########################################################################

##

## Copyright (C) 2012-2024 The Octave Project Developers

##

## See the file COPYRIGHT.md in the top-level directory of this

## or <https://octave.org/copyright/>.

##

## This file is part of Octave.

##

## Octave is free software: you can redistribute it and/or modify it

## under the terms of the GNU General Public License as published by

## the Free Software Foundation, either version 3 of the License, or

## (at your option) any later version.

##

## Octave is distributed in the hope that it will be useful, but

## WITHOUT ANY WARRANTY; without even the implied warranty of

## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

## GNU General Public License for more details.

##

## You should have received a copy of the GNU General Public License

## along with Octave; see the file COPYING. If not, see

## <https://www.gnu.org/licenses/>.

##

########################################################################

## -*- texinfo -*-

## @deftypefn {} {@var{tf} =} usejava (@var{feature})

## Return true if the Java element @var{feature} is available.

##

## Possible features are:

##

## @table @asis

## @item @nospell{@qcode{"awt"}}

## Abstract Window Toolkit for GUIs.

##

## @item @qcode{"desktop"}

## Interactive desktop is running.

##

## @item @qcode{"jvm"}

## Java Virtual Machine.

##

## @item @qcode{"swing"}

## Swing components for lightweight GUIs.

## @end table

##

## @code{usejava} determines if specific Java features are available in an

## Octave session. This function is provided for scripts which may alter

## their behavior based on the availability of Java. The feature

## @qcode{"desktop"} always returns @code{false} as Octave has no Java-based

## desktop. Other features may be available if Octave was compiled with the

## Java Interface and Java is installed.

## @seealso{javachk}

## @end deftypefn

function tf = usejava (feature)

if (nargin < 1 || ! ischar (feature))

print_usage ();

endif

tf = false;

switch (feature)

## For each feature, try methods() on a Java class of a feature

case "awt"

try

dum = methods ("java.awt.Frame");

tf = ! javaMethod ("isHeadless", "java.awt.GraphicsEnvironment");

end_try_catch

case "desktop"

## Octave has no Java based GUI/desktop, leave tf = false

case "jvm"

try

dum = methods ("java.lang.Runtime");

tf = true;

end_try_catch

case "swing"

try

dum = methods ("javax.swing.Popup");

tf = ! javaMethod ("isHeadless", "java.awt.GraphicsEnvironment");

end_try_catch

otherwise

error ("usejava: unrecognized FEATURE '%s'", feature);

endswitch

## Test input validation