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Thursday 18 July 2013

struts work flow

Steps for struts work flow:

  • web container loads web.xml and verifies whether the url-patterns are verified or not?, if matches web-container transfers the request to Filter Dispatcher
  • Filter Dispatcher handsover the request to ActionProxy (it is a proxy class which is responsible to apply before and after services to original business logic.)
  • Action Proxy contacts Configuration Manager class to know the suitable action for the request and the needed services for the request
  • configuration class loads struts.xml and provides the required information back to Action Proxy.
  • Action Proxy delegates the request along with its information to Action Invocation.
  • Action Invocation executes the Interceptors added to an Action form 1-N requests, after that it will calls the business logic implemented from N-1 in reverse order.
  • Action Invocation receives finally result produced by an Action class.
  • Action Proxy transfers the result back to FilterDispatcher
  • Filter Dispatcher selects an appropriated view, basing on the result
  • Finally Filter Dispatcher uses Request Dispatchers forwarding mechanism and forward a view as a response back to the client.

Saturday 1 June 2013

difference between struts 1.x and struts 2.x

struts 1.x and                                                                                            struts 2.x

front controller is Action servlet            front controller  Filter Dispather
Request Processor class            Interceptors instead Request Processor
Multiple tag librariers (html,logic, bean        single library
configuration file name can be any name        configuration file must be str                    .xml and we used to place                            in web-inf folder

Thursday 14 February 2013

Interview Questions


1. explain about ur project
2. what are the collection u have used in ur project (list, set, or map)

Ans: List, maps
3. write a program to create user de3fined exceptions

class NoBalanceException extends Exception 
{
     public NoBalanceException(String problem) 
     {
         super(problem);
     }
}
public class YesBank 
{
     public static void main( String args[ ] ) throws NoBalanceException 
     {
         int balance = 100, withdraw = 1000;
         if (balance < withdraw)
         {
              NoBalanceException e = new NoBalanceException("No balance please");
              throw e;
         }
         else
         {
               System.out.println("Draw & enjoy, Best wishes of the day");
         }
     }
}

4. explain the oops concepts of java
5. difference between string and string buffer and also write a program
import java.io.*;

public class stringBuffer{
  public static void main(String[] args) throws Exception{
  BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));
  String str;
  try{
  System.out.print("Enter your name: ");
  str = in.readLine();
  str += ",
This is the example of SringBuffer class and it's functions.";

  //Create a object of StringBuffer class
  StringBuffer strbuf = new StringBuffer();
  strbuf.append(str);
  System.out.println(strbuf);
  strbuf.delete(0,str.length());
 
  //append()
  strbuf.append("Hello");
  strbuf.append("World");   
//print HelloWorld
  System.out.println(strbuf);
 
  //insert()
  strbuf.insert(5,"_Java "); 
//print Hello_Java World
  System.out.println(strbuf);
   
  //reverse()
  strbuf.reverse();
  System.out.print("Reversed string : ");
  System.out.println(strbuf);   
//print dlroW avaJ_olleH
  strbuf.reverse();
  System.out.println(strbuf); 
//print Hello_Java World
 
  //setCharAt()
  strbuf.setCharAt(5,' ');
  System.out.println(strbuf);   
//prit Hello Java World
 
  //charAt()
  System.out.print("Character at 6th position : ");
  System.out.println(strbuf.charAt(6));   
//print J
 
  //substring()
  System.out.print("Substring from position 3 to 6 : ");
  System.out.println(strbuf.substring(3,7)); 
//print lo J
 
  //deleteCharAt()
  strbuf.deleteCharAt(3);
  System.out.println(strbuf); 
//print Helo java World
 
  //capacity()
  System.out.print("Capacity of StringBuffer object : ");
  System.out.println(strbuf.capacity());    //print 21
 
  //delete() and length()
  strbuf.delete(6,strbuf.length());   
  System.out.println(strbuf);   
//no anything
  }
  catch(StringIndexOutOfBoundsException e){
  System.out.println(e.getMessage());
  }
  }
}


6. wap to retrieve the elements from the list, set and map
                             /*Lists;*/
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;

public class ListExample {

    public static void main(String[] args) {

        // List Example implement with ArrayList
        List<String> ls=new ArrayList<String>();

        ls.add("one");
        ls.add("Three");
        ls.add("two");
        ls.add("four");

