How to link an Android app to a local library project

how-to-link-two-android-projects.md

How to link an Android app to a local dependency

Disclaimer: This is dumb. If anybody knows a better way, I'm all ears.

You have two Android projects. One is a library and one is an app that depends on that library. Both are on your local machine.

Now, say you want to test the library in the app before you publish it. Here's what you do.

You have an app and a lib:

.
├── myapp
│   ├── MyApp
│   ├── MyAppTest
│   └── MyAppTestApp
└── mylib
    ├── MyLib
    ├── MyLibTest
    └── MyLibTestApp

Make whatever changes to MyLib that you want to test in MyApp. Then add the following lines to myapp/settings.gradle:

include 'mylib'
project(':mylib').projectDir = new File('/absolute/or/relative/path/to/mylib/MyLib')

Then change the dependency declaration in myapp/MyApp/build.gradle to:

dependencies {
  // ...
  compile project(':mylib')
}

Whereas when you publish. your dependency might look like this:

dependencies {
  // ...
  compile 'com.mycompany.mylib:MyLib:1.0.2'
}

Note: if you have dependencies of dependencies that you want to link (e.g. A depends on B depends on C), then be prepared for sad times. I haven't figured that out yet.

Sometimes while trying this with third-party library, I got plugin with id 'com.android.library' not found.

This fixed it (add to the app project root build.gradle):

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.1.0'
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

Change compile with implementation