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େ վ ʂ ੩ త Ϗ ϑ Υ ʔ ɾ Ξ ϑ λ ʔ
d
4DBMBϦϑΝΫλϦϯάೖ
!UPEPLS
. : ✨
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#FUUFS+BWBͳίʔυ
4DBMBΒ͠͞Λ׆͔͠ɺΑΓݎ࿚ʹ
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ా ॴ ॣ ༎ ! U P E P L S
ג ࣜ ձ ࣾ Ϗ ζ Ϧ ʔ ν
ελ ϯόΠ ࣄ ۀ ෦ α ʔ ν ί Ξάϧ ʔϓ
Σ ϒΫ ϩ ʔ ϥ ʔ ͷ ։ ൃ ɾ ӡ ༻
݄ ೖ ࣾ ࡀ
4 D B M B ྺ ϲ ݄
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͓ ͢͠ Δ ͜ ͱ
w ͳͥ#FUUFS+BWBͷઌͳͷ͔ʁ4DBMBΒ͠͞ͷԸܙͱ
w ύλʔϯϚονͷύλʔϯΩϟετΛͳͯ҆͘͠શʹ
w λϓϧΛආ͚Δͦͷࣈʹҙຯ͋Δ͔ʁ
w 4DBMBͳྫ֎ॲཧޭɾࣦഊΛͱͯ͠දݱ͢Δ
w DBTFDMBTTʹ੍Λ࣋ͨͤΔSFRVJSFͷར༻
w TFBMFEUSBJUͰཏੑΛ୲อ͢ΔίϯύΠϥʹ͓ئ͍
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͓ ͢͠ Δ ͜ ͱ
w ͳͥ#FUUFS+BWBͷઌͳͷ͔ʁ4DBMBΒ͠͞ͷԸܙͱ
w ύλʔϯϚονͷύλʔϯΩϟετΛͳͯ҆͘͠શʹ
w λϓϧΛආ͚Δͦͷࣈʹҙຯ͋Δ͔ʁ
w 4DBMBͳྫ֎ॲཧޭɾࣦഊΛͱͯ͠දݱ͢Δ
w DBTFDMBTTʹ੍Λ࣋ͨͤΔSFRVJSFͷར༻
w TFBMFEUSBJUͰཏੑΛ୲อ͢ΔίϯύΠϥʹ͓ئ͍
ˠ 4 D B M B Λ ֶ ͼ ࢝ Ί ͨ ࠒ ͷ ࣗ ʹ
ɹ ڭ ͑ͯ ͋ ͛ ͨ ͍ ༰
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ͳ ͥ # F U U F S + B W B ͷ ઌ ͳ ͷ ͔ ʁ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
ͪΐͬͱ͍
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
ίʔυͷ͞ͱόάͷೖΓ͢͞
ਖ਼ൺྫ͢ΔɻͰ͖Εͬͱ͍ͨ͘͠ɻ
ͪΐͬͱ͍
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
ग़ޱ͕Օॴ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
ग़ޱ͕Օॴ
Ͱ͖Εذগͳ͍΄͏͕
γϯϓϧͰݎ࿚ɻ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
࠶ೖՄೳͳม
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1 def isBlank(str:String): Boolean = {
2 var strLen = 0
3
4 if(str == null || { strLen = str.length(); strLen } == 0) {
5 return true
6 }
7
8 var i = 0
9 while( i < strLen ){
10 if(Character.isWhitespace( str.charAt(i) ) == false){
11 return false
12 }
13 i += 1
14 }
15
16 return true
17 }
# F U U F S + B W B ͳ ελ Πϧ
࠶ೖՄೳͳม
࠶ೖՄೳʮঢ়ଶʯΛ࣋ͭͱ͍͏͜ͱɻ
ঢ়ଶΛؾʹ͢Δඞཁ͕͋Δɻ
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1 def isBlank(str: String): Boolean =
2 Option(str).fold(true)(_.forall(Character.isWhitespace))
4 D B M B Β ͠ ͍ ελ Πϧ
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1 def isBlank(str: String): Boolean =
2 Option(str).fold(true)(_.forall(Character.isWhitespace))
w ͘ಡΈ͘͢
w ذ͕গͳ͘
w ঢ়ଶΛؾʹ͢Δඞཁͳ͘
4 D B M B Β ͠ ͍ ελ Πϧ
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1 def isBlank(str: String): Boolean =
2 Option(str).fold(true)(_.forall(Character.isWhitespace))
w ͘ಡΈ͘͢
w ذ͕গͳ͘
w ঢ়ଶΛؾʹ͢Δඞཁͳ͘
4 D B M B Β ͠ ͍ ελ Πϧ
☺ όάͷࠞೖͷՄೳੑ͕Լ͕Δ
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ύ λ ʔϯ Ϛ ο ν ͷ ύ λ ʔϯ
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0 Q U J P O ͷ ύ λ ʔϯ Ϛ ο ν
1 option match {
2 case Some(x) => println(s"$x is here!")
