style: em.remove() kommentiert

Thomas Ziemer
1 parent 377d4aaa
Showing 1 changed file with 5 additions and 0 deletions
src/main/java/net/ziemers/swxercise/db/dao/GenericDao.java
@@ -63,8 +63,13 @@ public class GenericDao {
     }
     public <T extends BaseEntity> T remove(Class<T> entityType, Long primaryKey) {
+        // In order to delete an object from the database, it has to first be
+        // retrieved and then in an active transaction, it can be deleted using
+        // the remove() method.
         final T entity = findById(entityType, primaryKey);
+        // An "IllegalArgumentException" is thrown by remove(), if the argument
+        // is not an instance of an entity class or if it is a detached entity.
         entityManager.remove(entity);
         return entity;
     }