The document discusses various aspects of Java programming, including its versions and ecosystem, as well as provides coding examples and links to resources related to Java performance and libraries. It highlights features introduced in recent versions of Java, such as functional programming and concurrency. Additionally, it offers insights into Java's popularity over the years, coding best practices, and methodologies for effective software development.

2. 김대우
젬플레이 이사
http://lekdw.blogspot.kr/
정도현(정개발)
나는 프로그래머다 MC
일본 Mamezou소속 컨설턴트
http://Iamprogrammer.io
http://moreagile.net

4. James Gosling
Patrick Naughton
https://en.wikipedia.org/wiki/Java_(programming_language)

5. https://en.wikipedia.org/wiki/Java_(programming_language)

6. J2SE 5.0
Java SE 7
Java SE 8
https://en.wikipedia.org/wiki/Java_version_history

11. 연도별 언어 인기도
http://www.tiobe.com/index.p
hp/content/paperinfo/tpci/ind
ex.html

13. http://benchmarksgame.alioth.debian.org/u64/which-programs-are-fastest.html

14. http://www3.ntu.edu.sg/home/ehchua/programming/java/j5b_io.html

15. http://www.evanjones.ca/software/java-bytebuffers.html

16. http://netty.io/wiki/using-as-a-generic-library.html

17. http://terracotta.org/products/bigmemory

18. 모바일 게임 서버와 같이 Life Cycle이 짧은 데이터(객체)를 주로 처리하
는 경우, 별다른 튜닝없이 -server, -d64, -Xms, -Xmx 옵션으로 충분.

22. http://www.drdobbs.com/jvm/the-comparative-productivity-of-programm/240005881
Language Hours Per Function Point
ASP* 06.1
Visual Basic 08.5
Java 10.6
SQL 10.8
C++ 12.4
C 13.0
C# 15.5
PL/1 14.2
COBOL 16.8
ABAP 19.9

24. Checkstyle
Error Prone
FindBugs
PMD
SonarQube

27. http://readwrite.com/2011/01/24/the-java-ecosystem-infographic

28. JUnit
SLF4J API Module
Scala Library
Logback Classic Module
Guava: Google Core Libraries for Java
Mockito
Google APIs Client Library for Java
Apache Log4j
Commons IO
SLF4J LOG4J-12 Binding
osgi.core
JavaServlet(TM) Specification
TestNG
ScalaTest
Commons Lang
Joda-Time
Spring Context
Mockito
H2 Database Engine
Java Servlet API
http://www.77dev.com/2014/05/java-trends-top-100-mostly-used.html

29. JCL 1.1.1 implemented over SLF4J
jackson-databind
SLF4J Simple Binding
Apache CommonsCodec
Apache HttpClient
Apache Commons Lang
Commons Logging
Spring Core
osgi.cmpn
Google Guice - Core Library
SpringTestContext Framework
Jetty :: Server Core
Maven Plugin API
FindBugs-jsr305
BeanValidation API
Spring Beans
Groovy
Jackson-core
EasyMock
Spock Framework - Core Module

31. Java8

33. http://www.slideshare.net/shintanimoto/from-old-java-to-modern-java

34. private List m_list=null;
private int process_file(String str_file_name){
String str_line;
List list_lines=new ArrayList();
int i_result=read_file(str_file_name,list_lines);
if(i_result==0){
List list_record=new ArrayList();
for(int i=0;i<list_lines.size();i++){
str_line=(String)list_lines.get(i);
Record record=new Record();
i_result=parse_line(str_line,record);
if(i_result!=0){
return i_result;
}
list_recordord.add(record);
}
m_list=list_record;
return 0;
}else{
return i_result;
}
}
http://www.slideshare.net/shintanimoto/from-old-java-to-modern-java
C-ish java

35. private List resultList;
private List processFile(String fileName)throws
SystemException {
List lines = readFile(fileName);
List recordList = new ArrayList();
for (int i = 0; i < lines.size(); i++) {
String line = (String) lines.get(i);
Record record = parseLine(line);
recordList.add(record);
}
return recordList;
}
http://www.slideshare.net/shintanimoto/from-old-java-to-modern-java
Java 1.4

