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Kotlin'1.1'Standard'Libraryͷվળ
@RyotaMurohoshi
2017/06/29(ୈ6ճ(Kotlinษڧձ(@SanSan
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ॕ!Early!access!program!for!Kotlin!1.2!։࢝ʂ
h"ps:/
/blog.jetbrains.com/kotlin/2017/06/early
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͚ΕͲࠓɺKotlin'1.1ͷΛ͠·͢
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Kotlin'1.1ͱݴ͑ɽɽɽ
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Kotlin'1.1ͱݴ͑
• Corou&nes(experimental)
• Type5aliases
• Bound5callable5references
• Sealed5and5data5classes
ͳͲͳͲɽɽɽ
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ͦ͏͍͏ݴޠػೳ͚ͩͰͳ͘ɺ
Standard'Libraryʹ͍Ζ͍ΖՃ͞Ε͍ͯ·͢
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What's'New'in'Kotlin'1.1
Standard'library'ΑΓ
h"ps:/
/kotlinlang.org/docs/reference/whatsnew11.html#standard9library
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String'to'number'conversions
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val numString : String = loadString()
// ͔ͨ͠͠ΒParseࣦഊͯ͠
// NumberFormatException͕͛ΒΕΔ͔
val num: Int = numString.toInt()
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ͦ͜ͰɺtoIntOrNull
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val numString : String = loadString()
// Parseࣦഊͨ͠Βnull
val num:Int? = numString.toIntOrNull()
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// ڥมΛύʔε͢Δ͚Ͳɺ
// ࣦഊͨ͠Β80൪ʹ
val port = System.getenv("PORT")?.toIntOrNull() ?: 80
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• toDoubleOrNull
• toFloatOrNull
• toShortOrNull
• toLongOrNull
• toByteOrNull
جΛࢦఆ͢ΔΦʔόʔϩʔυ͋ΔΑ
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onEach()
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onEach()
֤छίϨΫγϣϯͷ֦ுؔ
forEach͡Όͳͯ͘ɺonEachͰ͢ʂ
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forEach
val unit: Unit = listOf(1, 2, 3)
.map { it * it }
.forEach { println(it) }
࣮ߦ݁Ռ
1
4
9
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onEach
val list: List = listOf(1, 2, 3)
.map { it * it }
.onEach { println(it) }
࣮ߦ݁Ռ
1
4
9
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ࣅ͍ͯ·͢Ͷ
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val unit: Unit = listOf(1, 2, 3)
.map { it * it }
.forEach { println(it) }
val list: List = listOf(1, 2, 3)
.map { it * it }
.onEach { println(it) }
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͓Θ͔Γ͍͚ͨͩ·͔ͨ͠ʁ
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forEachUnit
onEachList
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ίϨΫγϣϯͷϝιουνΣʔϯͷ్தͰɺ֤ཁૉʹॲཧΛߦ͏ϝιουɻ
ฦΓݩͷίϨΫγϣϯɻ
ίϨΫγϣϯࣗମͷมΘΒͳ͍ɻ
෭࡞༻͕͋Δϝιουͱ͔ɻRxͷdoΈ͍ͨ
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Sequenceͷ߹ɺ
ཁૉͷద༻ɾධՁଈ࣌Ͱͳ͍Ͱ͢ʂ
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val sequence: Sequence =sequenceOf(1, 2, 3)
.onEach { println(it) }
.map { it * it }
.onEach { println(it) }
println("============")
for (e in sequence){
println("$e in for")
}
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============
1
1
1 in for
2
4
4 in for
3
9
9 in for
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ͿͬͪΌ͚ίʔυݟͨํ͕ૣ͍Ͱ͢Ͷ
@SinceKotlin("1.1")
public inline fun > C.onEach(action: (T) -> Unit): C {
return apply { for (element in this) action(element) }
}
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also/takeIf/takeUnless
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ίʔυݟͨํ͕Θ͔Γ͍͢ʂ
takeIfͱtakeUnless
/**
* Returns `this` value if it satisfies the given [predicate] or `null`, if it doesn't.
*/
@kotlin.internal.InlineOnly
@SinceKotlin("1.1")
public inline fun T.takeIf(predicate: (T) -> Boolean): T? = if (predicate(this)) this else null
/**
* Returns `this` value if it _does not_ satisfy the given [predicate] or `null`, if it does.
