code style ( Code Style, )

, ( ), ( )

class CleanTab(context: Context) {

....val date = Date()

....val button = Button(context)
....val textView = TextView(context)
....val ratingBar = RatingBar(context)
....val imageView = ImageView(context)
}

class CleanTab(context: Context) {

-> val date = Date()

-> val button = Button(context)
-> val textView = TextView(context)
-> val ratingBar = RatingBar(context)
-> val imageView = ImageView(context)
}

code-style.

Date, button =, args main {

class CleanSpaces(context:Context) {

    val date = Date( )

    val button= Button(context)

    fun main(arg: Args){

    }
}

class CleanSpaces(context: Context) {

    val date = Date()

    val button = Button(context)

    fun main(arg: Args) {

    }
}

. , / .

else, catch , ( code style)

manyArguments 80 ( code style),

class CleanWrappingAndBraces {

    fun condition() {
        if (liveData != null) {
            <..>
        }
        else {
            <..>
        }
    }

    fun catching() {
        try {
            <..>
        }
        catch (e: Exception) {
            <..>
        }
    }

    fun manyArguments(userId: Int, issuerCountryId: String, sendingCountryId: String, receivingCountryId: String) {

    }
}

class CleanWrappingAndBraces {

    fun condition() {
        if (liveData != null) {
            <..>
        } else {
            <..>
        }
    }

    fun catching() {
        try {
            <..>
        } catch (e: Exception) {
            <..>
        }
    }

    fun manyArguments(userId: Int, issuerCountryId: String,
                    sendingCountryId: String,
                    receivingCountryId: String) {

}

. ( Code Style, )

}, 2

class CleanBlank {

    fun foo() {

    }

    fun bar() {

    }

}

class CleanBlank {

    fun foo() {

    }

    fun bar() {

    }

}

xmlns , code-style(xmlns:android , xmlns:<...> .

, xmlns:tools xmlns:app , . , rearrange

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    xmlns:tools="http://schemas.android.com/tools" android:layout_height="match_parent"
    android:orientation="vertical" xmlns:app="http://schemas.android.com/apk/res-auto">

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

</LinearLayout>

android:padding code-style. style android:id

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="8dp"
        android:paddingBottom="8dp"
        android:paddingLeft="8dp"
        android:paddingRight="8dp"
        tools:srcCompat="@tools:sample/avatars" />

    <TextView
        style="@style/TextAppearance.MaterialComponents.Body1"
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hello World" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="8dp"
        android:paddingTop="8dp"
        android:paddingRight="8dp"
        android:paddingBottom="8dp"
        tools:srcCompat="@tools:sample/avatars" />

    <TextView
        android:id="@+id/title"
        style="@style/TextAppearance.MaterialComponents.Body1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hello World" />

</LinearLayout>

optimize imports import java.util.* , ,

import android.content.Context
import android.widget.Button
import java.util.*

class RemoveUnused(context: Context) {

    val button = Button(context)
}

import android.content.Context
import android.widget.Button

class RemoveUnused(context: Context) {

    val button = Button(context)
}

n , .

m enum java static ,

Settings → Editor → Code Style → Kotlin → Imports

android.widget android.widget.*

import android.content.Context
import android.widget.Button
import android.widget.ImageButton
import android.widget.ImageView
import android.widget.TextView
import android.widget.RatingBar
import java.util.*

class MergeImport(context: Context) {

    <..>
}

import android.content.Context
import android.widget.*
import java.util.*

class MergeImport(context: Context) {

    <..>
}

, (m = 0, n=0), ( ) // .

import android.widget. import java.util.

import android.content.Context
import android.widget.*
import java.util.*

class MergeImport(context: Context) {

    <..>

import android.content.Context
import android.widget.Button
import android.widget.ImageButton
import android.widget.ImageView
import android.widget.TextView
import android.widget.RatingBar
import java.util.*

class MergeImport(context: Context) {

    <..>
}

, ,

import android.content.Context
import android.widget.Button
import android.widget.ImageView
import android.widget.TextView
import java.util.*
import android.widget.RatingBar

class SortImport(context: Context) {

    <..>
}

import android.content.Context
import android.widget.Button
import android.widget.ImageView
import android.widget.RatingBar
import android.widget.TextView
import java.util.*

class SortImport(context: Context) {

    <..>
}

fun TextView.format(message: String) {
   val htmlText = Html.fromHtml(message)
}

, :

Review :

-, .. non-nullable

data class User(val firstName: String, val secondName: String)

val user = User("", "")

fun getUserFullName(): String {
    val firstName = user?.firstName
    val secondName = user.secondName ?: return firstName

    return "$firstName $secondName"
}

data class User(val firstName: String, val secondName: String)

val user = User("", "")

fun getUserFullName(): String {
    val firstName = user.firstName
    val secondName = user.secondName

    return "$firstName $secondName"
}

public, ..

data class User(val firstName: String, val secondName: String)

val user = User("", "")

public fun getUserFullName(): String {
    val firstName = user.firstName
    val secondName = user.secondName

    return "$firstName $secondName"
}

data class User(val firstName: String, val secondName: String)

val user = User("", "")

fun getUserFullName(): String {
    val firstName = user.firstName
    val secondName = user.secondName

    return "$firstName $secondName"
}

class ExecutionClass(val exec: () -> Unit)

val exec = ExecutionClass() {
    doIt()
}

class ExecutionClass(val exec: () -> Unit)

val exec = ExecutionClass {
    doIt()
}

deprecated ReplaceWith(), cleanup . , — , ReplaceWith(). . / . / , ( ), , , . ,

@Deprecated(" ", ReplaceWith("newMethod()"))
fun oldMethod() = Unit

fun newMethod() = Unit

@Deprecated(" ", ReplaceWith("NewClass"))
class OldClass

class NewClass

class GetDeprecatedCodeUseCase(val clazz: OldClass) {

    init {
        val initData = oldMethod()
    }
}

@Deprecated(" ", ReplaceWith("newMethod()"))
fun oldMethod() = Unit

fun newMethod() = Unit

@Deprecated(" ", ReplaceWith("NewClass"))
class OldClass

class NewClass

class GetDeprecatedCodeUseCase(val clazz: NewClass) {

    init {
        val initData = newMethod()
    }
}