Convert samplestore app to Kotlin

.travis.yml

@@ -23,5 +23,5 @@ before_install:
   - yes | sdkmanager "platforms;android-28"
 
 script:
-  - ./gradlew :stripe:checkstyle :example:checkstyle :samplestore:checkstyle lint
+  - ./gradlew :stripe:checkstyle :example:checkstyle :samplestore:checkstyle :samplestore:ktlint lint
   - ./gradlew clean test

build.gradle

@@ -1,5 +1,6 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 buildscript {
+    ext.kotlin_version = '1.3.41'
     repositories {
         jcenter()
         google()
@@ -9,6 +10,7 @@ buildscript {
         classpath 'com.android.tools.build:gradle:3.5.0-rc02'
         classpath 'com.getkeepsafe.dexcount:dexcount-gradle-plugin:0.8.6'
         classpath 'io.codearte.gradle.nexus:gradle-nexus-staging-plugin:0.21.0'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
 

samplestore/build.gradle

@@ -1,9 +1,15 @@
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
 
 apply plugin: 'checkstyle'
 assemble.dependsOn('lint')
 check.dependsOn('checkstyle')
 
+configurations {
+    ktlint
+}
+
 android {
     compileSdkVersion rootProject.ext.compileSdkVersion
     buildToolsVersion rootProject.ext.buildToolsVersion
@@ -59,15 +65,15 @@ dependencies {
     implementation 'com.jakewharton.rxbinding2:rxbinding:2.2.0'
 
     /* Used for server calls */
-    implementation 'com.squareup.okio:okio:2.2.2'
-    implementation 'com.squareup.retrofit2:retrofit:2.6.0'
+    implementation 'com.squareup.okio:okio:2.3.0'
+    implementation 'com.squareup.retrofit2:retrofit:2.6.1'
     implementation 'com.facebook.stetho:stetho:1.5.1'
     implementation 'com.facebook.stetho:stetho-okhttp3:1.5.1'
 
     /* Used to make Retrofit easier and GSON & Rx-compatible*/
     implementation 'com.google.code.gson:gson:2.8.5'
-    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.6.0'
-    implementation 'com.squareup.retrofit2:converter-gson:2.6.0'
+    implementation 'com.squareup.retrofit2:adapter-rxjava2:2.6.1'
+    implementation 'com.squareup.retrofit2:converter-gson:2.6.1'
 
     // Used to debug your Retrofit connections
     // Do not upgrade as it will require increasing minSdkVersion to 21
@@ -78,4 +84,29 @@ dependencies {
     releaseImplementation 'com.squareup.leakcanary:leakcanary-android-no-op:1.6.3'
     // Optional, if you use support library fragments:
     debugImplementation 'com.squareup.leakcanary:leakcanary-support-fragment:1.6.3'
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+
+    ktlint "com.pinterest:ktlint:0.33.0"
+}
+
+repositories {
+    mavenCentral()
+}
+
+task ktlint(type: JavaExec, group: "verification") {
+    description = "Check Kotlin code style."
+    main = "com.pinterest.ktlint.Main"
+    classpath = configurations.ktlint
+    args "src/**/*.kt"
+    // to generate report in checkstyle format prepend following args:
+    // "--reporter=plain", "--reporter=checkstyle,output=${buildDir}/ktlint.xml"
+    // see https://github.com/pinterest/ktlint#usage for more
+}
+check.dependsOn ktlint
+
+task ktlintFormat(type: JavaExec, group: "formatting") {
+    description = "Fix Kotlin code style deviations."
+    main = "com.pinterest.ktlint.Main"
+    classpath = configurations.ktlint
+    args "-F", "src/**/*.kt"
 }

samplestore/src/main/java/com/stripe/samplestore/ItemDivider.kt

@@ -0,0 +1,37 @@
+package com.stripe.samplestore
+
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.drawable.Drawable
+import android.support.annotation.DrawableRes
+import android.support.v4.content.ContextCompat
+import android.support.v7.widget.RecyclerView
+
+/**
+ * Custom divider will be used in the list.
+ */
+internal class ItemDivider(
+    context: Context,
+    @DrawableRes resId: Int
+) : RecyclerView.ItemDecoration() {
+
+    private val divider: Drawable = ContextCompat.getDrawable(context, resId)!!
+
+    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
+        val start = parent.paddingStart
+        val end = parent.width - parent.paddingEnd
+
+        val childCount = parent.childCount
+        for (i in 0 until childCount) {
+            val child = parent.getChildAt(i)
+
+            val params = child.layoutParams as RecyclerView.LayoutParams
+
+            val top = child.bottom + params.bottomMargin
+            val bottom = top + divider.intrinsicHeight
+
+            divider.setBounds(start, top, end, bottom)
+            divider.draw(c)
+        }
+    }
+}