Installing Java vs. copying Java directory structure

Other than setting up the directory structure, what happens when you "install" the Java SDK from the Sun site? Are there environmental variables which are set? I was troubleshooting a client machine, and installed Java 1.5, which subsequently caused Java 1.3 apps on the machine to fail. I'd like to know more about the installation so I can avoid future problems.


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Frequently the JAVA_HOME environment variable is set. You might be able to point that back to the 1.3 installation and get those going again.
>> Frequently the JAVA_HOME environment variable is set

I'm not sure that is *ever* set in fact.
I could be nuts. Are you thinking that the path has been changed to point to the wrong version of Java?
On a Windows system, there are several Registry keys and values that should be written to the Win-Registry and, perhaps even some file-associations that are set for you like .jnlp, .jar and .java.

The reason your Java 1.3 apps failed was because Java 1.5 set itself as the "default" JVM to use on your client's machine.  If the machine is a Windows' based PC, look in regedit for something like this:

[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment]

Changing the value for the "CurrentVersion" key to "1.3" -- assuming that version is what's installed on your client's machine -- will revert the default JVM to the 1.3 version.

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