Entity classes are used to represent objects whose lifespan is longer than a typical program execution. This feature in NetBeans creates an entity class for each selected table, complete with named query annotations, fields representing columns, and relationships representing foreign keys.
1. Go to File | New File...
2. Select your Project (Inventory Management System in this example). Select Persistence form Categories and Entity Classes from Database from File Types.
3. Press Next.
4. Select the Database Connection. If you want to know how to create the connection, read the post Create Database Connection in NetBeans.
5. After selecting the connection, available database tables will be listed from which you just add the tables by pressing Add or Add All.
6. Press Next.
7. Class Names are listed. You can change the names if you want.Give a package name (ims.beans in this example).
8. Press the button Create Persistence Unit. Give a Persistence Unit Name or leave it for the default name. In this example the name is Inventory_Management_SystemPU. To know about the persistence unit and associated concepts read Managing Entities - the Java EE 5 Tutorial.
9. Select EclipseLink from the Persistence Library. Other library options are Hibernate, TopLink etc.
10. Select None from the Table Generation Strategy.
11. Press Create.
12. Press Next to Specify Mapping Options. Set default as the Association Fetch and java.util.List as the Collection Type. Alternative collection types are java.util.Collection and java.util.Set.
13. Press Finish and see all the entity classes are generated in the selected package.
