AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Somewhat of a big lie about OO in java book? Goto page 1, 2  Next          AppletTalk.com Forum Index -> Java Help View previous topic :: View next topic   Author Message Andrew Thompson Guest Posted: Thu May 13, 2004 7:05 am    Post subject: Re: Somewhat of a big lie about OO in java book? On Wed, 12 May 2004 23:43:52 -0800, [email]RobertMaas (AT) YahooGroups (DOT) Com[/email] wrote: .... Quote: The textbook for my java class (sorry for pun) is: Introduction to JAVA (tm) Programming I thought you had made a typo with 'JAVA', but.. Quote: by Y. Daniel Liang, Fourth Edition ISBN 0-13-100225-2 <http://images.amazon.com/images/P/0131002252.01.LZZZZZZZ.jpg> ...certainly speaks a thousand 'JAVA's. .... Quote: I like some things about this book, What does it get right? Quote: ..but this is one thing I detest, lies like this. Anyone agree with me? I would toss it, except for the fact it is your 'class' text. (no apologies for pun) -- Andrew Thompson http://www.PhySci.org/ Open-source software suite http://www.PhySci.org/codes/ Web & IT Help http://www.1point1C.org/ Science & Technology Back to top Roedy Green Guest Posted: Thu May 13, 2004 7:26 am    Post subject: Re: Somewhat of a big lie about OO in java book? On Wed, 12 May 2004 23:43:52 -0800, [email]RobertMaas (AT) YahooGroups (DOT) Com[/email] wrote or quoted : Quote: I like some things about this book, but this is one thing I detest, lies like this. Anyone agree with me? He is probably a professor. They learn to talk that way. Try my explanation. See if it makes any more sense. start at http://mindprod.com/jgloss/static.html and chase the links. -- Canadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. Back to top RobertMaas@YahooGroups.Co Guest Posted: Thu May 13, 2004 7:43 am    Post subject: Somewhat of a big lie about OO in java book? The textbook for my java class (sorry for pun) is: Introduction to JAVA (tm) Programming by Y. Daniel Liang, Fourth Edition ISBN 0-13-100225-2 On page 206, at the start of the chaper on Object-Oriented Programming, he says "Object-oriented programming places data and the operations pertain to them within a single entity called an OBJECT;" If you're talking only about static variables and static methods, and we're talking about a Class object, that's correct, but in general we deal with instances of a class which each contain their own set of instance variables, but the instance methods relating to them do *not* have a complete set within each object, rather there's a single set of instance methods within the class, so the variables and methods are in separate objects, each individual instance object vs. a single Class object. The diagrams at the bottom of that page and top of next page only emphasize the lie. I like some things about this book, but this is one thing I detest, lies like this. Anyone agree with me? Back to top VisionSet Guest Posted: Thu May 13, 2004 8:12 am    Post subject: Re: Somewhat of a big lie about OO in java book? <RobertMaas (AT) YahooGroups (DOT) Com> wrote Quote: The textbook for my java class (sorry for pun) is: Introduction to JAVA (tm) Programming by Y. Daniel Liang, Fourth Edition ISBN 0-13-100225-2 On page 206, at the start of the chaper on Object-Oriented Programming, he says "Object-oriented programming places data and the operations pertain to them within a single entity called an OBJECT;" If you're talking only about static variables and static methods, and we're talking about a Class object, that's correct, but in general we deal with instances of a class which each contain their own set of instance variables, but the instance methods relating to them do *not* have a complete set within each object, rather there's a single set of instance methods within the class, so the variables and methods are in separate objects, each individual instance object vs. a single Class object. The diagrams at the bottom of that page and top of next page only emphasize the lie. I like some things about this book, but this is one thing I detest, lies like this. Anyone agree with me? Personally I like to think of methods being per object rather than per class. The same method is executed in parallel for many objects. So there are as many instances of the methods as there are objects. -- Mike W Back to top Tom Guest Posted: Thu May 13, 2004 12:55 pm    Post subject: Re: Somewhat of a big lie about OO in java book? [email]RobertMaas (AT) YahooGroups (DOT) Com[/email] wrote in message news:<REM-2004may12-008 (AT) Yahoo (DOT) Com>... Quote: The textbook for my java class (sorry for pun) is: Introduction to JAVA (tm) Programming by Y. Daniel Liang, Fourth Edition ISBN 0-13-100225-2 On page 206, at the start of the chaper on Object-Oriented Programming, he says "Object-oriented programming places data and the operations pertain to them within a single entity called an OBJECT;" If you're talking only about static variables and static methods, and we're talking about a Class object, that's correct, but in general we deal with instances of a class which each contain their own set of instance variables, but the instance methods relating to them do *not* have a complete set within each object, rather there's a single set of instance methods within the class, so the variables and methods are in separate objects, each individual instance object vs. a single Class object. The diagrams at the bottom of that page and top of next page only emphasize the lie. I like some things about this book, but this is one thing I detest, lies like this. Anyone agree with me? I think you are making a mountain out of