How do i load a compiled Java class in JRuby?

Michal Štein :

So, I've started out with Java and having some trouble loading a class in a JRuby script, or in another Java app. Let's use this file as an example:

package dice;
import java.util.Random;
public class Dice {
    public int sides;
    private Random random;
    public Dice(int sides) {
        this.sides = sides;
        this.random = new Random();
    }
    public Dice() {
        this.sides = 6;
        this.random = new Random();
    }
}

When i compile it in NetBeans, it makes a jar file with that class file in it, and a META-INF file. I can require it in JRuby, but i can't do the java_import part:

irb(main):013:0> java.dice.Dice
Traceback (most recent call last):
        7: from C:/jruby-9.2.4.1/bin/jirb:13:in `<main>'
        6: from org/jruby/RubyKernel.java:1181:in `catch'
        5: from org/jruby/RubyKernel.java:1181:in `catch'
        4: from org/jruby/RubyKernel.java:1415:in `loop'
        3: from org/jruby/RubyKernel.java:1043:in `eval'
        2: from (irb):13:in `evaluate'
        1: from org/jruby/javasupport/JavaPackage.java:252:in `method_missing'
NameError (missing class name (`java.dice.Dice'))

Michal Štein :

Still upvoting, but found it out myself, i just need to do

Java::dice.Dice

because, it only works without the Java:: part when it is in the java folder of packages like

java.lang.System