Then check out our detailed Hibernate Interview Questions! Besides studying them online you may download the eBook in PDF format!. Hibernate is a popular framework of Java which allows an efficient Top 50 Hibernate Interview Questions & Answers .. Download PDF. Dear readers, these Hibernate Interview Questions have been designed specially to get As per my experience good interviewers hardly plan to ask any particular question they continue based on further discussion and what you answer.
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Hibernate is an ORM (object-relational mapping) tool for Java programming language. Download Hibernate Interview Questions PDF. Hibernate Interview medical-site.info - Free download as PDF File .pdf), Text File . txt) or read What are the most common methods of Hibernate configuration?. These interview questions and answers on Hibernate will help you strengthen your technical skills, PDF was generated at Saturday 10th January,
Latest Answer: Add the hibernate related jar files into lib directory of any web application using net beans. Latest Answer: cascade specifies which operations should be casecaded from the parent object to the associated object. Spring is a framework for enterprise applications with default APIs for presentation, middle tiers and presistence layers and allows to integrate with various presentations, middle tier and presistence APIs How well it is implemented in Hibernate Latest Answer: Preserving the data inside a database is database persistence.
Persistence is once of the fundamental concepts of application developement. There are many alternatives to implement persistence. Read Answers 2 Asked by : donna Answer Question Subscribe What is the difference between beans and hibernate which one is good? Java bean is a simple resuble component. There is no persistency on bean hibernate provides the service to make the bean persistent so that we can make use of it. In hibernate Latest Answer: Hibernate 3. Q2: Which one, among EJB 2.
Explain with reason. Q3: When to use EJB 2. Explain with scenarios. Latest Answer: 1 Hiberante is not tightly tied with any underlaying database. Where as JDBC is tighlty tield with the underlaying database. So can any one tell me how to develop a application using Hibernate in the Myeclipse I am new to Hibernate. So can any one tell me how to develop a application using Hibernate in the Myeclipse. Read Answers 3 Asked by : Sudarshan.. Answer Question Subscribe How to create primary key using hibernate?
This is a very convenient approach for functionality like "search" screens where there is a variable number of conditions to be placed upon the result set. What do you mean by fetching strategy? A fetching strategy is the strategy Hibernate will use for retrieving associated objects if the application needs to navigate the association.
What is automatic dirty checking? Automatic dirty checking is a feature that saves us the effort of explicitly asking Hibernate to update the database when we modify the state of an object inside a transaction.
What is transactional write-behind? Hibernate uses a sophisticated algorithm to determine an efficient ordering that avoids database foreign key constraint violations but is still sufficiently predictable to the user. This feature is called transactional write-behind. What are Callback interfaces? Callback interfaces allow the application to receive a notification when something interesting happens to an objectfor example, when an object is loaded, saved, or deleted.
Hibernate applications don't need to implement these callbacks, but they're useful for implementing certain kinds of generic functionality.
What are the types of Hibernate instance states? Three types of instance states: Transient -The instance is not associated with any persistence context Persistent -The instance is associated with a persistence context Detached -The instance was associated with a persistence context which has been closed currently not associated What are the differences between EJB 3.
Bidirectional relationships are implemented by two unidirectional relationships Entity Relationships are bidirectional or unidirectional What are the types of inheritance models in Hibernate? There are three types of inheritance models in Hibernate: Table per class hierarchy Table per subclass Table per concrete class www. Latest Answer: Read Answers 6 Asked by: In order to call a stored procedure using the hibernate , define a named query for a persistent class mapping document. Then call the named query from your java application.
Example is given in the Hibernate Reference documentation as follows: Read Answers 3 Asked by: These are the few questions that continuously get asked in most of forums. Whats really difference between two and really more importantly when should I use one over the other. Its pretty interesting question because there are major differences To make the application developemnt more productive. Read Answers 2 Asked by: Read Answers 5 Asked by: You can declare it as Named queiries in one of your mapping files and give unique name.
Call it in your code. Sample code is below. Read Answers 4 Asked by: In my opinion in case of Entity Beans our bean only work under contanier.
There is no concept of Detached Objects. But in case of hibernate we have detached object concepts.
Read Answers 1 Asked by: In other words, Proxies are created dynamically by subclassing your object at runtime. The subclass has all the methods of the parent, and when any of the methods are accessed, the proxy loads up the real object from the DB and calls the method for you.
Very nice in How will you configure Hibernate? The configuration files hibernate. Session instances are the primary interface for the persistence service. These two files are used to configure the hibernate sevice connection driver class, connection URL, connection username, connection password, dialect etc. If both files are present in the classpath then hibernate.
These files are used to map persistent objects to a relational database. It is the best practice to store each object in an individual mapping file i. The naming convention is to use the same name as the persistent POJO class name. For example Account.
What is a SessionFactory? Is it a thread-safe object? SessionFactory is Hibernate s concept of a single datastore and is threadsafe so that many threads can access it concurrently and request for sessions and immutable cache of compiled mappings for a single database. A SessionFactory is usually only built once at startup. SessionFactory should be wrapped in some kind of singleton so that it can be easily accessed in an application code.
What is a Session? Can you share a session object between different theads? Session is a light weight and a non-threadsafe object No, you cannot share it between threads that represents a single unit-of-work with the database. Sessions are opened by a SessionFactory and then are closed when all work is complete. Session is the primary interface for the persistence service. A session obtains a database connection lazily i.
To avoid creating too many sessions ThreadLocal class can be used as shown below to get the current session no matter how many times you make call to the currentSession method.
What are the benefits of detached objects? Detached objects can be passed across layers all the way up to the presentation layer without having to use any DTOs Data Transfer Objects.
