Hi

I have a persistent object "Model", which contains a set of persistent objects "Feature". "Feature" has a single parameter, "name". In "Feature" I have overridden equals and hashcode to check the "name" value instead. e.g.



I want to be able to do a comparison based on a String. e.g.


however, this always returns false. Everything I have read about overriding equals and hashcode in hibernate talks about comparing Objects across sessions, whereas I want to compare Objects based on their contents. Is this possible?

I have a solution by putting the Set into an ArrayList, but I had to override ArrayList to reverse the equals check. The default is that contains(String myString) does myString.equals(thisElement) which always failed, instead of thisElement.equals( myString ) which uses my overridden equals and hashCode. This is what I had to reverse by overriding indexOf in the ArrayList, which is EXTREMELY messy.

I'm sure that there must be a better way to do this, but I can't figure it out.

Please help

bump?

bump. again.

Hibernate will set equals and hashcode based on the key of your object.

It overrides your equals and hashcode for sets.

So you'll have:

YourClass{
private String mKey;
private String mName;

public void setName(String pName) {
mName = pName;
mKey = mName.toUppercase();
}

etc.

}

Of course, you'll have to set your mapping correctly ...

a++ Cédric

ps: BTW looks more like you need to get familiar with enums and how to handle them in Hibernate.

Hi crouvrais

thanks for the input, and please forgive me if I'm being a noob with this.

I assume by key you mean the primary key? In my case this is a long, not the string column I want to check on - we use numerical foreign-key references. Please can you give an example of

Here are my mappings:
Models


and Features:


forgive me if I am missing something blindingly obvious. I have looked through the documentation, and can't see anything.

Also, we are still using java 2 (1.4) so we don't use enums.

Why don't you do this : -

thanks JayeshJ, that works. I thought of that, but I assumed that it would try and create a new db entry if it didn't exist. Just run a test, and it doesn't seem to, so that solution works. Should have tried it before :p

When you create a new object, it only creates a new row in the db if you call save(). So you can quite happily create in-memory only instances of your persistent classes without affecting the db.