*/
@kotlin.internal.InlineOnly
@SinceKotlin("1.1")
public inline fun T.takeUnless(predicate: (T) -> Boolean): T? = if (!predicate(this)) this else null
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val evenOrNull: Int? = 2.takeIf { it % 2 == 0 }
Assert.assertEquals(2, evenOrNull)
val oddOrNull: Int? = 2.takeUnless { it % 2 == 0 }
Assert.assertEquals(null, oddOrNull)
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alsoapplyʹࣅ͍ͯΔ
͚ΕͲ
ϥϜμࣜͷதͷthisͷҙຯ͕ҧ͏
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val bundleB = Bundle().apply {
// ͜͜ͰthisBundle
putString("KEY1", "VALUE1")
this.putString("KEY2", "VALUE2")
// ίϯύΠϧΤϥʔ
//it.putString("KEY3", "VALUE3")
}
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val bundleA = Bundle().also {
// ͜͜ͰthisBundleͷ֎ଆ
it.putString("KEY1", "VALUE1")
// ίϯύΠϧΤϥʔ
//putString("KEY2", "VALUE2")
// ίϯύΠϧΤϥʔ
//this.putString("KEY3", "VALUE3")
}
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ίʔυݟͨํ͕Θ͔Γ͍͢ʂ
applyͱalso
/**
* Calls the specified function [block] with `this` value as its receiver and returns `this` value.
*/
@kotlin.internal.InlineOnly
public inline fun T.apply(block: T.() -> Unit): T { block(); return this }
/**
* Calls the specified function [block] with `this` value as its argument and returns `this` value.
*/
@kotlin.internal.InlineOnly
@SinceKotlin("1.1")
public inline fun T.also(block: (T) -> Unit): T { block(this); return this }
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groupingBy()
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ฦΓܕ৽ΠϯλʔϑΣʔε!Grouping
interface Grouping
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GroupingάϧʔϓԽͯ͠
͝ʹΐ͝ʹΐॲཧΛ͢ΔͨΊͷ
தؒͷσʔλߏΛ࢘ΔΠϯλʔϑΣʔε
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• aggregate
• fold
• reduce
• eachCount
ͳͲͳͲ
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groupBy͍ͬͯ͏ϝιου͋Γ·ͨ͠ΑͶʁ
data class ScoreRecord(
val stageId: Int,
val score: Int
)
val scoreRecordList = listOf(
ScoreRecord(stageId = 0, score = 1),
ScoreRecord(stageId = 0, score = 3),
ScoreRecord(stageId = 1, score = 2),
ScoreRecord(stageId = 0, score = 1),
ScoreRecord(stageId = 2, score = 4)
)
val map: Map> = scoreRecordList.groupBy { it.stageId }
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groupingByͱfoldͳͲͰɺ
ͬͱॊೈʹ
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val sumScores: Map = scoreRecordList
.groupingBy { it.stageId }
.fold(0, { acc, elm -> acc + elm.score })
val maxScores: Map = scoreRecordList
.groupingBy { it.stageId }
.fold(0, { acc, elm -> maxOf(acc, elm.score) })
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toMap()(ͱ(toMutableMap()
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toMap()(ͱ(toMutableMap()
MapͷίϐʔΠϯελϯεੜϝιου
val original = mutableMapOf(1 to "A", 2 to "B")
val copied = original.toMap()
original[3] = "C"
Assert.assertEquals(3, original.size)
Assert.assertEquals(2, copied.size)
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Map.minus(key)
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Kotlin'1.1ͷલʹɺ+ΦϖϨʔλ͋ͬͨ
val map = mapOf(1 to "A", 2 to "B")
// Kotlin 1.0Ͱ
// +ΦϖϨʔλʔͰཁૉΛՃͨ͠৽ͨͳMapΛੜͰ͖ͨ
val added = map + (3 to "C")
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Kotlin'1.1͔Βɺ*ΦϖϨʔλ͕ՃΘͬͨ
val map = mapOf(1 to "A", 2 to "B")
// Kotlin 1.1͔Β
// -ΦϖϨʔλʔͰࢦఆͨ͠ΩʔͷཁૉΛআͨ͠
// ৽ͨͳMapΛੜͰ͖ΔΑ͏ʹ
val added = map - 1
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minOf()(ͱ(maxOf()
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໊લͷ௨Γʂ
minOf&:&Ҿʹͨ͠ͷ͔Β࠷খΛฦ͢
maxOf&:&Ҿʹͨ͠ͷ͔Β࠷େΛฦ͢
2Ҿόʔδϣϯͱ3Ҿόʔδϣϯ͕͋Δ
