If all you've done is unpack it in /usr/local there'll be depending on whether it's the jre or sdk
j2sdk_whatever_theversion.bin
chmod u+x j2sdk_whatever_theversion.bin
./j2sdk_whatever_theversion.bin
And that'll create the the directory for it and install it in /usr/local as
you guessed it
j2sdk_whatever_theversion (or slightly different name if it's just the runtime environment you got)
Open Office should detect it if you put in
/etc/profile
Code:
JAVA_HOME=path_to_the_java_directory_you just installed
EXPORT JAVA_HOME
logout and back in again