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Hibernate - Interview Questions and Answers for 'Abs' - 23 question(s) found - Order By Newest

Frequently asked question in companies using Hibernate.
  Q1. What is Lazy Initialization in Hibernate ?Hibernate
Admin
info@buggybread.com
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

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   Like         Discuss         Correct / Improve     hibernate   lazy loading hibernate   lazy initialization hibernate   architecture     Asked in 77 Companies      Basic        frequent

Try 2 Question(s) Test


 Q2. What things you would care about to improve the performance of Application if its identified that its DB communication that needs to be improved ?Solution
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Ans. 1. Query Optimization ( Query Rewriting , Prepared Statements )

2. Restructuring Indexes.

3. DB Caching Tuning ( if using ORM )

4. Identifying the problems ( if any ) with the ORM Strategy ( If using ORM )

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   Like         Discuss         Correct / Improve     java   db   database   hibernate   orm   at&t   overstock.com   performance improvement   architecture   technical lead   architect      intermediate


 Q3. What is the use of @GeneratedValue annotation in Hibernate?Hibernate
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Ans. This annotation is added to the auto increment column with the strategy to increment the column value. Usually this is added to the surrogate primary key column and specified with the Database Sequence.

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   Like         Discuss         Correct / Improve     hibernate   hibernate annotations   @generatedvalue   database sequence


 Q4. Write a program to show thread usage in Java by implementing runnable interface2017-08-03 12:16:07

Ans. public class MyClass {
   static class MyThreadClass implements Runnable{

      public void start() {
         Thread t = new Thread(this,"threadName");
         t.start();
      }
      
      @Override
      public void run() {
         System.out.println("Hello");
         try {
            Thread.sleep(1000);
            System.out.println("Hello Again");
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
         
      }
      
   }
   
   public static void main(String[] args){
      MyThreadClass myThreadClass = new MyThreadClass();
      myThreadClass.start();
      
      MyThreadClass myThreadClass2 = new MyThreadClass();
      myThreadClass2.start();
   }
}

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   Like         Discuss         Correct / Improve     Threads  runnable interface


Very frequently asked Hibernate interview question. Frequently asked in TCS ( based on 2 feedback )
  Q5. What are different types of associations in Hibernate ?Hibernate
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Ans. There are 4 types of associations in Hibernate

One to One
One to Many
Many to One
Many to Many

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   Like         Discuss         Correct / Improve     hibernate   associations     Asked in 11 Companies        frequent


 Q6. What is the difference between these 2 annotations ?

@Entity ( name ="EMPLOYEES")
@Entity @Table ( name=""EMPLOYEES"" )

@Entity ( name="EMP")
@Table ( name="EMPLPYEES" )
Hibernate
Admin
info@buggybread.com
Ans. First Annotation will set the Entity name as EMPLOYEES and hence will try to map with the same Table name.

The second annotation will make the Entity mapped to table EMPLOYEES irrespective of the Entity Name ( which is class name in this case ).

Third Annotations will set the different names for Enitity and Table and will explicitly map them.

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   Like         Discuss         Correct / Improve     hibernate   hibernate annotations   entity annotation   table annotation


 Q7. What is the advantage of JPA ?Database
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Ans. Its a specification that guides the implementation of ORM frameworks. Implementations abiding by the specification would mean that one can be replaced with other in an application without much hassle. Only the Features that are added over the specification needs to be taken care of if any such change is made.

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   Like         Discuss         Correct / Improve     jpa   hibernate   orm   technologies


 Q8. How do we specify the criteria if it involves mapping between two entities or join between tables ?Hibernate
Admin
info@buggybread.com
Ans. The following code returns the list of Employee objects having employee name starting with A and Dept Name ( Department , Employee Mapped ).

session.createCriteria(Employee.class,"emp")
.createAlias("emp.department", "dept",Criteria.INNER_JOIN)
.add( Restrictions.like("name", "A%") )
.add(Restrictions.eq("dept.name","Finance")
.list();

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   Like         Discuss         Correct / Improve     hibernate   hibernate criteria   hibernate table mapping


 Q9. Difference between JDBC and Hibernate ?Database2016-12-06 09:57:14

Ans. JDBC is a standard Java Api for Database communication whereas Hibernate is an ORM framework that uses JDBC to connect with Database.

Hibernate is another layer of object table mapping over JDBC that provide a database independent, object oriented and an efficient way of database communication.

