Develop Reference

"Uses reserved file or directory name 'lib'" error when trying to build android app bundle

I'm trying to build an app bundle but I'm getting the following error:
File 'root/lib/x86_64-MacOSX-gpp/jni/libjunixsocket-native-2.0.4.jnilib' uses reserved file or directory name 'lib'.
For what I've seen from similar questions, this issue is normally solved juggling dependencies or files in the project structure, but in this case it seems to point to a native library involved in app architecture if i'm not mistaken. Any ideas how to solve this?

It looks like you are adding a dependency as a jar instead of an aar.
The aar contains the information of what files should be considered as Android resources, native libraries, etc. in the app. A jar is just a plain list of files without Android concept. Because the jar you're depending on contains a directory lib, the files would normally end up being considered as native libraries, but because the files come from a jar instead of an aar, the build system warns that it's unlikely to be a native library and may have unintended consequences at runtime.
Try to package that library as an .aar instead of a .jar. See this documentation: https://developer.android.com/studio/projects/android-library
Edit:
Note that this file could not be loaded by the Android platform if it was included as is in the APK, so even though the previous build systems would allow you to put anything in an APK, the Android App Bundle is more restrictive to ensure that you don't accidentally put unnecessary files which would increase unnecessarily the size of your app.

Ok it is working now! Steps I used to found the problem (thanks for pointing me in the right direction #Pierre)
Run a gradle build --scan from your terminal or go to the Gradle tab in Android Studio, select :app, help , androidDependencies to see your dependency graph.
Search the dependency graph for the library name related to the problem ( in my case I searched for socket, there was no match for libjunixsocket for example).
Going upwards on the dependency tree I realized it was caused by the 'io.voucherify.android.client:voucherify-android-sdk:2.1.0' dependency.
I just added #aar at the end of the dependency implementation, and I managed to build the app bundle.
implementation 'io.voucherify.android.client:voucherify-android-sdk:2.1.0#aar'

Using TabLayout in Android Eclipse project

I am trying to use a TabLayout in an Android project using Eclipse and Andmore but haven't been able to find a jar containing the required android.support.design.widget.TabLayout class.
Googling a bit, it seems I need the com.android.support:design:22.2.0 library. However, the latest version I can find in my SDK installation (under extras/android/support) is v17.
Where can I find this library (without having to migrate to Android Studio)?

Update your sdk using sdk manager.

With the help of a few other answers I finally managed to import everything. Putting it all together, just copyiing the jar into libs will not be sufficient. Here's how it works in Andmore (ADT should be similar but some options apparently differ):
Make sure your SDK is up to date. Specifically, you want the latest version of Extras > Android Support Library (should be version 22 or higher) and a matching version of Tools > Android SDK Build-tools.
If you have a copy of android-support-v4.jar in the libs folder of your app's source tree, replace it with a recent copy from <sdk>/extras/android/support/v7/appcompat/libs. (If you have other Android support JARs in that location, you may need to update those as well.)
Copy <sdk>/extras/android/support/v7/appcompat and <sdk>/extras/android/support/design into your workspace folder. (Not really necessary, but using a local copy will prevent polluting your SDK setup with Eclipse-generated files.
Select File > New... > Android Project.
Select Create project from existing source and select your copy of the appcompat folder. Be sure to select at least API 22 as a build target (I needed to use API 23, YMMV), and don't forget to give it a meaningful name.
When import has finished, open the properties of the new project, go to Android and check Is Library.
Repeat the same two steps to import the design library. After import, in its project properties, go to Android, and in Libraries add a reference to the appcompat project.
Open the properties of your app project, go to Android, and in Libraries add a reference to the design project.
I had to make some minor modifications to my source code as some resource identifiers are no longer constants as of API 14, requiring me to convert a switch statement to a series of ifs. After that, I could finally build my app.
This should work for other Android libraries as well – their locations are documented in http://developer.android.com/tools/support-library/features.html.
Edit: There may be an easier way: Both ADT and Andmore also have Android Tools > Add Support Library, which might make a few of the aforementioned steps easier, which installs the most recent version of the support library. But you still have to add them to your project by hand.

Got it. Everything's there if you update your SDK to the latest version, things are just a bit hidden in the folder tree. You'll need three JARs:
extras/android/support/v7/appcompat/libs/android-support-v4.jar (the file was already in my project but I upgraded it anyway – not sure if it was necessary)
extras/android/support/v7/appcompat/libs/android-support-v7-appcompat.jar
extras/android/support/design/libs/android-support-design.jar
Copy these three to your project's libs dir, refresh your project in Eclipse (cleaning won't hurt as well) and you should be good.
Library locations are documented in http://developer.android.com/tools/support-library/features.html

How to use/install certain library in Android Studio

I found this "amazing" library that i think it would look nice in my small project but i don't find how to use it / how to install.
This is the url:
https://github.com/kmshack/Android-ParallaxHeaderViewPager
Thanks.

It seems to be available via Maven (see here). It might be an old version however. You could also import the project into Android Studio, build the jar and put it in your project's libs folder. A third option would be to make it build as part of your own project. For the latter you can use this for inspiration.

how to use android project library in eclipse?

I am new in android. I see a lot of android libraries out there like github.com but when I download them none of them are a *.jar file like this one:
NumberProgressBar
It seems that all these libraries are for android studio NOT eclipse (Am I correct? This is important).
My question is: How do I use these libraries in eclipse?
I tried to import the downloaded library as an android project and then mark it as "is library" and then add to my project, but that did not work.

That library is designed to be built with Gradle for Android (with or without Android Studio), producing an AAR.
Eclipse does not have native AAR support. I have published a recipe and a Ruby script to convert an AAR into a library project that Eclipse can use, though I have not tested it much.
Or, you can download the source code and attempt to reorganize it into an Eclipse-style library project.

I just downloaded it and add it as library project and everything looks fine. How do you do it, it's extremely simple. Let us know in which step you have a problem so we can figure out what is wrong.

You have to build the library first.
For your example, read the Readme file, section 'Build'.

Android SDKTools r21 library errors

I have updated today to the latest SDKTools, r21 and the projects are no longer packed correctly.
I am using for instance ActionBarSherlock as a library project, and when I run the application I get the following error :
java.lang.NoClassDefFoundError: com.actionbarsherlock.R$styleable
I have reverted back to r20 and it works again.
Did anything changed, and we should add different the library projects? I can't see something like this in the Release General Notes.

Yeh, it is ADT r21 causing it.
http://tools.android.com/download/adt-21-preview#TOC-New-in-ADT-21-Preview-5
The R classes for library projects are generated with only the IDs needed by the libraries, reducing the risk of hitting dex files limits for fields and methods.
You need to clean up the bin folder in the library project manually.
You can check the update on Tor Norbye google+ page
https://plus.google.com/116539451797396019960/posts/KVax2483Erk

Same problem but i have fixed it.
What i did:
Project / Clean / Build on all library projects
Removed the library projects and readded it on the android project
Android Tools / Fix Project Properties on the android project
Project / Clean / Build on the android project
Hope this helps and is also working for you.