You can later on re-attach the detached objects to another session. What are the pros and cons of detached objects? You can use detached objects from the first transaction to carry data all the way up to the presentation layer. These detached objects get modified outside a transaction and later on re-attached to a new transaction via another session. Cons " In general, working with detached objects is quite cumbersome, and better to not clutter up the session with them if possible.
It is better to discard them and re-fetch them on subsequent requests. This approach is not only more portable but also more efficient because - the objects hang around in Hibernate's cache anyway. How does Hibernate distinguish between transient i. Answer " Hibernate uses the version property, if there is one. No identifier value means a new object. This does work only for Hibernate managed surrogate keys. Does not work for natural keys and assigned i. What is the difference between the session.
Both the session. But if there was not such object in the database then the method session. The session.
It is the best practice to use either session. Use session. When you reattach detached objects you need to make sure that the dependent objects are reatched as well. How would you reatach detached objects to a session when the same object has already been loaded into the session?
You can use the session. What are the general considerations or best practices for defining your Hibernate persistent classes? You must have a default no-argument constructor for your persistent classes and there should be getXXX i. You should implement the equals and hashCode methods based on your business key and it is important not to use the id field in your equals and hashCode definition if the id field is a surrogate key i. Hibernate managed identifier. This is because the Hibernate only generates and sets the field when saving the object.
It is recommended to implement the Serializable interface. This is potentially useful if you want to migrate around a multi-processor cluster. The persistent class should not be final because if it is final then lazy loading cannot be used by creating proxy objects.
Hibernate solves problems such as Object Relational impedance mismatch, etc. It is commonly used for object and query service. It helps data base developers develop classes which include inheritance, association, composition and polymorphism.
Primary feature of hibernate is to java classes to database tables. Data query and retrieval is also possible with Hibernate.
Application portability is a key feature in Hibernate it allows developers to port applications to almost all SQL databases. For proper functioning of the applications importance should be given to the methods equals and hash Code methods. It has a requirement which should be strictly followed in the applications which is a no-argument constructor.
Dirty checking feature of the Hibernate allows users or developers to avoid time consuming data base write actions.
This feature makes necessary updations and changes to the fields which require a change, remaining fields are left unchanged or untouched. It creates new hibernate sessions by referencing immutable and thread safe objects. Application using hibernate are usually allowed and desgined to implement single instance of the class using this interface. Only single instance of a class can be used which is using this interface. This represents hibernate session which perform the manipulation on the database entities.
Some of the activities performed by session interface are as follows they are managing the persistence state, fetching persisted ones and management of the transaction demarcation. Creating Database applications with Java is made simpler with Hibernate. First Plain old java object needs to be written, XML mapping file should be created which shows relationship between database and class attributes.
Hibernate APIs can be used to store persistent objects. Hibernate can be configured with two types of files out of which hibernate. Hibernate consults hibernate. These files are searched on class path.
Mapping description file is the second file which Hibernate uses to configure its functions. The usage of mapping description file rests entirely upon the business entity. Transactions denote a work file which can save changes made or revert back the changes. A transaction can be started by session.
When this session starts several transactions may occur. Mapping files forms the core of any database mapping tools. These files contain field to field mapping, usually this mapping occurs between classes and attributes.
After mapping files they can be persist to the database. Tags can be used to indicate the presence of a primary key. Criteria is a simple yet powerful API of hibernate which is used to retrieve entities through criteria object composition. Following are some key benefits of using Hibernate template: Session closing is automated. Interaction with hibernate session is simplified.
Exception handling is automated. We need to add following in hibernate configuration file to enable viewing SQL on the console for debugging purposes: Following are the two types of collections in hibernate: Sorted Collection b.
Order Collection. Hibernate can be used seamlessly with any type of database as its database independent while in case of JDBC, developer has to write database specific queries. In case of hibernate, there is no need to create connection pools as hibernate does all connection handling automatically while in case of JDBC, connection pools need to be created.
We can get hibernate statistics using getStatistics method of SessionFactory class as shown below: Hibernate provides dirty checking feature which can be used to reduce database write times. Dirty checking feature of hibernate updates only those fields which require a change while keeps others unchanged.
Callback interfaces of hibernate are useful in receiving event notifications from objects. For example, when an object is loaded or deleted, an event is generated and notification is sent using callback interfaces. When an instance was earlier associated with some persistent context e. Following are the four ORM levels in hibernate: Pure Relational b.
Light Object Mapping c. Medium Object Mapping d. Full Object Mapping. How It Works? Transaction management is the process of managing a set of statements or commands. In hibernate; transaction management is done by transaction interface as shown in below code: We can use any of the following two methods of hibernate configuration: XML based configuration using hibernate.
Programmatic configuration Using code logic. In hibernate; we have following two types of mapping associations between entities: One-to-One Association b. Many-to-Many Association. Hibernate provides following four ways to fetch objects from database: Using HQL b. Using identifier c. Using Criteria API d. Using Standard SQL. Database primary key is specified in the configuration file hbm.
Generator can also be used to specify how primary key is being created in the database. In the below example, deptId acts as primary key: Objects which have been detached and are no longer associated with any persistent entities can be reattached by calling session. Hibernate second level cache can be disabled using any of the following ways: Using cache provider as org.
What Is Orm Metadata? With hibernate 3. JMX provides tools for development of efficient and robust distributed, web based solutions. Hibernate session factory can be bound to JNDI by making configuration changes in hibernate. Managed associations relate to container management persistence and are bi-directional while hibernate associations are unidirectional.
What Is Light Object Mapping? Light Object Mapping is one of the levels of ORM quality in which all entities are represented as classes and they are mapped manually. Load configuration file and create object of configuration class.