Interview Questions and Answers - Order By Rating Q2431. What are the different types of inheritance in Hibernate ? Hibernate
Ans. Table Per Class , Table per Sub Class , Table per Concrete Class Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   orm   inheritance hibernate Asked in 1 Companies Basic   frequent Q2432. What is the purpose of dialect configured in Hibernate configuration file ? Hibernate
Ans. It tells the framework which SQL varient to generate. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   orm   hibernate configurationVery frequently asked Hibernate interview question. Frequently asked in TCS ( based on 2 feedback ) Q2433. What are different types of associations in Hibernate ? Hibernate
Ans. There are 4 types of associations in Hibernate
One to One
One to Many
Many to One
Many to Many Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   associations Asked in 11 Companies   frequent Q2434. What are the configuration files in Hibernate ? Hibernate
Ans. hibernate.cfg.xml ( Main Configuration File ) and *.hbm.xml files ( Mapping Files ) Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   configuration   mapping files Q2435. What are the contents of Hibernate configuration file ( hibernate.cfg.xml ) ? Hibernate
Ans. HBM Files ( Mapping )
DB Connection ( DB Connection String , User Name , Password , Pool Size )
SQL Dialect ( SQL variant to be generated )
Show SQL ( Show / No show SQL on Console )
Auto Commit ( True / False ) Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   configuration   barclays Asked in 11 Companies Very frequently asked if being interviewed for hibernate. Frequently asked in Tata Consultancy (TCS) and Overstock.com Q2436. Difference between load and get ? Hibernate
Ans. If id doesnt exist in the DB load throws an exception whereas get returns null in that case.get makes the call to DB immediately whereas load makes the call to proxy. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate Asked in 16 Companies basic   frequent Q2437. What is lazy fetching in Hibernate ? Hibernate
Ans. Lazy fetching is the technique of not loading the child objects when parent objects are loaded. By default Hibernate does not load child objects. One can specify whether to load them or not while doing the association. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   lazy fetching   architecture Asked in 11 Companies   frequent Try 2 Question(s) Test Q2438. Is It Good to use Reflection in an application ? Why ? Core Java
Ans. no, It's like challenging the design of application. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   reflection api   yes-no   architecture Asked in 1 Companies intermediate Q2439. Why is Reflection slower ?
Ans. Because it has to inspect the metadata in the bytecode instead of just using precompiled addresses and constants. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   reflection   reflection api   architecture Q2440. When should we use prototype scope and singleton scope for beans ? Spring
Ans. We should use singleton scope for beans when they are stateless and prototype when they are stateful. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  spring   bean scope   general electric   ge  singleton Q2441. Difference between Assert and Verify ? Testing
Ans. Assert works only if assertions ( -ea ) are enabled which is not required for Verify.Assert throws an exception and hence doesn't continue with the test if assert evaluates to false whereas it's not so with Verify. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  assert   junit   mockito   verify   testing   unit testing Asked in 5 Companies Very frequently asked. Favorite question in Walk in Drive of many Indian service companies. Q2442. What is the difference between ArrayList and LinkedList ? Core Java
Ans. Underlying data structure for ArrayList is Array whereas LinkedList is the linked list and hence have following differences -
1. ArrayList needs continuous memory locations and hence need to be moved to a bigger space if new elements are to be added to a filled array which is not required for LinkedList.
2. Removal and Insertion at specific place in ArrayList requires moving all elements and hence leads to O(n) insertions and removal whereas its constant O(1) for LinkedList.
3. Random access using index in ArrayList is faster than LinkedList which requires traversing the complete list through references.
4. Though Linear Search takes Similar Time for both, Binary Search using LinkedList requires creating new Model called Binary Search Tree which is slower but offers constant time insertion and deletion.