3 case None => println("oh…")
4 }
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γ ʔ έ ϯε ͷ ύ λ ʔϯ Ϛ ο ν
1 List("Noel", "Liam", "Gem", "Andy", "Alan") match {
2 case List(_, second, _*) => println(s"Hello $second!")
3 case _ =>
4 }
5 // => Hello Liam!
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ί ϯε τ ϥ Ϋ λύ λ ʔϯ
1 val user = User("Martin", Place("Tokyo", "Shibuya"))
2
3 user match {
4 case User(name, Place(pref, _)) => "$name in $pref"
5 case _ =>
6 }
7 // => Martin lives in Tokyo!
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ܕ ν Σ ο Ϋ ͱ Ω ϟε τ
1 def count2x(x: Any): Int = {
2 if (x.isInstanceOf[String]) {
3 x.asInstanceOf[String].length * 2
4 } else if (x.isInstanceOf[Int]) {
5 x.asInstanceOf[Int] * 2
6 } else -1
7 }
8
9 count2x("scala") // 10
10 count2x(7) // 14
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ܕ ν Σ ο Ϋ ͱ Ω ϟε τ
1 def count2x(x: Any): Int = {
2 if (x.isInstanceOf[String]) {
3 x.asInstanceOf[String].length * 2
4 } else if (x.isInstanceOf[Int]) {
5 x.asInstanceOf[Int] * 2
6 } else -1
7 }
8
9 count2x("scala") // 10
10 count2x(7) // 14
ܕνΣοΫ
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ܕ ν Σ ο Ϋ ͱ Ω ϟε τ
1 def count2x(x: Any): Int = {
2 if (x.isInstanceOf[String]) {
3 x.asInstanceOf[String].length * 2
4 } else if (x.isInstanceOf[Int]) {
5 x.asInstanceOf[Int] * 2
6 } else -1
7 }
8
9 count2x("scala") // 10
10 count2x(7) // 14
Ωϟετ
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ܕ ν Σ ο Ϋ ͱ Ω ϟε τ
1 def count2x(x: Any): Int = {
2 if (x.isInstanceOf[String]) {
3 x.asInstanceOf[String].length * 2
4 } else if (x.isInstanceOf[Int]) {
5 x.asInstanceOf[Int] * 2
6 } else -1
7 }
8
9 count2x("scala") // 10
10 count2x(7) // 14
Ωϟετ
গ͠ɻ
Θ͟Θ͟Ωϟετ͢Δͷةݥͳ߳Γɻ
ܕνΣοΫ
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ܕ ͖ ύ λ ʔϯ
1 def count2x(x: Any): Int = x match {
2 case x:String => x.length * 2
3 case x: Int => x * 2
4 case _ => -1
5 }
6
7 count2x("scala") // 10
8 count2x(7) // 14
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ܕ ͖ ύ λ ʔϯ
1 def count2x(x: Any): Int = x match {
2 case x:String => x.length * 2
3 case x: Int => x * 2
4 case _ => -1
5 }
6
7 count2x("scala") // 10
8 count2x(7) // 14 ☺ ίʔυͷݟ௨্͕͠ɻ
ΩϟετෆཁͰ҆৺ɻ
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ܕ ফ ڈ ʹ ҙ
1 def detectType(x: Any): String = x match {
2 case x: List[Int] => "This is List of Int!"
