New Features Overview

Transcription

1 Features pf JDK 7

2 New Features Overview Full List: JSR 334: Small language enhancements (Project Coin) Concurrency and collections updates (jsr166y) JSR 203: More new I/O APIs for the Java platform (NIO.2) NIO.2 file system provider for zip/jar archives SCTP (Stream Control Transmission Protocol) SDP (Sockets Direct Protocol) Use the Windows Vista IPv6 stack TLS 1.2

3 Other Features Unicode 6.0 Locale enhancement Separate user locale and user-interface locale Elliptic-curve cryptography (ECC) JDBC 4.1 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 Update the XML stack Enhanced Mbeans JSR 292: Support for dynamically-typed languages (InvokeDynamic) Strict class-file checking Upgrade class-loader architecture Method to close a URLClassLoader

4 Language Updates Strings in switch statements (FINALLY!) No more of this: if ( foo.equals( val1 ) ) { x++; } else if ( foo.equals( val2 ) ) { x += 2; } else if ( foo.equals( val3 ) ) { x += 3; } else { x = 0; }

5 Language Updates Now we can do this: switch ( foo ) { case val1 : x++; break; case val2 : x += 2; break; case val3 : x += 3; break; } default: x = 0;

6 Language Updates Try-with-resources No more of this: Connection con = getconnection(); Statement stmt = null; try { conn = conn.createstatement();... Use Conn... } catch ) SQLException ex ) { /* Stuff */ } finally { IOUtils.close( conn ); }

7 Language Updates Try-with-resources Instead do this: Connection con = getconnection(); try ( Statement stmt = conn.createstatement() ) {... Use Conn... } catch ) SQLException ex ) { /* Stuff */ } When upgrading, you'll gets lots of new warnings letting you know about your resource leaks as well. T-W-R looks for anything that implements java.io.closeable.

8 Language Updates Catch >1 exception in a catch() block. try { Path fp = path.torealpath( true ); } catch ( NoSuchFileException x ) { System.err.format("%s: no such file or directory%n", path); } catch ( IOException x ) { System.err.format("%s%n", x); }... can now be written as... try { Path fp = path.torealpath( true ); } catch ( NoSuchFileException IOException x ) { } System.err.format("%s: no such file or directory%n", path);

9 Language Updates More precise exception re-throwing JarFile retrieve(url url) throws IOException { } Path temp = Files.createTempFile("jar_cache", null); try (InputStream in = url.openstream()) { Files.copy(in, temp, REPLACE_EXISTING); return new JarFile(temp.toFile()); } catch (Throwable t) { } Files.delete(temp); throw t; In this case, the compiler knows that the only possible exception type is an IOException because that is what Files.copy can throw.

10 Language Updates Are diamonds a developers best friend? Rather unwieldy: Map<String, List<String>> mymap = new HashMap<String, List<String>>(); Much more readable: Map<String, List<String>> mymap = new HashMap<>();

11 Concurrency More scalable code using fork/join framework on multiple processors Introduced in the JDK 7 release, the fork/join framework uses the ExecutorService interface and allows you to recursively break down work to better utilize multiple processors. Convenience class for generating random numbers from multiple threads The java.util.concurrent.threadlocalrandom class has been added to make it easy to generate random numbers in applications that require random numbers from multiple threads, or from the fork/join mechanism.

12 Fork / Join Built in classes include RecursiveAction (no returned result) and RecursiveTask.

13 NIO.2 File metadata via java.nio.file.attribute package. This package includes support for accessing file permissions, the file's owner, and security attributes. Symbolic link support via the Path and Files classes. Scalable I/O file support no more hangs on large directories of files. File system search via PathMatcher API. The Watch Service api allows you to register a directory for file change notifications. An application can register for creation, deletion, or modification events. This feature can be implemented using the FileVisitor API to recursively watch an entire file tree for changes.

14 Dynamic Language Support Good in depth article: se/dyntypelang html New Java bytecode, invokedynamic, for use by languages such as Jruby/Jython. Uses method handles and reduces the strict-typing constraints. Basic aim is to allow the JVM to more easily power non-java dynamic languages by reducing the amount of hacky bytecode they need to implement to make the static checking of the older JVMs work.

15 Garbage First (G1) Collector In depth URL: Replacement for CMS Collector I tried it once, it was terrible and nearly locked the machine. Possibly need to spend more time tuning, but CMS worked far better out of the box... Targeted for multiprocessor machines with large memories. Meets garbage collection (GC) pause time goals with high probability, while achieving high throughput. Whole-heap operations, such as global marking, are performed concurrently with the application threads. Use cases More than 50% of the Java heap is occupied with live data. The rate of object allocation rate or promotion varies significantly. Undesired long garbage collection or compaction pauses (longer than 0.5 to 1 second)

16 Performance Enhancements In depth: Tiered Compilation Brings faster client startup speeds to server JVM. Compressed Ordinary Object Pointers (oops) Allows smaller memory footprint in 64-bit JVMs (physical RAM, mem bandwidth, and cache). Zero-based Compressed oops more efficient oops decoding on 64-bit systems. Escape Analysis Allows HotSpot to allocate objects on heap for efficiency. Will even eliminate synchronized blocks when object usage is thread local. NUMA (Non Uniform Memory Access) collector enhancements. Up to 40% collector improvement on 64 bit Vms.

17 Misc XML parsers are now JAXP 1.4, JAXB 2.2a, and JAX- WS 2.2. Check out the Nimbus LnF