36. private List<Record> processFile(String fileName)throws SystemException {
List<String> lines = readFile(fileName);
List<Record> recordList = new ArrayList();
for (String line : lines) {
Record record = parseLine(line);
recordList.add(record);
}
return recordList;
}
Java 1.7 generic + foreach

38. private List<String> readFile(String fileName) {
List<String> lines = new ArrayList<String>();
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(fileName));
String line;
while ((line = reader.readLine()) != null) {
lines.add(line);
}
} catch (FileNotFoundException ex) {
throw new SystemException(FILE_NOT_FOUND, ex);
} catch (IOException ex) {
throw new SystemException(FILE_READ_ERROR, ex);
}
finally {
try {
if (reader != null) {
reader.close();
}
} catch (IOException ex) {
// 이건 무시?
}
}
return lines;
}

39. private List<String> readFile(String fileName) {
List<String> lines = new ArrayList<>();
try (FileReader in = new FileReader(fileName);
BufferedReader reader = new BufferedReader(in)) {
String line;
while ((line = reader.readLine()) != null) {
lines.add(line);
}
} catch (FileNotFoundException ex) {
throw new SystemException(FILE_NOT_FOUND, ex);
} catch (IOException ex) {
throw new SystemException(FILE_READ_ERROR, ex);
}
return lines;
}
Java 7

40. private List<String> readFile(String fileName) {
try {
return Files.readAllLines(Paths.get(fileName), Charset.defaultCharset());
} catch (IOException ex) {
throw new SystemException(FILE_READ_ERROR, ex);
}
}
Java 7

41. https://ko.wikipedia.org/wiki/함수형_프로그래
밍

43. public static <E extends Comparable<? super E>>
List<E> quickSort(List<E> arr) {
if (!arr.isEmpty()) {
E pivot = arr.get(0); //This pivot can change
to get faster results
List<E> less = new LinkedList<E>();
List<E> pivotList = new LinkedList<E>();
List<E> more = new LinkedList<E>();
for (E i: arr) {
if (i.compareTo(pivot) < 0)
less.add(i);
else if (i.compareTo(pivot) > 0)
more.add(i);
else
pivotList.add(i);
}
less = quickSort(less);
more = quickSort(more);
less.addAll(pivotList);
less.addAll(more);
return less;
}
return arr;
}
http://rosettacode.org/wiki/Sorting_algorithms/Quicksort#Java
Java 7

44. public static <T> List<T> Quicksort(List<T> v, BiFunction<T, T,
Integer> comparer) {
if (v.size() < 2)
return v;
T pivot = v.get(v.size() / 2);
List<T> l = new LinkedList<T>(Quicksort(v.stream()
.filter(x -> comparer.apply(x, pivot) < 0)
.collect(Collectors.toList()), comparer));
l.addAll( v.stream().filter(x -> comparer
.apply(x, pivot) == 0).collect(Collectors.toList()) );
l.addAll( Quicksort(v.stream()
.filter(x -> comparer.apply(x, pivot) > 0)
.collect(Collectors.toList()), comparer) );
return l;
}
Java 8

45. qsort [] = []
qsort (x:xs) = qsort (filter (< x) xs) ++ [x] ++ qsort (filter (>= x) xs)
https://en.wikibooks.org/wiki/Algorithm_Implementation/Sorting/Quicksort#Haskell
Haskell

47. package org.ingini.spark.java8;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.TreeMap;
import static java.util.function.Function.identity;
import static java.util.stream.Collectors.counting;
import static java.util.stream.Collectors.groupingBy;
public class WordsCounterJava {
public static final String REGEX = "s+";
public TreeMap<String, Long> count(String source) throws IOException {
return Files.lines(Paths.get(source))
.map(line -> line.split(REGEX))
.flatMap(Arrays::stream)
.collect(groupingBy(identity(), TreeMap::new, counting()));
}
}