3 case _ => "What?"
4 }
5
6 detectType(List("string!")) // => This is List of Int!
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ܕ ফ ڈ ʹ ҙ
1 def detectType(x: Any): String = x match {
2 case x: List[Int] => "This is List of Int!"
3 case _ => "What?"
4 }
5
6 detectType(List("string!")) // => This is List of Int!
+BWBͱಉ༷ɺίϨΫγϣϯͷཁૉܕͷใ
࣮ߦ࣌ʹཧ͞Εͳ͍ ˞"SSBZΛআ͘
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λ ϓϧ Λ ආ ͚ Δ
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λ ϓϧ
1 //
2 case class Item(name: String, price: Int)
3
4 // ͷ੫ࠐՁ֨ͱՁ֨ϥϕϧΛฦ͢
5 def labelPriceWithTax(item: Item): (Int, String) = {
6 val withTax = item.price * 1.08
7 val label = s"ܹ҆େಛՁ ¥${item.price}ʢ੫ࠐʣ"
8 (withTax, label)
9 }
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λ ϓϧ
1 //
2 case class Item(name: String, price: Int)
3
4 // ͷ੫ࠐՁ֨ͱՁ֨ϥϕϧΛฦ͢
5 def labelPriceWithTax(item: Item): (Int, String) = {
6 val withTax = item.price * 1.08
7 val label = s"ܹ҆େಛՁ ¥${item.price}ʢ੫ࠐʣ"
8 (withTax, label)
9 }
☺ +BWBͰ-JTU0CKFDUͷΑ͏ʹฦ͍ͯͨ͠ͷ͕
ܕͷใΛΩʔϓͨ͠··ฦͤͯ҆৺
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Ξ ϯ νύ λ ʔϯ Ξ ϯ μʔε ί Ξ Ͱ ͷ ΞΫ η ε
1 val apple = Item("αϯ;͡", 158)
2 val x = labelPriceWithTax(apple)
3 println(s"${x._1}͕ͳΜͱ${x._2}!")
4 // αϯ;͕͡ͳΜͱܹ҆େಛՁ ¥158!
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Ξ ϯ νύ λ ʔϯ Ξ ϯ μʔε ί Ξ Ͱ ͷ ΞΫ η ε
1 val apple = Item("αϯ;͡", 158)
2 val x = labelPriceWithTax(apple)
3 println(s"${x._1}͕ͳΜͱ${x._2}!")
4 // αϯ;͕͡ͳΜͱܹ҆େಛՁ ¥158!
ʮY@ʯͷͳͲͷࣈ
ཁૉʹ͍ͭͯͷใΛԿ͍͑ͯͳ͍ɻ
औΓҧ͑ͯؾ͖ͮͮΒ͍ɻ
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վ ળ ྫ ม ೖ ࣌ ʹ λ ϓϧ Λ ղ
1 val apple = Item("αϯ;͡", 158)
2 val (name, priceLabel) = labelPriceWithTax(apple)
3 println(s"${name}͕ͳΜͱ${priceLabel}!")
4 // αϯ;͕͡ͳΜͱܹ҆େಛՁ ¥158!
ҙຯͷ͋Δม໊ͰΞΫηεͰ͖ͯ҆৺
ม͕૿͑ͯऔΓҧ͑ʹ͍͘
☺
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վ ળ ྫ ύ λ ʔϯ Ϛ ο ν Ͱ λ ϓϧ Λ ղ
1 val apple = Item("αϯ;͡", 158)
2 labelPriceWithTax(apple) match { case (name, price) =>
3 println(s"${name}͕ͳΜͱ${price}!")
4 }
5 // αϯ;͕͡ͳΜͱܹ҆େಛՁ ¥158!
