feat: add Kotlin android sample

android/src/main/java/com/amplitude/android/utilities/AndroidStorage.kt

@@ -92,7 +92,10 @@ class AndroidStorage(
     }
 
     override fun getEventCallback(insertId: String): EventCallBack? {
-        return eventCallbacksMap.getOrDefault(insertId, null)
+        if (eventCallbacksMap.contains(insertId)) {
+            return eventCallbacksMap.get(insertId)
+        }
+        return null
     }
 
     override fun removeEventCallback(insertId: String) {

core/src/main/java/com/amplitude/core/Amplitude.kt

@@ -29,6 +29,11 @@ import kotlinx.coroutines.launch
 import org.json.JSONObject
 import java.util.concurrent.Executors
 
+/**
+ * <h1>Amplitude</h1>
+ * This is the SDK instance class that contains all of the SDK functionality.<br><br>
+ * Many of the SDK functions return the SDK instance back, allowing you to chain multiple method calls together
+ */
 open class Amplitude internal constructor(
     val configuration: Configuration,
     val store: State,
@@ -68,104 +73,131 @@ open class Amplitude internal constructor(
     }
 
     @Deprecated("Please use 'track' instead.", ReplaceWith("track"))
-    fun logEvent(event: BaseEvent) {
-        track(event)
+    fun logEvent(event: BaseEvent): Amplitude {
+        return track(event)
     }
 
-    fun track(event: BaseEvent, callback: EventCallBack? = null) {
+    /**
+     * Track an event
+     */
+    fun track(event: BaseEvent, callback: EventCallBack? = null): Amplitude {
         callback ?. let {
             event.callback = it
         }
         process(event)
+        return this
     }
 
-    fun track(eventType: String, eventProperties: JSONObject? = null, options: EventOptions? = null) {
+    /**
+     * Log event with the specified event type, event properties, and optional event options
+     */
+    fun track(eventType: String, eventProperties: JSONObject? = null, options: EventOptions? = null): Amplitude {
         val event = BaseEvent()
         event.eventType = eventType
         event.eventProperties = eventProperties
         options ?. let {
             event.mergeEventOptions(it)
         }
         process(event)
+        return this
     }
 
     /**
      * Identify. Use this to send an Identify object containing user property operations to Amplitude server.
      */
-    fun identify(identify: Identify, options: EventOptions? = null) {
+    fun identify(identify: Identify, options: EventOptions? = null): Amplitude {
         val event = IdentifyEvent()
         event.userProperties = identify.properties
         options ?. let {
             event.mergeEventOptions(it)
         }
         process(event)
+        return this
     }
 
-    fun identify(userId: String) {
+    /**
+     * Sets the user id (can be null).
+     */
+    fun setUserId(userId: String?): Amplitude {
         this.idContainer.identityManager.editIdentity().setUserId(userId).commit()
+        return this
     }
 
-    fun setDeviceId(deviceId: String) {
+    /**
+     * Sets a custom device id. <b>Note: only do this if you know what you are doing!</b>
+     */
+    fun setDeviceId(deviceId: String): Amplitude {
         this.idContainer.identityManager.editIdentity().setDeviceId(deviceId).commit()
+        return this
     }
 
-    fun groupIdentify(groupType: String, groupName: String, identify: Identify, options: EventOptions? = null) {
+    /**
+     * Identify a group
+     */
+    fun groupIdentify(groupType: String, groupName: String, identify: Identify, options: EventOptions? = null): Amplitude {
         val event = GroupIdentifyEvent()
         var group: JSONObject? = null
         try {
             group = JSONObject().put(groupType, groupName)
         } catch (e: Exception) {
-            logger.error(e.toString())
+            logger.error("Error in groupIdentif: ${e.toString()}")
         }
         event.groups = group
         event.groupProperties = identify.properties
         options ?. let {
             event.mergeEventOptions(it)
         }
         process(event)
+        return this
     }
 
     /**
      * Sets the user's group.
      */
-    fun setGroup(groupType: String, groupName: String, options: EventOptions? = null) {
+    fun setGroup(groupType: String, groupName: String, options: EventOptions? = null): Amplitude {
         val identify = Identify().set(groupType, groupName)
         identify(identify, options)
+        return this
     }
 
     /**
      * ets the user's groups.
      */
-    fun setGroup(groupType: String, groupName: Array<String>, options: EventOptions? = null) {
+    fun setGroup(groupType: String, groupName: Array<String>, options: EventOptions? = null): Amplitude {
         val identify = Identify().set(groupType, groupName)
         identify(identify, options)
+        return this
     }
 
