from old Java to modern Java (2017) #jjug

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GSPNPME+BWBUPNPEFSO+BWB  +BWBॳ৺ऀ͔Β࣍ͷεςοϓ΁  ͋Δ͍͸ࡀ͔Βͷ+BWB࠶ೖ໳  #jjug Acroquest Technology Co., LTD.  Shin Tanimoto (@cero_t)

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 8IPBN* • ୩ຊ ৺ (Shin Tanimoto) • Acroquest Technologyגࣜձࣾ • ೔ຊJavaϢʔβάϧʔϓ (JJUG) • JavaOne / SpringOneεϐʔΧʔ • Microservices, Elasticsearch  • twitter: @cero_t • facebook: shin.tanimoto • 9݄16೔ੜ·Ε 2

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug ॻ੶Λॻ͖·ͨ͠ • Javaຊ֨ೖ໳ େ޷ධൃചதʂ • ॻ࣌͘ʹେ੾ʹͨ͜͠ͱ • ʮݱ৔Ͱͷʢ͍ۤʣܦݧʯΛ౿·͑ͯॻ͘ • ࣄ࣮ͷྻڍͰͳࣗ͘෼ͨͪͷࢥ૝Λॻ͘ • ৽چͷJavaίʔυΛฒ΂ͯܝࡌ͢Δ • ຊ೔΋ࡏݿ͖࣋ͬͯͯ·͢ʂ • ͓஋ஈͳΜͱ3,000ԁʂʂʢఆՁɿ3,218ԁʣ • ʮͤΖ͞Μ͸Ͳ͜ॻ͍ͨͷʁʯ͸࣭໰ېࢭͰ͢ 3

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 8 *OUSPEVDUJPO CSV File Java App ௥ه ಡΈࠐΈ 2017-04-25,100,123456,Acroquest,څ༩ 2017-05-02,100,-28980,λχϞτ,Χʔυར༻ 2017-05-03,100,-17712,λχϞτ,Χʔυར༻ 2017-05-20,100,3000000,gihyo,ҹ੫ 2017-06-22,100,200000,ΧΰΠέ,ATMৼΓࠐΈ 2017-06-22,100,-1000000,λχϞτ,ATMҾ͖ग़͠ ʢۜߦͷར༻໌ࡉͷΠϝʔδʣ  ೔෇,ޱ࠲൪߸,ֹۚ,ར༻ऀ,ࡉ໨

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 10 void append(String fileName, String[] items) { StringBuffer buffer = new StringBuffer(); for (int i = 0; i < items.length; i++) { if (buffer.length() > 0) { buffer.append(","); } buffer.append(items[i]); } String row = buffer.toString() + '\n'; Writer writer = null; try { writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName, true), "UTF-8")); writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } finally { try { if (writer != null) { writer.close(); } } catch (IOException e) { // ignore } } } ϑΝΠϧ΁ͷCSVߦ௥Ճ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 11 StringBuffer buffer = new StringBuffer(); for (int i = 0; i < items.length; i++) { if (buffer.length() > 0) { buffer.append(","); } buffer.append(items[i]); } String row = buffer.toString() + '\n'; ϑΝΠϧ΁ͷCSVߦ௥Ճʢจࣈ഑ྻͷ݁߹ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 12 Writer writer = null; try { writer = new BufferedWriter(new OutputStreamWriter(  new FileOutputStream(fileName, true), "UTF-8")); writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } finally { try { if (writer != null) { writer.close(); } } catch (IOException e) { // ignore } } ϑΝΠϧ΁ͷCSVߦ௥ՃʢϑΝΠϧ΁ͷ௥هʣ Ϧιʔε͸finallyͰclose͢Δ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 13 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx); } } catch (ParseException e) { throw new RuntimeException("failed to parse date", e); } catch (IOException e) { throw new RuntimeException("failed to read file: " + fileName, e); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { // ignore } } return list; } ϑΝΠϧͷಡΈࠐΈ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 14 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(  new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 15 } catch (ParseException e) { throw new RuntimeException("failed to parse date", e); } catch (IOException e) { throw new RuntimeException("failed to read file: " + fileName, e); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { // ignore } } return list; } ϑΝΠϧͷಡΈࠐΈʢޙ൒ʣ Ϧιʔε͸finallyͰclose͢Δʢେࣄʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 16 class Transaction { Date date; String accountId; Integer amount; String name; String note; public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } public String toString() { return date + " " + accountId + " " + amount + " " + name + " " + note; } } TransactionΫϥε

