WebFeb 28, 2013 · Hibernate is designed to work well if you don't override equals and hashcode at all, but you may have valid reasons to, most notably if you ever disconnect entities and want to compare them for equivalence. In my experience, if you implement hashcode and equals for any of the objects, you'll probably want to do it for all of them. WebNov 21, 2024 · - The ID class must be public - It must implement java.io.Serializable interface - It must have no-argument constructor - It must override equals() and hashCode() methods. ... And code of the ID class that maps to the composite primary key in the database table: package net.codejava.sale; import java.io.Serializable; import …
Chapter 5. Basic O/R Mapping - JBoss
Webe1 = em.merge (e1); Assert.assertTrue (e1.equals (e2)); Assert.assertTrue (e1 == e2); As you can see, Java’s default equals () and hashCode () methods only produce the required result if the Hibernate Session ensures that there is only 1 Java object that represents a specific record in the database table. WebSep 26, 2024 · Case 1: Overriding both equals (Object) and hashCode () method. You must override hashCode () in every class that overrides equals (). Failure to do so will result in a violation of the general contract for Object.hashCode (), which will prevent your class from functioning properly in conjunction with all hash-based collections, including ... chips auto and tire randolph vt
Hibernate Composite Primary Key Examples - codejava.net
WebJul 5, 2024 · Solution 2. When implementing equals you should use instanceof to allow comparing with subclasses. If Hibernate lazy loads a one to one or many to one relation, you will have a proxy for the class instead of the plain class. A proxy is a subclass. Comparing the class names would fail. http://www.javawenti.com/?post=22979 WebAnswer #2 100 %. Using JPA when you use composite key, you should use either IdClass or EmbeddedId using any of them you need to create an own class that act as a composite key, in order to be able to compare objects using this composite key which is required by several operations within the EntityManager that key classes must to override equals … chips auto transport walpole ma