Jackcess from R using rJava in OSX - java

I tried all the suggestions in this related question and still get the last error
library(rJava)
.jinit(force.init = T)
.jaddClassPath(dir('~/Dropbox/R_packages/JavaJS/',full.names = TRUE)))
mol.db <- "~/Downloads/SEPULVEDA_MOLECULAR.accdb"
jfile = .jnew('java/io/File',mol.db)
dbbo <- .jnew("com/healthmarketscience/jackcess/DatabaseBuilder")
dbbo <- .jcall(dbbo,"Lcom/healthmarketscience/jackcess/DatabaseBuilder;","setFile",jfile)
db <- .jcall(dbbo,"Lcom/healthmarketscience/jackcess/Database;","open",evalArray = FALSE,evalString = FALSE) # fails!!!!
Error in .jcall(dbbo, "Lcom/healthmarketscience/jackcess/Database;", "open", :
java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
Here is the result of .jclassPath()
"/Users/JS/Dropbox/R_packages/library/rJava/java"
"/Users/JS/Dropbox/R_packages/JavaJS/commons-codec-1.10"
"/Users/JS/Dropbox/R_packages/JavaJS/commons-lang-2.6"
"/Users/JS/Dropbox/R_packages/JavaJS/commons-logging-1.1.3"
"/Users/JS/Dropbox/R_packages/JavaJS/hsqldb-2.2.8.jar"
"/Users/JS/Dropbox/R_packages/JavaJS/jackcess-2.1.6.jar" "/Users/JS/Dropbox/R_packages/JavaJS/log4j-1.2.7.jar"
"/Users/JS/Dropbox/R_packages/JavaJS/poi-3.9"
"/Users/JS/Dropbox/R_packages/JavaJS/ucanaccess-3.0.7.jar"
sessionInfo()
R version 3.3.2 (2016-10-31)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X El Capitan 10.11.6
locale:
1 en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
1 stats graphics grDevices utils datasets methods base
other attached packages:
1 rJava_0.9-8 tibble_1.2 datapasta_1.0.0 rlist_0.4.6.1 pipeR_0.6.1.3 janitor_0.2.1 data.table_1.10.0
loaded via a namespace (and not attached):
1 magrittr_1.5 R6_2.2.0 assertthat_0.1 tools_3.3.2 DBI_0.5-1 dplyr_0.5.0 Rcpp_0.12.8
Thanks for any help!

Related

Why is the CLASSPATH failing for Python but working for RazorSQL?

On Windows Server 2016, we are trying to connect over JDBC with a Jython script but it is giving following error:
java.lang.ClassNotFoundException: java.lang.ClassNotFoundException:
com.microsoft.sqlserver.jdbc.SQLServerDriver
RazorSQL, on the same machine, connects without error using these settings:
Driver Class: com.microsoft.sqlserver.jdbc.SQLServerDriver
Driver Location: \Program Files (x86)\RazorSQL\drivers\sqlserver\sqljdbc.jar
As a result, we set the CLASSPATH to same location with this command:
set CLASSPATH=C:\Program Files (x86)\RazorSQL\drivers\sqlserver\sqljdbc.jar
...but when running the code below - we still get the same ClassNotFound error.
This is our Python code:
jclassname = "com.microsoft.sqlserver.jdbc.SQLServerDriver"
database = "our_database_name"
db_elem = ";databaseName={}".format(database) if database else ""
host = "###.##.###.###" # ip address
port = "1433"
user = "user_name"
password = "password"
url = (
 jdbc:sqlserver://{host}:{port}{db_elem}"
 ";user={user};password={password}".format(
host=host, port=port, db_elem=db_elem,
 er=user, password=password)
 )
print url
 
