赫顎温厩温の胆龍しい奮へ?圭

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Yousuke Matsumoto

Guavaとは
Javaの慌宥�I尖をまとめたライブラリ。
麼にGoogleのエンジニアが�_�kしています。
Apache Commonsがライバル。

Guavaの蒙�
? ジェネリクス��
? �K佩�I尖の�C嬬が�N源
? fluent interface
? 辛�i來が互い
? Apache Commonsと�穩耽�

Guavaの�C嬬
? com.google.common.annotations
? com.google.common.base
? com.google.common.cache
? com.google.common.collect
? com.google.common.eventbus
? com.google.common.io
? com.google.common.math
? com.google.common.net
? com.google.common.primitives
? com.google.common.reflect
? com.google.common.util.concurrent

collect
? Lists
List<String> list1 = Lists.newArrayList();
List<String> list2 = Lists.newArrayList(＾hoge￣, ￣fuga￣);
final List<String> list3 = ImmutableList.of(＾tako￣, ￣ika￣);

collect
? Lists
List<User> userList = getUserList();
// ＾taro￣,￣hanako￣
List<String> idList = Lists.transform(userList,
new Function<User, String>() {
@Override
public String apply(User user) {
return user.getId();
}
});

collect
? MultiMap
ListMultimap<String, String> map = ArrayListMultiMap.create();
map.put(＾pigg￣, ＾life￣);
map.put(＾pigg￣, ￣cafe￣);
map.put(＾card￣, ￣gf￣);
// ＾life￣,￣cafe￣
List<String> list = map.get(＾pigg￣);

base
? Joiner
List<String> list = Lists.newArrayList(＾hoge￣, null, ＾fuga￣);
// ＾hoge,fuga￣
String join = Joiner.on(＾,￣).skipNulls().join(list);

base
? Splitter
String val = ＾apple orange,peach￣;
CharMatcher matcher = CharMatcher.WHITESPACE
.or(CharMatcher.is(?,?));
// ＾apple￣,￣orange￣,￣peach￣
Iterable<String> split =
Splitter.on(matcher).omitEmptyStrings().split(val);

base
? Preconditions
Integer val = 10;
Preconditions.checkNotNull(val, ＾required.￣);
Preconditions.checkArgument(val > 10, ＾over 10.￣);

base
? Stopwatch
Stopwatch stopwatch = new Stopwatch().start();
execute();
stopwatch.stop();
// ＾elapsed time:12.3ms￣
log.info(＾elapsed time:￣ + stopwatch);

$io ? Files BufferedReader reader = null; try { reader = Files.newReader( new File(＾hoge.txt￣), Charsets.UTF_8); } finally { Closeables.closeQuietly(reader); }$

io
? Files
List<String> lines = Files.readLines(
new File(＾fuga.txt￣), Charsets.UTF_8);
byte[] bytes = Files.toByteArray(new File(＾sample.jpg￣));

util.concurrent
? ListeningFuture
ListeningExecutorService threadPool =
MoreExecutors.listeningDecorator(
Executors.newFixedThreadPool(32));
Callable<String> task = getTask();
ListeningFuture<String> future = theadPool.submit(task);

util.concurrent
? ListeningFuture
Futures.addCallback(future, new FutureCallback<String>() {
@Override
public void onSuccess(String s) {
log.info(＾success! result:￣ + s);
}
@Override
public void onFailure(Throwable throwable) {
log.error(＾error!￣, throwable);
}
});

util.concurrent
? RateLimiter
RateLimiter limiter = RateLimiter.create(100.0);
for (int i = 1; i <= 10000; i++) {
limiter.acquire();
execute();
}
for (byte[] bytes : getBytesList()) {
limiter.acquire(bytes.length);
execute(bytes);
}

