EY Interview Questions

1.What is difference between Iterator and ListIterator?

No.	Iterator	ListIterator
1)	Iterator traverses the elements in forward direction only.	ListIterator traverses the elements in backward and forward directions both.
2)	Iterator can be used in List, Set and Queue.	ListIterator can be used in List only.

Methods in Iterator :

1. hasNext()
2. next()
3. remove()  

Methods in ListIterator

1. hasNext()
2. next()
3. previous()
4. hasPrevious()
5. remove()
6. nextIndex()
7. previousIndex()

ListIterator listite = List.listIterator();

2.Can we Override main() method?
 ANS: No, because main is a static method.


3.Can we overload main() method?
ANS: YES
EX: 
public class ttt {
 public static void main(String[] a, int  b){
   System.out.println("Main1");
 }
 public static void main(int a, int  b){
   System.out.println("Main2");
 }
  public static void main(String[] args) {
    main(args,1);
    main(1,2);
  }
}

4.Can we overload methods that differ only by static keyword?
ANS: NO
EX:

public class Test {

    public static void foo() {

        System.out.println("Test.foo() called ");

    }

    public static void foo(int a) {

        System.out.println("Test.foo(int) called ");

    }

    public void foo(int a) { //GIVES COMPILE ERROR

        System.out.println("Test.foo(int) called ");

    }

    public static void main(String args[])

    {

        Test.foo();

        Test.foo(10);

    }

}



5.Can we overload methods static methods?

ANS: YES

6.Explain Overload?

If a class have multiple methods by same name but different parameters, it is known as Method Overloading.

Advantage :

Method overloading increases the readability of the program.
Different ways to overload the method

There are two ways to overload the method in java

1. By changing number of arguments
2. By changing the data type

EX:
public void add(int a, int b){};
public void add(String a, int b, int c){};

6.Explain Override?
If subclass (child class) has the same method as declared in the parent class, it is known as method overriding.
Advantage :

• Method Overriding is used to provide specific implementation of a method that is already provided by its super class.
• Method Overriding is used for Runtime Polymorphism

Rules for Method Overriding

1. method must have same name as in the parent class
2. method must have same parameter as in the parent class.
3. must be IS-A relationship (inheritance).

7.How to print salary less than 100 using Criteria in Hibernate?

    Criteria criteria = session.createCriteria(Employee.class);
    criteria.add(Restrictions.like("manager", "Anurag"));
    criteria.add(Restrictions.gt("salary", 1000));

Some more EX: 

Criteria cr = session.createCriteria(Employee.class);
cr.add(Restrictions.gt("salary", 2000));
cr.add(Restrictions.lt("salary", 2000));
cr.add(Restrictions.like("firstName", "zara%"));

// Case sensitive form of the above restriction.
cr.add(Restrictions.ilike("firstName", "zara%"));
cr.add(Restrictions.between("salary", 1000, 2000));

// To check if the given property is null
cr.add(Restrictions.isNull("salary"));

// To check if the given property is not null
cr.add(Restrictions.isNotNull("salary"));

// To check if the given property is empty
cr.add(Restrictions.isEmpty("salary"));

// To check if the given property is not empty
cr.add(Restrictions.isNotEmpty("salary"));

8.How to print collection data using JSTL?

<%
    String[] columnHeaders = {"Banana", "Apple", "Carrot", "Orange", "Lychee", "Permisson"};
    request.setAttribute("columnHeaders", columnHeaders);
%>

<c:forEach var="columnHeader" items="${columnHeaders}">
    <td>
        <c:out value="${columnHeader}" />
    </td>
</c:forEach>

9.Difference between ServletConfig and ServletContext?

Servlet Config	Servlet Context
Servlet config object represent single servlet	It represent whole web application running on particular JVM and common for all the servlet
Its like local parameter associated with particular servlet	Its like global parameter associated with whole application
It’s a name value pair defined inside the servlet section of web.xml file so it has servlet wide scope	ServletContext has application wide scope so define outside of servlet tag in web.xml file.
getServletConfig() method is used to get the config object	getServletContext() method is  used to get the context object.
for example shopping cart of a user is a specific to particular user so here we can use servlet config	To get the MIME type of a file or application session related information is stored using servlet context object.

 The ServletContext object is created per application (i.e. only one) whereas ServletConfig object is created per servlet (i.e. if there are 4 servlets, there will be 4 ServletConfig objects).
Non-technical differences are:
You may get the instance of ServletContext by calling the getServletContext() method of GenericServlet class whereas getServletConfig() method of Servlet interface returns the instance of ServletConfig.

ServletConfig

1.ServletConfig available in javax.servlet.*; package
2.ServletConfig object is one per servlet class
3.destroyed once the servlet execution is completed.
4.We should give request explicitly, in order to create ServletConfig object for the first time
5.Object of ServletConfig will be created during initialization process of the servlet
6.This Config object is public to a particular servlet only

ServletContext

1.ServletContext available in javax.servlet.*; package
2.ServletContext object is global to entire web application
3.Object of ServletContext will be created at the time of web application deployment
4.Scope: As long as web application is executing, ServletContext object will be available, and 5.it will be destroyed once the application is removed from the server.
6.ServletContext object will be available even before giving the first request

10.Can we call destroy() method in service()?
Yes, again, you can call destroy() from within the service() as it is also a method like any other. This can make sense sometimes, as destroy() will do whatever logic you have defined (cleanup, remove attributes, etc.).
Just bear in mind that simply calling destroy() won't won't unload the Servlet instance. You do not manage the life cycle of Servlets in the program, the Servlet Container does.

11.

Print PDF