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Java7 - Top 10 Features
 

Java7 - Top 10 Features

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My top 10 features in Java SE 7

My top 10 features in Java SE 7

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    Java7 - Top 10 Features Java7 - Top 10 Features Presentation Transcript

    • Java SE 7 {finally}
      2011-08-18
      Andreas Enbohm
    • 19 augusti 2011
      Sida 2
      Java SE 7
      A evolutionaryevolement of Java
      6 yearssince last update
      Somethingsleftout, will briefly discuss this at the end
      Oracle reallypushing Java forward- a lotpolitical problems with Sun made Java 7 postphonedseveraltimes
      Java still growing (1.42%), #1 mostusedlanguageaccording to TIOBE with 19.4% (Aug 2011)
      My top 10 new features (not ordered in anyway)
    • Java SE 7 – Language Changes
      Number 1:Try-with-resources Statement (or ARM-blocks)
      Before :
      19 augusti 2011
      Sida 3
      static String readFirstLineFromFileWithFinallyBlock(String path) throwsIOException {
      BufferedReaderbr = new BufferedReader(new FileReader(path));
      try {
      returnbr.readLine();
      } finally {
      if (br != null) {
      try {
      br.close();
      } catch (IOExceptionignore){
      //donothing
      }
      }
      }
      }
    • Java SE 7 – Language Changes
      Number 1:Try-with-resources Statement (or ARM-blocks)
      With Java 7:
      19 augusti 2011
      Sida 4
      static String readFirstLineFromFile(String path) throws IOException {
      try (BufferedReaderbr = new BufferedReader(new FileReader(path))) {
      return br.readLine();
      }
      }
    • Java SE 7 – Language Changes
      Number 1 - NOTE:
      The try-with-resources statement is a try statement that declares one or more resources. A resource is as an object that must be closed after the program is finished with it.
      The try-with-resources statement ensures that each resource is closed at the end of the statement.
      Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource.
      19 augusti 2011
      Sida 5
    • Java SE 7 – Language Changes
      Number 2: Strings in switch Statements
      19 augusti 2011
      Sida 6
      public String getTypeOfDayWithSwitchStatement(String dayOfWeekArg) {
      String typeOfDay;
      switch (dayOfWeekArg) {
      case "Monday":
      typeOfDay = "Start of work week";
      break;
      case "Tuesday":
      case "Wednesday":
      case "Thursday":
      typeOfDay = "Midweek";
      break;
      case "Friday":
      typeOfDay = "End of work week";
      break;
      case "Saturday":
      case "Sunday":
      typeOfDay = "Weekend";
      break;
      default:
      throw new IllegalArgumentException("Invalid day of the week: " + dayOfWeekArg);
      }
      return typeOfDay;
      }
    • Java SE 7 – Language Changes
      Number 2 - NOTE:
      The Java compiler generates generally more efficient bytecode from switch statements that use String objects than from chained if-then-else statements.
      19 augusti 2011
      Sida 7
    • Java SE 7 – Language Changes
      Number 3:Catching Multiple ExceptionTypes
      Before :
      Difficult to eliminatecodeduplicationdue to different exceptions!
      19 augusti 2011
      Sida 8
      try {

      } catch (IOException ex) {
      logger.log(ex);
      throw ex;
      } catch (SQLException ex) {
      logger.log(ex);
      throw ex;
      }
    • Java SE 7 – Language Changes
      Number 3:Catching Multiple ExceptionTypes
      With Java 7 :
      19 augusti 2011
      Sida 9
      try {

