Java 13 is a major feature release and it has brought many JVM specific changes to JAVA and few language specific changes. It followed the Java release cadence introduced Java 10 onwards and it was releasd on Sept 2019, just six months after Java 12 release.
Java 13 is a non-LTS release.
Following are the major new features which are introduced in Java 13.
JEP 354 - Switch Expressions - A preview feature allowing switch to use return values via yield.
JEP 355 - Text Blocks - A preview feature to handle multiline strings like JSON, XML easily.
String new methods - New Methods added to string to handle text blocks.
JEP 353 - Socket API Reimplementation - Underlying API is rewritten.
FileSystems.newFileSystem() - Three new methods added to make it easy to use.
DOM/SAX Factories - New methods added to add namespace support.
Dynamic CDS Archive - CDS archive can be created easily.
JEP 351 - ZGC Enhancements - ZGC enhanced to return unused heap memory to operating system.
Java 13 enhanced numerous APIs with new methods and options. We'll see these changes in next chapters.