sdk directory. You have to download everything from the sdk downloader (from inside the Android Studio App) again. Don't bother trying to switch the sdk download path to your current one. You will only encounter bugs (Or at least I did).
So your question is worded very confusingly. It sounds like you have a main module, and then you have a library module, and the library module uses the support library.
You'll need to set it up so the main module has a dependency on your library module. From there, you'll need to go into your library module's gradle file and tell it that you want to include the android support library
dependencies {
compile 'com.android.support:appcompat-v7:19.0.0'
}
The support library is a little weird in gradle. Gradle normally would download the dependencies you need. However, android studio requires that you have the support library installed through their sdk downloader (top-right group of icons in android studio. The download icon).
After you get all your dependencies entered into your gradle file, you'll then need to go to Tools -> Android -> Sync gradle files with project. From there compile errors should go away, and you should be able to run the project.
Best of luck. By the way, Here is the documentation on Gradle on the android website. I find myself having to go to it A LOT, especially when I made the switch from Eclipse to Android Studio. This + Various tutorials I found as needed via google. http://tools.android.com/tech-docs/new-build-system/user-guide
EDIT: This link might also be helpful. Google has some steps for switching from eclipse to Android Studio: http://developer.android.com/sdk/installing/migrate.html That with some of the stuff above may prove helpful.

While I haven't tried this myself, I suggest you use the recommended migration steps provided by Google in this article.
Before you do that, though, make sure that you either:
Check that both support libraries on the main project and dependencies have the same version (Eclipse will complain about it during build time, and will likely cause problems during conversion to Gradle script.); OR,
Uncheck the "Android Private Libraries" entry on the Order and Export tab of the dependency project's build settings.
If the migration process described doesn't work smoothly for you, you can always call the Ant build script from within the Gradle script, as described here.

The Android Studio uses only Gradle, but you can export Android ant project from eclipse.
To do that go to File -> import project usually next, next, next... works.
If not go to project setting Shift + Ctrl + Alt + S and under modules -> PROJECT_NAME -> Dependencies you can add your support library.
To add a Facebook library you must add it as another module to your project.
If you still want to use Ant there is another option: Use Intellij IDEA which support Ant.