Develop Reference

How to make a Programm written in jdk12 on windows over intellij and compiled to .jar run in Linux with openJDK

i have developed a small server, which works perfecctly in windows. i compiled this to a .jar file and pushed it to my linux server. I am unable to run the programm because of a version error. i found many informations on the internet but nothing solved my problem.
i developed it in windows with intellij using oracle jdk 12 and compiled it allready.
i have installed the default jdk (IcedTea 2.6.19) in my debian linux. i have also unzipped an openjdk 13 tar file but i dont know how and even if it is possible to execute this.
Exception in thread "main" java.lang.UnsupportedClassVersionError:
MultiThreadServer : Unsupported major.minor version 56.0
i would appriciate a solution. If i have to install an oracle jdk on my linux i would like to know how. i am new in windows and dont know how

You are probably trying to run your program against an inferior version of java. You can check it by typing java -version
In order to make sure you are running the right java version for your program you may try:
Use the full path of your JRE when launching the app. Let's say (I am only guessing where you could have unzipped your OpenJDK 13):
export JAVA_HOME=/opt/java/openjdk/13
$JAVA_HOME/bin/java -jar whatever_my_app.jar

How to resolve GLIBC 2.14 error from RHEL6 servers

I have recently installed openjdk8 on RHEL6 and 7 servers. Build works on RHEl7 but giving error on RHEL6:
/lib64/libc.so.6: version `GLIBC_2.14' not found (required by ../bin/../lib/amd64/jli/libjli.so)
ldd (GNU libc) 2.12 is installed on RHEL6, Do i need to upgrade it ?
How to resolve this issue ?

It seems that Java binary that you installed was compiled against different version of GLIBC. You might be using an RPM for RHEL7 on RHEL6.
You either need to compile the Java on RHEL6 yourself or find the correct RPM. As per OpenJDK Life Cycle and Support Policy docs Java 8 is only officially supported on RHEL 6.6 or higher.

Installing multiple java versions on Unix

Does installing JDK 1.7 remove JDK 1.5? Because when I tried to restart Tomcat which was using Java 1.5 I have got the below error:
/opt/tomcat/bin/catalina.sh: line 332: /usr/java/jdk1.5.0_22/bin/java: No such file or directory
Verified that this directory is gone. Tomcat services running fine until shutting down and attempting to restart last night. When trying to install Java 1.5 J have got the below error message:
Preparing... ########################################### [100%]
package jdk-2000:1.7.0_17-fcs.x86_64 (which is newer than jdk -2000:1.5.0_22-fcs.x86_64) is already installed"
Will installing JDK 1.7 remove JDK 1.5?
How do I install JDK 1.5?

It depends on how you installed (which package manager or if you used the self-extracting sh or unzip). Normally, no, they don't install over, they install alongside and simply replace symbolic links.
If you follow your symbolic links for java (which java | ls -l)... you'll find the install dir of the jdk1.7, and probably find 1.5 nearby.

You can download the JDK from the Oracle Java archive page and you can extract it to the required location to fix your problem.
http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-javase5-419410.html

Flex mxmlc error loading JVM windows 7 64 bit

I'am executing this command in my windows 7 console:
mxmlc
then I get:
Error loading: C:\Program Files (x86)\Java\jre7\bin\client\jvm.dll
How to fix this?
the jvm.dll exists in that directory, but why the error occurs?, I've tried to reinstall java, but it didn't helped

The flash compiler, mxmlc, does not run under a 64 bit jvm. According to the 4.6 SDK docs:
Note: You must use a 32-bit version of the JDK, version 1.5 or later. The command line compilers do not work with a 64-bit JDK.
Unfortunately, You will need to install a 32 bit jvm.

Java JRE versions incompatibilty

I have a question regarding the compatibility between different java versions.
On my computer, I have java version "1.7.0_02".
But when I uploaded the .class and embedded it in a webpage it does not work
I get the error:
"Unsupported major.minor version 51.0"
the heading at the top of the console says:
"Java Plug-in 1.6.0_31
Using JRE version 1.6.0_31-b05 Java HotSpot(TM) Client VM"
I would like to ask what is causing the problem. Is it really my java version?
I mean, I visited the site with the computer I compiled the applet in.

You can't use classes compiled to Java 1.7-compatibility class files with an earlier virtual machine, and that "Java Plug-in" error you're seeing says that's exactly what happen.
Two options:
if you're not using Java 1.7 only features, you can compile your code to be compatible with 1.6 JVM's using the option -target 1.6 (see docs here)
Upgrade the Java plug-in your browser is using to 1.7, if possible (I don't think you can do this on OS X, for example). You didn't note what OS and browser you're using so I'm not sure what the upgrade path would be, if any.

Thanks for the answers, I figured out what was wrong.
I started off with both 1.7 and 1.6 on my machine, and it was really confusing me.
The problem was, 1.7 was 64 bit, and 1.6 was 32 bit.
My browser was chrome 32 bit.
I just installed 1.7 32 bit and it was fine