jdk7 바낀것

Java(JDK) 7 특징

the proposed features in Java 7

1. Improved Type Inference for Generic Instance Creation
 - 단순해진 Generics

이전 : 

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

JDK7 : 

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

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-February/000009.html

2. Language support for collections
 - Java 코드의 사이즈를 줄여주고, 가독성을 높여줌

이전 :

final List<Integer> piDigits =

Collections.unmodifiableList(Arrays.asList(3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 9 ));

JDK7 : 

final List<Integer> piDigits = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 9];

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/001193.html

3. Automatic Resource Management
 - exception handling을 줄여줌
 - C++’s RAII과 C#’s using에 대응하기 위함

이전 :

static String readFirstLineFromFile(String path) throws IOException {

     BufferedReader br = new BufferedReader(new FileReader(path));

     try {

         return br.readLine();

     } finally {

         br.close();

     }

}

JDK7 :

static String readFirstLineFromFile2(String path) throws IOException {

     try (BufferedReader br = new BufferedReader(new FileReader(path)) {

        return br.readLine();

     }

}

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-February/000011.html

4. Added binary integer literals
 - Integer Literal에 Binary Integer Literal이 추가됨

BinaryIntegerLiteral:

        BinaryNumeral IntegerTypeSuffix_opt

BinaryNumeral:

        0 b BinaryDigits

        0 B BinaryDigits

BinaryDigits:

        BinaryDigit

        BinaryDigit BinaryDigits

BinaryDigit: one of

        0 1

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/000929.html

5. String literals in switch statements
 - 스위치문에 문자열 사용 가능

JDK7 :

String s = "first";

switch(s) {

 case "first":

    processFirst(s);

  case "second":

  case "third":

    processThird(s);

    break;

  case "fourth":

     processFourth(s);

  default:

    processDefault(s);

    break;

}

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-February/000001.html

6. Simplified Varargs Method Invocation
 - 컴파일 경고에서 메소드 선언 경고로 이동함

이전 :

static <T> List<T> asList(T... elements) { ... }

static List<Callable<String>> stringFactories() {

  Callable<String> a, b, c;

  ...

  *// Warning: **"uses unchecked or unsafe operations"*

  return asList(a, b, c);

}

JDK7 :

*// Warning: **"enables unsafe generic array creation"*

static <T> List<T> asList(T... elements) { ... }


static List<Callable<String>> stringFactories() {

  Callable<String> a, b, c;

  ...

  return asList(a, b, c);

}

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/000217.html

7. Enhanced null handling
 - Null-ignore invocation, Null-safe types

이전 :

String str = getStringMayBeNull();  

str = (str == null ? "" : str);

JDK7 :

String str = getStringMayBeNull() ?: "";

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/000217.html

8. Enum Comparisons
 - Enum에서 range(<, > 등) 연산 가능

이전 :

if(rank1.compareTo(rank2) < 0) ...

if(rank1.ordinal() < rank2.ordinal()) ...

JDK7 :

if(rank1 < rank2) ...

9. Chained Invocation
 - 체인형식으로 메소드 호출 가능

이전 :

DrinkBuilder margarita = new DrinkBuilder();

margarita.add("tequila");

margarita.add("orange liqueur");

margarita.add("lime juice");

margarita.withRocks();

margarita.withSalt();

Drink drink = margarita.drink();

JDK7 :

Drink margarita = new DrinkBuilder()

.add(“tequila”)

.add(“orange liqueur”)

.add(“lime juice”)

.withRocks()

.withSalt()

.drink();

10. Extension Methods
 - static import 확장

이전 :

List list = new ArrayList();

...

Collections.sort(list);

list.sort();

JDK7 :

import static java.util.Collections.sort;

List list = new ArrayList();

...

list.sort();

 - 레퍼런스 : http://www.javac.info/ExtensionMethods.html

11. Improved Exception Handling
 - 두개이상의 catch문 가능
 - catch문에서 rethrow가능

JDK7 : catch multiple exceptions

try {  

    return klass.newInstance();  

} catch (InstantiationException | IllegalAccessException e) {  

    throw new AssertionError(e);  

}  

JDK7 : rethrow exceptions

try {  

    doable.doIt();   

} catch (final Throwable ex) {  

    logger.log(ex);  

  

    // surrounding method can declare only checked thrown by doIt()  

    throw ex;    

} 

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-February/000003.html

12. Language support for JSR 292
 - 다이나믹 타입 지원(java.dyn.Dynamic)

JDK7 :

Dynamic x = (any type of expression can go here);

Object  y = x.foo("ABC").bar(42).baz();

 - 레퍼런스 : http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/001131.html