Launch Java from JRuby script throws TypeError: no public constructors for Java

Question

I have a Java application that I am trying to launch from a JRuby script. I've been googling/t-shooting/iterating through so many solutions - my "basic" script is:

include Java
require 'c:/nm/bin/h4j.jar'
module HOLTER
  include_package 'com.nemon.h4j.H4JFrame';
end
include_class Java::ComNemonH4j::H4JFrame
H4JFrame.new

This throws the following error:

TypeError: no public constructors for Java::ComNemonH4j::H4JFrame
  (root) at h4j_initialTest.rb:7

And I've found that this also throws the same error:

$nm = HOLTER::H4JFrame.new

The main constructor for my application is:

public static void main(String argv[])
{
  captureOutput();
  new H4JFrame(argv);
}

So what do I need to do to have my script simply launch my application? Any/all advice and pointers would be GREATLY appreciated!!

mike · Accepted Answer · 2019-03-15 15:11:56Z

1

Does H4JFrame have a 0 argument constructor? In your java main you show it being called with String argv[] as the argument, so I would assume it does not. To start your application with your current code, you would need to pass a Java String array to H4JFrame.

include Java
require 'c:/nm/bin/h4j.jar'
module HOLTER
  include_package 'com.nemon.h4j.H4JFrame';
end
include_class Java::ComNemonH4j::H4JFrame
str_arr = ["example input", "this is an array of strings", "it is a ruby object"]
H4JFrame.new(str_arr.to_java :String)

edited Mar 15, 2019 at 15:11

answered Aug 24, 2011 at 1:09

mike

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