AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  constant values in a switch clause          AppletTalk.com Forum Index -> comp.lang.java.developer View previous topic :: View next topic   Author Message Wojtek Bok Guest Posted: Mon Jun 06, 2005 7:35 pm    Post subject: constant values in a switch clause If I set up a class definition with: ------------------------------ public static final int SORT_FIRST_NAME = 0; public static final int SORT_LAST_NAME = 1; public static final int SORT_BIRTHDAY = 2; ------------------------------ then use this in a switch clause: ------------------------------ switch(sortOrder) { case SORT_FIRST_NAME: // do work case SORT_LAST_NAME: // do work case SORT_BIRTHDAY: // do work } ------------------------------ all is well. But, if I use dynamic allocation: ------------------------------ private static int cvCounter = 0; public static final int SORT_FIRST_NAME = cvCounter++; public static final int SORT_LAST_NAME = cvCounter++; public static final int SORT_BIRTHDAY = cvCounter++; ------------------------------ then the switch/case statements show errors (in Eclipse 3.02). Why? Eclipse accepts the value assignment. And the values ARE final, yet the switch/case shows an error that "case expressions must be constant expressions". Back to top Oliver Wong Guest Posted: Thu Aug 11, 2005 2:49 pm    Post subject: Re: constant values in a switch clause "Wojtek Bok" <wb (AT) nospam (DOT) com> wrote Quote: If I set up a class definition with: ------------------------------ public static final int SORT_FIRST_NAME = 0; public static final int SORT_LAST_NAME = 1; public static final int SORT_BIRTHDAY = 2; ------------------------------ then use this in a switch clause: ------------------------------ switch(sortOrder) { case SORT_FIRST_NAME: // do work case SORT_LAST_NAME: // do work case SORT_BIRTHDAY: // do work } ------------------------------ all is well. But, if I use dynamic allocation: ------------------------------ private static int cvCounter = 0; public static final int SORT_FIRST_NAME = cvCounter++; public static final int SORT_LAST_NAME = cvCounter++; public static final int SORT_BIRTHDAY = cvCounter++; ------------------------------ then the switch/case statements show errors (in Eclipse 3.02). Why? Eclipse accepts the value assignment. And the values ARE final, yet the switch/case shows an error that "case expressions must be constant expressions". My guess is that the compiler must know the values of the CASE statements at compile time. Since cvCounter is not final, it could be written like this: private static int cvCounter = Math.random(); public static final int SORT_FIRST_NAME = cvCounter++; public static final int SORT_LAST_NAME = cvCounter++; public static final int SORT_BIRTHDAY = cvCounter++; In which case the compiler couldn't know the values of the CASE statements at compile time. It's unfortunate, I know. - Oliver Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> comp.lang.java.developer 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.