Kotlin & Anko for Android Development

The main goal of this project is to learn and show how to use Kotlin & Anko for Android development.

Because I'm a big fan of the Requery library so I'm using it for persistent layer.

A whole project is now under development so it is not complete.

Name of application is Fibo - Finance Board - at the end it should be finance managers which you can find a lot of in Google Play store, but I want on this usecase show that using a Kotlin, Anko is very powerful for android development.

Used libraries/frameworks

• Kotlin 1.1-M04

• Anko 0.9

• Mosby - MVP - 2.0.1

• Requery 1.0.0-rc3

• Dagger 2.8

• RxAndroid 1.2.1

• RxKotlin 0.60.0

• kotpref 1.6.0

• PaperParcel 2.0.0-beta2

• Note

• Documentation is in progress

• Demo app is under development

App Description

In this application I would like to show you libraries which I think are very interesting and useful for Android development.

Login View

First screen of application is the Login view. There you must enter username and password.

In current version only a demo user can be used:

• username = frosty
• password = snow

You can find these default values below Sign In button as a hint.

Application allows to remember you - if you will check the Remember me checkbox then the next time app display the main dashboard directly.

The Sign In button is action process button which show progress state of checking authorization credentials. You will see for short time a green Sign In button in case of you entered authorization credentials correctly, otherwise you will see red text Bad Username or Password text bewlo button

The Login process is written in Kotlin and Anko is used to create UI not in XML but directly in code by using Anko DSL features.

See LoginView

What is interesting in this class - that UI is not created in XML but in code:

textView {
  id = R.id.errorView
  lparams {
    gravity = Gravity.CENTER
    topMargin = dip(8)
    bottomMargin = dip(16)
  }
  textColor = ContextCompat.getColor(ctx, R.color.red_error)
  text = string(R.string.error_view_login_text)
  textSize = 14f
  visibility = View.GONE
}
        
textView {
  lparams(width = matchParent, height = wrapContent) {
    gravity = Gravity.CENTER
    leftMargin = dip(16)
    rightMargin = dip(16)
  }
  textColor = ContextCompat.getColor(ctx, R.color.secondary_text)
  text = "Hint:\nusername = frosty   password = snow"
  textSize = 10f
}   

The connection between activity and View created in Anko is defined in onCreate() method in activity by calling: CreateUserView(bus).setContentView(this) (See CreateUserActivity)

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // DI
        activityComponent().inject(this)
        // Create view
        CreateUserView(bus).setContentView(this)
    }

In case of empty username or password -> application must show an alert dialog. By using Anko implementation of dialog is very simple

alert(title = resources.getString(R.string.create_user_alert_failed_title),
      message = resources.getString(R.string.create_user_alert_failed_message)) {
         positiveButton("Close") { this@alert.dismiss() }
}.show()

Dashboard View

Please keep in a mind that app is under development so do not expect some cool functionality yet.

Show Username

See DrawerActivity

private fun showUserInfo() {
  val userNameView = find<TextView>(R.id.contentText)

  doAsync {
    val user = userBl.getUser()

    uiThread {
      userNameView.text = user.username
    }
  }
}

Persistent Layer

As I already mentioned I'm using the Requery library.

Insert new user

See UserBL.kt

class UserBL @Inject constructor(val dataStore: KotlinEntityDataStore<Persistable>) : IUserBL { 

 override fun saveUser(userDO: UserDO) {
         val user = UserEntity()
         with(user) {
             userName = userDO.username
             password = userDO.password
         }
 
         doAsync {
             dataStore.insert(user)
         }
     }
}

How to check if user is in db?

override fun existUser() : Boolean{
  return dataStore.count(User::class).get().value() > 0
}

Load User from DB

    override fun getUser(): UserDO {
        val result = dataStore.select(UserEntity::class).get().first()

        return concertToDO(result)
    }

    private fun concertToDO(entity: UserEntity): UserDO {
        return UserDO(username = entity.userName, password = entity.password)
    }

User db table

@Entity
interface User : Persistable {

    @get:Key
    @get:Generated
    var id: Int

    @get:Column(length = 20, unique = true, nullable = false)
    var userName: String

    @get:Column(length = 20, nullable = false)
    var password: String

    @get:Column(length = 20)
    var firstName: String

    @get:Column(length = 20)
    var lastName: String

    @get:Column(length = 30)
    var email: String

    @get:OneToMany
    val userAccounts: List<UserAccount>
}

Next features will be added soon