Module java.base
Package java.lang

Class Runtime.Version

  • All Implemented Interfaces:
    Comparable<Runtime.Version>
    Enclosing class:
    Runtime

    public static final class Runtime.Version
extends Object
implements Comparable<Runtime.Version>
    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:

         $MAJOR.$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 a Maintenance 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: 

         $VNUM(-$PRE)?\+$BUILD(-$OPT)?
     $VNUM-$PRE(-$OPT)?
     $VNUM(+-$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:

         $VNUM(-$PRE)?

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

    Since:
    9

    • Method Detail

      • major

        public int major​()
        Returns the major version number.
        Returns:
        The major version number

      • minor

        public int minor​()
        Returns the minor version number or zero if it was not set.
        Returns:
        The minor version number or zero if it was not set

      • security

        public int security​()
        Returns the security version number or zero if it was not set.
        Returns:
        The security version number or zero if it was not set

      • version

        public List<Integer> version​()
        Returns an unmodifiable List of the integer numerals contained in the version number. The List always contains at least one element corresponding to the major version number.
        Returns:
        An unmodifiable list of the integer numerals contained in the version number

      • pre

        public Optional<String> pre​()
        Returns the optional pre-release information.
        Returns:
        The optional pre-release information as a String

      • optional

        public Optional<String> optional​()
        Returns optional additional identifying build information.
        Returns:
        Additional build information as a String

      • compareTo

        public int compareTo​(Runtime.Version obj)
        Compares this version to another.

        Each of the components in the version is compared in the following order of precedence: version numbers, pre-release identifiers, build numbers, optional build information.

        Comparison begins by examining the sequence of version numbers. 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.

        A version with a pre-release identifier is always considered to be less than a version without one. Pre-release identifiers are compared numerically when they consist only of digits, and lexicographically otherwise. Numeric identifiers are considered to be less than non-numeric identifiers.

        A version without a build number is always less than one with a build number; otherwise build numbers are compared numerically.

        The optional build information is compared lexicographically. During this comparison, a version with optional build information is considered to be greater than a version without one.

        Specified by:
        compareTo in interface Comparable<Runtime.Version>
        Parameters:
        obj - The object to be compared
        Returns:
        A negative integer, zero, or a positive integer if this Version is less than, equal to, or greater than the given Version
        Throws:
        NullPointerException - If the given object is null

      • compareToIgnoreOptional

        public int compareToIgnoreOptional​(Runtime.Version obj)
        Compares this version to another disregarding optional build information.

        Two versions are compared by examining the version string as described in compareTo(Version) with the exception that the optional build information is always ignored.

        This method provides ordering which is consistent with equalsIgnoreOptional().

        Parameters:
        obj - The object to be compared
        Returns:
        A negative integer, zero, or a positive integer if this Version is less than, equal to, or greater than the given Version
        Throws:
        NullPointerException - If the given object is null

      • toString

        public String toString​()
        Returns a string representation of this version.
        Overrides:
        toString in class Object
        Returns:
        The version string

      • equals

        public boolean equals​(Object obj)
        Determines whether this Version is equal to another object.

        Two Versions are equal if and only if they represent the same version string.

        Overrides:
        equals in class Object
        Parameters:
        obj - The object to which this Version is to be compared
        Returns:
        true if, and only if, the given object is a Version that is identical to this Version
        See Also:
        Object.hashCode(), HashMap

      • equalsIgnoreOptional

        public boolean equalsIgnoreOptional​(Object obj)
        Determines whether this Version is equal to another disregarding optional build information.

        Two Versions are equal if and only if they represent the same version string disregarding the optional build information.

        Parameters:
        obj - The object to which this Version is to be compared
        Returns:
        true if, and only if, the given object is a Version that is identical to this Version ignoring the optional build information