Where is _JAVA_OPTIONS
being set? In your .bashrc?
Use an alias instead, e.g.
alias java="`which java` -Dwhatever"
Actually, it is not necessary to know where it is being set to make this work:
_SILENT_JAVA_OPTIONS="$_JAVA_OPTIONS"
unset _JAVA_OPTIONS
alias java='java "$_SILENT_JAVA_OPTIONS"'