[KTLN-546] Passing a Class to a Function in Kotlin (#834)

* added unit tests

* added unit tests

* code refactor

Author: albertache1998

core-kotlin-modules/core-kotlin-advanced-3/pom.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin-advanced-3</artifactId>
+    <name>core-kotlin-advanced-3</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>core-kotlin-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+
+    </dependencies>
+</project>

core-kotlin-modules/core-kotlin-advanced-3/src/test/kotlin/com/baeldung/classParameterToFunction/ClassParameterToFunctionUnitTest.kt

@@ -0,0 +1,66 @@
+package com.baeldung.classParameterToFunction
+
+import org.junit.jupiter.api.Test
+import kotlin.reflect.KClass
+import kotlin.reflect.full.createInstance
+import kotlin.test.assertEquals
+
+class ClassParameterToFunctionUnitTest {
+
+    @Test
+    fun `passes class as function parameter using class reference`(){
+        val result = functionAcceptingClassReference(ParameterClass::class.java)
+
+        assertEquals("This is a method called on our class", result)
+    }
+    @Test
+    fun `passes class as function parameter using kclass reference`(){
+        val result = functionAcceptingKClassReference(ParameterClass::class)
+
+        assertEquals("This is a method called on our class", result)
+    }
+
+    @Test
+    fun `passes class as function parameter using reflection`(){
+        val result = functionAcceptingClassNameUsingReflection<ParameterClass>("com.baeldung.classParameterToFunction.ParameterClass")
+
+        assertEquals("This is a method called on our class", result)
+    }
+
+    @Test
+    fun `passes class as function parameter using reified parameters`(){
+        val result = functionAcceptingClassNameUsingReifiedParameters<ParameterClass>()
+
+        assertEquals("This is a method called on our class", result)
+    }
+}
+
+fun <T: ParameterClass> functionAcceptingClassReference(clazz: Class<T>): String {
+    val instance = clazz.newInstance()
+    return instance.parameterClassMethod()
+}
+
+fun <T: ParameterClass> functionAcceptingKClassReference(clazz: KClass<T>): String {
+    val instance = clazz.createInstance()
+
+    return instance.parameterClassMethod()
+}
+fun <T : ParameterClass> functionAcceptingClassNameUsingReflection(className: String): String {
+    val clazz = Class.forName(className) as Class<T>
+    val instance = clazz.newInstance()
+
+    return instance.parameterClassMethod()
+}
+
+inline fun <reified T: ParameterClass> functionAcceptingClassNameUsingReifiedParameters(): String {
+    val instance = T::class.java.newInstance()
+
+    return instance.parameterClassMethod()
+}
+
+class ParameterClass{
+
+    fun parameterClassMethod(): String{
+        return "This is a method called on our class"
+    }
+}

core-kotlin-modules/pom.xml

@@ -27,6 +27,7 @@
         <module>core-kotlin-10</module>
         <module>core-kotlin-advanced</module>
         <module>core-kotlin-advanced-2</module>
+        <module>core-kotlin-advanced-3</module>
         <module>core-kotlin-annotations</module>
         <module>core-kotlin-arrays</module>
         <module>core-kotlin-arrays-2</module>