Understanding Time-Based Release Versioning

Feature Release

Starting Java 10, a new strict, time-based release model has been adopted. In this new model, major releases (now called feature releases) of the Java platform will occur every 6 months (March and Sept).

Feature releases will contain language features, JVM features and new improved APIs. The feature release can also remove unwanted/deprecated old features.

The new time-based model has replaced the feature-based, multi-year release model of the past. Unlike the old releases, the new time-based releases will not be delayed and will be released every six months, with no constraints on what features can go out in the releases.

Update Release

The updates releases will occur every quarter (Jan, April, July, Oct).

Update releases will be strictly limited to fixes of security issues, regressions, and bugs in newer features.

Each feature release will receive two updates before the next feature release.

Long Term Release (LTS)

Every three years, starting in September of 2018, the feature release will be a long-term support release. Updates for these releases will be available for at least three years

Version Format

$FEATURE.$INTERIM.$UPDATE.$PATCH

A version number never has trailing zero elements. If an element and all those that follow it, have the value zero then all of them are omitted.

Using Runtime.Version

java.lang.RuntimeVersion can be used to get version information.

public class VersionTest {
  public static void main(String[] args) {
      Runtime.Version version = Runtime.version();
      printVersionInfo(version);
  }

  private static void printVersionInfo(Runtime.Version version) {
      int feature = version.feature();
      int interim = version.interim();
      int update = version.update();
      int patch = version.patch();
      System.out.printf(" feature: %s%n interim: %s%n update: %s%n patch: %s%n",
              feature, interim, update, patch);
  }
}

 feature: 10
 interim: 0
 update: 0
 patch: 0

We can also use Version#parse() method to test version strings. For example Java 10 next update (in April 2018) will have version string 10.0.1. Let's try that:

public class VersionParseTest {
  public static void main(String[] args) {
      Runtime.Version version = Runtime.Version.parse("10.0.1");
      printVersionInfo(version);
  }

  private static void printVersionInfo(Runtime.Version version) {
      int feature = version.feature();
      int interim = version.interim();
      int update = version.update();
      int patch = version.patch();
      System.out.printf(" feature: %s%n interim: %s%n update: %s%n patch: %s%n",
              feature, interim, update, patch);
  }
}

 feature: 10
 interim: 0
 update: 1
 patch: 0

The old methods major() and minor() have been deprecated. They forward calls to feature() and interim() respectively:

public class VersionMajorMinor {
  public static void main(String[] args) {
      Runtime.Version version = Runtime.version();
      System.out.println(version.major());
      System.out.println(version.minor());
  }
}

10
0

Using SourceVersion

package com.logicbig.example;

import javax.lang.model.SourceVersion;

public class SourceVersionTest {
  public static void main(String[] args) {
      SourceVersion latest = SourceVersion.latest();
      System.out.println(latest);
  }
}

RELEASE_10

Version related new System properties

java.version.date: The general-availability (GA) date of this release.

java.vendor.version: An implementor-specific product version string.

public class VersionSystemProperties {
  public static void main(String[] args) {
      String versionDate = System.getProperty("java.version.date");
      System.out.println("java.version.date: " + versionDate);

      String vendorVersion = System.getProperty("java.vendor.version");
      System.out.println("java.vendor.version: " + vendorVersion);
  }
}

java.version.date: 2018-03-20
java.vendor.version: 18.3

Other than above new properties, followings are other version related properties:

public class VersionSystemProperties2 {
  public static void main(String[] args) {
      System.out.println("java.version: " +
              System.getProperty("java.version"));
      System.out.println("java.runtime.version: " +
              System.getProperty("java.runtime.version"));
      System.out.println("java.vm.version: " +
              System.getProperty("java.vm.version"));
      System.out.println("java.specification.version: " +
              System.getProperty("java.specification.version"));
      System.out.println("java.vm.specification.version: " +
              System.getProperty("java.vm.specification.version"));
  }
}

java.version: 10
java.runtime.version: 10+46
java.vm.version: 10+46
java.specification.version: 10
java.vm.specification.version: 10

Java Launcher version string

$ java -version
java version "10" 2018-03-20
Java(TM) SE Runtime Environment 18.3 (build 10+46)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10+46, mixed mode)

The output of the java launcher is formatted as follows:

$ java --version
java version ${java.version} ${java.version.date}${LTS}
${java.runtime.name}${JVV} (build ${java.runtime.version})
${java.vm.name}${JVV} (build ${java.vm.version}, ${java.vm.info})

The build number can also be found via Runtime.Version.build().

Class File Version Number

The class file version has been changed from 53 to 54 (JDK-8191510), even though JDK 10 did not introduce the changes to the class file format.

The class file version number can be seen via javap command:

$ javap -verbose output/com.logicbig.example.SourceVersionTest
 Last modified Apr 2, 2018; size 723 bytes
 MD5 checksum 7db715f4329811ca26194813f4f3e08b
 Compiled from "SourceVersionTest.java"
public class com.logicbig.example.SourceVersionTest
 minor version: 0
 major version: 54
 flags: (0x0021) ACC_PUBLIC, ACC_SUPER
 this_class: #5 // com/logicbig/example/SourceVersionTest
 super_class: #6 // java/lang/Object
 interfaces: 0, fields: 0, methods: 2, attributes: 1

.......

Example Project

Dependencies and Technologies Used:

• JDK 9.0.1