add: chapter 9 소스 코드 작성

ryeojin/source/src/main/kotlin/ch09/9.1.1_1_GenericFunctionsAndProperties.kt

@@ -0,0 +1,7 @@
+package ch09.ex1_1_1_GenericFunctionsAndProperties
+
+fun main(args: Array<String>) {
+    val letters = ('a'..'z').toList()
+    println(letters.slice<Char>(0..2))
+    println(letters.slice(10..13))
+}

ryeojin/source/src/main/kotlin/ch09/9.1.1_2_GenericFunctionsAndProperties1.kt

@@ -0,0 +1,8 @@
+package ch09.ex1_1_2_GenericFunctionsAndProperties1
+
+val <T> List<T>.penultimate: T
+    get() = this[size - 2]
+
+fun main(args: Array<String>) {
+    println(listOf(1, 2, 3, 4).penultimate)
+}

ryeojin/source/src/main/kotlin/ch09/9.1.3_1_TypeParameterConstraints.kt

@@ -0,0 +1,9 @@
+package ch09.ex1_3_1_TypeParameterConstraints
+
+fun <T : Number> oneHalf(value: T): Double {
+    return value.toDouble() / 2.0
+}
+
+fun main(args: Array<String>) {
+    println(oneHalf(3))
+}

ryeojin/source/src/main/kotlin/ch09/9.1.3_2_TypeParameterConstraints1.kt

@@ -0,0 +1,9 @@
+package ch09.ex1_3_2_TypeParameterConstraints1
+
+fun <T: Comparable<T>> max(first: T, second: T): T {
+    return if (first > second) first else second
+}
+
+fun main(args: Array<String>) {
+    println(max("kotlin", "java"))
+}

ryeojin/source/src/main/kotlin/ch09/9.1.3_3_TypeParameterConstraints2.kt

@@ -0,0 +1,16 @@
+package ch09.ex1_3_3_TypeParameterConstraints2
+
+import java.time.Period
+
+fun <T> ensureTrailingPeriod(seq: T)
+        where T : CharSequence, T : Appendable {
+    if (!seq.endsWith('.')) {
+        seq.append('.')
+    }
+}
+
+fun main(args: Array<String>) {
+    val helloWorld = StringBuilder("Hello World")
+    ensureTrailingPeriod(helloWorld)
+    println(helloWorld)
+}

ryeojin/source/src/main/kotlin/ch09/9.2.1_1_GenericsAtRuntimeTypeChecksAndCasts.kt

@@ -0,0 +1,11 @@
+package ch09.ex2_1_1_GenericsAtRuntimeTypeChecksAndCasts
+
+fun printSum(c: Collection<*>) {
+    val intList = c as? List<Int>
+            ?: throw IllegalArgumentException("List is expected")
+    println(intList.sum())
+}
+
+fun main(args: Array<String>) {
+    printSum(listOf(1, 2, 3))
+}

ryeojin/source/src/main/kotlin/ch09/9.2.1_2_GenericsAtRuntimeTypeChecksAndCasts1.kt

@@ -0,0 +1,11 @@
+package ch09.ex2_1_2_GenericsAtRuntimeTypeChecksAndCasts1
+
+fun printSum(c: Collection<Int>) {
+    if (c is List<Int>) {
+        println(c.sum())
+    }
+}
+
+fun main(args: Array<String>) {
+    printSum(listOf(1, 2, 3))
+}

ryeojin/source/src/main/kotlin/ch09/9.2.2_1_DeclaringFunctionsWithReifiedTypeParameters.kt

@@ -0,0 +1,8 @@
+package ch09.ex2_2_1_DeclaringFunctionsWithReifiedTypeParameters
+
+inline fun <reified T> isA(value: Any) = value is T
+
+fun main(args: Array<String>) {
+    println(isA<String>("abc"))
+    println(isA<String>(123))
+}

ryeojin/source/src/main/kotlin/ch09/9.2.2_2_DeclaringFunctionsWithReifiedTypeParameters1.kt

@@ -0,0 +1,6 @@
+package ch09.ex2_2_2_DeclaringFunctionsWithReifiedTypeParameters1
+
+fun main(args: Array<String>) {
+    val items = listOf("one", 2, "three")
+    println(items.filterIsInstance<String>())
+}

ryeojin/source/src/main/kotlin/ch09/9.3.1_WhyVarianceExists.kt

@@ -0,0 +1,9 @@
+package ch09.ex3_1_WhyVarianceExists
+
+fun printContents(list: List<Any>) {
+    println(list.joinToString())
+}
+
+fun main(args: Array<String>) {
+    printContents(listOf("abc", "bac"))
+}

