これからのJavaのとっかかりを掴む

͜Ε͔Βͷ+BWBͷ ͱ͔͔ͬΓΛ௫Ή ळͷؔδϟόࡇΓ LBOKBWB !JSPG +BWB%BZ5PLZP KEU !JSPG

+BWBΤϯδχΞཆ੒ಡຊ  +BWBೖ໳ ։ൃݱ৔ʹ఻͍͑ͨͷ͜ͱ  ಓ۩ʹؔ͢ΔΑ͠ͳ͠͝ͱ ؔ੢+BWBΤϯδχΞͷձ @irof IPHFۦಈ ϨϏϡΞʔ

͜Ε͔Β͢Δ࿩ ͜Ε·Ͱͷ+BWBΛৼΓฦͬͯ ͍·Ͳ͖ͷ+BWBͷ଍৔ݻΊ ͜Ε͔Βͷ+BWBͷͱ͔͔ͬΓ ˞ϓϩάϥϚ޲͚

͠ͳ͍࿩ +BWBҎ߱ͷ۩ମతͳ࿩

͜Ε·Ͱͷ+BWBΛ ৼΓฦͬͯ ͜Ε·Ͱͷ+BWB+BWB4&͋ͨΓ

ʮ͜Ε·Ͱʯ ʹؚ·ΕΔ΋ͷ δΣωϦΫε FOVN ֦ுGPS Ξϊςʔγϣϯ $PODVSSFODZ6UJMJUJFT

͜Ε·Ͱͷ+BWBΛΠϝʔδͰ࿩͠·͢ ˞ݸਓͷײ૝Ͱ͢

+BWBݴޠ

+BWBݴޠ ݎ͍ۤ͠ ੩తܕ෇͚ΦϒδΣΫτࢦ޲ݴޠ ৑௕ͳߏจ ྼԽ999ݴޠ อकత ݹष͍ ख͕ؒଟ͍ ਐԽ͕஗͍ ॲཧ͕஗͍
ىಈ͕஗͍ Α͘࢖ΘΕ͍ͯΔ ϙετ$0#0- Ϋϥεϕʔε

+BWB؀ڥ

+BWB؀ڥ ࣮੷ࣄྫ͕ଟ͍ ԯͷσόΠεͰಈ͘ +7. αʔόʔ͔ΒϞόΠϧ·Ͱ +7.ݴޠ ৘ใ͕ಘ΍͍͢ ๲େͳϥΠϒϥϦ΍ ϑϨʔϜϫʔΫ ॆ࣮ͨ͠։ൃπʔϧ
Φʔϓϯιʔε

͜Ε·Ͱͷ+BWBͷΠϝʔδ ݴޠ͸Α͘࢖ΘΕ͍ͯΔ ҰํͰωΨςΟϒͳҹ৅΋ڧͦ͏ ؀ڥ͸جຊతʹϙδςΟϒͳײ͡

Ҏ্͕z͜Ε·Ͱzͷ࿩

+BWB͸มΘ͍ͬͯ·͢ ʢͨͿΜʣ

͍·Ͳ͖ͷ+BWBͷ ଍৔ݻΊ

͍·Ͳ͖ͷ+BWBݴޠ ͍·Ͳ͖ͷ+BWB+BWB +BWB ίʔυͱͱ΋ʹ͓͞Β͍ɻ

+BWBϐοΫΞοϓ +BWB4& +43 1SPKFDU$PJO +43 /*0 +43

+431SPKFDU$PJO USZXJUISFTPVSDFT EJBNPOEPQFSBUPS $PJOͰ΋Α͘࢖͏΋ͷ

USZXJUISFTPVSDFT Closeable resource = create();  try {  // resource Λ࢖͏ॲཧ... 
} finally {  resource.close();  } try (AutoCloseable resource = create()) {  // resource Λ࢖͏ॲཧ...  }

EJBNPOEPQFSBUPS Map<String, List<Map<String, String>>> map  = new HashMap<String, List<Map<String, String>>>(); 
Map<String, List<Map<String, String>>> map  = new HashMap<>();

