8.2.2 Entity class
When you use the JPA, you create a class that forms a data container with applications. This class is called the entity class. Normally, you create the entity class so that one object of the entity class corresponds to one line in the database table. You create an entity class using the normal Java class (POJO). Special interfaces need not be implemented.
You specify the mapping for the values of the entity class fields and the columns of the database table where the values are stored, using annotations in the items such as the entity class fields. However, the CoC concept has been introduced in JPA in order to improve the easy development. If you do not specify mapping explicitly, the default mapping rules are applied. For example, if the mapping of fields is not explicitly specified, the corresponding column is presumed from the field name and mapped.