AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  What exception to use with invalid data fields on object pas          AppletTalk.com Forum Index -> comp.lang.java.developer View previous topic :: View next topic   Author Message davout Guest Posted: Mon May 07, 2007 7:06 pm    Post subject: What exception to use with invalid data fields on object pas I have a question about what the convention is for throwing exceptions on validating data passed to business tier objects. If I have a business tier service like where 'AccountManager', a business tier that maintains accounts... public class Account { ... private String fTitle; private String fAccountCode .... } public class AccountManager { ... public void addAccount(Account aNewAccount); ... } .... and any new account must have a non null title and a non-null account code. If the 'aNewAccount' parameter is passed with a null title field or a null account code field what type of exception should I throw? Should the business tier code be throwing an IllegalArgumentException? If so, how can my GUI tier determine what field failed the validation test? Or should I use a separate custom exceptions for each validation point? One custom exception for title, another for alias etc. Back to top Thomas Fritsch Guest Posted: Mon May 07, 2007 7:46 pm    Post subject: Re: What exception to use with invalid data fields on object davout wrote: Quote: I have a question about what the convention is for throwing exceptions on validating data passed to business tier objects. If I have a business tier service like where 'AccountManager', a business tier that maintains accounts... public class Account { ... private String fTitle; private String fAccountCode .... } public class AccountManager { ... public void addAccount(Account aNewAccount); ... } ... and any new account must have a non null title and a non-null account code. Given your requirement above, I think the natural place for these checks would be the the Account constructor (and its setTitle/setAccountCode methods, if there are such) rather than the AccountManager: public class Account { ... public Account(String title, String accountCode) { if (title == null) throw new IllegalArgumentException("title is null"); if (accountCode == null) throw new IllegalArgumentException("accountCode is null"); fTitle = title; fAccount = accountCode; } ... } Quote: If the 'aNewAccount' parameter is passed with a null title field or a null account code field what type of exception should I throw? Should the business tier code be throwing an IllegalArgumentException? If so, how can my GUI tier determine what field failed the validation test? Or should I use a separate custom exceptions for each validation point? One custom exception for title, another for alias etc. I personally would prefer IllegalArgumentException for all (with different detail messages), instead of lots of custom exception classes. -- Thomas Back to top Mich Guest Posted: Mon May 07, 2007 7:47 pm    Post subject: Re: What exception to use with invalid data fields on object "davout" <davoutXXXYYYWWWZZZ (AT) dsl (DOT) pipex.com> wrote in message news:L7-dnT7iDP7Dr6LbnZ2dnUVZ8vqdnZ2d (AT) pipex (DOT) net... Quote: I have a question about what the convention is for throwing exceptions on validating data passed to business tier objects. If I have a business tier service like where 'AccountManager', a business tier that maintains accounts... public class Account { ... private String fTitle; private String fAccountCode .... } public class AccountManager { ... public void addAccount(Account aNewAccount); ... } ... and any new account must have a non null title and a non-null account code. If the 'aNewAccount' parameter is passed with a null title field or a null account code field what type of exception should I throw? Should the business tier code be throwing an IllegalArgumentException? If so, how can my GUI tier determine what field failed the validation test? Or should I use a separate custom exceptions for each validation point? One custom exception for title, another for alias etc. Why not create your own exception, such as NullAccountField with a different message for each field? Back to top Lew Guest Posted: Tue May 08, 2007 1:53 am    Post subject: Re: What exception to use with invalid data fields on object davout wrote: Quote: I have a question about what the convention is for throwing exceptions on validating data passed to business tier objects. If the 'aNewAccount' parameter is passed with a null title field or a null account code field what type of exception should I throw? Should the business tier code be throwing an IllegalArgumentException? If so, how can my GUI tier determine what field failed the validation test? Or should I use a separate custom exceptions for each validation point? One custom exception for title, another for alias etc. Thomas Fritsch wrote: Quote: I personally would prefer IllegalArgumentException for all (with different detail messages), instead of lots of custom exception classes. I concur with Thomas, although there really is no well-established convention. The best practice is to use the exception that makes the most sense, which Thomas's sure seems to do. You ask for an exception that indicates that an argument is illegal, and Hey, presto! java.lang.IllegalArgumentException provides exactly that, as an unchecked Exception. There is an argument to use NullPointerException if the null-pointerness is what's most important to you, as opposed to IllegalArgumentException if the illegal-argumentness is what's most significant. In the world of RuntimeExceptions there's almost always a suitable one available in the standard API, usually from java.lang. For checked Exceptions there's a better case for writing (usually only) one custom, application-specific Exception that uses any underlying Throwable as its cause. Creating a hierarchy of custom (checked) Exceptions is possible but to my mind offers little to negative benefit. The question of whether to throw checked or unchecked Exceptions is subtler. Think as an API designer when pondering it. -- Lew Back to top Wojtek Guest Posted: Tue May 08, 2007 3:29 am    Post subject: Re: What exception to use with invalid data fields on object Thomas Fritsch wrote : Quote: I personally would prefer IllegalArgumentException for all (with different detail messages), instead of lots of custom exception classes. Except where you want to control which exception gets handled where. The alternative is to parse the exception message (or custom flag) and if you do not want to handle it there, re-throw the exception. Not as clean as a custom exception class. -- Wojtek Back to top Reinder Verlinde Guest Posted: Sat May 19, 2007 3:25 am    Post subject: Re: What exception to use with invalid data fields on object In article <mn.3ba17d751a41a264.70216 (AT) a (DOT) com>, Wojtek <nowhere (AT) a (DOT) com> wrote: Quote: Thomas Fritsch wrote : I personally would prefer IllegalArgumentException for all (with different detail messages), instead of lots of custom exception classes. Except where you want to control which exception gets handled where. In that case, you can do: class myIllegalArgumentException extends IllegalArgumentException { ... } ... try { ... } catch( myIllegalArgumentException e) { ... } catch( IllegalArgumentException e) { ... } Reinder 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.