まとめ
Guavaを旋喘するとコ�`ディングしやすくな
り、
ソ�`スの辛�i來も�貧します。宴旋な�C嬬が�g表
あるので、ぜひ旋喘してみてください。

赫顎温厩温の胆龍しい奮へ?圭

1. Guavaの奮べ圭 2013/04/25 防云 �初

2. Guavaとは Javaの慌宥�I尖をまとめたライブラリ。麼にGoogleのエンジニアが�_�kしています。 Apache Commonsがライバル。

3. Guavaの蒙� ? ジェネリクス�� ? �K佩�I尖の�C嬬が�N源 ? fluent interface ? 辛�i來が互い ? Apache Commonsと�穩耽�

4. Guavaの�C嬬 ? com.google.common.annotations ? com.google.common.base ? com.google.common.cache ? com.google.common.collect ? com.google.common.eventbus ? com.google.common.io ? com.google.common.math ? com.google.common.net ? com.google.common.primitives ? com.google.common.reflect ? com.google.common.util.concurrent

5. Guavaの�C嬬 ? com.google.common.annotations ? com.google.common.base ? com.google.common.cache ? com.google.common.collect ? com.google.common.eventbus ? com.google.common.io ? com.google.common.math ? com.google.common.net ? com.google.common.primitives ? com.google.common.reflect ? com.google.common.util.concurrent

6. collect ? Lists List<String> list1 = Lists.newArrayList(); List<String> list2 = Lists.newArrayList(＾hoge￣, ￣fuga￣); final List<String> list3 = ImmutableList.of(＾tako￣, ￣ika￣);

7. collect ? Lists List<User> userList = getUserList(); // ＾taro￣,￣hanako￣ List<String> idList = Lists.transform(userList, new Function<User, String>() { @Override public String apply(User user) { return user.getId(); } });

8. collect ? MultiMap ListMultimap<String, String> map = ArrayListMultiMap.create(); map.put(＾pigg￣, ＾life￣); map.put(＾pigg￣, ￣cafe￣); map.put(＾card￣, ￣gf￣); // ＾life￣,￣cafe￣ List<String> list = map.get(＾pigg￣);

9. base ? Joiner List<String> list = Lists.newArrayList(＾hoge￣, null, ＾fuga￣); // ＾hoge,fuga￣ String join = Joiner.on(＾,￣).skipNulls().join(list);

10. base ? Splitter String val = ＾apple orange,peach￣; CharMatcher matcher = CharMatcher.WHITESPACE .or(CharMatcher.is(?,?)); // ＾apple￣,￣orange￣,￣peach￣ Iterable<String> split = Splitter.on(matcher).omitEmptyStrings().split(val);

11. base ? Preconditions Integer val = 10; Preconditions.checkNotNull(val, ＾required.￣); Preconditions.checkArgument(val > 10, ＾over 10.￣);

12. base ? Stopwatch Stopwatch stopwatch = new Stopwatch().start(); execute(); stopwatch.stop(); // ＾elapsed time:12.3ms￣ log.info(＾elapsed time:￣ + stopwatch);

13. io ? Files BufferedReader reader = null; try { reader = Files.newReader( new File(＾hoge.txt￣), Charsets.UTF_8); } finally { Closeables.closeQuietly(reader); }

14. io ? Files List<String> lines = Files.readLines( new File(＾fuga.txt￣), Charsets.UTF_8); byte[] bytes = Files.toByteArray(new File(＾sample.jpg￣));

15. util.concurrent ? ListeningFuture ListeningExecutorService threadPool = MoreExecutors.listeningDecorator( Executors.newFixedThreadPool(32)); Callable<String> task = getTask(); ListeningFuture<String> future = theadPool.submit(task);

16. util.concurrent ? ListeningFuture Futures.addCallback(future, new FutureCallback<String>() { @Override public void onSuccess(String s) { log.info(＾success! result:￣ + s); } @Override public void onFailure(Throwable throwable) { log.error(＾error!￣, throwable); } });

17. util.concurrent ? RateLimiter RateLimiter limiter = RateLimiter.create(100.0); for (int i = 1; i <= 10000; i++) { limiter.acquire(); execute(); } for (byte[] bytes : getBytesList()) { limiter.acquire(bytes.length); execute(bytes); }

18. まとめ Guavaを旋喘するとコ�`ディングしやすくなり、ソ�`スの辛�i來も�貧します。宴旋な�C嬬が�g表あるので、ぜひ旋喘してみてください。

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赫顎温厩温の胆龍しい奮へ?圭

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