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val min = minOf(1, 2)
val max = maxOf(2.3, 5.1, 4.7)
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ComparableΛ࣮ͨ͠ͷͰ͖Δ
val min = minOf(
LocalDate.parse("2017-07-21"),
LocalDate.parse("2017-07-20")
)
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ൺֱ݅ΛҾͱͯ͠ࢦఆͰ͖Δ
val alphabetical = minOf(
"Java",
"Kotlin",
"Android"
)
val length = minOf(
"Java",
"Kotlin",
"Android",
Comparator { a, b -> a.length - b.length }
)
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Array%like*List*instan/a/on*
func/ons
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Kotlin'1.0͔Β
࣮ྻͷॳظԽɺ͜Μͳײ͡Ͱ͔͚ͨ
val zeroFilledZize10 = Array(size=10) { 0 }
val indexedFilled = Array(size=3) {index -> index }
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͜ΕʹࣅͨListͱMutableListΛੜ͢Δ
ʮؔʯ͕Kotlin'1.1͔ΒՃΘͬͨ
val zeroFilledSize10 = MutableList(size=10) { 0 }
val squaredIndexList = List(size = 4) { it * it }
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େจࣈͰ࢝·Δ͚Ͳ
Ϋϥε໊͡Όͳͯ͘ɺؔͷ໊લʂ
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Map.getValue()
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val map: Map = mapOf(1 to "A", 2 to "B")
// 0ͱ͍͏Ωʔͳ͍͔ΒɺnullΛฦ͢
val valueOrNull : String? = map[0]
// 0ͱ͍͏Ωʔͳ͍͔ΒɺNoSuchElementExceptionΛ͛Δ
val value: String = map.getValue(0)
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Abstract(collec,ons
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Abstract(collec,ons
ίϨΫγϣϯͷநΫϥε
• AbstractCollec-on/
• AbstractList
• AbstractSet
• AbstractMap
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Abstract(collec,ons
ίϨΫγϣϯͷநΫϥε
• AbstractMutableCollec/on
• AbstractMutableList
• AbstractMutableSet
• AbstractMutableMap
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java.u&l.AbstractCollec&onͬͯ͋Γ·ͨ͠ΑͶʁ
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JVMͰɺ
kotlin.collec*ons.MutableܥͷίϨΫγϣϯɺ
java.utl.AbstractܥͷίϨΫγϣϯΛܧঝ࣮ͯ͠͞Ε͍ͯΔ
kotlin.collec*ons.AbstractMutableCollec*onɺjava.u*l.AbstractCollec*onΛܧঝ
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JavaScriptͰɺ
͜ΕΒͷίϨΫγϣϯΛܧঝ֤ͯ͠छίϨΫγϣϯΛ࡞͍ͬͯΔ
kotlin.collec*ons.ArrayListɺkotlin.collec*ons.AbstractMutableListΛܧঝ͍ͯ͠Δ
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Kotlin'1.1͔Βొ
kotlin.collec*ons.ArrayList
JVMͰɺjava.u)l.ArrayListͷtypealias
JavaScriptͰɺkotlin.collec0ons.AbstractMutableListΛܧঝͨ͠Ϋϥε
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ίϨΫγϣϯ͚ͩ͡Όͳͯ͘ɺExcep&onܥ
JVMͰtypealiasɺJavaScriptͰಠࣗఆٛ
ClassCastExcep+on,IllegalStateExcep+on
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Array%manipula,on%func,ons
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ྻͷཁૉ͝ͱ͝ʹΐ͝ʹΐ͢Δϝιου͕
Standard'Libraryʹ
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ྻͷtoString()
println(arrayOf(1, 2, 3).toString())
࣮ߦ݁Ռ
Ljava.lang.Integer;@46ee7fe8
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͍ɺ͜Ε͕ݟ͍ͨΜ͡Όͳͯ͘orz
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ͦ͜ͰcontentToStringͰ͢Α
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ྻͷcontentToString()
println(arrayOf(1, 2, 3).contentToString())
࣮ߦ݁Ռ
[1, 2, 3]
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equalsͱcontentEquals
// false
println(arrayOf(1, 2, 3).equals(arrayOf(1, 2, 3)))
// true
println(arrayOf(1, 2, 3).contentEquals(arrayOf(1, 2, 3)))
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͍͍Ͷʂ
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·ͱΊ
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Standard'Library
ຯʹ͔ͬ͠ΓਐԽ͍ͯͨͥ͠ʂ
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͓·͚
kotlin'stdlib'jre8ͰStream2APIͱ͔