compilation - The best way to integrate third party library in Android studio

Question

We can find some very good open source libraries for android. I want to know what is the best way to integrate them to our own projects in Android studio. Here are some basic methods:

• Copy the source code and resource files into our own project. We need to change a lot of codes (the package name, and the name in xml,etc)
• If jar files is provided, I just create libs folder for my project and copy the jar files inside. And add the jar file in Module setting's dependencies. But unfortunately I got a lot of error messages like "Gradle: Package com.google.gson doesn't exist".

Is there a general rule to add third party source or jar files into an existing android studio project? Thanks

Answer 1

I prefer to use central repository for dependencies management. So for gson 2.3 dependency you should add to build.gradle file:

• Specify that you want to use maven central repository for your dependency

  repositories {jcenter()}

• Add compile dependency to gson 2.6.2

  dependencies {compile 'com.google.code.gson:gson:2.6.2'}

Android Studio as well as your CI server should easily build your project now. And you can continue app development.

I prefer to use central repository for dependencies management because:

• easier scope management - some libraries are only for testing, some should be included to apk and some are part of running environment (like android.jar itself)
• easier transitive dependencies management - it is quite hard to collect libraries dependencies and if you use "jar-with-dependencies" you could get error "class already added" during dexing
• lighter repository and easier dependency upgrade

Examples:

• Robolectric jar should be used for unit testing only and shouldn't be part of apk itself
• Repository is clean from different folders with jars, checkout takes much less. No needs to download and replace old jars with new jars

I should notice:

• Not many libraries are in maven central and you should make some effort to use them such way in your project
• You could much easier get to "class already added" error during dexing with central repository approach
• You can mix usage of dependencies from central repository and from lib folder, but I prefer to use only one way for simplicity