How to apply unique constraints using annotation

Question

@Column(name = \"userId\")
    @UniqueConstraint
    private Integer userId;

I am using these annotation for entering data into database table. i want

Answer 1

And this is the explanation of the Hibernate doc version 3.5 for @UniqueConstraint definition.

 @Entity
    @Table(name="tbl_sky",uniqueConstraints = {@UniqueConstraint(columnNames={"month", "day"})})
    public class Sky implements Serializable {
       ...
    }

and this is for Hibernate 4.3 example for @UniqueConstraint