48. -Djava.util.concurrent.ForkJoinPool.common.parallelism=1

49. SELECT * FROM BOOK
WHERE BOOK.PUBLISHED_IN = 2011
ORDER BY BOOK.TITLE
jOOQ
create.selectFrom(BOOK)
.where(BOOK.PUBLISHED_IN.eq(2011))
.orderBy(BOOK.TITLE)
http://www.jooq.org/

51. http://java2practice.com/2014/03/16/java-8-functional-interface-example/
Thread t =new Thread(new Runnable(){
public void run(){
System.out.println("Runnable implemented by using Lambda Expression");
}
});
Thread t = new Thread(()->{
System.out.println("Runnable implemented by using Lambda Expression");
});
Java 7
Java 8

52. interface DefaultInterfaceTest{
void show();
default void display(){
System.out.println("Default method from interface can have body..!");
}
}
public class DefaultInterfaceTestImpl implements DefaultInterfaceTest{
public void show(){
System.out.println("show method");
}
//we dont need to provide any implementation to default method.
public static void main(String[] args){
DefaultInterfaceTest obj = new DefaultInterfaceTestImpl();
obj.show();//out puts: show method
obj.display();//outputs : Default method from interface can have body..!
}
}
Default Method

54. •Function <T, R> - T를 입력으로 R을 출력으로 반환
•Predicate <T> - T를 입력으로 boolean을 출력으로 반환
•Consumer <T> - T를 입력으로 아무것도 반환하지 않는다
•Supplier <T> - 입력을 취하지 않고 T를 반환
•BinaryOperator <T> - 2 개의 T를 입력으로 하나의 T를 출력으로
반환

55. http://www.ibm.com/developerworks/library/j-jvmc2/index.html

56. Runnable task = () -> {
String threadName = Thread.currentThread().getName();
System.out.println("Hello " + threadName);
};
task.run();
Thread thread = new Thread(task);
thread.start();

57. ExecutorService executor = Executors.newSingleThreadExecutor();
executor.submit(() -> {
String threadName = Thread.currentThread().getName();
System.out.println("Hello " + threadName);
});
try {
//attempt to shutdown executor
executor.shutdown();
executor.awaitTermination(5, TimeUnit.SECONDS);
}
catch (InterruptedException e) {
System.err.println("tasks interrupted");
}
finally {
if (!executor.isTerminated()) {
executor.shutdownNow();
}
System.out.println("shutdown finished");
}
Executors
http://winterbe.com/posts/2015/04/07/java8-concurrency-tutorial-thread-executor-examples/

58. http://ariya.ofilabs.com/2014/03/nashorn-the-new-rhino-on-the-block.html

59. interface CustomerRepository extends Repository<Customer, Long> {
@Query("select c from Customer c")
Stream<Customer> streamAllCustomers();
}
try (Stream<Customer> customers = repository.streamAllCustomers()) {
// use the stream here
}
Support for JDK 8' Stream in repository methods

60. interface CustomerRepository extends Repository<Customer, Long> {
@Async
CompletableFuture<List<Customer>> readAllBy();
}
CompletableFuture<List<Customer>> future =
repository.readAllBy().thenApply(this::doSomethingWithCustomers);
while (!future.isDone()) {
log.info("Waiting for the CompletableFuture to finish...");
TimeUnit.MILLISECONDS.sleep(500);
}
List<Customer> processedCustomers = future.get();

61. http://doc.akka.io/docs/akka/2.3.0-RC1/java/lambda-actors.html
import akka.actor.AbstractActor;
import akka.event.Logging;
import akka.event.LoggingAdapter;
import akka.japi.pf.ReceiveBuilder;
import scala.PartialFunction;
import scala.runtime.BoxedUnit;
public class MyActor extends AbstractActor {
private final LoggingAdapter log = Logging.getLogger(context().system(), this);
@Override
public PartialFunction<Object, BoxedUnit> receive() {
return ReceiveBuilder.
match(String.class, s -> s.equals("test"), s -> log.info("received test")).
matchAny(o -> log.info("received unknown message")).build();
}
}

62. https://blogs.oracle.com/javatraining/entry/announcing_jdk_8_mooc_lambdas