Java Instance of: Supertypes und Subtypes seem to be equal? How to test exaclty for Type?
- by jens
Hello,
i would be thankful for your advice. I need to test, if an instance is exactly of a given type. But it seems that instanceof returns true also if the subtype is tested for the supertype (case 3). I never knew this before and I am quite surprised. Am I doing something wrong here? How do I exactly test for a given typen?
//..
class DataSourceEmailAttachment extends EmailAttachment
//...
EmailAttachment emailAttachment = new EmailAttachment();
DataSourceEmailAttachment emailAttachmentDS = new DataSourceEmailAttachment();
if (emailAttachment instanceof EmailAttachment){
System.out.println(" 1");
}
if (emailAttachment instanceof DataSourceEmailAttachment){
System.out.println(" 2");
}
if (emailAttachmentDS instanceof EmailAttachment){
System.out.println(" 3 ");
}
if (emailAttachmentDS instanceof DataSourceEmailAttachment){
System.out.println(" 4");
}
RESULT:
1
3
4
I want to avoid case 3, I only want "exact matches" (case 1 and 4) how to thest for them??
thanks!!!
Jens