a molehill. Yes, there is only one set of methods stored in memory. Big deal. That saves memory, since the code for the methods is identical. The point is that in OOP, an objects instance variables and instance methods are joined-at-the-hip, unlike procedural languages where the data and methods are separate. I wouldn't waste too much time worrying about a minor inaccuracy. Back to top Chris Smith Guest Posted: Thu May 13, 2004 4:47 pm    Post subject: Re: Somewhat of a big lie about OO in java book? VisionSet wrote: Quote: Personally I like to think of methods being per object rather than per class. The same method is executed in parallel for many objects. So there are as many instances of the methods as there are objects. I disagree with this interpretation. It's just as possible to have only one object, but execute a method thousands of times concurrently on that one object. (Providing the method is not explicitly coded to prevent this, as with the 'synchronized' keyword.) Hence, I find that explanation more likely to confuse than help. -- www.designacourse.com The Easiest Way to Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation Back to top Chris Smith Guest Posted: Thu May 13, 2004 4:59 pm    Post subject: Re: Somewhat of a big lie about OO in java book? [email]RobertMaas (AT) YahooGroups (DOT) Com[/email] wrote: Quote: On page 206, at the start of the chaper on Object-Oriented Programming, he says "Object-oriented programming places data and the operations pertain to them within a single entity called an OBJECT;" Yes, that's true. I believe you're confusing model with implementation. It's not specified in the general OO model, nor in Java, whether there is only one copy of a method's code held in memory, or one copy per object, or anything else. The one-copy case is more likely than the per-object case for performance reasons... but that's an implementation concern about the existence of code; the ownership of a method is a different matter. You'll often hear OO people proclaim that an object owns its "state", "behavior", and "identity". What we mean by an object owning its behavior is that the behavior depends on which object you're working with. Basically, that's polymorphism. You can interact with two objects in exactly the same way, and they may act differently because they are different objects. (Your author's use of the term "operations" instead of "behavior" is somewhat ambiguous because the former could be interpreted as the client interface, i.e. the set of possible operations, which is not owned by the object at all.) Note that this doesn't conflict with methods being defined in classes. In Java, they definitely are (though there are other class-less or prototype-model OO languages where this isn't necessarily the case either). Another way of putting it is that the point really relates to locating knowledge. When code A interacts with object B, is the behavior determined by prior knowledge from A, or from B. In an OO language (and using OO language features... hence, not with static methods in Java, nor with non-virtual methods in C++), the answer is B. I hope that clarifies things. In essence, I think your author is right. -- www.designacourse.com The Easiest Way to Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation Back to top Roedy Green Guest Posted: Thu May 13, 2004 6:50 pm    Post subject: Re: Somewhat of a big lie about OO in java book? On Thu, 13 May 2004 10:47:15 -0600, Chris Smith <cdsmith (AT) twu (DOT) net> wrote or quoted : Quote: The same method is executed in parallel for many objects. So there are as many instances of the methods as there are objects. First there is only one copy of each method. Each object has a hidden pointer to a hidden object with a list of "active" methods for that class, and the superclass. From that it can figure out where to get its methods from -- this class or one of its ancestors. Second there is only one thread to start, so no matter how many objects you have only one method as a time executes. You can create new threads, but there is never one thread per object, except for a few special classes. -- Canadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. Back to top Chris Smith Guest Posted: Thu May 13, 2004 7:47 pm    Post subject: Re: Somewhat of a big lie about OO in java book? Roedy Green wrote: Quote: On Thu, 13 May 2004 10:47:15 -0600, Chris Smith wrote or quoted : The same method is executed in parallel for many objects. So there are as many instances of the methods as there are objects. Roedy, despite your introduction saying "wrote or quoted", it would only take a tiny effort to get your attributions right in the first place. -- www.designacourse.com The Easiest Way to Train Anyone... Anywhere. Chris Smith - Lead Software Developer/Technical Trainer MindIQ Corporation Back to top Roedy Green Guest Posted: Thu May 13, 2004 8:56 pm    Post subject: Re: Somewhat of a big lie about OO in java book? On Thu, 13 May 2004 13:47:58 -0600, Chris Smith <cdsmith (AT) twu (DOT) net> wrote or quoted : Quote: Roedy, despite your introduction saying "wrote or quoted", it would only take a tiny effort to get your attributions right in the first place. I don't think it matters. What counts is what is said, not who said it. -- Canadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. Back to top VisionSet Guest Posted: Thu May 13, 2004 8:58 pm    Post subject: Re: Somewhat of a big lie about OO in java book? "Roedy Green" <look-on (AT) mindprod (DOT) com.invalid> wrote Quote: On Thu, 13 May 2004 10:47:15 -0600, Chris Smith wrote or quoted : The same method is executed in