     @Deprecated("Please use 'revenue' instead.", ReplaceWith("revenue"))
-    fun logRevenue(revenue: Revenue) {
+    fun logRevenue(revenue: Revenue): Amplitude {
         revenue(revenue)
+        return this
     }
 
     /**
      * Create a Revenue object to hold your revenue data and properties,
      * and log it as a revenue event using this method.
      */
-    fun revenue(revenue: Revenue, options: EventOptions? = null) {
+    fun revenue(revenue: Revenue, options: EventOptions? = null): Amplitude {
         if (!revenue.isValid()) {
-            return
+            logger.warn("Invalid revenue object, missing required fields")
+            return this
         }
         val event = revenue.toRevenueEvent()
         options ?. let {
             event.mergeEventOptions(it)
         }
         revenue(event)
+        return this
     }
 
     /**
      * Log a Revenue Event
      */
-    fun revenue(event: RevenueEvent) {
+    fun revenue(event: RevenueEvent): Amplitude {
         process(event)
+        return this
     }
 
     private fun process(event: BaseEvent) {

core/src/main/java/com/amplitude/core/events/Identify.kt

@@ -569,7 +569,7 @@ class Identify() {
             properties.getJSONObject(operation.operationType).put(property, value)
             propertySet.add(property)
         } catch (e: Exception) {
-            ConsoleLogger.logger.error(e.toString())
+            ConsoleLogger.logger.error("Error in set uset property: ${e.toString()}")
         }
     }
 

core/src/main/java/com/amplitude/core/platform/EventPipeline.kt

@@ -80,7 +80,7 @@ class EventPipeline(
                 storage.writeEvent(message.event)
             } catch (e: Exception) {
                 e.message?.let {
-                    amplitude.logger.error(it)
+                    amplitude.logger.error("Error when write event: $it")
                 }
             }
 
@@ -117,7 +117,7 @@ class EventPipeline(
                     responseHandler?.handle(connection.response)
                 } catch (e: Exception) {
                     e.message?.let {
-                        amplitude.logger.error(it)
+                        amplitude.logger.error("Error when upload event: $it")
                     }
                 }
             }

core/src/main/java/com/amplitude/core/utilities/JSONUtil.kt

@@ -157,50 +157,50 @@ internal fun JSONArray.toIntArray(): IntArray {
 internal fun JSONObject.toBaseEvent(): BaseEvent {
     val event = BaseEvent()
     event.eventType = this.getString("event_type")
-    event.userId = this.optString("user_id", null)
-    event.deviceId = this.optString("device_id", null)
+    event.userId = this.optionalString("user_id", null)
+    event.deviceId = this.optionalString("device_id", null)
     event.timestamp = if (this.has("time")) this.getLong("time") else null
-    event.eventProperties = this.optJSONObject("event_properties", null)
-    event.userProperties = this.optJSONObject("user_properties", null)
-    event.groups = this.optJSONObject("groups", null)
-    event.appVersion = this.optString("app_version", null)
-    event.platform = this.optString("platform", null)
-    event.osName = this.optString("os_name", null)
-    event.osVersion = this.optString("os_version", null)
-    event.deviceBrand = this.optString("device_brand", null)
-    event.deviceManufacturer = this.optString("device_manufacturer", null)
-    event.deviceModel = this.optString("device_model", null)
-    event.carrier = this.optString("carrier", null)
-    event.country = this.optString("country", null)
-    event.region = this.optString("region", null)
-    event.city = this.optString("city", null)
-    event.dma = this.optString("dma", null)
-    event.language = this.optString("language", null)
+    event.eventProperties = this.optionalJSONObject("event_properties", null)
+    event.userProperties = this.optionalJSONObject("user_properties", null)
+    event.groups = this.optionalJSONObject("groups", null)
+    event.appVersion = this.optionalString("app_version", null)
+    event.platform = this.optionalString("platform", null)
+    event.osName = this.optionalString("os_name", null)
+    event.osVersion = this.optionalString("os_version", null)
+    event.deviceBrand = this.optionalString("device_brand", null)
+    event.deviceManufacturer = this.optionalString("device_manufacturer", null)
+    event.deviceModel = this.optionalString("device_model", null)
+    event.carrier = this.optionalString("carrier", null)
+    event.country = this.optionalString("country", null)
+    event.region = this.optionalString("region", null)
+    event.city = this.optionalString("city", null)
+    event.dma = this.optionalString("dma", null)
+    event.language = this.optionalString("language", null)
     event.price = if (this.has("price")) this.getDouble("price") else null
     event.quantity = if (this.has("quantity")) this.getInt("quantity") else null
     event.revenue = if (this.has("revenue")) this.getDouble("revenue") else null
-    event.productId = this.optString("productId", null)
-    event.revenueType = this.optString("revenueType", null)
+    event.productId = this.optionalString("productId", null)
+    event.revenueType = this.optionalString("revenueType", null)
     event.locationLat = if (this.has("location_lat")) this.getDouble("location_lat") else null
     event.locationLng = if (this.has("location_lng")) this.getDouble("location_lng") else null
-    event.ip = this.optString("ip", null)
-    event.idfa = this.optString("idfa", null)
-    event.idfv = this.optString("idfv", null)
-    event.adid = this.optString("adid", null)
-    event.androidId = this.optString("android_id", null)
+    event.ip = this.optionalString("ip", null)
+    event.idfa = this.optionalString("idfa", null)
+    event.idfv = this.optionalString("idfv", null)
+    event.adid = this.optionalString("adid", null)
+    event.androidId = this.optionalString("android_id", null)
     event.eventId = if (this.has("event_id")) this.getInt("event_id") else null
     event.sessionId = this.getLong("session_id")
-    event.insertId = this.optString("insert_id", null)
+    event.insertId = this.optionalString("insert_id", null)
     event.library = if (this.has("library")) this.getString("library") else null
-    event.partnerId = this.optString("partner_id", null)
+    event.partnerId = this.optionalString("partner_id", null)
     event.plan = if (this.has("plan")) Plan.fromJSONObject(this.getJSONObject("plan")) else null
     return event
 }
 