driver_args = [url]
jars = None
libs = None
db = jaydebeapi.connect(jclassname, driver_args, jars=jars,
libs=libs)
This is how we are running our Python script:
C:\jython2.7.0\bin\jython.exe C:\path_to_our_script.py
How is that RazorSQL is connecting fine - but somehow Python cannot? How do we remove this CLASSPATH error?
You have to load the JARs at runtime using the system Classloader.
Please refer to this answer.
The following code snippet has been taken from this Gist.
def loadJar(jarFile):
'''load a jar at runtime using the system Classloader (needed for JDBC)
adapted from http://forum.java.sun.com/thread.jspa?threadID=300557
Author: Steve (SG) Langer Jan 2007 translated the above Java to Jython
Reference: https://wiki.python.org/jython/JythonMonthly/Articles/January2007/3
Author: seansummers#gmail.com simplified and updated for jython-2.5.3b3+
>>> loadJar('jtds-1.3.1.jar')
>>> from java import lang, sql
>>> lang.Class.forName('net.sourceforge.jtds.jdbc.Driver')
<type 'net.sourceforge.jtds.jdbc.Driver'>
>>> sql.DriverManager.getDriver('jdbc:jtds://server')
jTDS 1.3.1
'''
from java import io, net, lang
u = io.File(jarFile).toURL() if type(jarFile) <> net.URL else jarFile
m = net.URLClassLoader.getDeclaredMethod('addURL', [net.URL])
m.accessible = 1
m.invoke(lang.ClassLoader.getSystemClassLoader(), [u])
if __name__ == '__main__':
import doctest
doctest.testmod()
Also look at - https://wiki.python.org/jython/JythonMonthly/Articles/January2007/3

R: JDBC() not finding Java drivers path when connecting to Teradata

I'm trying to connect to Teradata through RStudio, but for some reason JDBC function has problems recognizing the path where Java drivers sit. See the code below:
library(RODBC)
library(RJDBC)
library(rJava)
# both Java drivers definitely exist
file.exists('/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/tdgssconfig.jar')
[1] TRUE
file.exists('/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/terajdbc4.jar')
[1] TRUE
But when I paste those paths in JDBC call...
# allow more elaborated error messages to appear
.jclassLoader()$setDebug(1L)
drv = JDBC("com.teradata.jdbc.TeraDriver","/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/tdgssconfig.jar;/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/terajdbc4.jar")
... I get the following error:
RJavaClassLoader: added
'/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/tdgssconfig.jar;/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/terajdbc4.jar'
to the URL class path loader WARNING: the path
'/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/tdgssconfig.jar;/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/terajdbc4.jar'
does NOT exist, it will NOT be added to the internal class path!
RJavaClassLoader: added
'/Library/Frameworks/R.framework/Versions/3.4/Resources/library/RJDBC/java/RJDBC.jar'
to the URL class path loader RJavaClassLoader: adding Java archive
file
'/Library/Frameworks/R.framework/Versions/3.4/Resources/library/RJDBC/java/RJDBC.jar'
to the internal class path
RJavaClassLoader#3d4eac69.findClass(com.teradata.jdbc.TeraDriver)
- URL loader did not find it: java.lang.ClassNotFoundException: com.teradata.jdbc.TeraDriver
RJavaClassLoader.findClass("com.teradata.jdbc.TeraDriver")
- trying class path "/Library/Frameworks/R.framework/Versions/3.4/Resources/library/rJava/java"
Directory, can get
'/Library/Frameworks/R.framework/Versions/3.4/Resources/library/rJava/java/com/teradata/jdbc/TeraDriver.class'?
NO
- trying class path "/Library/Frameworks/R.framework/Versions/3.4/Resources/library/RJDBC/java/RJDBC.jar"
JAR file, can get 'com/teradata/jdbc/TeraDriver'? NO
ClassNotFoundException Error in .jfindClass(as.character(driverClass)[1]) : class not found
Running the same code in R, rather than RStudio, returns the same error.
Also, re-installing RJDBC package (as suggested here) didn't solve the issue.
Can anyone explain why this is happening? Thanks for help.
Here's my session info:
> sessionInfo()
R version 3.4.1 (2017-06-30)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.3
Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRlapack.dylib
locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] devtools_1.13.4 RJDBC_0.2-7 rJava_0.9-9 DBI_0.8 RODBC_1.3-15
[6] dplyr_0.7.4 readr_1.1.1
loaded via a namespace (and not attached):
[1] Rcpp_0.12.15 bindr_0.1 magrittr_1.5 hms_0.3 R6_2.2.2
[6] rlang_0.1.6 httr_1.3.1 tools_3.4.1 git2r_0.19.0 withr_2.1.1.9000
[11] yaml_2.1.16 assertthat_0.2.0 digest_0.6.15 tibble_1.4.2 bindrcpp_0.2
[16] curl_3.0 memoise_1.1.0 glue_1.2.0 compiler_3.4.1 pillar_1.1.0
[21] pkgconfig_2.0.1
That's a mistake in the path - you have inadvertently pasted two paths together (note the semicolon between the paths). You probably intended
drv <- JDBC("com.teradata.jdbc.TeraDriver",
c("/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/tdgssconfig.jar",
"/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/terajdbc4.jar"))
note that you probably can make your life easier by simply using
drv <- JDBC("com.teradata.jdbc.TeraDriver", Sys.glob("/Users/KULMAK/Documents/TeraJDBC__indep_indep.16.10.00.03/*.jar"))
This worked for me. Just make sure that both jars are located in the referenced directory.
library(RJDBC)
drv <- RJDBC::JDBC(driverClass = "com.teradata.jdbc.TeraDriver", classPath = Sys.glob("~/drivers/teradata/*"))
conn <- dbConnect(drv,'jdbc:teradata://<server>/<db>',"un","pw")
result.df<- dbGetQuery(conn,"select * from table")

