Javaʹ͓͚Δ ؔ਺ܕϓϩάϥϛϯά΁ͷऔΓ૊Έ ᓎఉ
༞Ұ Java in the Box 

Java 8 2014: Project Lambda Lambda ࣜ

& Stream API ແ໊ؔ਺ ಺෦ΠςϨʔλʔ var nums = List.of(0, 1, 2, 3, 4); ྫ 
ϦετͷཁૉΛ  ৐ͨ͠ϦετΛ࡞੒ var squared = nums.stream() .map( x -> x*x ) .toList(); ετϦʔϜม׵ ϥϜμࣜ 

Function f = x -> x*x; ؔ਺ܕͰ͸ͳ͍ ϝιουΛ  ͚ͭͩఆٛͨ͠ΠϯλϑΣʔε f ͸ Function ΦϒδΣΫτ 

Function f = x -> x*x; ϝιουΛ  ͚ͭͩఆٛͨ͠ ΠϯλϑΣʔεΛ࣮૷ͨ͠ ΫϥεͷΠϯελϯγΤʔγϣϯ x*x ͕ϝιουͷϘσΟ 

Java ͷݴޠ࢓༷ͷมߋ Java Lang Spec ͚ͩͷมߋͰࡁΉ࢓༷มߋ ൺֱత༰қʹมߋՄೳ JVM Spec ͷมߋ͕ඞཁͱͳΔ࢓༷มߋ ͱͯ΋ϋʔυϧ͕ߴ͍ ؔ਺ܕͷಋೖ͸ JVM Spec ͷมߋ͕ඞཁ 

Lambdaࣜͷ࣮ݱํ๏ InvokeDynamicͷ׆༻ ݩʑ͸JRubyͳͲಈతܕ෇͚ݴޠͷͨΊʹ Java 7Ͱಋೖ͞Εͨϝιουίʔϧ༻ͷόΠτίʔυ ࣮ߦ࣌ʹίʔϧ͢ΔϝιουΛ୳ࡧ͔ͯ͠Β ϝιουίʔϧΛߦ͏ LambdaࣜͰ͸ಈతʹΫϥεੜ੒Λߦ͔ͬͯΒ ΦϒδΣΫτΠϯελϯγΤʔγϣϯΛߦ͏ 

InvokeDynamicͷಈ࡞ ొ৔ਓ෺ bootstrapϝιου CallSiteΫϥε MethodHandleΫϥε ୳ࡧΛߦ͍݁ՌΛCallSiteͰ໭͢ϝιου MethodHandleΛอ࣋͢Δίϯςφ ࣮ߦ͢ΔϝιουΛࣔ͢ indy ॳճ bootstrap ϝιου୳ࡧ CallSite MethodHandle ੜ੒ λʔήοτϝιου ࣮ߦ 

InvokeDynamicͷಈ࡞ ొ৔ਓ෺ bootstrapϝιου CallSiteΫϥε MethodHandleΫϥε ୳ࡧΛߦ͍݁ՌΛCallSiteͰ໭͢ϝιου MethodHandleΛอ࣋͢Δίϯςφ ࣮ߦ͢ΔϝιουΛࣔ͢ indy bootstrap CallSite MethodHandle λʔήοτϝιου ճ໨Ҏ߱ ࣮ߦ 

Lambdͷࣜͷಈ࡞ Java ιʔείʔυ ΫϥεϑΝΠϧ ίϯύΠϧ ϥϜμࣜͷϝιουϘσΟΛ static ϝιουԽͯ͠௥Ճ -BNCEB ࣮ࣜߦ CPPUTUSBQ ॳճ ΠϯλϑΣʔε࣮૷ΫϥεΛಈతੜ੒ static ϝιουΛίʔϧ͢ΔΑ͏ʹ͢Δ ಈతੜ੒ΫϥεΛΠϯελϯγΤʔγϣϯ͢Δ CallSite Λੜ੒ CallSite ͔ΒΠϯελϯγΤʔγϣϯ࣮ߦ 

Lambdͷࣜͷಈ࡞ Java ιʔείʔυ ΫϥεϑΝΠϧ ίϯύΠϧ ϥϜμࣜͷϝιουϘσΟΛ static ϝιουԽͯ͠௥Ճ -BNCEB ࣮ࣜߦ CPPUTUSBQ ॳճ ΠϯλϑΣʔε࣮૷ΫϥεΛಈతੜ੒ static ϝιουΛίʔϧ͢ΔΑ͏ʹ͢Δ ಈతੜ੒ΫϥεΛΠϯελϯγΤʔγϣϯ͢Δ CallSite Λੜ੒ CallSite ͔ΒΠϯελϯγΤʔγϣϯ࣮ߦ ճ໨Ҏ߱ 

Project LambdaҎ߱ͷؔ਺ܕϓϩάϥϛϯάػೳ Optional Record Πϛϡʔλϒϧͳσʔλܕ Sealed Class ܧঝͷ੍ݶ ୅਺తσʔλܕ switchࣜ ܕʹΑΔύλʔϯϚονϯά ͚͍ܽͯΔ΋ͷ if ࣜ ྫ֎ॲཧ


EitherͳͲ͸ఏڙ͞Ε͍ͯͳ͍ I/O ैདྷͷखଓ͖తͳI/OॲཧͷΈ 

Project LambdaҎ߱ͷؔ਺ܕϓϩάϥϛϯάػೳ ࠓޙಋೖ༧ఆ Stream Gatherer Streamͷ΢Οϯυ΢ॲཧ null ڐ༰ܕඇڐ༰ܕ JVMSͷมߋ͕ඞཁ 

JavaΛ࢖͏ଆͷঢ়گ खଓ͖తهड़͔Βએݴతهड़΁ͷա౉ظ એݴతͳඪ४ϥΠϒϥϦ CompletableFuture Flow (Reactive Stream) HTTP Client એݴతͳϥΠϒϥϦϑϨʔϜϫʔΫ Spring WebFlux Oracle Helidon Red Hat Quarkus 

·ͱΊ Java 8ͰͷProject Lambda͕୺ॹ LambdaࣜΛؔ਺ͱͯ͠ѻ͏ ύλʔϯϚονϯά
ADTͳͲͷಋೖ͕ਐΉ ݱࡏ͸એݴతهड़΁ͷա౉ظ 

Javaʹ͓͚Δ ؔ਺ܕϓϩάϥϛϯά΁ͷऔΓ૊Έ ᓎఉ
༞Ұ Java in the Box