java-7 - Java 7 中的新特性

Question

Java 7 中将实现哪些新特性？ 他们现在在做什么？

Answer 1

Java SE 7 Features and Enhancements来自 JDK 7 发行说明

这是来自 OpenJDK 7 features page 的 Java 7 新特性摘要:

vm  JSR 292: Support for dynamically-typed languages (InvokeDynamic)
        Strict class-file checking
lang    JSR 334: Small language enhancements (Project Coin)
core    Upgrade class-loader architecture
        Method to close a URLClassLoader
        Concurrency and collections updates (jsr166y)
i18n    Unicode 6.0
        Locale enhancement
        Separate user locale and user-interface locale
ionet   JSR 203: More new I/O APIs for the Java platform (NIO.2)
        NIO.2 filesystem provider for zip/jar archives
        SCTP (Stream Control Transmission Protocol)
        SDP (Sockets Direct Protocol)
        Use the Windows Vista IPv6 stack
        TLS 1.2
sec     Elliptic-curve cryptography (ECC)
jdbc    JDBC 4.1
client  XRender pipeline for Java 2D
        Create new platform APIs for 6u10 graphics features
        Nimbus look-and-feel for Swing
        Swing JLayer component
        Gervill sound synthesizer [NEW]
web     Update the XML stack
mgmt    Enhanced MBeans [UPDATED]

Java 1.7 中新功能的代码示例

Try-with-resources 语句

这个:

BufferedReader br = new BufferedReader(new FileReader(path));
try {
   return br.readLine();
} finally {
   br.close();
}

变成:

try (BufferedReader br = new BufferedReader(new FileReader(path)) {
   return br.readLine();
}

您可以声明多个要关闭的资源:

try (
   InputStream in = new FileInputStream(src);
   OutputStream out = new FileOutputStream(dest))
{
 // code
}

数字文字中的下划线

int one_million = 1_000_000;

开关中的字符串

String s = ...
switch(s) {
 case "quux":
    processQuux(s);
    // fall-through

  case "foo":
  case "bar":
    processFooOrBar(s);
    break;

  case "baz":
     processBaz(s);
    // fall-through

  default:
    processDefault(s);
    break;
}

二进制字面量

int binary = 0b1001_1001;

改进了通用实例创建的类型推断

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

变成:

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

多个异常捕获

这个:

} catch (FirstException ex) {
     logger.error(ex);
     throw ex;
} catch (SecondException ex) {
     logger.error(ex);
     throw ex;
}

变成:

} catch (FirstException | SecondException ex) {
     logger.error(ex);
    throw ex;
}

SafeVarargs

这个:

@SuppressWarnings({"unchecked", "varargs"})
public static void printAll(List<String>... lists){
    for(List<String> list : lists){
        System.out.println(list);
    }
}

变成:

@SafeVarargs
public static void printAll(List<String>... lists){
    for(List<String> list : lists){
        System.out.println(list);
    }
}