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 17 class Transaction { public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } public String toString() { return date + " " + accountId + " " + amount + " " + name + " " + note; } } TransactionΫϥεʢϝιουͷΈʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 18 String fileName = "./transactions.csv"; SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); append(fileName, new Transaction(df.parse("2017-04-25"), "100", 123456, "Acroquest", "給与")); append(fileName, new Transaction(df.parse("2017-05-02"), "100", -28980, "タニモト", "カード利用")); append(fileName, new Transaction(df.parse("2017-05-03"), "100", -17712, "タニモト", "カード利用")); append(fileName, new Transaction(df.parse("2017-05-20"), "100", 3000000, "gihyo", "印税")); append(fileName, new Transaction(df.parse("2017-06-22"), "100", 200000, "カゴイケ", "ATM振り込み")); append(fileName, new Transaction(df.parse("2017-06-22"), "100", -1000000, "タニモト", "ATM引き出し")); ར༻ଆͷྫ - σʔλͷ௥Ճ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 19 List list = read(fileName); int sum = 0; for (int i = 0; i < list.size(); i++) { Transaction tx = (Transaction) list.get(i); sum += tx.amount; } System.out.println(sum); ར༻ଆͷྫ - ࢒ߴͷܭࢉ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug *OUSPEVDUJPO 20 List list = read(fileName); for (int i = 0; i < list.size(); i++) { Transaction tx = (Transaction) list.get(i); Calendar cal = Calendar.getInstance(); cal.setTime(tx.date); if (cal.get(Calendar.MONTH) == 5) { System.out.println(tx); } } ར༻ଆͷྫ - 6݄෼ͷऔҾͷΈදࣔ ݄͸0͔Β࢝·Δ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 27 StringBuffer buffer = new StringBuffer(); for (int i = 0; i < items.length; i++) { if (buffer.length() > 0) { buffer.append(","); } buffer.append(items[i]); } String row = buffer.toString() + '\n'; จࣈ഑ྻͷ݁߹

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 28 StringBuilder builder = new StringBuilder(); for (String item : items) { if (builder.length() > 0) { builder.append(","); } builder.append(item); } String row = builder.toString() + '\n'; จࣈ഑ྻͷ݁߹

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 29 StringBuilder builder = new StringBuilder(); for (String item : items) { if (builder.length() > 0) { builder.append(","); } builder.append(item); } String row = builder.toString() + '\n'; จࣈ഑ྻͷ݁߹ StringBuilderͷํ͕  ཧ࿦తʹੑೳ͕ྑ͍ foreachจʢ֦ுforจʣͰ  ϧʔϓΛ؆ܿʹॻ͘

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 31 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(  new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 32 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(  new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 33 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(  new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ GenericsͰܕΛ໌֬ʹ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 34 List list = read(fileName); int sum = 0; for (int i = 0; i < list.size(); i++) { Transaction tx = (Transaction) list.get(i); sum += tx.amount; } System.out.println(sum); ར༻ଆͷྫ - ࢒ߴͷܭࢉ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 35 List list = read(fileName); int sum = 0; for (Transaction tx : list) { sum += tx.amount; } System.out.println(sum); ར༻ଆͷྫ - ࢒ߴͷܭࢉ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 36 List list = read(fileName); int sum = 0; for (Transaction tx : list) { sum += tx.amount; } System.out.println(sum); ར༻ଆͷྫ - ࢒ߴͷܭࢉ ΩϟετʢܕΛ໌ࣔʣΛͤͣʹ  ར༻Ͱ͖Δ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 38 class Transaction { public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } public String toString() { return date + " " + accountId + " " + amount + " " + name + " " + note; } } TransactionΫϥεʢϝιουͷΈʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 39 class Transaction { public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } @Override public String toString() { return date + " " + accountId + " " + amount + " " + name + " " + note; } } TransactionΫϥεʢϝιουͷΈʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 40 class Transaction { public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } @Override public String toString() { return date + " " + accountId + " " + amount + " " + name + " " + note; } } TransactionΫϥεʢϝιουͷΈʣ ϝιουͷܧঝʢ࣮૷ʣͰ͋Δ͜ͱΛ  ໌ࣔͯ͠ϛεΛ๷͙

