It's good to write Golang for producing binary file, then use it everywhere

Cython could do the same thing by convert python to c, then c to binary.

First, you should write a program at ~/go/github/yingshaoxo/hi/main.go

package greeting

func SayHi() string {
    return "Hi!"
}

Capitalize the function name, so golang would treat that function as public.

Then, compile it to binary file

go get golang.org/x/mobile/cmd/gomobile
gomobile init

gomobile bind -target=android

If it ask for NDK, install it and make sure the Environmental-Variable was set right.

If everything was right, you'll get two files: greeting.aar and greeting-sources.jar

Let's import it to Android Studio Project

1. Let's assume you have a project which was named ABI_Test
2. mkdir ABI_Test/app/libs
3. mv greeting.aar ABI_Test/app/libs/ and mv greeting-sources.jar ABI_Test/app/libs/
4. add implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar']) to ABI_Test/app/build.gradle
5. rebuild the project

Let's use it with the following codes

import greeting.Greeting

var words = Greeting.sayHi()
Toast.makeText(applicationContext, words, Toast.LENGTH_LONG).show()

The real codes

import greeting.Greeting

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var words = Greeting.sayHi()
        Toast.makeText(applicationContext, words, Toast.LENGTH_LONG).show()
    }
}