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4 D B M B ͳ ྫ ֎ ॲ ཧ
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ྫ ֎ ॲ ཧ
1 // ྫ֎Λ͛ΔՄೳੑͷ͋Δϝιου
2 def detect(bytes: Array[Byte]): Charset = {
3 val detectedCharsetName: String = ...
4 Charset.forName(detectedCharsetName)
5 }
6
7 // ϝιουͷݺͼग़͠ݩͰྫ֎ॲཧ
8 try {
9 detect(bytes)
10 ...
11 } catch {
12 case e: Exception => ...
13 }
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ྫ ֎ ॲ ཧ
1 // ྫ֎Λ͛ΔՄೳੑͷ͋Δϝιου
2 def detect(bytes: Array[Byte]): Charset = {
3 val detectedCharsetName: String = ...
4 Charset.forName(detectedCharsetName)
5 }
6
7 // ϝιουͷݺͼग़͠ݩͰྫ֎ॲཧ
8 try {
9 detect(bytes)
10 ...
11 } catch {
12 case e: Exception => ...
13 }
ޭPSࣦഊΛͱͯ͠ѻ͍ɺ
੍ޚϑϩʔΛγϯϓϧʹ͍ͨ͠
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ྫ ֎ Ͱ ͳ ͘ ʜ
ޭPSࣦഊΛදݱ͢ΔܕͱͦͷΛ༻͍Δ
w 0QUJPO<5>
ޭ࣌ͷΛ4PNFɺࣦഊΛ/POFͰදݱ
w &JUIFS<"
#>
ޭ࣌ͷใΛ3JHIUͰɺࣦഊͷใΛ-FGUͰදݱ
w 5SZ<5>
ྫ֎Λ͛ΔՄೳੑͷ͋ΔॲཧΛநԽɺ4VDDFTTͱ'BJMVSFͰ݁ՌΛදݱ
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0 Q U J P O ܕ
w 4PNFͱ/POFͱ͍͏छྨ
w ͕ଘࡏ͢Δ͜ͱΛද͢4PNF W
w ͕ଘࡏ͠ͳ͍͜ͱΛද͢/POF
w 0QUJPOܕˠʮ͕ଘࡏ͠ͳ͍Մೳੑ͕͋Δʯͱ͍͏ϝοηʔδ
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0 Q U J P O Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 // try / catchͰOptionΛฦ͢
2 def detect(bytes: Array[Byte]): Option[Charset] = {
3 val detectedCharsetName: String = ...
4 try {
5 Some(Charset.forName(detectedCharsetName))
6 } catch {
7 case e: Exception => None
8 }
9 }
ޭ࣌4PNFɺࣦഊ࣌/POFͰฦ͢
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0 Q U J P O Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 // ࣦഊͨ͠ΒσϑΥϧτΛ͏
2 detect(bytes).getOrElse(Charset.defaultCharset)
3
4 // ࣦഊͨ͠ΒԿ͠ͳ͍
5 detect(bytes).map { charset =>
6 // Կ͔ॲཧ
7 }
ݺͿଆͰͷѻ͍
݁ՌʹԠͨ͡ॲཧ͕҆શ͔ͭॊೈʹͰ͖Δ
☺
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& J U I F S ܕ
w 3JHIU D
ͱ-FGU F
ͱ͍͏छྨ
w 3JHIUʮਖ਼͍͠ʯʹ͔͚ͯޭ࣌ͷΛ֨ೲ͢Δͷ͕ओྲྀ
w -FGUΛ࣋ͯΔͷͰɺࣦഊ࣌ͷใΛ֨ೲͰ͖Δ
w &JUIFSܕˠʮࣦഊ͢ΔՄೳੑ͕͋Δʯͱ͍͏ϝοηʔδ
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& J U I F S Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 // try / catchͰOptionΛฦ͢
2 def detect(bytes: Array[Byte]): Either[Exception, Charset] = {
3 val detectedCharsetName: String = ...
