can JRuby read java's data structure

ruby-talk
1

Such as Map, List etc.

Thanks

2

You can reference a Java class in JRuby in at least two different ways.

The first is to map Java names like org.foo.department.Widget to Ruby
nested modules format. This works as follows:

  Java: org.foo.department.Widget
  Ruby: Java::OrgFooDepartment::Widget

Second way: for the top-level Java packages java, javax, org, and com
you can type in a fully qualified class name basically as in Java,
for example, java.lang.System or org.abc.def.ClassName

With the java_import statement, you can access the Java class via a
constant that java_import creates for you in the current namespace.

A random example:

  require "java"
  include_class "java.util.ArrayList"
    arrlist = ArrayList.new
    arrlist.add "Amit"
    arrlist.add "Kumar"
    arrlist.add "Vineet"
  puts "#{arrlist}"

···

On 1/20/22, Adriel Peng <peng.adriel@gmail.com> wrote:

[can JRuby read java's data structure] Such as Map, List etc.

3

That's right, thanks Frank. My purpose is to check if I can read data from
the backend service (big data part) and have the results presented in the
front-end via web interface by Ruby.

Kind regards,
Adriel

···

On Fri, Jan 21, 2022 at 10:23 PM Frank J. Cameron <fjc@fastmail.net> wrote:

On 1/20/22, Adriel Peng <peng.adriel@gmail.com> wrote:
> [can JRuby read java's data structure] Such as Map, List etc.

You can reference a Java class in JRuby in at least two different ways.

The first is to map Java names like org.foo.department.Widget to Ruby
nested modules format. This works as follows:

        Java: org.foo.department.Widget
        Ruby: Java::OrgFooDepartment::Widget

Second way: for the top-level Java packages java, javax, org, and com
you can type in a fully qualified class name basically as in Java,
for example, java.lang.System or org.abc.def.ClassName

With the java_import statement, you can access the Java class via a
constant that java_import creates for you in the current namespace.

CallingJavaFromJRuby · jruby/jruby Wiki · GitHub

A random example:

        require "java"
        include_class "java.util.ArrayList"
          arrlist = ArrayList.new
          arrlist.add "Amit"
          arrlist.add "Kumar"
          arrlist.add "Vineet"
        puts "#{arrlist}"

ArrayList example in JRuby

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4

Hi Adriel,

That's right, thanks Frank. My purpose is to check if I can read data from the backend service (big data part) and have the results presented in the front-end via web interface by Ruby.

In short, yes - that should be very much possible.

I have an example of using a Java library (Apache POI) from Ruby code running on JRuby on my site here:

Also, the JRuby community is very helpful (as is the Ruby community) - so, you'll be able to get help once you start to get clearer on what you want to achieve.

Best Regards,
Mohit.

···

On 2022-1-22 8:08 am, Adriel Peng wrote:

--
Mohit Sindhwani
W: notepad.onghu.com
Tw: @onghu