Devoxx 2009: JDK 7 Update

18/11/2009, Mark Reinhold

higlight: Closures in java are BACK!

Aims of JDK7

• modular platform
  • JDK7 status:
    • 13MB download with pack200 compression
    • difficult to support smaller (embedded) hardware
  • → Jigsaw project
    • low-level modules, at the rt.jar level
    • language support: module-info.java file
      • explicit module / version requirements
      • create simpler OS-specific package, with correct dependencies (e.g. deb-packages)
    • OSGi interoperability
• multi-lingual support
  • better JRuby, Jython support on the JVM
  • InvokeDynamic
  • “Da Vinci Machine project”
• productivity enhancement
  • “Project Coin”
  • language changes that improve programming experience. E.g.:
    • type inference with the <> (aka. 'diamond') operator: Map <String,String> m = new <> HashMap();
    • split numbers with '_' for better readability: int a=123_456_789;
    • support binary notation: int b=0b00100100001;
    • Lists: direct construction and access to set/get with []: a[4] = b[5];
    • Map: direct construction and access to set/get with {}: a{“b”}=”xyz”;
    • auto-close Closeable interfaces: try(File f = new File()) where f is always closed correctly.
• performance
  • multi-cores are there! → java support needed.
  • → fork/join framework
  • Dual-Pivot Quicksort
  • Closures: “It's time to add them” – I thought this was dropped from Java7 plans...
    • needed:
      • function literals
      • function types
      • extension methods
    • “doesn't fit in java”:
      • non-local control transfer
      • capture non-final vars
      • library-defined control structures

When?

• Planning shifted
• Milestone 10: 2010/09/09: release candidate