JAVA_VERSION get version of Java Virtual Machine

this gives a long string with more detail version("-java")

% these give the Matlab version, not the JVM version.
% java.lang.Runtime.version()
% java.lang.Runtime.getRuntime().version

function v = java_version()

try
  v = java.lang.System.getProperty('java.version');
catch
  v = '';
end

v = char(v);

end