Always strong floating point semantics
API of third party functions and memory
Unified API for pseudo-random number generators
Java 17, due out in September, continues to take shape, with nine features planned for an upgrade to standard Java, and two features are being removed and two features are no longer supported. The latest changes, as of May 24, added pattern matching for switch expressions and restored the always strong floating point semantics.
Java Development Kit (JDK) 17 will be a Long Term Support (LTS) release, with extended support for Oracle expected over several years. Features introduced as part of OpenJDK's JDK 17 include the following:
With restoring always strong floating point semantics, floating point operations will be permanently strict, instead of having both strict floating point semantics (strictfp) and slightly different default floating point semantics. This restores the original floating point semantics for the language and virtual machine, matching the semantics prior to the introduction of strong and floating point modes by default in Java Standard Edition 1.2. The goals of this cost include to facilitate the development of numeric-sensitive libraries, including java.lang.Math and java.lang.StrictMath. The incentive to change the default floating point semantics in the late 1990s. was caused by poor interaction between the original Java language and JVM semantics, as well as some peculiarities of the x87 floating point coprocessor instruction set of the popular x86 architecture.Matching exact floating point semantics in all cases, including subnormal operands and results, required a large overhead of additional instructions. Comparison of results without overflow or underflow can be done with less overhead, which is about what the revised default floating point semantics introduced in Java SE 1.2 allows. But the Streaming SIMD Extensions 2 (SSE2) shipped in Pentium 4 and later processors starting around 2001 were able to directly support the JVM's strict floating point operations without excessive overhead. Since Intel and AMD support SSE2 and later extensions, which allow native support for strong floating point semantics,the technical motivation for using default floating point semantics other than strict is no longer there.
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Improved support for streaming programming providing streams of PRNG objects.
Eliminate code duplication in existing PRNG classes.
Preserving the existing behavior of the java.util.Random class.
JDK 17 is slated to go public on September 14th. The production release will be preceded by roll-out phases in June and July, and the release of candidates in August. Open source early access JDK 17 builds can be found at jdk.java.net .
LTS releases like JDK 17 appear every three years. The latest LTS release, JDK 11, was published in September 2018. New versions of Java appear every six months.