from old Java to modern Java (2017) #jjug

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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@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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@cero_t #jjug
4
ݹ͍όʔδϣϯͷ+BWBͰ 
ॻ͍ͨίʔυΛ 
࠷ۙͷόʔδϣϯͷ+BWBͷίʔυʹ 
ม͍͑ͯ͘ͱ͍͏͓࿩Ͱ͢

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@cero_t #jjug
5BCMFPGDPOUFOUT
1. Introduction
2. From 1.4 to 5.0
3. From 5.0 to 7
4. From 7 To 8
5

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@cero_t #jjug
#1 
Introduction
6

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@cero_t #jjug
7
ࠓճ঺հ͢Διʔείʔυ
$47ϑΝΠϧͷಡΈॻ͖
*OUSPEVDUJPO

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@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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@cero_t #jjug
9
؆୯ʹιʔεݟͤ·͢
*OUSPEVDUJPO

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@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();
}
// ignore
}
}
}
ϑΝΠϧ΁ͷCSVߦ௥Ճ

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@cero_t #jjug
*OUSPEVDUJPO
11
buffer.append(",");
}
}
ϑΝΠϧ΁ͷCSVߦ௥Ճʢจࣈ഑ྻͷ݁߹ʣ

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@cero_t #jjug
*OUSPEVDUJPO
12
try {
writer = new BufferedWriter(new OutputStreamWriter( 
new FileOutputStream(fileName, true), "UTF-8"));
writer.write(row);
} finally {
try {
writer.close();
}
// ignore
}
}
ϑΝΠϧ΁ͷCSVߦ௥ՃʢϑΝΠϧ΁ͷ௥هʣ
Ϧιʔε͸finallyͰclose͢Δ

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@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);
throw new RuntimeException("failed to read file: " + fileName, e);
} finally {
try {
if (reader != null) {
reader.close();
}
// ignore
}
}
return list;
}
ϑΝΠϧͷಡΈࠐΈ

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@cero_t #jjug
*OUSPEVDUJPO
14
try {
reader = new BufferedReader(new InputStreamReader( 
new FileInputStream(fileName), "UTF-8"));
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}
ϑΝΠϧͷಡΈࠐΈʢલ൒ʣ

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@cero_t #jjug
*OUSPEVDUJPO
15
} finally {
try {
reader.close();
}
// ignore
}
}
return list;
}
ϑΝΠϧͷಡΈࠐΈʢޙ൒ʣ
Ϧιʔε͸finallyͰclose͢Δʢେࣄʣ

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@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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@cero_t #jjug
*OUSPEVDUJPO
17
class Transaction {
}
this.date = date;
this.name = name;
this.note = note;
}
}
}
TransactionΫϥεʢϝιουͷΈʣ

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@cero_t #jjug
*OUSPEVDUJPO
18
String fileName = "./transactions.csv";
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("2017-05-20"), "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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@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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@cero_t #jjug
*OUSPEVDUJPO
20
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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@cero_t #jjug
21
͍·ݟͤͨίʔυ͸ 
+BWBͰಈ͖·͢
*OUSPEVDUJPO

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@cero_t #jjug
#2
From 1.4 to 5.0
22

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@cero_t #jjug
23
+BWB4&
'SPNUP

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@cero_t #jjug
24
(FOFSJDT
'SPNUP
GPSFBDI
WBSBSHT FOVN
TUBUJDJNQPSU
BVUPCPYJOH
ʜBOENPSF

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@cero_t #jjug
25
+BWBจ๏ͷجૅ
'SPNUP

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@cero_t #jjug
26
จࣈ഑ྻͷ݁߹ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
27
buffer.append(",");
}
}
จࣈ഑ྻͷ݁߹

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@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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@cero_t #jjug
'SPNUP
29
}
}
จࣈ഑ྻͷ݁߹
StringBuilderͷํ͕ 
ཧ࿦తʹੑೳ͕ྑ͍
foreachจʢ֦ுforจʣͰ 
ϧʔϓΛ؆ܿʹॻ͘