ଞͷ$PJOͨͪ όΠφϦϦςϥϧ ਺஋ϦςϥϧͷΞϯμʔείΞ 4USJOHTTXJUDI ϚϧνΩϟον

ଞͷ$PJOͨͪ όΠφϦϦςϥϧ ਺஋ϦςϥϧͷΞϯμʔείΞ 4USJOHTTXJUDI ϚϧνΩϟον Ϧςϥϧ ͋Μ·Γ ॻ͔ͳ͍

4USJOH4XJUDI switch (str) {  case "java":  // ...  break;  case
"groovy":  // ...  break;  default:  // ...  } OVMM͜Θ͍ CSFBLΊΜͲ͍ JGͰॻ͘ΑΓ  ߦ਺ଟ͍

ϚϧνΩϟον try {  this.getClass().getMethod("method").invoke(this);  } catch (IllegalAccessException  | NoSuchMethodException  |
InvocationTargetException e) {  // ...  } try {  this.getClass().getMethod("method").invoke(this);  } catch (ReflectiveOperationException e) {  // ...  } ϦϑϨΫγϣϯ͸جఈྫ֎ΫϥεͷDBUDIͰΑ͛͞

+43/*0 +BWBͰϑΝΠϧΛѻ͏ؾʹͳΕΔʢॏཁʣ

/*0 List<String> lines = new ArrayList<String>();  BufferedReader br = new
BufferedReader(  new InputStreamReader(  new FileInputStream(fileName), StandardCharsets.UTF_8));  for (String line; (line = br.readLine()) != null; ) {  lines.add(line);  } List<String> lines = Files.readAllLines(path); 🌾DMPTFলུ

+BWBϐοΫΞοϓ +BWB4& +43 1SPKFDU-BNCEB +43 %BUFBOE5JNF"1* +43

+43 1SPKFDU-BNCEB -BNCEB&YQSFTTJPO .FUIPE3FGFSFODF 0QUJPOBM

-BNCEB&YQSFTTJPO (String arg) -> { /* ͳΜ͔ॲཧ */ } arg
-> /* ͳΜ͔ࣜ */ System.out::println .FUIPE3FGFSFODF

0QUJPOBM MBNCEBͱͷซ༻͕جຊ JT1SFTFOU࢖͏ͱΠϚΠν OVMMΛࠜઈ΍͠ʹͯ͠΄͍͠ Optional<String> java = Optional.of(“java");   java.ifPresent(System.out::println);

+43 %BUFBOE5JNF"1* %BUF5JNF%BUF5JNF -PDBM;POFE %BUF5JNF'PSNBUUFS ͳͲʜʜ

͋Θͤͯݟͯཉ͍͠

͍·Ͳ͖ͷ+BWB؀ڥ ϥΠϒϥϦ΍ϑϨʔϜϫʔΫ *%& ϏϧυγεςϜ

ϥΠϒϥϦ΍ ϑϨʔϜϫʔΫ ૬มΘΒͣͨ͘͞Μ͋Δ Ή͠Ζ૿͑ΔҰํ ੈ୅ަ୅΍ํ޲ੑͷมಈ͕ىͬͯͨ͜Γ +BWB&&΍4QSJOH#PPUͳͲͷྲྀΕ

*%& &DMJQTFͷಠஃ৔͔Βબ୒΁ &DMJQTF /FU#FBOT *OUFMMJ+*%&"