parallel for many objects. So there are as many instances of the methods as there are objects. First there is only one copy of each method. Each object has a hidden pointer to a hidden object with a list of "active" methods for that class, and the superclass. From that it can figure out where to get its methods from -- this class or one of its ancestors. Second there is only one thread to start, so no matter how many objects you have only one method as a time executes. You can create new threads, but there is never one thread per object, except for a few special classes. And you quoted a little too little: VisionSet wrote: Quote: Personally I like to think of methods being per object rather than per class. *I like to think of* As in I know it isn't really the case, but personally it helps me to think of it that way. If you think of it as the one method per class than it can seem a little confusing that the method can be a)executed concurrently amongst different objects and b) that execution carries its own separate set of local variables. So I don't see anything wrong with what I wrote, especially if you explain the proviso that the memory footprint is of just the one method. I found OO totally baffling when I started 3+ years back, though I never found this method definition business a difficult concept in the slightest. And Roedy I have to agree with Chris please try and reply to the person you intend to, you do this all the time ) -- Mike W Back to top Québec Guest Posted: Fri May 14, 2004 2:07 am    Post subject: Re: Somewhat of a big lie about OO in java book? Real chaos. There is a fight: a priest comes by and preach, receive a fist on the nose an join the fighters, so does the police, the army, etc. when getting near to the chaos'black hole. Ok, brigth guys, I am all mixed up. Java is confusing? Jean =================== If static method = one method for every instances? If instance method = one method per instance? One instance per thread at a time? If more than one instance per thread deadlock is probable? Per instance? Back to top Andrew Thompson Guest Posted: Fri May 14, 2004 4:52 am    Post subject: Re: Somewhat of a big lie about OO in java book? On Thu, 13 May 2004 20:56:03 GMT, Roedy Green wrote: Quote: On Thu, 13 May 2004 13:47:58 -0600, Chris Smith wrote or quoted : .... Roedy, despite your introduction saying "wrote or quoted", it would only take a tiny effort to get your attributions right in the first place. .... I don't think it matters. Again, Roedy. People are different. I was quite surprised that 'Chris' said that. Further, at times when I am skimming, I may jump over what a or b in a converstion wrote, to read only the parts written by a single person. I would ask you to please put more attention to it. If we were to follow your scheme of 'anonymous' it would make best sense to leave all attributions off, rather than have them incorrect. Quote: What counts is what is said, not who said it. Perhaps a good point, but if a reader consistantly finds the posts of one person to be accurate and informative, while the posts of another trivial and sarcastic,they may prefer to read the former and ignore the latter. To put in even finer edge on it. Would you want people to believe that things *I write* were written by 'Roedy Green'? I do not imagine you would be comfortable with that, or that it would best serve the reader (..,you *or* me). -- Andrew Thompson http://www.PhySci.org/ Open-source software suite http://www.PhySci.org/codes/ Web & IT Help http://www.1point1C.org/ Science & Technology Back to top Roedy Green Guest Posted: Fri May 14, 2004 6:33 am    Post subject: Re: Somewhat of a big lie about OO in java book? On Fri, 14 May 2004 04:52:39 GMT, Andrew Thompson <SeeMySites (AT) www (DOT) invalid> wrote or quoted : Quote: Perhaps a good point, but if a reader consistantly finds the posts of one person to be accurate and informative, while the posts of another trivial and sarcastic,they may prefer to read the former and ignore the latter. I am so annoyed with how flaky the attributions scheme is. I can't stand the thought of wasting time frigging around with something so hopelessly inept. It should be automated so that it CAN'T go wrong. see http://mindprod.com/projmailreadernewsreader.html I don't think you will persuade me. I pay no attention to them myself. -- Canadian Mind Products, Roedy Green. Coaching, problem solving, economical contract programming. See http://mindprod.com/jgloss/jgloss.html for The Java Glossary. Back to top Andrew Thompson Guest Posted: Fri May 14, 2004 6:45 am    Post subject: Re: Somewhat of a big lie about OO in java book? On Fri, 14 May 2004 06:33:11 GMT, Roedy Green wrote: (attributions in posts) Quote: It should be automated so that it CAN'T go wrong. Agree fully. Pity it's not. Quote: see http://mindprod.com/projmailreadernewsreader.html I don't think you will persuade me. Probably not. [ ] But before I leave the subject I thought I should just state specifically that I feel that.. "Correct attributions server the reader, the OP and other contributors to the thread best". [ ..I have certainly badly stuffed up attributions myself, ..and been on the receiving end of full-on abuse for things I _never_ said (HTML group). :-/ ] Now ..checks subject.. OO? Oh! :-O Outta' here. -- Andrew Thompson http://www.PhySci.org/ Open-source software suite http://www.PhySci.org/codes/ Web & IT Help http://www.1point1C.org/ Science & Technology Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java Help All times are GMT Goto page 1, 2  Next Page 1 of 2   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.