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 47 Writer writer = null; try { writer = new BufferedWriter(new OutputStreamWriter(  new FileOutputStream(fileName, true), "UTF-8")); writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } finally { try { if (writer != null) { writer.close(); } } catch (IOException e) { // ignore } } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 48 try (Writer writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 49 try (Writer writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه try-with-resourecesʹΑΔ  ϦιʔεͷࣗಈΫϩʔζ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 51 try (Writer writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه try/catch͔Βൈ͚ͨ࣌ʹ ( ) Ͱએݴ͍ͯͨ͠Ϧιʔε͕close͞ΕΔɻ  ( ) ͷதͰએݴͰ͖Δม਺͸AutoCloseableΠϯλϑΣʔεͷΫϥεͷΈɻ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 52 try (Writer writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) { writer.write(row); } ϑΝΠϧ΁ͷ௥ه catchͤͣʹϝιουʹ throws IOExceptionΛ͚ͭΔ࣌Ͱ΋  try-with-resourcesʹ͓͚ͯ͠͹ɺ͖ͪΜͱclose͞ΕΔɻ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 53 try (Writer writer = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه ϑΝΠϧΤϯίʔυΛStringͰ͸ͳ͘CharsetͰࢦఆ͢ΔͨΊʹ  ୅දతͳΤϯίʔυΛྻڍ͢ΔStandardCharsetsΛར༻͢Δɻ  Τϯίʔυ͕ݟ͔ͭΒͳ͍࣌ͷྫ֎ൃੜΛ๷͛Δɻ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 55 try (Writer writer = Files.newBufferedWriter(Paths.get(fileName), StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND)) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 56 try (Writer writer = Files.newBufferedWriter(Paths.get(fileName), StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND)) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه ϑΝΠϧͷૢ࡞΍Ϧιʔεͷ࡞੒Λ؆ܿʹॻ͚Δ  FilesΫϥε͕௥Ճʢnio2ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 57 try (Writer writer = Files.newBufferedWriter(Paths.get(fileName), StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND)) { writer.write(row); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه OptionͷࢦఆͰॻ͖ࠐΈͷϧʔϧΛࢦఆɻ  ͜ͷྫͰ͸࣍ͷΦϓγϣϯΛࢦఆ  ɹɾϑΝΠϧ͕ͳ͚Ε͹৽ن࡞੒ɺطʹ͋Ε͹ͦΕΛ࢖͏  ɹɾϑΝΠϧʹ͸௥ه͢Δʢ্ॻ͖Ͱ͸ͳ͍ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 59 String row = builder.toString(); try { List rows = Collections.singletonList(row); Files.write(Paths.get(fileName), rows, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 60 String row = builder.toString(); try { List rows = Collections.singletonList(row); Files.write(Paths.get(fileName), rows, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه FilesͷwriteϝιουͰɺϦετʢIterableʣΛ  ·ͱΊͯϑΝΠϧʹॻ͖ࠐΈՄೳɻ  ͳ͓ߦ຤ʹ͸վߦίʔυ͕ೖΔɻ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 62 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList(); BufferedReader reader = null; try { reader = new BufferedReader(new InputStreamReader(  new FileInputStream(fileName), "UTF-8")); String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 63 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList<>(); try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName), StandardCharsets.UTF_8)) { String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 64 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList<>(); try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName), StandardCharsets.UTF_8)) { String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ μΠΞϞϯυԋࢉࢠͰ  هड़Λ؆ܿʹ try-with-resourcesͱɺFilesͷϦιʔεੜ੒ɺ  StandardCharsets͸΋͏ֶͼ·ͨ͠

