AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  1.5.0 Bytecode Compatibility          AppletTalk.com Forum Index -> JVM, native methods and hardware View previous topic :: View next topic   Author Message Benji Smith Guest Posted: Fri Feb 06, 2004 9:21 pm    Post subject: 1.5.0 Bytecode Compatibility Most of the language changes in the new 1.5.0 Beta seem to be changes that could be implemented pretty simply by the compiler, without any changes made to the bytecode format. So, I'm curious...if I compile code that uses the new 1.5.0 features, can I subsequently execute those bytecode in the 1.4.2_03 JVM? Back to top Michael Amling Guest Posted: Sat Feb 07, 2004 3:01 am    Post subject: Re: 1.5.0 Bytecode Compatibility Benji Smith wrote: Quote: Most of the language changes in the new 1.5.0 Beta seem to be changes that could be implemented pretty simply by the compiler, without any changes made to the bytecode format. So, I'm curious...if I compile code that uses the new 1.5.0 features, can I subsequently execute those bytecode in the 1.4.2_03 JVM? I haven't looked, but even if the bytecodes haven't changed (and I suspect they haven't), there's a danger that a builtin class in 1.5 may not exist in 1.4 or may not have all the fields or methods that 1.5 has. --Mike Amling Back to top Chris Uppal Guest Posted: Sat Feb 07, 2004 10:40 am    Post subject: Re: 1.5.0 Bytecode Compatibility Benji Smith wrote: Quote: So, I'm curious...if I compile code that uses the new 1.5.0 features, can I subsequently execute those bytecode in the 1.4.2_03 JVM? All the new semantics is realized through tricks that work just as well on pre-1.5 JVMs. A few new attributes have been added, but that's completely downwards compatible. However, from a post by Neil Grafter on c.l.j.programmer: You can translate 1.5-style classfiles into 1.4-style classfiles by discarding the stackmaps and changing the version number. Almost. Class literals generate a single bytecode instruction (ldc) in 1.5, and that must be translated into the mass of code that was used in previous releases. So I suspect that (if the feature makes it into the final release) code compiled with -target 1.5 may not be able to run on a 1.4 JVM (but then, I don't suppose it would anyway given the version number checking). -- chris Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> JVM, native methods and hardware All times are GMT Page 1 of 1   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.