        Iterator it=ls.iterator();

        while(it.hasNext())
        {
          String value=(String)it.next();

          System.out.println("Value :"+value);
        }
    }
}
/*
List Value  One
List Value :Three
List Value :two
List Value :four
*/

set
Set interface is part of java.util package. Set interface can add value elements by add(value) method.
Set can implement TreeSet class.
Set value can get by Iterator interface.

import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;

public class SetExample {

    public static void main(String[] args) {

        // Set example with implement TreeSet
        Set<String> s=new TreeSet<String>();

        s.add("b");
        s.add("a");
        s.add("d");
        s.add("c");

        Iterator it=s.iterator();

        while(it.hasNext())
        {
          String value=(String)it.next();

          System.out.println("Value :"+value);
        }
    }
}
/*
Set Value :a
Set Value :b
Set Value :c
Set Value :d
*/

/* map:
Map interface is part of java.util package. Map interface can add key and value put(key, value) pair elements. This Map permits null value. Map is interface. Key and value of Map can get by Set Interface and Map interface through Iterator interface.

Map example give a method, how to use Map in java.
*/
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class MapExample {

    public static void main(String[] args) {

        Map<Object,String> mp=new HashMap<Object, String>();

        // adding or set elements in Map by put method key and value pair
        mp.put(new Integer(2), "Two");
        mp.put(new Integer(1), "One");
        mp.put(new Integer(3), "Three");
        mp.put(new Integer(4), "Four");

        //Get Map in Set interface to get key and value
        Set s=mp.entrySet();

        //Move next key and value of Map by iterator
        Iterator it=s.iterator();

        while(it.hasNext())
        {
            // key=value separator this by Map.Entry to get key and value
            Map.Entry m =(Map.Entry)it.next();

            // getKey is used to get key of Map
            int key=(Integer)m.getKey();

            // getValue is used to get value of key in Map
            String value=(String)m.getValue();

            System.out.println("Key :"+key+"  Value :"+value);
        }
    }
}
Output

Key :1 Value :One
Key :2 Value :Two
Key :3 Value :Three
Key :4 Value :Four


7. explain how did u manage exceptions in ur project and name some of the exceptions u have faced in the project
8. draw the architecture of the project
9. explain the difference between the comparator and comparable interfaces witha program



Java.lang.Comparable
            To implements comparable interface, class must implement a single method compareTo()
            int a.compareTo(b)
            A comparable object is comparing itself with another object.
            You must modify the class whose instance you want to sort.
            So that only one sort sequence can be created per class.
           



Java.lang.Comparator
            To implements comparator interface, class must implement a single method compare()
            int compare (a,b)
            A comparator object is comparing two different objects.You build a class separate
            from class whose instance you want to sort. So that multiple sort sequence can be
            created per class.

A comparator object is capable of comparing two different objects. Comparators can be passed to a sort method (such as Collections.sort) to allow precise control over the sort order. Comparators can also be used to control the order of certain data structures (such as TreeSet or TreeMap).

public interface Comparator {
    int compare(T o1, T o2);
}
Refer below code to demonstrate the collection custom object sorting example using Comparator interface.

package com.net.technicalkeeda;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class EmployeeSort {

            /**
             * @param args
             */
            public static void main(String[] args) {
                        List employees = new ArrayList();
                        employees.add(new Employee(10, "Dinesh", 18000));
                        employees.add(new Employee(16, "Pankaj", 19000));
                        employees.add(new Employee(13, "Mayur", 14000));
                        employees.add(new Employee(9, "Pravin", 22000));

                        System.out.println("----Sort By Employee Id----");
                        Collections.sort(employees, new EmployeeSortById());
                        printEmployees(employees);
                        System.out.println("----Sort By Employee Name----");
                        Collections.sort(employees, new EmployeeSortByName());
                        printEmployees(employees);

            }
           
            // print employee
            public static void printEmployees(List employees) {
                        for (Employee e : employees) {
                                    System.out.println("Id->" + e.emplId + " Name-> " + e.empName
                                                            + " Salary-> " + e.empSalary);
                        }
            }

}

// Employee Object
class Employee {
            public int emplId;
            public String empName;
            public double empSalary;

            public Employee(int emplId, String empName, double empSalary) {
                        this.emplId = emplId;
                        this.empName = empName;
                        this.empSalary = empSalary;
            }