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   Like         Discuss         Correct / Improve     JDBC  Hibernate  JDBC vs Hibernate     Asked in 3 Companies


 Q10. What are the methods to connect to database in Java ?Database2017-02-05 09:00:41

Ans. JDBC ( Java Database Connectivity ),ODBC (Open Database Connectivity), Hibernate, JPA ( Java Persistence API ), JOOQ,MyBatis

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   Like         Discuss         Correct / Improve     database connection  jdbc  ORM  Hibernate     Asked in 1 Companies


 Q11. What is the difference between JDBC, Hibernate and ODBC ?Database2017-06-18 17:52:39

 This question was recently asked at 'Oracle Argentina'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     jdbc  odbc  hibernate  jdbc vc odbc  jdbc vs hibernate     Asked in 1 Companies


 Q12. Which jar files need to be included for using Hibernate ?Hibernate2018-07-23 11:25:33

Ans. hibernate-orm
hibernate-validator
hibernate-ogm
hibernate-search

or you can download hibernate core with all dependencies.

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   Like         Discuss         Correct / Improve     hibernate jar files   hibernate     Asked in 1 Companies


 Q13. Explain Hibernate caching mechanismHibernate2018-11-14 12:53:50

Ans. Every fresh session having its own cache memory, Caching is a mechanism for storing the loaded objects into cache memory. The advantage of cache mechanism is, whenever again we want to load the same object from the database then instead of hitting the database once again, it loads from the local cache memory only, so that the no. of round trips between an application and a database server got decreased. It means caching mechanism increases the performance of the application.

In hibernate we have two levels of caching

First Level Cache [ or ] Session Cache
Second Level Cache [ or ] Session Factory Cache [ or ] JVM Level Cache

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   Like         Discuss         Correct / Improve          Asked in 23 Companies


 Q14. Write a Program to swap 2 variables ( using 3rd variable )Core Java2017-07-25 19:41:20

Ans. int x = 1;
int y = 2;
int z = x;
x = y;
y = z;

System.out.println("x="+x);
System.out.println("y="+y);

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   Like         Discuss         Correct / Improve     swap 2 variables  code  coding     Asked in 1 Companies      basic


 Q15. Write a Program to swap two variables ( without using 3rd variable )2017-07-25 19:42:32

Ans.
int x = 1;
int y = 2;

x = x+y;
y = x-y;
x = x-y;

System.out.println("x="+x);
System.out.println("y="+y);

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   Like         Discuss         Correct / Improve     swap 2 variables


 Q16. Which method needs to be implemented if a class is implementing comparable interface ?Core Java
a. comp
b. compare
c. compareTo
d. compareEquals

Ans.c. compareTo

 Q17. What is Dirty Read in Database Transactions ?Database
a. Data Read by Transaction 2 which hasn't yet updated by Transaction 1
b. Data Read by Transaction 2 which has been updated and commited by Transaction 1
c. Data Read by Transaction 2 which has been updated but not commited by Transaction 1
d. Inability of Transaction 2 to read Data when Transaction 1 is updating.

Ans.c. Data Read by Transaction 2 which has been updated but not commited by Transaction 1

 Q18. Which of the following is not true for abstract classes ?Core Java
a. Abstract Class is only meant to be sub classed and not supposed to be instantiated.
b. Abstract class handlers can be used to handle derived class objects.
c. We can't have an abstract class without abstract methods.
d. Abstract class has member elements.

Ans.c. We can't have an abstract class without abstract methods.

 Q19. Which of the following class creates immutable objects ?Core Java
a. String
b. StringBuffer
c. StringBuilder
d. None of these create immutable objects.

Ans.a. String

 Q20. Which of the following can be declared abstract ?Core Java
a. static methods
b. instance methods
c. static variable
d. instance variables

Ans.b. instance methods

 Q21. In majority of the cases, the following join will give maximum number of results ?Database
a. Inner Join
b. Outer Join
c. Left Join
d. Right Join

Ans.b. Outer Join

 Q22. Which if the following is true for SQL Joins ?Database
a. Left Join and Right Join gives equal number of Results
b. Outer Join and Inner Join gives equal number of Results
c. Inner Join gives maximum number of results records
d. Inner Join gives minimum number of result records

Ans.d. Inner Join gives minimum number of result records

 Q23. Which of the following is not true for Prepared Statements ?Database
a. Prepared Statements provides better performance
b. Prepared Statements prevent SQL Injection attacks
c. Prepared Statements provide ORM capabilities
d. Prepared Statement provides DB side caching

Ans.c. Prepared Statements provide ORM capabilities



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