Runtime.Version (Java SE 9 & JDK 9 ) (original) (raw)

A representation of a version string for an implementation of the Java SE Platform. A version string consists of a version number optionally followed by pre-release and build information.

Version numbers

A version number, $VNUM, is a non-empty sequence of elements separated by period characters (U+002E). An element is either zero, or an unsigned integer numeral without leading zeros. The final element in a version number must not be zero. The format is:

[1-9][0-9]*((\.0)*\.[1-9][0-9]*)*

The sequence may be of arbitrary length but the first three elements are assigned specific meanings, as follows:

<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>M</mi><mi>A</mi><mi>J</mi><mi>O</mi><mi>R</mi><mi mathvariant="normal">.</mi></mrow><annotation encoding="application/x-tex">MAJOR.</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6833em;"></span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mord mathnormal">A</span><span class="mord mathnormal" style="margin-right:0.09618em;">J</span><span class="mord mathnormal" style="margin-right:0.00773em;">OR</span><span class="mord">.</span></span></span></span>MINOR.$SECURITY

$MAJOR --- The major version number, incremented for a major release that contains significant new features as specified in a new edition of the Java SE Platform Specification, e.g., JSR 337 for Java SE 8. Features may be removed in a major release, given advance notice at least one major release ahead of time, and incompatible changes may be made when justified. The $MAJOR version number of JDK 8 is 8; the $MAJOR version number of JDK 9 is 9. When $MAJOR is incremented, all subsequent elements are removed.
$MINOR --- The minor version number, incremented for a minor update release that may contain compatible bug fixes, revisions to standard APIs mandated by aMaintenance Release of the relevant Platform Specification, and implementation features outside the scope of that Specification such as new JDK-specific APIs, additional service providers, new garbage collectors, and ports to new hardware architectures.
$SECURITY --- The security level, incremented for a security update release that contains critical fixes including those necessary to improve security. $SECURITY is not reset when $MINOR is incremented. A higher value of $SECURITY for a given $MAJOR value, therefore, always indicates a more secure release, regardless of the value of $MINOR.

The fourth and later elements of a version number are free for use by downstream consumers of this code base. Such a consumer may,e.g., use the fourth element to identify patch releases which contain a small number of critical non-security fixes in addition to the security fixes in the corresponding security release.

The version number does not include trailing zero elements;i.e., $SECURITY is omitted if it has the value zero, and $MINOR is omitted if both $MINOR and $SECURITY have the value zero.

The sequence of numerals in a version number is compared to another such sequence in numerical, pointwise fashion; e.g., 9.9.1 is less than 9.10.3. If one sequence is shorter than another then the missing elements of the shorter sequence are considered to be less than the corresponding elements of the longer sequence; e.g., 9.1.2 is less than 9.1.2.1.

Version strings

A version string, $VSTR, consists of a version number $VNUM, as described above, optionally followed by pre-release and build information, in one of the following formats:

<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mi>N</mi><mi>U</mi><mi>M</mi><mo stretchy="false">(</mo><mo>−</mo></mrow><annotation encoding="application/x-tex">VNUM(-</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.22222em;">V</span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">(</span><span class="mord">−</span></span></span></span>PRE)?\+$BUILD(-$OPT)?
<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mi>N</mi><mi>U</mi><mi>M</mi><mo>−</mo></mrow><annotation encoding="application/x-tex">VNUM-</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.7667em;vertical-align:-0.0833em;"></span><span class="mord mathnormal" style="margin-right:0.22222em;">V</span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mord">−</span></span></span></span>PRE(-$OPT)?
<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mi>N</mi><mi>U</mi><mi>M</mi><mo stretchy="false">(</mo><mo>+</mo><mo>−</mo></mrow><annotation encoding="application/x-tex">VNUM(+-</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.22222em;">V</span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">(</span><span class="mord">+</span><span class="mord">−</span></span></span></span>OPT)?

where:

$PRE, matching ([a-zA-Z0-9]+) --- A pre-release identifier. Typically ea, for a potentially unstable early-access release under active development, or internal, for an internal developer build.
$BUILD, matching (0|[1-9][0-9]*) --- The build number, incremented for each promoted build. $BUILD is reset to 1 when any portion of $VNUM is incremented.
$OPT, matching ([-a-zA-Z0-9.]+) --- Additional build information, if desired. In the case of an internal build this will often contain the date and time of the build.

A version string 10-ea matches $VNUM = "10" and$PRE = "ea". The version string 10+-ea matches$VNUM = "10" and $OPT = "ea".

When comparing two version strings, the value of $OPT, if present, may or may not be significant depending on the chosen comparison method. The comparison methods compareTo() and compareToIgnoreOptional() should be used consistently with the corresponding methods equals() and equalsIgnoreOptional().

A short version string, $SVSTR, often useful in less formal contexts, is a version number optionally followed by a pre-release identifier:

<span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mi>N</mi><mi>U</mi><mi>M</mi><mo stretchy="false">(</mo><mo>−</mo></mrow><annotation encoding="application/x-tex">VNUM(-</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:1em;vertical-align:-0.25em;"></span><span class="mord mathnormal" style="margin-right:0.22222em;">V</span><span class="mord mathnormal" style="margin-right:0.10903em;">N</span><span class="mord mathnormal" style="margin-right:0.10903em;">U</span><span class="mord mathnormal" style="margin-right:0.10903em;">M</span><span class="mopen">(</span><span class="mord">−</span></span></span></span>PRE)?

This is a value-based class; use of identity-sensitive operations (including reference equality (==), identity hash code, or synchronization) on instances ofVersion may have unpredictable results and should be avoided.