}
// sort by employee id
class EmployeeSortById implements Comparator {
            public int compare(Employee emp1, Employee emp2) {
                        int value = 0;
                        if (emp1.emplId > emp2.emplId)
                                    value = 1;
                        else if (emp1.emplId < emp2.emplId)
                                    value = -1;
                        else if (emp1.emplId == emp2.emplId)
                                    value = 0;

                        return value;
            }
}
// sort by name
class EmployeeSortByName implements Comparator {
            public int compare(Employee emp1, Employee emp2) {
                        return emp1.empName.compareTo(emp2.empName);
            }
}

Output of EmployeeSort.java
----Sort By Employee Id----
Id->9 Name-> Pravin Salary-> 22000.0
Id->10 Name-> Dinesh Salary-> 18000.0
Id->13 Name-> Mayur Salary-> 14000.0
Id->16 Name-> Pankaj Salary-> 19000.0
----Sort By Employee Name----
Id->10 Name-> Dinesh Salary-> 18000.0
Id->13 Name-> Mayur Salary-> 14000.0
Id->16 Name-> Pankaj Salary-> 19000.0
Id->9 Name-> Pravin Salary-> 22000.0

Java Comparable Example

package com.net.technicalkeeda;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class EmployeeComparableSort {

            /**
             * @param args
             */
            public static void main(String[] args) {
                        List employees = new ArrayList();
                        employees.add(new Employee(10, "Dinesh", 18000));
                        employees.add(new Employee(16, "Pankaj", 19000));
                        employees.add(new Employee(13, "Mayur", 14000));
                        employees.add(new Employee(9, "Pravin", 22000));

                        System.out.println("----Sort By Employee Id----");
                        Collections.sort(employees);
                        printEmployees(employees);

            }

            // print employee
            public static void printEmployees(List employees) {
                        for (Employee e : employees) {
                                    System.out.println("Id->" + e.emplId + " Name-> " + e.empName
                                                            + " Salary-> " + e.empSalary);
                        }
            }

}

// Employee Object
class Employee implements Comparable {
            public int emplId;
            public String empName;
            public double empSalary;

            public Employee(int emplId, String empName, double empSalary) {
                        this.emplId = emplId;
                        this.empName = empName;
                        this.empSalary = empSalary;
            }

            public int compareTo(Employee otherEmployee) {
                        int id = ((Employee) otherEmployee).emplId; // same type object
                        if (this.emplId > id)
                                    return 1;
                        else if (this.emplId < id)
                                    return -1;
                        else
                                    return 0;
            }

}
Output of EmployeeComparableSort.java
----Sort By Employee Id----
Id->9 Name-> Pravin Salary-> 22000.0
Id->10 Name-> Dinesh Salary-> 18000.0
Id->13 Name-> Mayur Salary-> 14000.0
Id->16 Name-> Pankaj Salary-> 19000.0

10. explain the life cycle of struts

Steps for request lifecycle in strut two applications:-

1)      In first step user sends a request to the server for some resource.

2)      The filterDispatcher accept the request and then it determines the appropriate action.

3)      The interceptors configured for applying the common functionalities like workflow, validation, and file upload etc and these functionalities are automatically to the request. The Interceptors are helps to specify the “request-processing lifecycle” for an action. Interceptors are configured to apply the common functionalities like workflow, validation etc to the request.

4)      The action method executed to perform the database related operations such as storing and retrieving data from the database.

5)      The result rendered the output.

6)      The request returns through the interceptors in the reverse order.  The retuning request permits us to perform the clean up or additional processing.

7)      The final step is returned to the servlet container which sends the output to the user browser.

The flow of strut application is given below.

The ActionServlet stands as a back bone of the struts applications. First the request is handled by the either doGet() or doPost() method of the Action Servlet. After that the   Action Servlet calls the process() method of its own. This method gets the Current Request Processor associated with the request. Then this request processor calls its process() method. The Request Processor also a type of Servlet. This is the actual place where the request is handled. This method reads the struts-config.xml file and find outs the Action class by seeing the request URL path.

Eg: -

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Incoming request URL path is:/login
struts-config.xml:
<action path=“/login” type=“Test.LoginClass”>
<forward name=“Succes” path=“/Welcome.jsp”/>
<forward name=“failure” path=“/Login.jsp”/>
</action>
After identifying the Action class it checks the whether the request is associated with any form bean. This can be checked by using the name attribute of the action element from the struts-config.xml.