Error in RWeka in R package

I have searched SO and everywhere else and nothing works to fix the unsupported major.minor version 51 error. I uninstalled Java 8 and installed Java 7. No luck.
Thank you for your help.
I am using:
R 3.3.1
Java 8.91
OSX, el capitan
library(NLP)
library(tm)
library(RWeka)
library(rJava)
library((RWekajars))
library(parallel)
options(mc.cores=1)
Here is the R code causing the error:
trigram <- function(x){NGramTokenizer(x,control=Weka_control(min=3,max=3))}
tdm <- TermDocumentMatrix(corpus2,control=list(tokenize=trigram))
Here is the error I get.
Error in .jnew(name) :
java.lang.UnsupportedClassVersionError: weka/core/tokenizers/NGramTokenizer : Unsupported major.minor version 51.0
9 stop(structure(list(message = "java.lang.UnsupportedClassVersionError: weka/core/tokenizers/NGramTokenizer : Unsupported major.minor version 51.0",
call = .jnew(name), jobj = <S4 object of class structure("jobjRef", package = "rJava")>), .Names = c("message",
"call", "jobj"), class = c("UnsupportedClassVersionError", "ClassFormatError",
"LinkageError", "Error", "Throwable", "Object", "Exception", ...
8 .jnew(name)
7 NGramTokenizer(x, control = Weka_control(min = 3, max = 3))
6 .tokenize(doc)
5 FUN(X[[i]], ...)
4 lapply(X = X, FUN = FUN, ...)
3 mclapply(unname(content(x)), termFreq, control)
2 TermDocumentMatrix.VCorpus(corpus2, control = list(tokenize = trigram))
1 TermDocumentMatrix(corpus2, control = list(tokenize = trigram))
I was also using NGramTokenizer(x, control = Weka_control(min = 3, max = 3))
and it was creating errors for me. I came across this tokenizer and it fixed the issue for me.
TrigramTokenizer <-
function(x)
unlist(lapply(ngrams(words(x), 3), paste, collapse = " "), use.names = FALSE)
please see: https://rpubs.com/hokumski/capstone-milestone-week2 for more information
I've been trying to solve this same issue all week. I've been using Java 1.8 which I read is fine. However the problem seems to be in the rJava package that's installing inside of R. Once I installed from rforge.net using the following line everything worked.
install.packages("rJava","http://rforge.net/",type="source")

