Kotlin Nested and Inner Classes Code SampleCode

Issue: BAEL-1759

core-kotlin/pom.xml

@@ -106,22 +106,22 @@
             <artifactId>klaxon</artifactId>
             <version>${klaxon.version}</version>
         </dependency>
-		<dependency>
+        <dependency>
-		    <groupId>io.ktor</groupId>
+            <groupId>io.ktor</groupId>
-		    <artifactId>ktor-server-netty</artifactId>
+            <artifactId>ktor-server-netty</artifactId>
-		    <version>${ktor.io.version}</version>
+            <version>${ktor.io.version}</version>
-		</dependency>
+        </dependency>
-		<dependency>
+        <dependency>
-		    <groupId>io.ktor</groupId>
+            <groupId>io.ktor</groupId>
-		    <artifactId>ktor-gson</artifactId>
+            <artifactId>ktor-gson</artifactId>
-		    <version>${ktor.io.version}</version>
+            <version>${ktor.io.version}</version>
-		</dependency>				
+        </dependency>
-		<dependency>
+        <dependency>
-		    <groupId>ch.qos.logback</groupId>
+            <groupId>ch.qos.logback</groupId>
-		    <artifactId>logback-classic</artifactId>
+            <artifactId>logback-classic</artifactId>
-		    <version>1.2.1</version>
+            <version>1.2.1</version>
-		    <scope>test</scope>
+            <scope>test</scope>
-		</dependency>		     
+        </dependency>
     </dependencies>
 
     <build>
@@ -166,13 +166,13 @@
                     <target>${java.version}</target>
                 </configuration>
                 <executions>
-                    <!-- Replacing default-compile as it is treated specially 
+                    <!-- Replacing default-compile as it is treated specially
                         by maven -->
                     <execution>
                         <id>default-compile</id>
                         <phase>none</phase>
                     </execution>
-                    <!-- Replacing default-testCompile as it is treated specially 
+                    <!-- Replacing default-testCompile as it is treated specially
                         by maven -->
                     <execution>
                         <id>default-testCompile</id>
@@ -224,10 +224,10 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <kotlin-maven-plugin.version>1.2.51</kotlin-maven-plugin.version>
+        <kotlin-maven-plugin.version>1.2.60</kotlin-maven-plugin.version>
-        <kotlin-test-junit.version>1.2.51</kotlin-test-junit.version>
+        <kotlin-test-junit.version>1.2.60</kotlin-test-junit.version>
-        <kotlin-stdlib.version>1.2.51</kotlin-stdlib.version>
+        <kotlin-stdlib.version>1.2.60</kotlin-stdlib.version>
-        <kotlin-reflect.version>1.2.51</kotlin-reflect.version>
+        <kotlin-reflect.version>1.2.60</kotlin-reflect.version>
         <kotlinx.version>0.22.5</kotlinx.version>
         <ktor.io.version>0.9.2</ktor.io.version>
         <mockito-kotlin.version>1.5.0</mockito-kotlin.version>
@@ -235,9 +235,9 @@
         <klaxon.version>3.0.4</klaxon.version>
         <khttp.version>0.1.0</khttp.version>
         <commons-math3.version>3.6.1</commons-math3.version>
-        <junit.platform.version>1.0.0</junit.platform.version>
+        <junit.platform.version>1.1.1</junit.platform.version>
         <junit.vintage.version>5.2.0</junit.vintage.version>
         <assertj.version>3.10.0</assertj.version>
     </properties>
 
-</project>
+</project>

core-kotlin/src/main/kotlin/com/baeldung/nested/Computer.kt

@@ -0,0 +1,75 @@
+package com.baeldung.nested
+
+import org.slf4j.Logger
+import org.slf4j.LoggerFactory
+
+class Computer(val model: String) {
+
+    companion object {
+        const val originCountry = "China"
+        fun getBuiltDate(): String {
+            return "2018-05-23"
+        }
+
+        val log: Logger = LoggerFactory.getLogger(Computer::class.java)
+    }
+
+    //Nested class
+    class MotherBoard(val manufacturer: String) {
+        fun getInfo() = "Made by $manufacturer installed in $originCountry - ${getBuiltDate()}"
+    }
+
+    //Inner class
+    inner class HardDisk(val sizeInGb: Int) {
+        fun getInfo() = "Installed on ${this@Computer} with $sizeInGb GB"
+    }
+
+    interface Switcher {
+        fun on(): String
+    }
+
+    interface Protector {
+        fun smart()
+    }
+
+    fun powerOn(): String {
+        //Local class
+        var defaultColor = "Blue"
+
+        class Led(val color: String) {
+            fun blink(): String {
+                return "blinking $color"
+            }
+
+            fun changeDefaultPowerOnColor() {
+                defaultColor = "Violet"
+            }
+        }
+
+        val powerLed = Led("Green")
+        log.debug("defaultColor is $defaultColor")
+        powerLed.changeDefaultPowerOnColor()
+        log.debug("defaultColor changed inside Led class to $defaultColor")
+        //Anonymous object
+        val powerSwitch = object : Switcher, Protector {
+            override fun on(): String {
+                return powerLed.blink()
+            }
+
+            override fun smart() {
+                log.debug("Smart protection is implemented")
+            }
+
+            fun changeDefaultPowerOnColor() {
+                defaultColor = "Yellow"
+            }
+        }
+        powerSwitch.changeDefaultPowerOnColor()
+        log.debug("defaultColor changed inside powerSwitch anonymous object to $defaultColor")
+        return powerSwitch.on()
+    }
+
+    override fun toString(): String {
+        return "Computer(model=$model)"
+    }
+}

core-kotlin/src/test/kotlin/com/baeldung/nested/ComputerUnitTest.kt

@@ -0,0 +1,28 @@
+package com.baeldung.nested
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class ComputerUnitTest {
+
+    @Test
+    fun givenComputer_whenPowerOn_thenBlink() {
+        val computer = Computer("Desktop")
+
+        assertThat(computer.powerOn()).isEqualTo("blinking Green")
+    }
+
+    @Test
+    fun givenMotherboard_whenGetInfo_thenGetInstalledAndBuiltDetails() {
+        val motherBoard = Computer.MotherBoard("MotherBoard Inc.")
+
+        assertThat(motherBoard.getInfo()).isEqualTo("Made by MotherBoard Inc. installed in China - 2018-05-23")
+    }
+
+    @Test
+    fun givenHardDisk_whenGetInfo_thenGetComputerModelAndDiskSizeInGb() {
+        val hardDisk = Computer("Desktop").HardDisk(1000)
+
+        assertThat(hardDisk.getInfo()).isEqualTo("Installed on Computer(model=Desktop) with 1000 GB")
+    }
+}