ryeojin/source/src/main/kotlin/ch09/9.3.5_1_CopyDataAny.kt

@@ -0,0 +1,15 @@
+package ch09.CopyDataAny
+
+fun <T: R, R> copyData(source: MutableList<T>,
+                       destination: MutableList<R>) {
+    for (item in source) {
+        destination.add(item)
+    }
+}
+
+fun main(args: Array<String>) {
+    val ints = mutableListOf(1, 2, 3)
+    val anyItems = mutableListOf<Any>()
+    copyData(ints, anyItems)
+    println(anyItems)
+}

ryeojin/source/src/main/kotlin/ch09/9.3.5_2_CopyDataOut.kt

@@ -0,0 +1,15 @@
+package ch09.CopyDataOut
+
+fun <T> copyData(source: MutableList<out T>,
+                 destination: MutableList<T>) {
+    for (item in source) {
+        destination.add(item)
+    }
+}
+
+fun main(args: Array<String>) {
+    val ints = mutableListOf(1, 2, 3)
+    val anyItems = mutableListOf<Any>()
+    copyData(ints, anyItems)
+    println(anyItems)
+}

ryeojin/source/src/main/kotlin/ch09/9.3.5_3_CopyDataIn.kt

@@ -0,0 +1,15 @@
+package ch09.CopyDataIn
+
+fun <T> copyData(source: MutableList<T>,
+                 destination: MutableList<in T>) {
+    for (item in source) {
+        destination.add(item)
+    }
+}
+
+fun main(args: Array<String>) {
+    val ints = mutableListOf(1, 2, 3)
+    val anyItems = mutableListOf<Any>()
+    copyData(ints, anyItems)
+    println(anyItems)
+}

ryeojin/source/src/main/kotlin/ch09/9.3.6.2_1_printFirst.kt

@@ -0,0 +1,11 @@
+package ch09.printFirst
+
+fun printFirst(list: List<*>) {
+    if (list.isNotEmpty()) {
+        println(list.first())
+    }
+}
+
+fun main(args: Array<String>) {
+    printFirst(listOf("Svetlana", "Dmitry"))
+}

ryeojin/source/src/main/kotlin/ch09/9.3.6.2_2_StarProjection1.kt

@@ -0,0 +1,11 @@
+package ch09.ex3_6_2_2_StarProjection1
+
+fun <T> printFirst(list: List<T>) {
+    if (list.isNotEmpty()) {
+        println(list.first())
+    }
+}
+
+fun main(args: Array<String>) {
+    printFirst(listOf("Svetlana", "Dmitry"))
+}

ryeojin/source/src/main/kotlin/ch09/9.3.6.2_3_FieldValidator.kt

@@ -0,0 +1,21 @@
+package ch09.FieldValidator
+
+import kotlin.reflect.KClass
+
+interface FieldValidator<in T> {
+    fun validate(input: T): Boolean
+}
+
+object DefaultStringValidator : FieldValidator<String> {
+    override fun validate(input: String) = input.isNotEmpty()
+}
+
+object DefaultIntValidator : FieldValidator<Int> {
+    override fun validate(input: Int) = input >= 0
+}
+
+fun main(args: Array<String>) {
+    val validators = mutableMapOf<KClass<*>, FieldValidator<*>>()
+    validators[String::class] = DefaultStringValidator
+    validators[Int::class] = DefaultIntValidator
+}

ryeojin/source/src/main/kotlin/ch09/9.3.6.2_4_StarProjection3.kt

@@ -0,0 +1,38 @@
+package ch09.ex3_6_2_4_StarProjection3
+
+import kotlin.reflect.KClass
+
+interface FieldValidator<in T> {
+    fun validate(input: T): Boolean
+}
+
+object DefaultStringValidator : FieldValidator<String> {
+    override fun validate(input: String) = input.isNotEmpty()
+}
+
+object DefaultIntValidator : FieldValidator<Int> {
+    override fun validate(input: Int) = input >= 0
+}
+
+object Validators {
+    private val validators =
+            mutableMapOf<KClass<*>, FieldValidator<*>>()
+
+    fun <T: Any> registerValidator(
+            kClass: KClass<T>, fieldValidator: FieldValidator<T>) {
+        validators[kClass] = fieldValidator
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    operator fun <T: Any> get(kClass: KClass<T>): FieldValidator<T> =
+        validators[kClass] as? FieldValidator<T>
+                ?: throw IllegalArgumentException(
+                "No validator for ${kClass.simpleName}")
+}
+
+fun main(args: Array<String>) {
+    Validators.registerValidator(String::class, DefaultStringValidator)
+    Validators.registerValidator(Int::class, DefaultIntValidator)
+    println(Validators[String::class].validate("Kotlin"))
+    println(Validators[Int::class].validate(42))
+}