Java check latest version programmatically

Goal: check java's version on a machine (I can get this from java -version). Compare it with latest available from java website
I would like to know if there is any way I can check for latest Java releases assuming that I have JRE/JDK installed on a machine.
If I can do this through Java itself, my solution would become platform independent. I could use java.net.URL class to send a request to Java website and get the HTML, however the response would be dynamic as Oracle can change their website and styles and possibly will have maintenance issues in long run.
I have looked at javatester.org, but I would not want it through an applet but through command line (which I can add to a script).
Through javacpl.exe, I can schedule periodic checks, but I would like to do it on demand.
The answer is actually quite simple. http://java.com/en/download/testjava.jsp issues a request to http://java.com/applet/JreCurrentVersion2.txt. That file currently contains a single version number: '1.7.0_11'...which is the latest and greatest, indeed.
Java code example
try (BufferedReader br = new BufferedReader(new InputStreamReader(new URL(
"http://java.com/applet/JreCurrentVersion2.txt").openStream()))) {
String fullVersion = br.readLine();
String version = fullVersion.split("_")[0];
String revision = fullVersion.split("_")[1];
System.out.println("Version " + version + " revision " + revision);
} catch (IOException e) {
// handle properly
}
Update 2014-03-20
Eventhough Java 8 was recently released http://java.com/applet/JreCurrentVersion2.txt currently still returns 1.7.0_51.
Update 2016-07-13
Looks like we need to come back to this every few months... Currently you need to scan http://java.com/en/download/installed8.jsp for a JavaScript variable latest8Version. So, you could run curl -s https://java.com/en/download/installed8.jsp | grep latest8Version.
Update 2018-08-19
http://javadl-esd-secure.oracle.com/update/baseline.version is another hot spot as mentioned in some other answer.
An URL very similar to the now defunct "JreCurrentVersion2.txt":
http://javadl-esd-secure.oracle.com/update/baseline.version
The contents of the link look like this:
1.8.0_111
1.7.0_121
1.6.0_131
1.5.0_99
1.4.2_43
You can easily parse the contents to find the latest JRE versions.
UPDATE: I don't recommend this method because this JRE is the one that has the Ask.com toolbar. You're better off downloading it yourself and distributing it yourself.
The jusched.exe program accesses the following URL to find out what versions are available. I think it's less likely to change because jusched is installed on millions of computers.
https://javadl-esd-secure.oracle.com/update/1.7.0/map-m-1.7.0.xml
Here is a snippet of what it returns for me:
<?xml version="1.0" encoding="ISO-8859-1" standalone="yes" ?>
<java-update-map version="1.0">
<mapping>
<version>1.7.0_17</version>
<url>https://javadl-esd-secure.oracle.com/update/1.7.0/au-descriptor-1.7.0_25-b17.xml</url>
</mapping>
<mapping>
<version>1.7.0_21</version>
<url>https://javadl-esd-secure.oracle.com/update/1.7.0/au-descriptor-1.7.0_25-b17.xml</url>
</mapping>
</java-update-map>
To get the actual version that it is pointing to you have to fetch the above URL. Here is another snippet of what this XML looks like:
xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!-- XML file to be staged anywhere, and pointed to by map.xml file -->
<java-update>
<information version="1.0" xml:lang="en">
<caption>Java Update - Update Available</caption>
<title>Java Update Available</title>
<description>Java 7 Update 25 is ready to install. Installing Java 7 Update 25 might uninstall the latest Java 6 from your system. Click the Install button to update Java now. If you wish to update Java later, click the Later button.</description>
<moreinfo>http://java.com/moreinfolink</moreinfo>
<AlertTitle>Java Update Available</AlertTitle>
<AlertText>A new version of Java is ready to be installed.</AlertText>
<moreinfotxt>More information...</moreinfotxt>
<url>http://javadl.sun.com/webapps/download/GetFile/1.7.0_25-b17/windows-i586/jre-7u25-windows-i586-iftw.exe</url>
<version>1.7.0_25-b17</version>
<post-status>https://nometrics.java.com</post-status>
<cntry-lookup>http://rps-svcs.sun.com/services/countrylookup</cntry-lookup>
<predownload></predownload>
<options>/installmethod=jau FAMILYUPGRADE=1 SPWEB=http://javadl-esd.sun.com/update/1.7.0/sp-1.7.0_25-b17</options>
<urlinfo>24595ec7f861bc67e572f1e4ad3992441335e1a7</urlinfo>
</information>
</java-update>
The version tag contains the full version number.
You could parse the Java SE Downloads page to extract the Java versions.
That way, you get the version of both JDK6 and JDK7, which allows you to test your particular JDK (6 or 7) against the latest Oracle one.
(As opposed to the Free Java Download page, which only lists the JDK7)
Her is a crude script in Go, which you can compile on Windows, Unix, MacOs into a single independent executable, and use within a command line or a script:
package main
import (
"bytes"
"encoding/xml"
"fmt"
"io/ioutil"
"net/http"
"os/exec"
"regexp"
)
type Jdk struct {
Url string
Ver string
update string
}
func main() {
resp, err := http.Get("http://www.oracle.com/technetwork/java/javase/downloads/index.html")
if err != nil {
fmt.Printf("Error on http Get: %v\n", err)
return
}
bodyb, err := ioutil.ReadAll(resp.Body)
if err != nil {
fmt.Printf("QueriesForOwner: error in ReadAll: %v\n", err)
return
}
br := bytes.NewBuffer(bodyb)
jdkre, err := regexp.Compile(`h3[^\r\n]+(/technetwork/java/javase/downloads/(jdk(?:6|7)(?:u(\d+))?)-downloads-\d+\.html)`)
if err != nil {
fmt.Printf("extract: error in regexp compilation: %v\n", err)
return
}
jdks := jdkre.FindAllSubmatch(br.Bytes(), -1)
jdk7 := Jdk{string(jdks[0][4]), string(jdks[0][5]), string(jdks[0][6])}
jdk6 := Jdk{string(jdks[1][7]), string(jdks[1][8]), string(jdks[1][9])}
