What does @ElementCollection with @Column mean ?

[Sreyan Chakravarty]

I have come across this piece of code -:

@ElementCollection  // use default table (PERSON_NICKNAMES)
       @Column(name="name", length=50)
       protected Set<String> nickNames = new HashSet();

From the Oracle documentation over here http://docs.oracle.com/javaee/6/api/javax/persistence/CollectionTable.html

Why specify @Column after @ElementCollection what does that mean ?

I have used the following pattern in my code and I have noticed no difference whatsoever. So why use it ?

[Roel De Nijs]

When I have a doubt about JPA, I always check the Java Persistence Wikibook first. Most of the time my doubts are cleared, it's really an awesome resource! Here is the page about ElementCollection (and @CollectionTable) which also has an example of @ElementCollection followed by @Column.

[Sreyan Chakravarty]

Roel De Nijs wrote:When I have a doubt about JPA, I always check the Java Persistence Wikibook first. Most of the time my doubts are cleared, it's really an awesome resource! Here is the page about ElementCollection (and @CollectionTable) which also has an example of @ElementCollection followed by @Column.

So correct me if I am wrong here. @Column is used to specify the name of that column which is created in the sub table ? In the above example the column will be named "name" and the value will be varchar(50) right ?

[Roel De Nijs]

Sreyan Chakravarty wrote:@Column is used to specify the name of that column which is created in the sub table ? In the above example the column will be named "name" and the value will be varchar(50) right ?

That's indeed my understanding as well!

It's used when you have a basic collection (that's a collection of strings, integers,...). Then @Column will be the name of the column where the strings, integers,... will be stored. With a complex type (like Phone), the column names will be mapped in the Phone class (and you'll use the @Column in this class).

Hope it helps!
Kind regards,
Roel