java-13

Java 13

To run each example use: java --enable-preview --source 13 <FileName.java>

JEPs

• 354 - Switch expression (preview 2)
• 355 - Text blocks (preview)
• 350 - Dynamic CDS Archives
• 351 - ZGC: Uncommit Unused Memory
• 353 - Reimplement the Legacy Socket API

Features

• Switch Expressions (second preview)
  • Changed break from Java 12 to yield
• Text Blocks (preview)
  • flag to compile: -Xlint:text-blocks
• Reimplement Legacy Socket API
  • Socket and ServerSocket reimplementation (alignment to Project Loom)

API

• String methods:
  • stripIdent: same operation done by the compiler to strip incidental identation from text block';
  • translateEscapes: same operation done by the compiler to translate escapes in strings;
  • formatted: shortcut to String.format '"%s years old".formatted(42))
• NIO improvements

JVM

• Creating Class-Data archives For AppCDS
  • flag to java -XX:ArchiveClassesAtExit=<FileHere.jsa> to generate class-data on exit
  • run with it: -XX:SharedArchiveFile=<FileHere.jsa>
• ZGC (Oracle's Z GC) returns unused memory to SO
  • -XX:ZUncommitDelay=<seconds> to set the delay in seconds
  • -XX:SoftMaxHeapSize: soft (won't generate OutOfMemoryError - will request more) limit to avoid the JVM to grow in memory

Links

• Java 13 Documentation
• Java 13 Guide
• Switch Expression
• Text Block Guid