Getting Java version at runtime

Question

I need to work around a Java bug in JDK 1 5 which was fixed in 1 6  I m using the following condition   if  System getProperty  java version   startsWith  1 5                 else               Will this work for other JVMs  Is there a better way to check this

User · Answer

Don t know another way of checking this  but this  http   java sun com j2se 1 5 0 docs api java lang System html getProperties    implies  java version  is a standard system property so I d expect it to work with other JVMs

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Here s the implementation in JOSM          Returns the Java version as an int value      return the Java version as an int value  8  9  etc       since 12130     public static int getJavaVersion         String version   System getProperty  java version        if  version startsWith  1               version   version substring 2                Allow these formats         1 8 0 72-ea        9-ea        9        9 0 1     int dotPos   version indexOf           int dashPos   version indexOf  -        return Integer parseInt version substring 0              dotPos  gt  -1   dotPos   dashPos  gt  -1   dashPos   1

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java version is a system property that exists in every JVM  There are two possible formats for it    Java 8 or lower  1 6 0 23  1 7 0  1 7 0 80  1 8 0 211 Java 9 or higher  9 0 1  11 0 4  12  12 0 1   Here is a trick to extract the major version  If it is a 1 x y z version string  extract the character at index 2 of the string  If it is a x y z version string  cut the string to its first dot character  if one exists   private static int getVersion         String version   System getProperty  java version        if version startsWith  1               version   version substring 2  3         else           int dot   version indexOf               if dot    -1    version   version substring 0  dot           return Integer parseInt version       Now you can check the version much more comfortably   if getVersion    lt  6

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If you can have dependency to apache utils you can use org apache commons lang3 SystemUtils       System out println  Is Java version at least 1 8      SystemUtils isJavaVersionAtLeast JavaVersion JAVA 1 8

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Runtime version   Since Java 9  you can use Runtime version    which returns a Runtime Version  Runtime Version version   Runtime version

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What about getting the version from the package meta infos   String version   Runtime class getPackage   getImplementationVersion      Prints out something like   1 7 0 13

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Just a note that in Java 9 and above  the naming convention is different  System getProperty  java version   returns  9  rather than  1 9

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The simplest way  java specification version    double version   Double parseDouble System getProperty  java specification version      if  version    1 5           1 5 specific code   else                  or something like  java version    String   javaVersionElements   System getProperty  java version   split          int major   Integer parseInt javaVersionElements 1     if  major    5           1 5 specific code   else                  or if you want to break it all up  java runtime version        String discard  major  minor  update  build   String   javaVersionElements   System getProperty  java runtime version   split        -b     discard   javaVersionElements 0   major     javaVersionElements 1   minor     javaVersionElements 2   update    javaVersionElements 3   build     javaVersionElements 4

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Example for Apache Commons Lang   import org apache commons lang SystemUtils       Float version   SystemUtils JAVA VERSION FLOAT       if  version  lt  1 4f                legacy       else if  SystemUtils IS JAVA 1 5               1 5 specific code       else if  SystemUtils isJavaVersionAtLeast 1 6f                1 6 compatible code       else              dodgy clause to catch 1 4

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Does not work  need --pos to evaluate double       String version   System getProperty  java version        System out println  version     version       int pos   0  count   0      for    pos  lt  version length    amp  amp  count  lt  2  pos              if  version charAt pos                        count                         --pos    EVALUATE double      double dversion   Double parseDouble version substring 0  pos        System out println  dversion     dversion       return dversion

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These articles seem to suggest that checking for 1 5 or 1 6 prefix should work  as it follows proper version naming convention   Sun Technical Articles   J2SE SDK JRE Version String Naming Convention Version 1 5 0 or 5 0     J2SE also keeps the version number 1 5 0  or 1 5  in some places that are visible only to developers  or where the version number is parsed by programs     java version system property    Version 1 6 0 Used by Developers    Java SE keeps the version number 1 6 0  or 1 6  in some places that are visible only to developers  or where the version number is parsed by programs      java version system property

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Here is the answer from  mvanle  converted to Scala   scala gt  val Array javaVerPrefix  javaVerMajor  javaVerMinor          System getProperty  java runtime version   split        -b   javaVerPrefix  String   1 javaVerMajor  String   8 javaVerMinor  String   0

[java] Getting Java version at runtime

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