Hello,

I've got 2 types of databags in my Java-code. One represents a 'Class' (a bunch of students) and the other represents a 'Test' (something the students have to do). I want to link all the Tests they may do, to a particular Class. I want to use a collection (Map) for this.

I have therefore 3 tables in my database: 'classes' (with primary key 'class_id'), 'tests' (primary key is 'test_id') and an association/join-table 'classes_tests'. This table got two foreign keys 'class_id' and 'test_id' and a third column 'obligatory' that is set true when the test has to be performed.

I use annotations to map the database with the databags. I didn't had any problems until this point, but now I don't succeed to use a 'Map' (like HashMap) wich has a Test as key and the column obligatory as value.

This is the code I have so far for this Map:

I've tried some things and now it works. I had to use MapKeyManyToMany.

But now I get an error in Netbeans:

basic attributes can only be of the following types: java primitive types,wrapper of primitive types, String, java.math.bigInteger, java.math.BigDecimal, java,util.Date, java.util.Calendar, java.sql.Data, java.sql.TimeStamp, byte[], Byte[], char[], Character[], enums, or any Serializable type

Nobody has ever got this error?