AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Structs and null pointer exceptions          AppletTalk.com Forum Index -> Java and CORBA View previous topic :: View next topic   Author Message Guest Posted: Fri Jun 30, 2006 12:11 am    Post subject: Structs and null pointer exceptions I have an IDL looking something like this module LMS { struct Alarm { string sensor; string zone; }; interface LMSIF { void raise_alarm(in Alarm aReading); void send_alarm_to_rmc(in string alarm); string test_case(); }; }; and a java file looking something like: class LMSServant extends _LMSIFImplBase { Alarm al; //functions here public LMSServ() { //this line causes the problem. al.sensor = "Sensor 1"; } } The problem i'm having is when i try to modify or write to the Alarm struct i get a NullPointerException every time. Am i doing something wrong? Do i need to define anything extra to get an IDL struct to work as a java class? I tried redefining Alarm as a class with the same variables but this caused all sorts of other errors.. Any help appreciated Back to top Piet van Oostrum Guest Posted: Sat Jul 01, 2006 5:07 pm    Post subject: Re: Structs and null pointer exceptions Quote: jamesb457 (AT) gmail (DOT) com (J) wrote: J> I have an IDL looking something like this J> module LMS J> { J> struct Alarm J> { J> string sensor; J> string zone; J> }; J> interface LMSIF J> { J> void raise_alarm(in Alarm aReading); J> void send_alarm_to_rmc(in string alarm); J> string test_case(); J> }; J> }; J> and a java file looking something like: J> class LMSServant extends _LMSIFImplBase J> { J> Alarm al; J> //functions here J> public LMSServ() J> { J> //this line causes the problem. J> al.sensor = "Sensor 1"; J> } J> } J> The problem i'm having is when i try to modify or write to the Alarm J> struct i get a NullPointerException every time. J> Am i doing something wrong? yes. You only declare the Alarm variable al, but you don't reserve any memory for it. It initializes with null. In Java Corba structs are classes and you have to create an instance with new. In contrast to C and C++ where structs get memory automatically. So Alarm al = new Alarm(); should solve it I think. -- Piet van Oostrum <piet (AT) cs (DOT) uu.nl> URL: http://www.cs.uu.nl/~piet [PGP 8DAE142BE17999C4] Private email: piet (AT) vanoostrum (DOT) org Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java and CORBA 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.