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@cero_t #jjug
30
ϑΝΠϧಡΈࠐΈ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
31
try {
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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@cero_t #jjug
'SPNUP
32
try {
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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@cero_t #jjug
'SPNUP
33
try {
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}
GenericsͰܕΛ໌֬ʹ

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@cero_t #jjug
'SPNUP
34
int sum = 0;
sum += tx.amount;
}

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@cero_t #jjug
'SPNUP
35
int sum = 0;
for (Transaction tx : list) {
sum += tx.amount;
}

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@cero_t #jjug
'SPNUP
36
int sum = 0;
sum += tx.amount;
}
ΩϟετʢܕΛ໌ࣔʣΛͤͣʹ 
ར༻Ͱ͖Δ

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@cero_t #jjug
37
7BMVF0CKFDU 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
38
class Transaction {
}
this.date = date;
this.name = name;
this.note = note;
}
}
}

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@cero_t #jjug
'SPNUP
39
class Transaction {
}
this.date = date;
this.name = name;
this.note = note;
}
@Override
}
}

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@cero_t #jjug
'SPNUP
40
class Transaction {
}
this.date = date;
this.name = name;
this.note = note;
}
@Override
}
}
ϝιουͷܧঝʢ࣮૷ʣͰ͋Δ͜ͱΛ 
໌ࣔͯ͠ϛεΛ๷͙

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@cero_t #jjug
41
͕͢͞ʹ͜ͷล͸ 
େৎ෉Ͱ͢ΑͶ☺
'SPNUP

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@cero_t #jjug
#3
From 5.0 to 7
42

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@cero_t #jjug
43
+BWB4&
'SPNUP

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@cero_t #jjug
44
USZXJUISFTPVSDFT
'SPNUP
EJBNPOEPQFSBUPS
OJP NVMUJDBUDI
ʜBOENPSF

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@cero_t #jjug
45
͜ͷลΓ͔Βগ͠ཧղ͕ 
ո͘͠ͳΔਓ͕͍Δ
'SPNUP

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@cero_t #jjug
46
ϑΝΠϧॻ͖ࠐΈ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
47
try {
writer = new BufferedWriter(new OutputStreamWriter( 
new FileOutputStream(fileName, true), "UTF-8"));
writer.write(row);
} finally {
try {
writer.close();
}
// ignore
}
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
48
try (Writer writer = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream(fileName, true), StandardCharsets.UTF_8))) {
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
49
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
try-with-resourecesʹΑΔ 
ϦιʔεͷࣗಈΫϩʔζ

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@cero_t #jjug
50
pOBMMZͰDMPTF͢Δͷ͸ 
ݹ͍ఆੴ
'SPNUP

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@cero_t #jjug
'SPNUP
51
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
try/catch͔Βൈ͚ͨ࣌ʹ ( ) Ͱએݴ͍ͯͨ͠Ϧιʔε͕close͞ΕΔɻ 
( ) ͷதͰએݴͰ͖Δม਺͸AutoCloseableΠϯλϑΣʔεͷΫϥεͷΈɻ

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@cero_t #jjug
'SPNUP
52
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
catchͤͣʹϝιουʹ throws IOExceptionΛ͚ͭΔ࣌Ͱ΋ 
try-with-resourcesʹ͓͚ͯ͠͹ɺ͖ͪΜͱclose͞ΕΔɻ

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@cero_t #jjug
'SPNUP
53
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
ϑΝΠϧΤϯίʔυΛStringͰ͸ͳ͘CharsetͰࢦఆ͢ΔͨΊʹ 
୅දతͳΤϯίʔυΛྻڍ͢ΔStandardCharsetsΛར༻͢Δɻ 
Τϯίʔυ͕ݟ͔ͭΒͳ͍࣌ͷྫ֎ൃੜΛ๷͛Δɻ

