Help - can't run logstash with java 1.8.0_77? (logstash 2.3.4 and 2.3.2)

(background: I'm new to logstash and have just installed on CentOS 6.7 with java 1.8.0_77 installed)

when I attempt to run 'logstash' or even run 'plugin list' all I am seeing is...

WARNING: Default JAVA_OPTS will be overridden by the JAVA_OPTS...
Usage: java...
...
where options include:
...
(Prepend -J in front of these options when using 'jruby' command)

Do I need to drop back to java 1.7? or am I doing something else wrong?

(after I couldn't get logstash 2.3.4 to work I tried with 2.3.2 with the same results)

thanks in advance, Allen

solved. turns out my env JAVA_OPTS were set for another software framework/project and they were causing jruby and subsequently logstash not to start. I removed the offending JAVA_OPTS and logstash now runs.