{"id":10411,"date":"2013-03-26T22:00:23","date_gmt":"2013-03-26T20:00:23","guid":{"rendered":"http:\/\/www.javacodegeeks.com\/?p=10411"},"modified":"2013-03-27T07:04:36","modified_gmt":"2013-03-27T05:04:36","slug":"ejb-inheritance-is-different-from-java-inheritance","status":"publish","type":"post","link":"https:\/\/www.javacodegeeks.com\/2013\/03\/ejb-inheritance-is-different-from-java-inheritance.html","title":{"rendered":"EJB Inheritance is Different From Java Inheritance"},"content":{"rendered":"

Despite the fact that EJB inheritance sometimes uses Java inheritance \u2014 they\u2019re not<\/b> always the same. Just as you could read in my previous post<\/a>, EJB doesn\u2019t have to implement any interface to expose<\/b> a business interface.
\nThe other way around is also true \u2014 just because EJB is implementing some interface or extending<\/b> other EJB doesn\u2019t mean it exposes<\/b> all or any of its views.<\/p>\n

Let\u2019s say we want to have some basic EJB exposing remote business interface. We then want to extend this EJB and override remote business methods.
\nNothing fancy, right? But let\u2019s take a look at some examples.
\n 
\n <\/p>\n

Remote business interface:<\/h4>\n
public interface RemoteA {\r\n    void remoteA();\r\n}\r\n<\/pre>\n
Base EJB:<\/h4>\n
@Stateless \r\n@Remote(RemoteA.class) \r\npublic class SuperclassEJB implements RemoteA {   \r\n    public void remoteA() {\r\n        \/\/ Some basic code that can be overriden.\r\n    }\r\n}\r\n<\/pre>\n
The above SuperclassEJB<\/code> is our base EJB. It exposes one remote business interface with one method. Now let\u2019s move to subclasses of our EJB:<\/p>\n
Case 1 \u2013 Java Inheritance<\/h2>\n
@Stateless \r\npublic class SubclassEJB1 extends SuperclassEJB {\r\n    \/\/ 'remoteA' is not EJB business method. EJB inheritance is strictly for implementation reusing.\r\n}\r\n<\/pre>\n
SubclassEJB1<\/code> is an EJB \u2013 that\u2019s for sure. But what interfaces does it expose? Because an EJB component must explicitly define what business interfaces it\u2019s defining \u2013 our EJB doesn\u2019t have any real business methods at all! It\u2019s new, fresh no-interface view EJB.
 
<\/div> <\/div><\/p>\n
This means that if in your code you\u2019ll do:<\/p>\n