Re: Problem creating an NSButton subclass in Java
Re: Problem creating an NSButton subclass in Java
- Subject: Re: Problem creating an NSButton subclass in Java
- From: Tom Sutcliffe <email@hidden>
- Date: Sat, 2 Aug 2003 12:34:11 +0100
I'm trying to subclass an NSButton in my program with a Java class, so
I've picked NSButton in IB, subclassed it, clicked the button in my
form, set the custom class property to my new subclass, and created
the file
for my new class. (Did I miss anything?)
For whatever reason, my program won't run when my subclass is set at
the button's custom class. I get this cryptic console error:
jobjc_jvm_newObject(): constructor with signature
(Ljava/io/InputStream;)V on class java/io/ObjectInputStream failed
(should morph the java exception)
I don't know what this is referring to, as I don't use the
java.io.ObjectInputStream class. Am I missing a step in my above
procedure? Thanks for any help.
You've run into a problem when subclassing any object that goes through
the java bridge. Basically you have to define a no-arguments
constructor in your subclass. It's to do with how the NSArchiving of
stuff in IB works, if you don't define this method the runtime can't
instantiate your class.
public class MyButton extends NSButton {
public MyButton() {
super(); // Need to call this
// Otherwise you can leave this blank.
}
}
Happy subclassing,
Tom
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