DrJava is incompatible with Java 9 and Java 10.  After Java 8, Oracle completely changed the packaging of the JDK and JRE distributions of Java (which had been invariant since Java 1.2 [2] twenty years ago.  We are working on a new version that is compatible with Java 9/10 but we no longer have any outside funding supporting DrJava development so it is being done in our "spare time".  In the near term, you need to download a Java 8 JDK.  I am currently running JDK 8 build 181 on my Linux laptop.  I hope that we will have a Java 9/10 compatible version available at www.cs.rice.edu/~javaplt/drjavarice by the end of October.

Incidentally, I know of no advantages to using Java 9 or 10 for CS A (or the defunct AB for that matter) over Java 8.  My online notes "The Elements of Object-Oriented Progam Design" (in Java) were originally written when Java 1.2, 1.3, and 1.4 were in widespread use.  Java 1.5 (5) introduced generic types so I added a few uses of generic types in my notes with a promise (still unfulfilled) to include a short section in the notes explaining generic types.  Perhaps I will write such a section soon; I had forgotten that it was still missing!  BTW, the simple Java subset that I use in my notes does not look anything like what is typically taught in the CS A AP course (which generally ignores object-orientation).  My notes treat Java as a mostly functional language (like Scheme [Racket] or some variant of ML [other than Haskell which is purely functional]).  See https://www.cs.rice.edu/~javaplt/papers/OOPEnrichesFP.pdf.  Functional programming in Java is wordy, wordy, wordy (in sharp contrast to OCaml or Haskell) but still much nicer than imperative Java (which looks like C dressed up in class definitions).

On Mon, Sep 10, 2018 at 7:37 PM Saige Gootman <saigegootman@users.sourceforge.net> wrote:

[bugs:#974] Most recent version of Java on Mac = can't open Dr. Java

Status: open
Group: 4: Serious
Created: Tue Sep 11, 2018 12:37 AM UTC by Saige Gootman
Last Updated: Tue Sep 11, 2018 12:37 AM UTC
Owner: nobody
Attachments:

Hello,

I was told to download Dr. Java to use for my AP Computer Science A class, but there seems to be a very large problem. I downloaded it onto my MacBook Air through the Dr. Java website. Once I dragged it from Downloads to Applications, I attempted to open the file (through control right click to override the protection layer on the Mac) and it didn't open immediately. I then got a popup about 30 seconds after I attempted to open it saying the following:

"The Java JAR file "drjavabeta-20160913-225446.jar" could not be launched. Check the Console for possible error messages."

A classmate had the same problem, while all of the other computers could open Dr. Java easily. Both of our computers are updated with the latest version of Java, and none of the other class computers are. Dr. Java is not compatible with the latest version of Java, so therefore it cannot run on my computer! Please fix this because I need it for class.

Thanks.

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