![]() ![]() When an entity method is called, the entity is loaded and the proxy becomes an initialized proxy object. The proxy implementation delegates all property methods except for the to the session which will in turn populate the instance. The session.load() method creates an uninitialized proxy object for our desired entity class. When a load() method is called on session, a proxy is returned and this proxy contains the actual method to load the data. Ī proxy is defined as a function which acts as a substitute to another function. When using a map for mapping, a map-key has to be provided along with the key column. There are different associations for mapping the class with the corresponding table. The Hibernate mapping element used for mapping a collection depends upon the type of interface. To map these collections, the type of collection must be declared from one of the following: There are five types of collections in Hibernate. Collection instances are like value types and are automatically persisted when referenced by a persistent object and deleted when unreferenced. The Hibernate collections behave like HashMap, HashSet, TreeMap, TreeSet or ArrayList. This is a frequently asked question in hibernate interview questions for freshers. The hbm mapping for the above class would be: In the above example, the annotation refers to the MONTHLY_SALARY column in the database table and not the monthlySalary property in the class. A simple example of a POJO class is as below: public class Student Use of POJOs instead of simple java classes results in an efficient and well – constructed code. An ID is mandatory for each object of these classes as they will be mapped to the primary column of the table. These classes should be non-final or have an interface with all the public methods declared. These classes also have a default constructor. These classes have proper getter and setter methods for every property. Such classes whose objects are stored in a database are known as persistent classes. Hibernate is based on the concept of taking values from Java class attributes and storing them in a database. ![]()
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