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 65 } catch (ParseException e) { throw new RuntimeException("failed to parse date", e); } catch (IOException e) { throw new RuntimeException("failed to read file: " + fileName, e); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { // ignore } } return list; } ϑΝΠϧͷಡΈࠐΈʢޙ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 66 } catch (ParseException | IOException e) { throw new RuntimeException("failed to parse date or read file”, e); } return list; } ϑΝΠϧͷಡΈࠐΈʢޙ൒ʣ ෳ਺ͷྫ֎Λ·ͱΊͯcatchͰ͖Δ  ʢຊདྷ͸ɺྫ֎ॲཧͷ಺༰͕શ͘ಉ࣌͡ʹ࢖͏ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 73 StringBuilder builder = new StringBuilder(); for (String item : items) { if (builder.length() > 0) { builder.append(","); } builder.append(item); } String row = builder.toString() + '\n'; try { List rows = Collections.singletonList(row); Files.write(Paths.get(fileName), rows, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 74 String row = String.join(",", items); try { List rows = Collections.singletonList(row); Files.write(Paths.get(fileName), rows, // StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 75 String row = String.join(",", items); try { List rows = Collections.singletonList(row); Files.write(Paths.get(fileName), rows, // StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND); } catch (IOException e) { throw new RuntimeException("unable to write file: " + fileName, e); } ϑΝΠϧ΁ͷ௥ه ͱ͏ͱ͏join͕Մೳʹʂ ϑΝΠϧΤϯίʔυࢦఆͷলུ͕Մೳɻ  লུͨ͠৔߹͸UTF-8ͱͳΔɻ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 77 class Transaction { Date date; String accountId; Integer amount; String name; String note; public Transaction() { } public Transaction(Date date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } TransactionΫϥεʢtoStringলུʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 78 class Transaction { LocalDate date; String accountId; Integer amount; String name; String note; public Transaction() { } public Transaction(LocalDate date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } TransactionΫϥεʢtoStringলུʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 79 class Transaction { LocalDate date; String accountId; Integer amount; String name; String note; public Transaction() { } public Transaction(LocalDate date, String accountId, Integer amount, String name, String note) { this.date = date; this.accountId = accountId; this.amount = amount; this.name = name; this.note = note; } TransactionΫϥεʢtoStringলུʣ LocalDateͰ೔෇ͷΈΛѻ͏ɻ  ଞʹ΋LocalDateTime΍LocalTimeɺ  OffsetDateTimeɺZonedDateTimeͳͲ͋Γ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 80 List read(String fileName) { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList<>(); try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName), StandardCharsets.UTF_8)) { String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = df.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 81 List read(String fileName) { // SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList<>(); try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName))) { String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = LocalDate.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 'SPNUP 82 List read(String fileName) { // SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); List list = new ArrayList<>(); try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName))) { String line; while ((line = reader.readLine()) != null) { String[] s = line.split(","); Transaction tx = new Transaction(); tx.date = LocalDate.parse(s[0]); tx.accountId = s[1]; tx.amount = Integer.valueOf(s[2]); tx.name = s[3]; tx.note = s[4]; list.add(tx);  } ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ ϋΠϑϯ۠੾Γͷ  ISO 8601ܗࣜͷ೔࣌ͳΒ  ϑΥʔϚολͳ͠ͰύʔεՄೳ ΤϯίʔυΛলུ͢Δͱ  UTF-8ͱͳΔ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug String fileName = "./transactions.csv"; SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); append(fileName, new Transaction(df.parse("2017-04-25"), "100", 123456, "Acroquest", "給与")); append(fileName, new Transaction(df.parse("2017-05-02"), "100", -28980, "タニモト", "カード利用")); append(fileName, new Transaction(df.parse("2017-05-03"), "100", -17712, "タニモト", "カード利用")); append(fileName, new Transaction(df.parse("2017-05-20"), "100", 3000000, "gihyo", "印税")); append(fileName, new Transaction(df.parse("2017-06-22"), "100", 200000, "カゴイケ", "ATM振り込み")); append(fileName, new Transaction(df.parse("2017-06-22"), "100", -1000000, "タニモト", "ATM引き出し")); 83 ར༻ଆͷྫ - σʔλͷ௥Ճ 'SPNUP

