Hibernate - Interview Questions and Answers for 'Abs' - 15 question(s) found - Order By Newest Frequently asked question in companies using Hibernate. Q1. 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 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
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 ) Help us improve. Please let us know the company, where you were asked this question : 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
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. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate annotations   @generatedvalue   database sequenceVery frequently asked Hibernate interview question. Frequently asked in TCS ( based on 2 feedback ) Q4. 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 Q5. Write a program to show thread usage in Java by implementing runnable interface
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();
}
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  Threads  runnable interface Q6. What is the difference between these 2 annotations ?
@Entity ( name ="EMPLOYEES")
@Entity @Table ( name=""EMPLOYEES"" )
@Entity ( name="EMP")
@Table ( name="EMPLPYEES" ) Hibernate
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. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate annotations   entity annotation   table annotation Q7. What is the advantage of JPA ? Database
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. Help us improve. Please let us know the company, where you were asked this question : 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
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(); Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate   hibernate criteria   hibernate table mapping Q9. Difference between JDBC and Hibernate ? Database
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. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  JDBC  Hibernate  JDBC vs Hibernate Asked in 3 Companies Q10. What are the methods to connect to database in Java ? Database
Ans. JDBC ( Java Database Connectivity ),ODBC (Open Database Connectivity), Hibernate, JPA ( Java Persistence API ), JOOQ,MyBatis Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  database connection  jdbc  ORM  Hibernate Asked in 1 Companies Q11. What is the difference between JDBC, Hibernate and ODBC ? Database
This question was recently asked at 'Oracle Argentina'.This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : 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 ? Hibernate
Ans. hibernate-orm
hibernate-validator
hibernate-ogm
hibernate-search
or you can download hibernate core with all dependencies. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  hibernate jar files   hibernate Asked in 1 Companies Q13. Explain Hibernate caching mechanism Hibernate
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 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve   Asked in 23 Companies Q14. Write a Program to swap 2 variables ( using 3rd variable ) Core Java
Ans. int x = 1;
int y = 2;
int z = x;
x = y;
y = z;
System.out.println("x="+x);
System.out.println("y="+y); Help us improve. Please let us know the company, where you were asked this question : 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 )
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); Help us improve. Please let us know the company, where you were asked this question : 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. compareEqualsAns.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
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.
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 variablesAns.b. instance methods
Q21. In majority of the cases, the following join will give maximum number of results ? Reference Database
a. Inner Join b. Outer Join c. Left Join d. Right JoinAns.b. Outer Join
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 recordsAns.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 cachingAns.c. Prepared Statements provide ORM capabilities