      } catch (IOException|SQLException ex) {
      logger.log(ex);
      throw ex;
      }
    • Java SE 7 – Language Changes
      Number 3 - NOTE:Catching Multiple ExceptionTypes
      Bytecode generated by compiling a catch block that handles multiple exception types will be smaller (and thus superior) than compiling many catch blocks that handle only one exception type each.
      19 augusti 2011
      Sida 10
    • Java SE 7 – Language Changes
      Number 4:TypeInference for GenericInstance Creation
      Before:
      Howmanytimeshave you swornabout this duplicatedcode? 
      19 augusti 2011
      Sida 11
      Map<String, List<String>> myMap = new HashMap<String, List<String>>();
    • Java SE 7 – Language Changes
      Number 4:TypeInference for GenericInstance Creation
      With Java 7:
      19 augusti 2011
      Sida 12
      Map<String, List<String>> myMap = new HashMap<>();
    • Java SE 7 – Language Changes
      Number 4 - NOTE:TypeInference for GenericInstance Creation
      Writing new HashMap() (withoutdiamond operator) will still use the rawtype of HashMap (compilerwarning)
      19 augusti 2011
      Sida 13
    • Java SE 7 – Language Changes
      Number 5:Underscores in NumericLiterals
      19 augusti 2011
      Sida 14
      longcreditCardNumber = 1234_5678_9012_3456L;
      longsocialSecurityNumber = 1977_05_18_3312L;
      float pi = 3.14_15F;
      longhexBytes = 0xFF_EC_DE_5E;
      longhexWords = 0xCAFE_BABE;
      longmaxLong = 0x7fff_ffff_ffff_ffffL;
      long bytes = 0b11010010_01101001_10010100_10010010;
    • Java SE 7 – Language Changes
      Number 5 - NOTE:Underscores in NumericLiterals
      You can place underscores only between digits; you cannot place underscores in the following places:
      At the beginning or end of a number
      Adjacent to a decimal point in a floating point literal
      Prior to an F or L suffix
      In positions where a string of digits is expected
      19 augusti 2011
      Sida 15
    • Java SE 7 – ConcurrentUtilities
      Number 6:Fork/JoinFramework (JSR 166)
      ” a lightweightfork/joinframework with flexible and reusablesynchronizationbarriers, transfer queues, concurrent linked double-endedqueues, and thread-localpseudo-random-number generators.”
      19 augusti 2011
      Sida 16
    • Java SE 7 – ConcurrentUtilities
      Number 6:Fork/JoinFramework (JSR 166)
      19 augusti 2011
      Sida 17
      if (my portion of the work is small enough)
      do the work directly
      else
      split my work into two pieces invoke the two pieces and wait for the results
    • Java SE 7 – ConcurrentUtilities
      Number 6:Fork/JoinFramework (JSR 166)
      19 augusti 2011
      Sida 18
    • Java SE 7 – ConcurrentUtilities
      Number 6:Fork/JoinFramework (JSR 166)
      New Classes
      • ForkJoinTask
      • RecursiveTask
      • RecursiveAction
      • ThreadLocalRandom
      • ForkJoinPool
      19 augusti 2011
      Sida 19
    • Java SE 7 – Filesystem API
      Number 7: NIO 2 Filesystem API (Non-Blocking I/O)
      Bettersupports for accessingfile systems such and support for customfile systems (e.g. cloudfile systems)
      Access to metadata such as file permissions
      Moreeffecient support whencopy/movingfiles
      EnchancedExceptionswhenworking on files, i.e. file.delete() nowthrowsIOException (not just Exception)
      19 augusti 2011
      Sida 20
    • Java SE 7 – JVM Enhancement
      Number 8:InvokeDynamic (JSR292)
      Support for dynamiclanguages so theirperformance levels is near to that of the Java language itself
      At byte code level this means a new operand (instruction) called invokedynamic
      Make is possible to do efficient method invocation for dynamic languages (such as JRuby) instead of statically (like Java) .
      Huge performance gain
      19 augusti 2011
      Sida 21
    • Java SE 7 – JVM Enhancement
      Number 9: G1 and JVM optimization
      G1 morepredictable and uses multiple coresbetterthan CMS
      Tiered Compilation –Bothclient and server JIT compilers are usedduringstarup
      NUMA optimization - Parallel Scavenger garbage collector has been extended to take advantage of machines with NUMA (~35% performance gain)
      EscapeAnalysis - analyze the scope of a new object's and decide whether to allocate it on the Java heap
      19 augusti 2011
      Sida 22
    • Java SE 7 – JVM Enhancement
      Number 9:EscapeAnalysis
      19 augusti 2011
      Sida 23
      public class Person {
      private String name; private int age;
      public Person(String personName, intpersonAge) {
      name = personName; age = personAge; }
      public Person(Person p) {
      this(p.getName(), p.getAge());
      }
      }
      public classEmployee {
      private Person person; // makes a defensive copy to protectagainstmodifications by caller
      public Person getPerson() {
      return new Person(person)
      };
      public voidprintEmployeeDetail(Employeeemp) {
      Person person = emp.getPerson(); // this callerdoes not modify the object, so defensive copywasunnecessary
      System.out.println ("Employee'sname: " + person.getName() + "; age: " + person.getAge()); }
      }
    • Java SE 7 - Networking
      Number 10: Support for SDP 
      SocketDirectProtocol (SDP) enablesJVMs to use Remote Direct Memory Access (RDMA). RDMA enables moving data directly from the memory of one computer to another computer, bypassing the operating system of both computers and resulting in significant performance gains.
      The result is High throughput and Low latency (minimal delay between processing input and providing output) such as you would expect in a real-time application.
      19 augusti 2011
      Sida 24
    • Java SE 7 - Networking
      Number 10 - NOTE: Support for SDP
      The Sockets Direct Protocol (SDP) is a networking protocol developed to support stream connections over InfiniBand fabric.
      Solaris 10 5/08 has support for InfiniBand fabric (which enables RDMA). On Linux, the InfiniBand package is called OFED (OpenFabrics Enterprise Distribution).
      19 augusti 2011
      Sida 25
    • Java SE 7
      A complete list of all new features can be seen on http://www.oracle.com/technetwork/java/javase/jdk7-relnotes-418459.html
      19 augusti 2011
      Sida 26
    • Java SE 8
      Some features whereleftout in Java 7; mostimportant are Project Lambda (closures) and Project Jigsaw (modules) targeted for Java 8 (late 2012)
      Lambdas (and extension methods) willprobably be the biggestsinglechangeevermade on the JVM. Will introduce a powerfulprogrammingmodel, however it comes with a great deal of complexity as well.
      Moduleswillmade it easier to version modules (no moreJAR-hell) and introducea new way of definingclasspaths
      19 augusti 2011
      Sida 27
    • Java SE 7 & 8
      Questions?
      19 augusti 2011
      Sida 28