fmt.Printf("Jdk7: %v\nJdk6: %v\n", jdk7, jdk6)
jver, err := exec.Command("java", "-version").CombinedOutput()
if err != nil {
fmt.Printf("*ExitError from java -version:", err)
return
}
fmt.Println("JVer: '", string(jver), "'")
jverre, err := regexp.Compile(`1.(\d).\d(?:_(\d+))"`)
jvers := jverre.FindSubmatch(jver)
jj := string(jvers[0])
jv := string(jvers[1])
ju := string(jvers[2])
jdk := jdk6
if jv == "7" {
jdk = jdk7
}
if jdk.update != ju {
fmt.Println("Local JDK *NOT* up-to-date: you have ", jj, ", Oracle has ", jdk.Ver)
} else {
fmt.Println("Local JDK *up-to-date*: you have ", jj, ", equals to Oracle, which has", jdk.Ver)
}
}
Again, this is a crude script, oriented toward JDK, and you would need to adapt it to your specific need, making its output and exit status match what you need for your script.
On my (PC) workstation, it returns:
Jdk7: {/technetwork/java/javase/downloads/jdk7u9-downloads-1859576.html jdk7u9 9}
Jdk6: {/technetwork/java/javase/downloads/jdk6u37-downloads-1859587.html jdk6u37 37}
JVer: ' java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b05)
Java HotSpot(TM) Client VM (build 20.6-b01, mixed mode, sharing)
'
Local JDK *NOT* up-to-date: you have 1.6.0_31" , Oracle has jdk6u37
I don't know what information you are exactly looking for, but you can get some version information using
System.getProperty("java.version");
If this is not what you're looking for, check the other available properties here:
http://docs.oracle.com/javase/6/docs/api/java/lang/System.html#getProperties()
As for the latest available version, I guess you'd have to parse this site manually:
http://java.com/en/download/index.jsp
The latest version is on there, currently it's
Version 7 Update 9
You write that this is not what you want because "Oracle can change their website and styles". However, you want to find out the latest version of Java by accessing their service (website in this case). As long as you're not paying for this, they have no obligation to you, and can change the service whenever they want without your consent. And even when you're a paying customer, the best you can hope for is that they will inform you of upcoming changes, and your maintenance issues will remain.
Remember, it's THEIR service you want to use.
I have solved a similar issue some time ago with this groovy script (disclaimer: is somehow a "toy" script):
#Grapes([
#Grab(group='org.ccil.cowan.tagsoup', module='tagsoup', version='1.2.1')
])
def slurper = new XmlSlurper(new org.ccil.cowan.tagsoup.Parser())
def url = new URL("http://www.java.com/download/manual.jsp")
def html
url.withReader { reader ->
html = slurper.parse(reader)
}
def lastJava = html.body.div.div.div.strong.text()
println "Last available java version: ${lastJava}"
println "Currently installed java version: ${System.properties["java.version"]}"
It yields something like:
Last available java version:
Version 7 Update 9
Currently installed java version: 1.7.0_07
If you want to avoid maintenance issues due to changes to the page structure, maybe a better option is to search for a line containing "Version x Update y".
To get all system variables
Properties properties = System.getProperties();
System.out.println(properties);
Sample output, this might be different in your system depending on your OS and Java JDK/JRE version.
{
java.runtime.name = Java(TM) SE Runtime Environment,
sun.boot.library.path = C:\Program Files\Java\jdk1.8.0_31\jre\bin,
java.vm.version = 25.31-b07,
java.vm.vendor = Oracle Corporation,
java.vendor.url = http://java.oracle.com/,
path.separator = ;,
idea.launcher.port = 7534,
java.vm.name = Java HotSpot(TM) 64-Bit Server VM,
file.encoding.pkg = sun.io,
user.country = NP,
user.script = ,
sun.java.launcher = SUN_STANDARD,
sun.os.patch.level = ,
java.vm.specification.name = Java Virtual Machine Specification,
user.dir = C:\Users\...\roid,
java.runtime.version = 1.8.0_31-b13,
java.awt.graphicsenv = sun.awt.Win32GraphicsEnvironment,
java.endorsed.dirs = C:\Program Files\Java\jdk1.8.0_31\jre\lib\endorsed,
os.arch = amd64,
java.io.tmpdir = C:\Windows\TEMP\,
line.separator = ,
java.vm.specification.vendor = Oracle Corporation,
user.variant = ,
os.name = Windows 8.1,
sun.jnu.encoding = Cp1252,
java.library.path = C:\Program...roid,
java.specification.name = Java Platform API Specification,
java.class.version = 52.0,
sun.management.compiler = HotSpot 64-Bit Tiered Compilers,
os.version = 6.3,
user.home = C:\Users\Xxx,
user.timezone = Asia/Kathmandu,
java.awt.printerjob = sun.awt.windows.WPrinterJob,
file.encoding = UTF-8,
idea.launcher.bin.path = C:\Program Files (x86)\xxx\bin,
java.specification.version = 1.8,
java.class.path = C:\Program Files\Java\jdk1.8.0_31\jre\lib\charsets.jar;...,
user.name = Xxx,
java.vm.specification.version = 1.8,
sun.java.command = com.xxxx.ameras,
java.home = C:\Program Files\Java\jdk1.8.0_31\jre,
sun.arch.data.model = 64,
user.language = en,
java.specification.vendor = Oracle Corporation,
awt.toolkit = sun.awt.windows.WToolkit,
java.vm.info = mixed mode,
java.version = 1.8.0_31,
java.ext.dirs = C:\Program Files\Java\jdk1.8.0_31\jre\lib\ext;...,
java.vendor = Oracle Corporation,
file.separator = \,
java.vendor.url.bug = http://bugreport.sun.com/bugreport/,
sun.io.unicode.encoding = UnicodeLittle,
sun.cpu.endian = little,
sun.desktop = windows,
sun.cpu.isalist = amd64
}
Retrive only specific variable
String javaVersion = System.getProperty("java.version");
System.out.println(javaVersion);
Output
1.8.0_31
#MarcelStör's solution no longer works - the version in the file is 1.8.0_51, while the actual latest version is 1.8.0_91/92. If you go to the Java test page in Firefox or Chrome and open the development console you can get the variable latest8Version which currently is 1.8.0_91. This could be wrapped in a Selenium/Firefox solution, but is an incredibly hacky way of getting this information.
System.getProperty("java.vm.specification.version");
System.getProperty("java.version");