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@cero_t #jjug
54
͞Βʹ 
BGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
55
try (Writer writer = Files.newBufferedWriter(Paths.get(fileName),
StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.APPEND)) {
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
56
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
ϑΝΠϧͷૢ࡞΍Ϧιʔεͷ࡞੒Λ؆ܿʹॻ͚Δ 
FilesΫϥε͕௥Ճʢnio2ʣ

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@cero_t #jjug
'SPNUP
57
writer.write(row);
}
ϑΝΠϧ΁ͷ௥ه
OptionͷࢦఆͰॻ͖ࠐΈͷϧʔϧΛࢦఆɻ 
͜ͷྫͰ͸࣍ͷΦϓγϣϯΛࢦఆ 
ɹɾϑΝΠϧ͕ͳ͚Ε͹৽ن࡞੒ɺطʹ͋Ε͹ͦΕΛ࢖͏ 
ɹɾϑΝΠϧʹ͸௥ه͢Δʢ্ॻ͖Ͱ͸ͳ͍ʣ

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@cero_t #jjug
58
͞Βʹ͞Βʹ 
BGUFS
'SPNUP

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@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);
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
60
String row = builder.toString();
try {
}
ϑΝΠϧ΁ͷ௥ه
FilesͷwriteϝιουͰɺϦετʢIterableʣΛ 
·ͱΊͯϑΝΠϧʹॻ͖ࠐΈՄೳɻ 
ͳ͓ߦ຤ʹ͸վߦίʔυ͕ೖΔɻ

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@cero_t #jjug
61
ϑΝΠϧಡΈࠐΈ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
62
try {
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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@cero_t #jjug
'SPNUP
63
List list = new ArrayList<>();
try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName),
StandardCharsets.UTF_8)) {
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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@cero_t #jjug
'SPNUP
64
String line;
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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@cero_t #jjug
'SPNUP
65
} finally {
try {
reader.close();
}
// ignore
}
}
return list;
}

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@cero_t #jjug
'SPNUP
66
} catch (ParseException | IOException e) {
throw new RuntimeException("failed to parse date or read file”, e);
}
return list;
}
ෳ਺ͷྫ֎Λ·ͱΊͯcatchͰ͖Δ 
ʢຊདྷ͸ɺྫ֎ॲཧͷ಺༰͕શ͘ಉ࣌͡ʹ࢖͏ʣ

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67
USZXJUISFTPVSDFT͸ 
ͱʹ͔͘ඇৗʹେ੾ͳػೳ
'SPNUP

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@cero_t #jjug
#4
From 7 to 8
68

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@cero_t #jjug
69
4USFBN"1*
'SPNUP
-BNCEB
%BUFBOE5JNF"1*
ʜBOENPSF

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70
4USFBN"1*ͱ-BNCEBࣜͰ 
Ұؾʹจ๏͕มΘͬͨ
'SPNUP

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@cero_t #jjug
71
ɾɾɾ͚ͲɺͦΕ͸ޙʹͯ͠ 
ͦΕҎ֎ͷݟམͱ͞Ε͕ͪͳ 
ͱ͜Ζ͔Β΍Γ·͢
'SPNUP

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72
จࣈ഑ྻͷ݁߹ͱ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
73
}
}
try {
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
74
String row = String.join(",", items);
try {
Files.write(Paths.get(fileName), rows, // StandardCharsets.UTF_8,
}
ϑΝΠϧ΁ͷ௥ه

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@cero_t #jjug
'SPNUP
75
String row = String.join(",", items);
try {
Files.write(Paths.get(fileName), rows, // StandardCharsets.UTF_8,
}
ϑΝΠϧ΁ͷ௥ه ͱ͏ͱ͏join͕Մೳʹʂ
ϑΝΠϧΤϯίʔυࢦఆͷলུ͕Մೳɻ 
লུͨ͠৔߹͸UTF-8ͱͳΔɻ