4 try {
5 Right(Charset.forName(detectedCharsetName))
6 } catch {
7 case e: Exception => Left(e)
8 }
9 }
ޭ࣌3JHIUɺࣦഊ࣌-FGUͰฦ͢
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& J U I F S Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 //
2 val charset = detect(bytes) match {
3 case Right(charset) => charset
4 case Left(e) =>
5 logger.error(s"Oops! :$e")
6 Charset.defaultCharset
7 }
ݺͿଆͰͷѻ͍
ݺͼग़͢ਓʹ݁ՌͷνΣοΫΛڧ੍Ͱ͖Δ
ࣦഊ࣌ͷใ͕࣋ͯΔͷͰϩάʹग़ͨ͠ΓͳͲ
☺
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5S Z ܕ
w 4VDDFTT W
ͱ'BJMVSF F
ͱ͍͏छྨ
w 4VDDFTT W
ʹޭ࣌ͷ
w 'BJMVSF F
ʹࣦഊ࣌ͷใ
w ྫ֎͕͛ΒΕΔ͔͠Εͳ͍ॲཧΛ5SZͰғΉ͚ͩͰ0,
w 5SZܕˠʮࣦഊ͢ΔՄೳੑ͕͋Δʯͱ͍͏ϝοηʔδ
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5S Z Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 // ݁ՌΛTryͰड͚औΔ
2 import scala.util.Try
3 def detect(bytes: Array[Byte]): Try[Charset] = {
4 val detectedCharsetName: String = ...
5 Try(Charset.forName(ud.getDetectedCharset))
6 }
7
ࣦഊ͢Δ͔͠Εͳ͍ॲཧΛ5SZ
ͰแΉ
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5S Z Ͱ ޭ ࣦ ഊ Λ ද ݱ ͢ Δ
1 //
2 val charset = detect(bytes) match {
3 case Success(charset) => charset
4 case Failure(e) =>
5 logger.error(s"Oops! :$e")
6 Charset.defaultCharset
7 }
ݺͿଆͰͷѻ͍
4VDDFTT'BJMVSFͰύλʔϯϚον
☺
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' B J M V S F ʹ ͳ Δ ͷ / P O ' B U B M ͳ ͷ
• VirtualMachineError
• ThreadDeath
• InterruptedException
• LinkageError
• ControlThrowable
'BUBMͳΤϥʔɾྫ֎ͦͷ··εϩʔ͞ΕΔ
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5S Z ͱ G P S ࣜ
1 // ྫ֎Λى͔͜͢͠Εͳ͍ϝιου
2 def someMethod: Int = ???
3 def anotherMethod: Int = ???
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5S Z ͱ G P S ࣜ
1 // TryΛforࣜͰ߹͢Δ
2 val result = for {
3 result1 <- Try(someMethod)
4 result2 <- Try(anotherMethod)
5 } yield result1 + result2
6
7 result match {
8 case Success(result) => println(result)
9 case Failure(e) => println(s"Opps: ", e)
10 }
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5S Z ͱ G P S ࣜ
1 // TryΛforࣜͰ߹͢Δ
2 val result = for {
3 result1 <- Try(someMethod)
4 result2 <- Try(anotherMethod)
5 } yield result1 + result2
6
7 result match {
8 case Success(result) => println(result)
9 case Failure(e) => println(s"Opps: ", e)
10 }
ʮ"ͱ#͕྆ํޭͨ͠ͱ͖ͷΈ9͢Δʯ
ͳͲ͕͔Γ͘͢දݱͰ͖Δ
☺
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D B T F D M B T T ʹ ੍ Λ ࣋ ͨ ͤ Δ
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Ұ ݟ ͳ Μ ͷ ม ͳ ͍ D B T F D M B T T
1 case class Person(
2 name: String,
3 age: Int
4 )
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Ұ ݟ ͳ Μ ͷ ม ͳ ͍ D B T F D M B T T
1 case class Person(
2 name: String,
3 age: Int
4 )
ࡀͱ͔ͳ͍ΑͶɻ
ҾΛνΣοΫ͠ͳ͖Όɻ
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 if(age < 0)
throw new IllegalArgumentException("Age must be natural!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 if(age < 0)
throw new IllegalArgumentException("Age must be natural!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
ࣄલ݅Ͱ͋Δ͜ͱΛ
ͬͱ໌֬ʹ͍͑ͨ
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
ࣄલ݅
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
ࣄલ݅Λຬͨ͞ͳ͍߹ͷ
Τϥʔϝοηʔδ
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
1 val joe = Person("Joe Cool", -2))
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
1 val joe = Person("Joe Cool", -2))
2 // => java.lang.IllegalArgumentException:
requirement failed: Age must be natural number!
