time   calls  line
                  1 function isok = usejava(feature)
                  2 %USEJAVA  True if the specified Java feature is supported in MATLAB.
                  3 %   USEJAVA(LEVEL) returns 1 if the feature is supported and 
                  4 %   0 otherwise.
                  5 %
                  6 %   The following levels of support exist:
                  7 %
                  8 %   LEVEL      MEANING
                  9 %   -----------------------------------------------------
                 10 %   'jvm'      The Java Virtual Machine is running.
                 11 %   'awt'      AWT components are available.
                 12 %   'swing'    Swing components are available.
                 13 %   'desktop'  The MATLAB interactive desktop is running.
                 14 %
                 15 %   "AWT components" refers to Java's GUI components in the Abstract 
                 16 %   Window Toolkit.  "Swing components" refers to Java's lightweight 
                 17 %   GUI components in the Java Foundation Classes.
                 18 %
                 19 %   EXAMPLES:
                 20 %
                 21 %   If you want to write a MATLAB program that displays a Java Frame and want
                 22 %   to be robust to the case when there is no display set or no JVM
                 23 %   available, you can do the following:
                 24 %   
                 25 %   if usejava('awt')
                 26 %      myFrame = java.awt.Frame;
                 27 %   else
                 28 %      disp('Unable to open a Java Frame.');
                 29 %   end
                 30 %
                 31 %   If you want to write a MATLAB program that uses Java code and want it to
                 32 %   fail gracefully when run in a MATLAB session that does not have access
                 33 %   to a JVM, you can add the following check:
                 34 %
                 35 %   if ~usejava('jvm')
                 36 %      error([mfilename ' requires Java to run.']);
                 37 %   end
                 38 %
                 39 %   See also JAVACHK
                 40 
                 41 %   Copyright 1984-2010 The MathWorks, Inc.
                 42 %   $Revision: 1.6.4.4 $  $Date: 2010/06/15 01:38:44 $
                 43 
  0.01      40   44 if nargin < 1 
                 45     error(nargchk(1,1,nargin,'struct'));
                 46 end
            40   47 isok = system_dependent('useJava',feature);