ϏϧυγεςϜ "OU.BWFO͔Β(SBEMF΁ʁ ҰؾʹมΘΔؾ഑͸ͳͦ͞͏ ঃʑʹมΘ͍ͬͯΔҹ৅͸͋Δ

͜Ε·Ͱ͍·Ͳ͖ ݴޠ ݹष͞΍৑௕͞͸১ΘΕͭͭ͋Δ ؀ڥ ͜Ε·ͰΛϕʔεʹΑΓڧྗʹ

࣌ʹ l͍·Ͳ͖ͷ+BWBz ࢖ͬͯ·͢ʁ

͍·Ͳ͖ͷ+BWB ͳΜ͔ඍົͳײ͕͢͡ΔɻͳΜͰʁ ࢖͑Δਓ͕͍ͳ͍ʁ ಈ͔ͳ͍ʁ

࢖͑Δਓ͕͍ͳ͍ʁ ࢖ͬͯͳ͍΋ͷΛ࢖͑ΔΑ͏ʹɺͳΜͯ  ͳΔΘ͚͕ͳ͍ɻ ࢖ͬͯͳ͍͔Β࢖Θͳ͍ͱ͔ݴͬͯΔͱ  ͍ͭ·Ͱ΋มΘΒͳ͍ɻ

࢖͑Δਓ͕͍ͳ͍ʁ +BWB4& ͷ৘ใ͸े෼ग़ճͬͯΔ ͦͷลΛݟͯษڧ͍ͯ͠Δํʑ΋ډΔ ʮ࢖ͬͨ͜ͱͳ͍ਓ͕ଟ͍ʯͳΒɺ࢖͑͹͍ ͍͚ͩͷ࿩ ࢖ͬͨ͜ͱͷ͋Δਓ͸૿͑Δ͜ͱ͸͋ͬͯ ΋ݮΓ͸͠ͳ͍ͷ͔ͩΒ

ಈ͔ͳ͍ʁ όʔδϣϯΞοϓͨ͠Βಈ͔ͳ͘ͳΔͱݴ͏ ࿩͕ͪΒ΄Βͱ

+BWBͷޓ׵ੑ

;ͭ͏ʹແཧͳ͜ͱ +%,Ͱ;ͭ͏ʹίϯύΠϧͨ͠ DMBTTϑΝΠϧΛ+3&͸ಡΊͳ͍ -BNCEB ஌ΒΜ͕ͳʜʜ ͱ͸͍͑ʜʜ +3&͞Μ

ޙํޓ׵ੑ͸΄΅໰୊ແ͍ +4&࣌୅ͷίʔυ͸ ͍͍ͩͨ+%,ͰίϯύΠϧՄೳ +4&࣌୅ͷDMBTT΍KBS͸ ͍͍ͩͨ+3&Ͱ࣮ߦՄೳ

ӡ͕ѱ͍ͱࣄނΔ ม਺໊ʹFOVNΛ࢖ͬͯͯίϯύΠϧΤϥʔ ΠϯλϑΣʔεʹϝιου͕૿͑ͯίϯύΠϧ Τϥʔ ࠶ίϯύΠϧͤͣಈ͔ͨ͠Β࣮ߦ࣌ྫ֎ ϦϑϨΫγϣϯͰऔΕΔॱ൪͕มΘͬͯ༧ظ ͠ͳ͍ྫ֎ ͱ͸ݴ͑͜Ε͸ӡ͕ѱ͍࿩

+BWBࣗମ͸ͱ΋͔͘ ϥΠϒϥϦ͸ͭΒ͍

ରԠ͍ͯ͠ͳ͍ϥΠϒϥϦ͕͋Δ

ରԠ͍ͯ͠ͳ͍ϥΠϒϥϦ͕͋Δ ର৅ϥΠϒϥϦͷΞοϓσʔτ

ରԠ͍ͯ͠ͳ͍ϥΠϒϥϦ͕͋Δ ର৅ϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ

ରԠ͍ͯ͠ͳ͍ϥΠϒϥϦ͕͋Δ ର৅ϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ґଘ͢ΔϥΠϒϥϦͷΞοϓσʔτ ͭΒ͍

+BS)FMM ੲ͸KBSΛखಈͰ͔͖ूΊΔ͜ͱʹΑΔ࡞ۀ஍ ࠈΛҙຯ͍ͯͨ͠ Ϗϧυπʔϧ͕ґଘΛࣗಈͰղܾ͢Δ͜ͱͰ ऴΘ͔ͬͨʹࢥ͕͑ͨ ࠷ۙ͸KBSؒͷґଘ͕ಊʑ८Γ͢Δ͜ͱʹΑΔ ແؒ஍ࠈΛҙຯͯ͠ΔΑ͏ͳؾ͕͢Δ

