Martin Carlyle wrote: <<Believe it or not, even at the US Air Force Academy, someone suggested just this week that we replace Ada with Java in our curriculum. I had a fit (moderate overstatement). Nonetheless, I told the Colonel (department head), "Whatever you think we need that Java has, I will deliver it by next fall." I think they were surprised I could make such a bold claim. In reality, I doubt that I'll end up having to do any additional work at all.>> I think that in an Ada versus Java battle for the hearts and minds of academia, we who advocate Ada can be on the offense versus the defense. If someone suggests replacing Ada by Java, here are some comments I'd make: 1) In Java, OOP is the only show in town, and if you want to write a simple non-OO application you need to use some heavyweight concepts -- eg a noninstantiable class with a private constructor. Ada supports both OO and non-OO apps impartially, and writing a simple non-OO app does not require advanced features. Students should use a language that is not biased towards a particular design style. 2) The Java thread model is inferior to Ada's tasking. Race conditions and deadlock are much likelier to occur in Java. (E.g. Java suffers from the "nested monitor" problem, whereas in Ada an implementation that supports Ceiling_Locking avoids this issue.) Despite the presence of priorities in Java, the semantics of scheduling/priorities is completely implementation dependent, whereas the Ada Real-Time Annex defines scheduling semantics and pragmas for the user to set various policies. 3) Among other omissions, Java lacks enumeration types, fixed-point types, subtypes, strongly typed scalar types, a parameter passing mode that allows updating a scalar parameter, named parameter associations, default values for parameters, and (quite significantly) generics. 4) Java does not have general block structure. Ada allows subprograms to be declared directly in other subprograms. In Java a method may not be declared local to another method. It may be declared in an inner class that is local to a method, but that introduces some conceptual complexity. I would think that from an instructional viewpoint the traditional Algol 60 style block structure would be the preferred mechanism to present. 5) Java does not allow a method to be passed as a parameter. There are workarounds but at least to me these have the look and feel of a workaround and not a solution. 6) Java presents a skewed view of data structures, since it uses pointers implicitly for all aggregate data. IMHO a student should be exposed to the basics of record types and array types and understand the issues posed by a language that supports pointers explicitly. Java has garbage collection, which from an app delevoper's point of view is great but from the viewpoint of teaching students about data structures is not good. It's a little like deciding if a calculator should be allowed in an elementary school course that is supposed to teach arithmetic. After the students understand the concepts behind long division then they can use a calculator to ease their work, but giving this to them before means that they might fail to learn the basic concepts/issues. 7) Java has nothing close to Ada's support for interfacing to foreign code. Java "native methods" are far weaker and less portable than Ada's interfacing facilities. 8) Simple interactive IO (especially input) is surprisingly complicated. If you thought that the Ada 83 need to instantiate a generic for simple integer IO was a pedagogical problem, look at the code in a Java application that reads an integer value from the keyboard. Of course it would be naive to suggest that Java has no technical advantages. Here are a few that Javaphiles may suggest, along with my comments: 1) Java has a lighter-weight syntax for OOP. This is definitely true, and I have found that Java's approach to multiple inheritance through interface implementation is conceptually simpler than Ada's techniques (generics or access discriminants). But some of Java's succinctness comes from its merging a module spec and a module body into one unit, the class. Ada separates a spec and a body, a better methodological approach. Moreover, multiple inheritance is not something that students need to do all the time. 2) Java has a more extensive class library than Ada. Agreed (with some envy :-) although with several current Ada vendors (such as Intermetrics, Aonix and GNAT) one can interface to Java classes. 3) Java's JVM offers "Write Once, Run Everywhere" (or so says Sun :-) There are some glaring exceptions to this rule in the Java language spec, e.g. thread scheduling as mentioned above, and current implementations of the AWT also show platform-specific behavior (not just different look and feel). Moreover, the Sun/Microsoft battle has users wondering what the Java language actually will be. In contrast, Ada is an ISO standard, and portability experience has been quite good. And in any event the portability benefit of the JVM can be achieved by generating JCode from Ada source, as is currently supported by several Ada vendors. 4) Java is hot new technology, and universities need to teach it in order to compete for students. I understand this motivation, but my suggestion would be to introduce Java _after_ students have learned Ada. This way they get to learn first a language that is design methodology-neutral and that instills good habits of program development. Ben Brosgol Aonix 200 Wheeler Rd Burlington, MA 01803 (781) 221-7317 (phone) (781) 270-6882 (FAX) [log in to unmask] PS- With apologies for this mini-ad at the end of this message, and with my SIGAda chair hat on, I want to remind fellow Team-Adians about the SIGAda '98 Conference (formerly Tri-Ada) which will be held Nov 8-12 in Washington, DC. Go to the URL http://www.acm.org/sigada/conf/sa98 for more information. Articles, abstracts, panel and workshop proposals are due May 1, and experience reports are due on June 5.