Android Studio - Creating Modules without copying files?

Yes, you can do it. The module needs to have a Gradle build file set up for it. If it's got that, then in the project you're linking to it, add this to the settings.gradle file at the project root:

include ':libraryName'
project(':libraryName').projectDir=new File('/path/to/library')

where the path you specify in the second line is the path to the directory containing the library's build.gradle file. The path can be relative or absolute.

The solution:

include ':libraryName'
project(':libraryName').projectDir=new File('/path/to/library')

was not working for me. After couple of wasted hours I figured out the issue. There are two build.gradle files, one for project and one for library name. If the library is in the folder '\MyLib' then there will be a build.gradle in '\MyLib' and another at '\MyLib\app'. You have to point to the '\MyLib\app' and not '\Mylib'.

Hopefully this saves some time for others.

You can also use android { sourceSets{ main.java.srcDirs += '../../../library/src' }} in your app build.gradle . Not sure about supporting all android resources, for pure java library works well.

If you have, like myself, have multiple modules (I only realised today that copies were included, I thought that the project included links to the source.)

You can have multiple modules/projects along the lines of :-

include ':app', ':sqlwords', ':dbindex', ':dbcolumn', ':dbtable', ':dbdatabase', ':displayhelp', ':pickdate'
project(':sqlwords').projectDir= new File('d:/Android_Applications/Modules/sqlwords')
project(':dbcolumn').projectDir= new File('d:/Android_Applications/Modules/dbcolumn')
project(':dbtable').projectDir= new File('d:/Android_Applications/Modules/dbtable')
project(':dbindex').projectDir= new File('d:/Android_Applications/Modules/dbindex')
project(':dbdatabase').projectDir= new File('d:/Android_Applications/Modules/dbdatabase')
project(':displayhelp').projectDir= new File('d:/Android_Applications/Modules/displayhelp')
project(':pickdate').projectDir= new File('d:/Android_Applications/PickDateShowCase/pickdate')