Rococoa – Bringing Cocoa to Java

In my opinion, Objective-C’s big strength is the awesome Cocoa libraries. So as a Java programmer I was pleasantly surprised to discover the Rococoa project. Rococoa allows any Java program on Mac OS X to (sort of) easily access any Cocoa library.

If you want to use Rococoa I recommend learning how to code in Objective-C first. That will make it easier to understand what’s going on and why you need to do things like creating an auto-release memory pool.

The hardest part of Rococoa’s learning curve was getting a small but useful program working. Once I achieved that the other parts fell into place. So to help others, here is a working example, in two classes. The first class, NSWorkspace is an access point to Cocoa’s NSWorkspace class. The second class uses NSWorkspace to dump to the console a list of all applications currently running on your Mac.

You’ll need to add the Rococoa libraries to your classpath.

package com.barbarysoftware.pokercopilot.jna;

import org.rococoa.NSClass;
import org.rococoa.NSObject;
import org.rococoa.Rococoa;
import org.rococoa.cocoa.foundation.NSArray;

public interface NSWorkspace extends NSObject {

public static final _Class CLASS = Rococoa.createClass("NSWorkspace", _Class.class);

    public interface _Class extends NSClass {
        // class (aka static) methods go here
        NSWorkspace sharedWorkspace();
    }

    // instance methods go here
    NSArray launchedApplications();
}

---

package com.barbarysoftware.pokercopilot.jna;

import org.rococoa.Foundation;
import org.rococoa.NSObject;
import org.rococoa.cocoa.foundation.NSArray;
import org.rococoa.cocoa.foundation.NSAutoreleasePool;

public class HelloRococoaWorld {

    public static void main(String[] args) {
        final NSAutoreleasePool pool = NSAutoreleasePool.new_();
        try {
            showRunningApplications();
        } finally {
            pool.drain();
        }
    }

    private static void showRunningApplications() {
        final NSWorkspace nsWorkspace = NSWorkspace.CLASS.sharedWorkspace();
        final NSArray nsArray = nsWorkspace.launchedApplications();
        final int size = nsArray.count();
        for (int i = 0; i < size; i++) {
            final NSObject nsObject = nsArray.objectAtIndex(i);
            // dump object to console the Java way
            System.out.println("nsObject = " + nsObject);
            // dump object to console the Cocoa way
            Foundation.nsLog("%@", nsObject.id());
        }
    }
}