ϥΠϒϥϦͱޓ׵ੑ Ϋϥεͷ౷ഇ߹ɺجఈΫϥε΍ΠϯλϑΣʔ εͷมߋʹΑΓιʔεޓ׵͸͋ͬ͞ΓଛͳΘ Εͯ͠·͏ʢ͜ͱ΋͋Δʣ ϦϑϨΫγϣϯͷಈ࡞΍ɺΫϥεϑΥʔϚο τͳͲɺ௨ৗͷޓ׵ੑ΄ͲڧݻʹकΒΕ͍ͯ ͳ͍΋ͷʹґଘ͍ͯ͠Δʢ͜ͱ΋͋Δʣ ڧྗͳϥΠϒϥϦ΄Ͳ܏޲͸ڧ͍ʢؾ͕͢Δʣ

ϥΠϒϥϦͱޓ׵ੑ +BWBͷڧΈͷ͸ͣͷʮϥΠϒϥϦͷॆ࣮ʯ ޓ׵ੑΛߟ͑ΔͱωοΫʹͳΔ όʔδϣϯΞοϓ࣌͸ಛʹݦஶ ৐Γӽ͑ͳ͍ͱz͍·Ͳ͖ͷ+BWBz͕࢖͑ͳ͍

ͱ͸͍͑ ద੾ͳॱ൪Ͱόʔδϣϯ͍͚͋͛ͯ͹ɺҙ֎ ͱ͢ΜͳΓ্͛ΒΕͨΓ͢Δɻ ϝδϟʔόʔδϣϯΞοϓز͔ͭ΍͚ͬͨͲɺ ϋϚΔͷ͸ʮ·͍͔ͨͭ͜ʯͱ͍͏Ұ෦Ͱ͢ɻ

ͳΜͱ͔ͳΔ

ੜ͖ͨ+BWBΛ࢖͍ͬͯͨ͘Ίʹ΋ɺ͍·Ͳ͖ ͷ+BWBΛ஌ͬͯ࢖͍͖ͬͯ·͠ΐ͏ɻ

͜Ε͔Βͷ+BWBͷ ͱ͔͔ͬΓ

͜Ε͔Βͷ+BWB 1SPKFDU+JHTBX 1SPKFDU7BMIBMMB 1SPKFDU1BOBNB ࠷ॳʹݴͬͨ௨Γ ͜ͷลͷ࿩͸͠·ͤΜ

͜Ε·Ͱˠ͜Ε͔Β Ұ൪ͷҧ͍͸ʮ+BWBࣗ਎͕੒௕͢Δʯ͜ͱ গ͠લʹ+BWB4&͕ग़ͯ ͦͷ೥ͪΐ͍ޙʹ+BWB4&͕ग़ͯ ͨͿΜ೥͘Β͍ޙʹ+BWB4&͕ग़Δ

೥લ ೥લ

J2SE 5.0 ೥લ ೥લ

J2SE 5.0 Java SE 6 ೥લ ೥લ

J2SE 5.0 Java SE 6 Java SE 7 ೥લ
೥લ

J2SE 5.0 Java SE 6 Java SE 7 Java SE
8 ೥લ ೥લ

J2SE 5.0 Java SE 6 Java SE 7 Java SE
8 ೥લ ೥લ ໿೥

̑೥ͷϒϥϯΫ +BWB͔ΒΛݟૹͬͨΒܖػΛࣦͬͨ +BWBͰ࡞ͬͨΒػձ͕དྷͳ͔ͬͨ ্͛ΒΕͳ͍··ಈ͚ͳ͘ͳͬͯ͠·ͬͨ J2SE 5.0 Java SE 6 Java
SE 7 Java SE 8 ໿೥