 internal fun JSONArray.toEvents(): List<BaseEvent> {
     val events = mutableListOf<BaseEvent>()
-    this.forEach {
-        events.add((it as JSONObject).toBaseEvent())
+    (0 until this.length()).forEach {
+        events.add((this.getJSONObject(it)).toBaseEvent())
     }
     return events
 }
@@ -209,11 +209,11 @@ internal fun JSONArray.split(): Pair<String, String> {
     val mid = this.length() / 2
     val firstHalf = JSONArray()
     val secondHalf = JSONArray()
-    this.forEachIndexed { index, obj ->
+    (0 until this.length()).forEach { index, ->
         if (index < mid) {
-            firstHalf.put(obj)
+            firstHalf.put(this.getJSONObject(index))
         } else {
-            secondHalf.put(obj)
+            secondHalf.put(this.getJSONObject(index))
         }
     }
     return Pair(firstHalf.toString(), secondHalf.toString())
@@ -224,3 +224,17 @@ internal fun JSONObject.addValue(key: String, value: Any?) {
         this.put(key, value)
     }
 }
+
+inline fun JSONObject.optionalJSONObject(key: String, defaultValue: JSONObject?): JSONObject?{
+    if (this.has(key)) {
+        return this.getJSONObject(key)
+    }
+    return defaultValue
+}
+
+inline fun JSONObject.optionalString(key: String, defaultValue: String?): String?{
+    if (this.has(key)) {
+        return this.getString(key)
+    }
+    return defaultValue
+}

samples/kotlin-android-app/build.gradle

@@ -0,0 +1,49 @@
+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+}
+ext {
+    AMPLITUDE_API_KEY = ""
+}
+
+android {
+    compileSdk 31
+
+    defaultConfig {
+        applicationId "com.amplitude.android.sample"
+        minSdk 16
+        targetSdk 31
+        versionCode 1
+        versionName "1.0"
+        multiDexEnabled true
+        buildConfigField "String", "AMPLITUDE_API_KEY", "\"${AMPLITUDE_API_KEY}\""
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+    lintOptions {
+        abortOnError false
+    }
+}
+
+dependencies {
+    implementation project(':android')
+    implementation 'androidx.core:core-ktx:1.7.0'
+    implementation 'androidx.appcompat:appcompat:1.4.1'
+    implementation 'com.google.android.material:material:1.5.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.3'
+    implementation 'com.google.android.gms:play-services-ads:20.6.0'
+    implementation 'com.google.android.gms:play-services-appset:16.0.2'
+}

samples/kotlin-android-app/proguard-rules.pro

@@ -0,0 +1,23 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
+play-services-ads.-keep class com.google.android.gms.ads.** { *; }
+