5. For a set of integers you want to sort using quicksort, it's probably faster to use an array; for a set of large structures you want to sort using selection sort, a linked list will be faster. Sample Code for ArrayList Sample Code for LinkedList Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  collections   java   data structures   arraylist   linkedlist   arraylist vs linkedlist Asked in 61 Companies Basic   frequent Try 1 Question(s) Test Q2443. How many SessionFactory and Session objects are created ? Java EE
Ans. Single SessionFactory object and multiple session objects for opening different session. Hibernate creates new Session object per thread. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   sessionfactory hibernate   session hibernate Q2444. What is the way to rollback transaction if something goes wrong using hibernate API ? Hibernate
Ans. We can have the code calling Hibernate API within try block and can have transaction.rollback within Catch. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate rollback Q2445. What is the use of hbm2ddl Configuration in Hibernate ? Hibernate
Ans. This configuration specifies if hibernate should creates the Schema / Table on its own if the respective table is not found. "update" doesn't create the table if it's not found whereas configuration set as "create" creates the schema automatically. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate configuration   hibernate.cfg.xml   hbm2ddl Q2446. What are the different ID generating strategies using @GeneratedValue annotation ? Hibernate
Ans. Auto , Identity , Sequence and Table. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   generatedvalue annotations   architecture Q2447. How to do Eager loading in Hibernate ? Hibernate
Ans. Using lazy = false in hibernate config file or @Basic(fetch=FetchType.EAGER) at the mapping Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   lazy loading hibernate   basic annotation hibernate   architectureFrequently asked question in companies using Hibernate. Q2448. What is Lazy Initialization in Hibernate ? Hibernate
Ans. It's a feature to lazily initialize dependencies , relationship and associations from the Database. Any related references marked as @OneToMany or @ManyToMany are loaded lazily i.e when they are accessed and not when the parent is loaded. Sample Code for Lazy Initialization Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   lazy loading hibernate   lazy initialization hibernate   architecture Asked in 77 Companies Basic   frequent Try 2 Question(s) Test Q2449. What are the ways to avoid LazyInitializationException ? Hibernate
Ans. 1. Set lazy=false in the hibernate config file.
2. Set @Basic(fetch=FetchType.EAGER) at the mapping.
3. Make sure that we are accessing the dependent objects before closing the session.
4. Force initialization using Hibernate.initialize
5. Using Fetch Join in HQL. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   lazy loading hibernate   lazy initialization hibernate   lazyinitializationexception   architecture Asked in 2 Companies Try 2 Question(s) TestAns. Instead of Saving Parent as well as Child Entities individually , Hibernate provides the option to persist / delete the related entities when the Parent is persisted. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   cascade   hibernate relationship   hibernate associations Q2451. What are the different Cascade types ? Hibernate
Ans. Detach, Merge , Persist , Remove , Refresh Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   cascade   cascade type Q2452. Which type of associated Entities are Eagerly loaded by Default ? Hibernate
Ans. OneToOne Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate associations   hibernate relationship Q2453. Can we declare Entity class as final ? Hibernate
Ans. Yes but as Hibernate creates the Proxy Classes inherited from the Entity Classes to communicate with Database for lazy initialization. Declaring entity classes as final will prohibit communication with database lazily and hence will be a performance hit. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   proxy objects   proxy classes   entity hibernate Q2454. What are the restrictions for the entity classes ? Hibernate
Ans. 1. Entity classes should have default constructor. 2. Entity classes should be declared non final. 3. All elements to be persisted should be declared private and should have public getters and setters in the Java Bean style. 4. All classes should have an ID that maps to Primary Key for the table. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   entity classes hibernate Q2455. What is the difference between int[] x; and int x[]; ? Core Java
Ans. No Difference. Both are the acceptable ways to declare an array. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   array   arrays   array declaration   difference between Asked in 3 Companies basic Q2456. What is asynchronous I/O ?
Ans. It is a form of Input Output processing that permits other processing to continue before the I/O transmission has finished. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   io   file   fileio   java7   architectureFrequently asked these days as there are major changes in Java 8. Q2457. What are new features introduced with Java 8 ? Core Java
Ans. Lambda Expressions , Interface Default and Static Methods , Method Reference , Parameters Name , Optional , Streams, Concurrency. Sample Code for Lambda Sample Code for interface default Sample Code for Optional Sample Code for Streams Sample Code for java.time Sample Code for Predicate Sample Code for Consumer Sample Code for MapMerge Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   java8   technical lead   technical architect Asked in 14 Companies expert   frequent Rarely asked as default methods have been introduced with Java 8. Q2458. Can we have a default method without a Body ? Core Java
Ans. No. Compiler will give error. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   java8   default method   yes-no   rare Q2459. Does java allow implementation of multiple interfaces having Default methods with Same name and Signature ? Core Java
Ans. No. Compilation error. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   java8   default method   yes-no Asked in 1 Companies intermediate Ans. With Java 8, We can provide method definitions in the Interfaces that gets carried down the classes implementing that interface in case they are not overridden by the Class. Keyword "default" is used to mark the default method. Sample Code for interface default Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java   java8   default methods Asked in 7 Companies expert   frequent