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76
೔෇ΛؚΉ7BMVF0CKFDU 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
'SPNUP
77
class Transaction {
Date date;
String accountId;
Integer amount;
String name;
String note;
}
this.date = date;
this.name = name;
this.note = note;
}
TransactionΫϥεʢtoStringলུʣ

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@cero_t #jjug
'SPNUP
78
class Transaction {
LocalDate date;
String accountId;
Integer amount;
String name;
String note;
}
public Transaction(LocalDate date, String accountId, Integer amount, String name, String note) {
this.date = date;
this.name = name;
this.note = note;
}

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@cero_t #jjug
'SPNUP
79
class Transaction {
LocalDate date;
String accountId;
Integer amount;
String name;
String note;
}
public Transaction(LocalDate date, String accountId, Integer amount, String name, String note) {
this.date = date;
this.name = name;
this.note = note;
}
LocalDateͰ೔෇ͷΈΛѻ͏ɻ 
ଞʹ΋LocalDateTime΍LocalTimeɺ 
OffsetDateTimeɺZonedDateTimeͳͲ͋Γ

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@cero_t #jjug
'SPNUP
80
String line;
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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@cero_t #jjug
'SPNUP
81
// SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName))) {
String line;
tx.date = LocalDate.parse(s[0]);
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}

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'SPNUP
82
try (BufferedReader reader = Files.newBufferedReader(Paths.get(fileName))) {
String line;
tx.date = LocalDate.parse(s[0]);
tx.name = s[3];
tx.note = s[4];
list.add(tx); 
}
ϋΠϑϯ۠੾Γͷ 
ISO 8601ܗࣜͷ೔࣌ͳΒ 
ϑΥʔϚολͳ͠ͰύʔεՄೳ
ΤϯίʔυΛলུ͢Δͱ 
UTF-8ͱͳΔ

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@cero_t #jjug
append(fileName, new Transaction(df.parse("2017-04-25"), "100", 123456, "Acroquest", "給与"));
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
'SPNUP

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@cero_t #jjug
84
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, 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"));
'SPNUP

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@cero_t #jjug
85
append(fileName, new Transaction(LocalDate.of(2017, 4, 25), "100", 123456, "Acroquest", "給与"));
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"));
೥ɺ݄ɺ೔ɺ࣌ɺ෼ɺඵͳͲΛࢦఆͯ͠ 
Πϯελϯεੜ੒͕Մೳɻ 
͔͠΋݄͸1͔Β࢝·Δʂ
'SPNUP

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@cero_t #jjug
86
೔෇ܭࢉ 
CFGPSFBGUFS
'SPNUP

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@cero_t #jjug
87
}
}
'SPNUP

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@cero_t #jjug
88
}
}
'SPNUP
݄͸0͔Β࢝·ΔͷͰɺ6݄͸5ʹͳΔɻ 
ʢCalendar.JUNEͱ͍͏ఆ਺΋ར༻Մೳʣ

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@cero_t #jjug
89
if (tx.date.getMonth() == Month.JUNE) {
}
}
'SPNUP

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@cero_t #jjug
90
if (tx.date.getMonth() == Month.JUNE) {
}
}
'SPNUP
݄͸enumͱͯ͠ఆٛ͞Ε͓ͯΓ 
enumಉ࢜ͷൺֱͰ൑ఆ͢Δ

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@cero_t #jjug
91
4USFBN-BNCEBͷ 
ӨʹӅΕ͕͚ͪͩͲ 
༗༻ͳ"1*͕૿͍͑ͯΔ
'SPNUP

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@cero_t #jjug
92
Ͱɺ؊৺ͷ 
4USFBN"1*ͱ-BNCEB 
͸ɾɾɾʁ
'SPNUP

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@cero_t #jjug
93
ޙ൒ʹͭͮ͘ʂ

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@cero_t #jjug
94
Ξϯέʔτޚڠྗ͓ئ͍͠·͢ 
http://bit.ly/jjug201706

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from old Java to modern Java (2017) #jjug

from old Java to modern Java (2017) #jjug

Shin Tanimoto

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