[Octave-bug-tracker] [bug #60058] Feature request: function javaversion()

[Ernst Reissner]

URL:
  <https://savannah.gnu.org/bugs/?60058>

                 Summary: Feature request: function javaversion()
                 Project: GNU Octave
            Submitted by: ernstreissner
            Submitted on: Sun 14 Feb 2021 09:24:09 PM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: Reissner 
        Originator Email: 
             Open/Closed: Open
                 Release: dev
         Discussion Lock: Any
        Operating System: Any

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Details:

I think one needs a function displaying the version 
of the java virtual machine JVM. 

This is very simple to do: 


%% -*- texinfo -*-
%% @deftypefn  {Function File} {@var{res}} javaversion() 
%%
%% Returns the java version as a string
%% of the form @code{major.minor.update-patch}. 
%%
%%  @example
%%    javaversion()
%%  @end example
%%
%% @end deftypefn

function str = javaversion() 
  v = javaMethod("version", "java.lang.Runtime");
  str = [num2str(v.feature()) "." num2str(v.interim()) "." num2str(v.update())
"-" num2str(v.patch())];
endfunction


This allows also to check versions: 


v = javaMethod("version", "java.lang.Runtime");
v11 = javaMethod("parse", "java.lang.Runtime$Version", "11.3.2.3");
v16 = javaMethod("parse", "java.lang.Runtime$Version", "16.1.0.1");
printf("versions this to max %d, this to min %d"
,v.compareTo(v16),v.compareTo(v11))


a.compareTo(b) >=0 iff a >= b and so on. 
This allows to check java versions 
in the context of package loading. 





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