golab-2017-training-nocomments.slide

Write your next Android app in Go
GoLab, Florence 2017

Elias Naur
elias.naur@gmail.com
@elias_naur

* Prerequisites

- Laptop running a 64 bit OS; Linux, macOS or Windows.
- Go 1.7 (64 bit).
- Android SDK/Android studio.
- Android NDK (64 bit), downloaded through the Android SDK manager. Command line:
   sdkmanager ndk-bundle
- A working and recent Android device or emulator.
- On a device, enable developer mode and USB debugging.

* Setup

- Environment
- ANDROID_HOME should point to your Android SDK
- gomobile
	$ go get -u golang.org/x/mobile/cmd/...
	$ gomobile init

* Training files

Slides

	https://talks.godoc.org/github.com/eliasnaur/golab-2017-training/golab-2017-training-nocomments.slide

Example code

    $ git clone https://github.com/eliasnaur/golab-2017-training.git

Add the golab-2017-training directory to your GOPATH.

* The first run

	$ cd golab-2017-basic/basic

Linux/macOS

    $ ./gradlew installDebug

Windows

    $ gradlew.bat installDebug

* Logging

    $ abd log cat -s Go:* GoLog:*

Java

	android.util.Log.i("Go", ...);


* Structs

Go

    type AGoStruct struct {
      ...
    }

    func NewAGoStruct() *AGoStruct {
      ...
    }

    func (s *AGoStruct) AGoMethod() {
      ...
    }

Java

	goapp.AGoStruct s = new goapp.AGoStruct();
	s.aGoMethod()

* Structs (cont.)

You can use all the basic types (string, int, float32 etc.), other structs and interfaces.

Go

	func F(str *GoStruct, interf GoInterface, i int, f float32) string

* Go interfaces

Go

	type SomeGoInterface interface {
		F(i int) string
	}

Java

	class ImplementsGo implements goapp.SomeGoInterface {
		@Override public String f(i long, s goapp.AGoStruct) {
			...
		}
	}

* Go interfaces (cont.)

Go

	func TakesAnInterface(i SomeGoInterface) string {
		return i.F(10)
	}

Java

	String res = goapp.takesAnInterface(new ImplementsGo());
	android.util.Log.i("Go", "The result: " + res);

* Reverse bindings

Go

	package gorev

	import (
		"Java/android/os"
		"Java/android/support/v7/app"

		"Java/android/databinding/DataBindingUtil"
		"Java/gorev/databinding/ActivityMainBinding"

		rlayout "Java/gorev/R/layout"

		// The Java package for "gorev".
		gopkg "Java/gorev"
	)

	type GoActivity struct {
		app.AppCompatActivity
	}


* Reverse bindings (cont.)

	func (a *GoActivity) OnCreate(this gopkg.GoActivity, b os.Bundle) {
		this.Super().OnCreate(b)
			db := DataBindingUtil.SetContentView(this, rlayout.Activity_main)
			binding := ActivityMainBinding.Cast(db)
			binding.SetText("Hello from the reverse")
	}