How to Call Java Method From Jruby?

To call a Java method from JRuby, you can use the Java module provided by JRuby. You can import the Java class or package using import statement and then call the desired method using dot notation. Here's an example:

First, import the Java class or package:

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import java.util.ArrayList

Then, create an instance of the Java class and call its method:

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list = ArrayList.new
list.add("Hello")

You can also call static methods of Java classes using the Java::static_method_name syntax:

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result = Java::Math.abs(-10)

By using these techniques, you can easily call Java methods from your JRuby code.

What is the recommended approach for unit testing Java methods in JRuby scripts?

When unit testing Java methods in JRuby scripts, the recommended approach is to use a testing framework such as JUnit or TestNG.

1. Create a test class that extends the JUnit or TestNG framework and includes test methods for each Java method you want to test.
2. Use the JRuby runtime to load and execute the Java methods within your test methods.
3. Set up any necessary mock objects or dependencies using a mocking framework such as Mockito.
4. Write assertions to validate the results of the Java methods.
5. Run the test class using the JUnit or TestNG test runner to execute the tests and ensure the Java methods are functioning correctly.

How to handle object references in Java method calls from JRuby?

In JRuby, you can pass Java objects to methods just like you would in Java. When passing object references to Java methods from JRuby, you need to be aware of how JRuby handles Java methods and objects.

1. Import Java classes: Before you can use Java classes in JRuby, you need to import them using the import keyword.

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require 'java'

java_import 'java.util.ArrayList'

1. Create Java objects: You can create Java objects using the new keyword just like in Java.

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list = ArrayList.new

1. Pass Java object references to method calls: When passing object references to methods, you need to ensure that the method signature matches the type of the Java object.

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list.add("Hello")

1. Handle method calls that return Java objects: If a method call returns a Java object, you can store the reference in a JRuby variable and use it just like any other Java object.

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element = list.get(0)
puts element

Overall, handling object references in Java method calls from JRuby is similar to using Java objects and methods in Java, with the added benefit of JRuby's dynamic language features.

How to create a JRuby script?

To create a JRuby script, you can follow these steps:

1. Install JRuby: First, you need to have JRuby installed on your system. You can download JRuby from the official website and follow the installation instructions.
2. Create a new file: Open your text editor and create a new file with a .rb extension. This will be your JRuby script file.
3. Write your Ruby code: Write your Ruby code in the script file using the JRuby syntax. You can use any Ruby code, libraries, and gems that are compatible with JRuby.
4. Save the file: Save your script file with a meaningful name and the .rb extension.
5. Run the script: To run your JRuby script, you can use the jruby command followed by the path to your script file. For example, if your script file is named example.rb, you can run it using the command jruby example.rb.

That's it! Your JRuby script should now run and execute the code you wrote. You can continue to edit and enhance your script as needed.