Develop Reference

UnsupportedClassVersionError... but with same JAVA version

I am trying to migrate a tomcat server.
Both are using tomcat7 version and all is supossed to be ready to take my java/jsp files from one server to another.
I did and I got UnsupportedClassVersionError error.
It was normal as in the old one I had JRE 1.8 version and in the new installation I had JRE 1.7 version (both from Oracle).
I proceeded to upgrade the second to 1.8. And everything was fine as in the new the output for java -version is:
java version "1.8.0_191" Java(TM) SE Runtime Environment (build
1.8.0_191-b12) Java HotSpot(TM) 64-Bit Server VM (build 25.191-b12, mixed mode)
While in the old one:
java version "1.8.0_131" Java(TM) SE Runtime Environment (build
1.8.0_131-b11) Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)
In both echo $JAVA_HOME outputs:
/usr/lib/jvm/java-8-oracle
I restarted tomcat and server itself... but the UnsupportedClassVersionError persists.
I don't know if:
Somewhere I still point to the JRE 1.7 installation
Or 1.8.0_191 is considered another version than 1.8.0_131
Note: the compiler is the same as they have not been recompiled. Just take the compiled ones from old server (where there is no problem version) to the new one.
Has anyone a hint for me?
Thank you very much

As pointed in comments, sometimes JAVA_HOME is not checked and the decision on what jvm should be used is taken with another criteria (can't say which ones). So removing the old version of java forced the process to choose the desired one as it was unique.

How to find the java update version?

I have a jre installed installed in my windows.
When I use the command
java -version
I get the output -
java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) Client VM (build 21.0-b17, mixed mode)
I can see only the major version 1.7.
How to know which version of JRE update it is ?

Calling java -version will give you the installed version, including the update number (here: 51):
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)
It seems like you have the base version installed, so there is no update number:
java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) Client VM (build 21.0-b17, mixed mode)

I guess the build gives you the update you have.
You can try this as well-
java -fullversion
Version number translation: 1.6.0_34 is, in English, Java 6 Update 34

Looking at this page from the release note: http://www.oracle.com/technetwork/java/javase/jdk7-naming-418744.html
It seems you have the 1st java 7 version.
Oracle periodically makes updates available and, when an update occurs, the version string will also include the update version number. So, JDK 7 update 4, or JDK 7u4, will have the version string "1.7.0_4".

Normally the jre folder is named something like 1.VersionNumber.0_UpdateNumber
For 64 bit you can find this folder under C:\Program Files (x86)\Java
If your version Number just look like this: 1.VersionNumber.0, this means that you have the first release of given Java Version.

Why isn't javafx on the default classpath even when I have installed Oracle JDK 1.8?

I'm using Oracle JDK 1.8.0.45 on Kubuntu Linux which I installed following these instructions. I had to do the manual install since the automatic one didn't work.
Even with the Oracle JDK I still can't use javafx without manually setting the classpath. What could cause javafx to not be on the default classpath as it should be in 1.8?
EDIT: Java -version in terminal gives:
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.45-b02, mixed mode)

Problems with Java in OSX Mavericks

I'm trying to install Netbeans 8 but the installer is not finding JDK.
But, I can't update my Java, I installed the update 51 of java 7 but when I go in terminal I get it:
Alessandros-MacBook:~ alessandrogarcez$ java -version
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)
In "System preferences", I have version 7 installed.
It seems to have both version of java installed in my mac.
Someone can help me to solve it?
Thanks

I was trying to install jre-7u45-macosx-x64.dmg and I don't know why it doesn't overwrite java 6.
I've read a lot of topics, tried all of them.
http://support.apple.com/kb/DL1572?viewlocale=en_US
http://www.cc.gatech.edu/~simpkins/teaching/gatech/cs2340/guides/java7-macosx.html
After all of it, I just downloaded jdk-7u51-macosx-x64.dmg and it worked. The version 7 overwrited the 6.
Alessandros-MacBook:~ alessandrogarcez$ java -version
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

What is the source of the discrepancy in Java versions: Java 6 (in Terminal, Eclipse) and Java 7 (in Java Control panel)?

Eclipse complains: JRE version is 1.6.0; version 1.7.0 or later is needed to run Google Plugin for Eclipse.
In the Terminal, java concurs:
> java -version
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)
But in System Preferences \ Java \ the Java Control Panel says Your system has the recommended version of Java: Java 7 Update 51
and points to /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java.
Eclipse preferences show that the installed JRE is at:
/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
To point Eclipse to Java 7 (1.7.0), it's enough to change the preference:
What is the source of the discrepancy in Java versions? Is this an instance of having different PATHs between the command-line Mac and the windowed-Mac?
Edit
If I edit /usr/local/adt-bundle-mac-x86_64/eclipse/Eclipse.app/Contents/MacOS/eclipse.ini by adding
-vm
"/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java"
Eclipse refuses to start.
And yet this is indeed 1.7:
> "/Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home/bin/java" -version
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

If you want to be certain of the JVM that is used to run Eclipse, you need to specify it in your eclipse.ini file, according to these instructions.

Installing this update might fix your problem:
http://support.apple.com/kb/dl1572