Mac OS JarLauncher problem

I am running a jar file on mac os.It generates following error
9/2/09 1:17:54 PM [0x0-0x30c30c].com.apple.JarLauncher[11128] at
content.Main.(Main.java:18)
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130]
SystemFlippers: didn't consume all data for long ID 0 (pBase =
0x10012ecc0, p = 0x10012ecc4, pEnd = 0x10012ecc8)
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130]
SystemFlippers: didn't consume all data for long ID 0 (pBase =
0x100110140, p = 0x100110144, pEnd = 0x100110148)
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130]
SystemFlippers: didn't consume all data for long ID 0 (pBase =
0x100110140, p = 0x100110144, pEnd = 0x100110148)
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130]
Exception in thread "main"
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130]
java.lang.NoClassDefFoundError: javax/swing/GroupLayout$Group
9/2/09 1:18:06 PM [0x0-0x30d30d].com.apple.JarLauncher[11130] at
content.Main.(Main.java:18)
Are there required java libraries i need on my mac ?
Thanks in Advance.
GroupLayout is introduced in java 1.6 , mac os 10.4 ,10.5 still uses java 1.5 by default. Even when 1.6 is installed you have to manually set os x to use 1.6. Or if you are the developer of the application, there are separate jars for GroupLayout. you can bundle that with your application and use GroupLayout with java 1.5.
Strange error.
From this line it looks like you are missing Swing:
java.lang.NoClassDefFoundError: javax/swing/GroupLayout$Group
It may be the case you are using gcj? Try downloading the latest version of Java and see if that improves things.
you can check which version you are currently using with:
java -version

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