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1 case class Person(
2 name: String,
3 age: Int
4 ) {
5 require(age >= 0, "Age must be natural number!")
6 }
੍ Λ ͨ ͤ ͨ D B T F D M B T T
&JUIFS5SZͱΈ߹ΘͤΔͱ͏Ε͍͠
☺
1 val joe = Person("Joe Cool", -2))
2 // => java.lang.IllegalArgumentException:
requirement failed: Age must be natural number!
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T F B M F E U S B J U Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
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Ϣ ʔ β ʔϓ ϥ ϯ Λ ύ λ ʔϯ Ϛ ο ν
1 case class User(name: String, age: Int)
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Ϣ ʔ β ʔϓ ϥ ϯ Λ ύ λ ʔϯ Ϛ ο ν
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan // ແྉϓϥϯ
5 case class Premium(user: User) extends Plan // ϓϨϛΞϜϓϥϯ
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Ϣ ʔ β ʔϓ ϥ ϯ Λ ύ λ ʔϯ Ϛ ο ν
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan // ແྉϓϥϯ
5 case class Premium(user: User) extends Plan // ϓϨϛΞϜϓϥϯ
6
7 val userA = Free(User("Taro", 23))
8 val userB = Premium(User("Jiro", 25))
9
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Ϣ ʔ β ʔϓ ϥ ϯ Λ ύ λ ʔϯ Ϛ ο ν
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan // ແྉϓϥϯ
5 case class Premium(user: User) extends Plan // ϓϨϛΞϜϓϥϯ
6
7 val userA = Free(User("Taro", 23))
8 val userB = Premium(User("Jiro", 25))
9
10 userB match {
11 case Free(User(name, _)) => println(s"Hi, $name.")
12 case Premium(User(name, _)) => println(s"Hello, $name!")
13 }
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Ϣ ʔ β ʔϓ ϥ ϯ Λ ύ λ ʔϯ Ϛ ο ν
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan // ແྉϓϥϯ
5 case class Premium(user: User) extends Plan // ϓϨϛΞϜϓϥϯ
6
7 val userA = Free(User("Taro", 23))
8 val userB = Premium(User("Jiro", 25))
9
10 userB match {
11 case Free(User(name, _)) => println(s"Hi, $name.")
12 case Premium(User(name, _)) => println(s"Hello, $name!")
13 }
14 // => Hello, Jiro!
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ϓ ϥ ϯ Λ ૿ ͢
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
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ϓ ϥ ϯ Λ ૿ ͢
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
6 case class Campaign(user: User) extends Plan
7
8 val userA = Free(User("Taro", 23))
9 val userB = Premium(User("Jiro", 25))
10 val userC = Campaign(User("Saburo", 28))
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ϓ ϥ ϯ Λ ૿ ͢
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
6 case class Campaign(user: User) extends Plan
7
8 val userA = Free(User("Taro", 23))
9 val userB = Premium(User("Jiro", 25))
10 val userC = Campaign(User("Saburo", 28))
11
12 Seq(userA, userB, userC) foreach {
13 case Free(User(name, _)) => println(s"Hi, $name.")
14 case Premium(User(name, _)) => println(s"Hello, $name!")
15 }
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ϓ ϥ ϯ Λ ૿ ͢
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
6 case class Campaign(user: User) extends Plan
7
8 val userA = Free(User("Taro", 23))
9 val userB = Premium(User("Jiro", 25))
10 val userC = Campaign(User("Saburo", 28))
11
12 Seq(userA, userB, userC) foreach {
13 case Free(User(name, _)) => println(s"Hi, $name.")