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 84 String fileName = "./transactions.csv"; // SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); append(fileName, new Transaction(LocalDate.of(2017, 4, 25), "100", 123456, "Acroquest", "給与")); append(fileName, new Transaction(LocalDate.of(2017, 5, 2), "100", -28980, "タニモト", "カード利用")); append(fileName, new Transaction(LocalDate.of(2017, 5, 3), "100", -17712, "タニモト", "カード利用")); append(fileName, new Transaction(LocalDate.of(2017, 5, 20), "100", 3000000, "gihyo", "印税")); append(fileName, new Transaction(LocalDate.of(2017, 6, 22), "100", 200000, "カゴイケ", "ATM振り込み")); append(fileName, new Transaction(LocalDate.of(2017, 6, 22), "100", -1000000, "タニモト", “ATM引き出し")); ར༻ଆͷྫ - σʔλͷ௥Ճ 'SPNUP

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 85 String fileName = "./transactions.csv"; // SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd"); append(fileName, new Transaction(LocalDate.of(2017, 4, 25), "100", 123456, "Acroquest", "給与")); append(fileName, new Transaction(LocalDate.of(2017, 5, 2), "100", -28980, "タニモト", "カード利用")); append(fileName, new Transaction(LocalDate.of(2017, 5, 3), "100", -17712, "タニモト", "カード利用")); append(fileName, new Transaction(LocalDate.of(2017, 5, 20), "100", 3000000, "gihyo", "印税")); append(fileName, new Transaction(LocalDate.of(2017, 6, 22), "100", 200000, "カゴイケ", "ATM振り込み")); append(fileName, new Transaction(LocalDate.of(2017, 6, 22), "100", -1000000, "タニモト", “ATM引き出し")); ར༻ଆͷྫ - σʔλͷ௥Ճ ೥ɺ݄ɺ೔ɺ࣌ɺ෼ɺඵͳͲΛࢦఆͯ͠  Πϯελϯεੜ੒͕Մೳɻ  ͔͠΋݄͸1͔Β࢝·Δʂ 'SPNUP

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 87 List list = read(fileName); for (Transaction tx : list) { Calendar cal = Calendar.getInstance(); cal.setTime(tx.date); if (cal.get(Calendar.MONTH) == 5) { System.out.println(tx); } } ར༻ଆͷྫ - 6݄෼ͷऔҾͷΈදࣔ 'SPNUP

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 88 List list = read(fileName); for (Transaction tx : list) { Calendar cal = Calendar.getInstance(); cal.setTime(tx.date); if (cal.get(Calendar.MONTH) == 5) { System.out.println(tx); } } ར༻ଆͷྫ - 6݄෼ͷऔҾͷΈදࣔ 'SPNUP ݄͸0͔Β࢝·ΔͷͰɺ6݄͸5ʹͳΔɻ  ʢCalendar.JUNEͱ͍͏ఆ਺΋ར༻Մೳʣ

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 89 List list = read(fileName); for (Transaction tx : list) { if (tx.date.getMonth() == Month.JUNE) { System.out.println(tx); } } ར༻ଆͷྫ - 6݄෼ͷऔҾͷΈදࣔ 'SPNUP

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Copyright © Acroquest Technology Co., Ltd. All rights reserved. @cero_t #jjug 90 List list = read(fileName); for (Transaction tx : list) { if (tx.date.getMonth() == Month.JUNE) { System.out.println(tx); } } ར༻ଆͷྫ - 6݄෼ͷऔҾͷΈදࣔ 'SPNUP ݄͸enumͱͯ͠ఆٛ͞Ε͓ͯΓ  enumಉ࢜ͷൺֱͰ൑ఆ͢Δ