ͱ͸ݴ͑͜Ε͔Β͸ߋ৽͞Ε͍ͯ͘ͷͰɺ  ண͍͍͖͍ͯͨͱ͜ΖͰ͸͋Δɻ

ߋ৽ͯ͠Έͨ࿩ͦͷ ࣮ߦ؀ڥ͚ͩ+BWBʹͯ͠Έͨ ίʔυɺίϯύΠϥ͸+BWBͷ·· ϥΠϒϥϦ͸ߋ৽ͤͣ ͍͚ͨˠͳΜͷ໰୊΋ͳ͘ಈ͍͍ͯΔ

ߋ৽ͯ͠Έͨ࿩ͦͷ ࣮ߦ؀ڥ͚ͩ+BWBʹͯ͠Έͨ ίʔυɺίϯύΠϥ͸+BWBͷ·· ϥΠϒϥϦ͸ߋ৽ͤͣ ͩΊͩͬͨˠ࣮ߦ؀ڥͷόʔδϣϯ֬ೝ͠ ͍ͯΔϥΠϒϥϦ͕͋ͬͨʜʜ

ߋ৽ͯ͠Έͨ࿩ͦͷ ίϯύΠϥ͚ͩ+BWBʹͯ͠Έͨ UBSHFU ίʔυɺ࣮ߦ؀ڥ͸+BWBͷ·· ϥΠϒϥϦ͸ߋ৽ͤͣ ͍͚ͨˠͳΜͷ໰୊΋ͳ͘ಈ͍͍ͯΔ

ߋ৽ͯ͠Έͨ࿩ͦͷ ίϯύΠϥ࣮ߦ؀ڥͱ΋ʹ+BWBʹͯ͠Έͨ ίʔυ͸+BWBͷ·· ϥΠϒϥϦ͸ߋ৽ͤͣ ͍͚ͨˠͳ͔ͥಈ͍ͯ͠·ͬͨ ͚ͲMBNCEBͭॻ͍ͨॠؒམͪͨ

͜Ε͔Βͷͱ͔͔ͬΓ +BWB͸ੜ͖ͯͯɺݩؾʹಈ͖࢝Ίͨ ͦΜͳ+BWBʹৼΓམͱ͞Εͳ͍ͨΊʹ

ݴޠͷͱ͔͔ͬΓ -BNCEBʹ͍ͭͯ͜ΕͯΔʁ (SPPWZ΍4DBMBͳΜ͔Λ΍ͬͯͨਓ͸ฏવ ͱѻͬͯΔ ࠓޙͷ+BWBʹ௥ਵ͢ΔͨΊʹผͷݴޠʹ΋৮ Ε͓ͯ͘ͱ͍͍͔΋

؀ڥͷͱ͔͔ͬΓ Ϗϧυπʔϧ͸ΑΓਐԽ͍ͯ͘͠͸ͣ ΋ͬͱେ͖͘ͳ؀ڥΛϏϧυͦ͠͏ ͦͷ͏ͪ+BS)FMMΛղফͯ͘͠ΕΔ͔΋ ݱঢ়Ͱ΋ཧղ͓͚ͯ͠͹े෼ͳ෢ثʹͳΔ

લʹਐΉͳΒ͹ ৽چͷ৘ใͷݟۃΊ͸೉͘͠ͳ͍ͬͯ͘ ෆ҆ͳϥΠϒϥϦͷ૊Έ߹Θͤ΋ ΞμϓλΛ࣮૷͢Δඞཁ΋͋Δ͔΋ ಈ͔ͯ͠ݕূ͢Δࣗಈςετ͸·͢·͢ॏཁ ʹͳͬͯ͘Δͱࢥ͏

ཹ·Δ༐ؾ ແཧͤͣཹ·Δબ୒ࢶ΋ߟྀʹೖΕΔ ݹ͍ίʔυɺݹ͍ίϯύΠϥɺ৽͍࣮͠ߦ ؀ڥͱ͔Ͱ΋͍͍ͩͨେৎ෉ ҆શࡦΛͱΔͳΒ࣮ߦ؀ڥ΋αϙʔτड͚Ε ʢۚͰͿΜԥΕ͹ͳΜͱ͔ͳΔʣ &OEPG1VCMJD6QEBUFT&0-

प೥Λܴ͑ɺ+BWB͸·͢·͢ݩؾ ͜Ε͔Β΋+BWBͱڞʹߦͨ͘Ίʹ  ͓ޓ͍ʹ৘ใग़͠߹͍͖ͬͯ·ͤΜ͔ʁ ͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠

これからのJavaのとっかかりを掴む

これからのJavaのとっかかりを掴む

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