14 case Premium(User(name, _)) => println(s"Hello, $name!")
15 }
16 // => Hi, Taro.
17 // => Hello, Jiro!
18 // => scala.MatchError: Campaign(User(Saburo,28)) …
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ϓ ϥ ϯ Λ ૿ ͢
1 case class User(name: String, age: Int)
2
3 trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
6 case class Campaign(user: User) extends Plan
7
8 val userA = Free(User("Taro", 23))
9 val userB = Premium(User("Jiro", 25))
10 val userC = Campaign(User("Saburo", 28))
11
12 Seq(userA, userB, userC) foreach {
13 case Free(User(name, _)) => println(s"Hi, $name.")
14 case Premium(User(name, _)) => println(s"Hello, $name!")
15 }
16 // => Hi, Taro.
17 // => Hello, Jiro!
18 // => scala.MatchError: Campaign(User(Saburo,28)) …
.BUDI&SSPS࣮ߦ࣌Τϥʔɻ
࣮ߦલʹύλʔϯͷ࿙Εʹؾ͖͍ͮͨ
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4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
1 case class User(name: String, age: Int)
2
3 trait Plan
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4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
1 case class User(name: String, age: Int)
2
3 sealed trait Plan
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4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
1 case class User(name: String, age: Int)
2
3 sealed trait Plan
w ಉ͡ϑΝΠϧͰܧঝՄೳ
w ผͷϑΝΠϧ͔ΒܧঝෆՄ
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4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
1 case class User(name: String, age: Int)
2
3 sealed trait Plan
w ಉ͡ϑΝΠϧͰܧঝՄೳ
w ผͷϑΝΠϧ͔ΒܧঝෆՄ
͜ͷϑΝΠϧͰఆٛ͞ΕͨͷҎ֎ʹ
1MBOଘࡏ͠ͳ͍͜ͱ͕อূ͞ΕΔ
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4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
1 case class User(name: String, age: Int)
2
3 sealed trait Plan
4 case class Free(user: User) extends Plan
5 case class Premium(user: User) extends Plan
6 case class Campaign(user: User) extends Plan
7
8 val userA = Free(User("Taro", 23))
9 val userB = Premium(User("Jiro", 25))
10 val userC = Campaign(User("Saburo", 28))
11
12 Seq(userA, userB, userC) foreach {
13 case Free(User(name, _)) => println(s"Hi, $name.")
14 case Premium(User(name, _)) => println(s"Hello, $name!")
15 }
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[warn] It would fail on the following input: Campaign(_)
[warn] Seq(userA, userB, userC) foreach {
[warn] ^
[warn] one warning found
4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
ίϯύΠϧ͢Δͱʜ
ʮ$BNQBJHO͕དྷͨΒམͪΔͰʂʯͱ
ίϯύΠϥ͕ڭ͑ͯ͘ΕΔ
☺
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[warn] It would fail on the following input: Campaign(_)
[warn] Seq(userA, userB, userC) foreach {
[warn] ^
[warn] one warning found
4 F B M F E म ০ ࢠ Ͱ ཏ ੑ Λ ୲ อ ͢ Δ
ίϯύΠϧ͢Δͱʜ
ʮ$BNQBJHO͕དྷͨΒམͪΔͰʂʯͱ
ίϯύΠϥ͕ڭ͑ͯ͘ΕΔ
☺
8BSOJOHແࢹ͠ͳ͍ͰͶ
☺
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͓ ͠ ͠ ͨ ͜ ͱ
w ͳͥ#FUUFS+BWBͷઌͳͷ͔ʁ
w ύλʔϯϚονͷύλʔϯ
w λϓϧΛආ͚Δ
w 4DBMBͳྫ֎ॲཧ
w DBTFDMBTTʹ੍Λ࣋ͨͤΔ
w TFBMFEUSBJUͰཏੑΛ୲อ͢Δ
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) B W F B ( P P E 4 D B M B - J G F
. : ✨