Eg: -

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<form-beans>
<form name=“loginForm” type=“Test.LoginForm”/>
</form-beans>
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<action-mappings>
<action path=“/login”type=“Test.LoginClass”
name=“loginForm”>
…..
</action-mappings>
Then it made the instance of ActionForm and calls the corresponding getter and setter methods for the incoming request parameters. We can validate the request parameter by calling the validate() method in ActionForm. For this we need to specify validate=“true” and input=“/Login.jsp” in struts-config.xml file. Now the actual request is handled by the Action class by calling the execute() method. Output of this method is the response of the request and the return type of this request is ActionMappings.

The browser creates a request to the struts application, the request is processed through ActionServlet. Here the ActionServlet indicates the controller of the strut application. The controller fill the ActionForm or view the object with the HTML form data and invokes it’s validate() method. The controller executes the action object.  The action object is also a controller. The action controller interfaces with model components and make data for view. The action controller forwards control to the JSP or view page. The JSP or view uses model data to generate a response to the browser.

For the compilation of the entire development cycle we uses strut 2 frameworks. This framework includes building, developing and maintaining whole application. The features of strut 2 framework are,

1)      Struts Architecture : – In the architecture of the strut first the web browser requests a resource for which the Filter Dispatcher decides the suitable action. After one request is made the interceptors use the available functions and after that the Action method executes all the functions such as storing and retrieving data from a database. Then the result can be seen on the output of the browser in HTML, PDF, images or any other.

2)      Struts Tags : – Tags in Strut 2 permits to developing dynamic web applications with less number of coding. These tags include the output data but also provide style sheet driven markup that in turn helps in creating pages with less code. Here the tags also helps for validation and localization of coding that in turn offer more utilization. The less number of codes also makes it easy to read and maintain.

3)      Struts MVC: – The Model View Controller in Strut 2 framework acts as a coordinator between application(s) model and web view. Its Controller and View components can come together with other technology to develop the model. The framework has its library and markup tags to present the data dynamically.

4)      Struts Configuration: – The configuration provides a deployment descriptor to initialize resources in XML format. The initialization takes place simply by scanning all the classes using Java packages or you can use an application configuration file to control the entire configuration. Its general-purpose defaults permit to using struts directly Out of the box. The configuration files are reloaded that permits to changes without restarting the web container.

5)      Other Struts  features

All framework classes are based on interfaces and core interfaces are independent from HTTP.
Check boxes do not require any kind of special application for false values.
Any class can be used as an action class and one can input properties by using any JavaBean directly to the action class.
Strut 2 actions are Spring friendly and so easy to Spring integration.
AJAX theme enables to make the application more dynamic.
Portal and servlet deployment are easy due to automatic portlet support without altering code.
The request handling in every action makes it easy to customize, when required.

11. difference between dispatch and lookup dispatch action and wap for bothe of them

LookupDispatchAction is subclass of DispatchAction.
In case of DispatchAction, you have to declare the method name in the JSP page.
For Example :
http://localhost:8080/emp/empaction.do?step=add // IN CASE OF DispatchAction
here step=add , we are delaring method name in JSP.
or
<html:submit property="step">Add</html:submit> //IN CASE OF DispatchAction
so we can't use localization for button.


To over come both the issues below
a)method name declaration in JSP
b)can't use localization for button
We will go for LookupDispatchAction.

In the LookupDispatchAction :
For example :
If there are three operation like add, delete, update employee.
You can create three different Actions ?
AddEmpAction, DeleteEmpAction and UpdateEmpAction.
This is a valid approach, although not elegant since there might be duplication of code across
the Actions since they are related. LookupDispatchAction is the answer to this
problem. With LookupDispatchAction, you can combine all three Actions into one.

Example :
Step 1.
three buttons might be
<html:submit property="step">
<bean:message key="button.add"/>
</html:submit>
<html:submit property="step">
<bean:message key="button.delete"/>
</html:submit>
<html:submit property="step">
<bean:message key="button.update"/>
</html:submit>

//No need method name declaration in JSP . Button name from resource bundle.

Step 2.
In the the Resource Bundle. //Here you can add localization.
button.add=Add
button.delete=Delete
button.update=Update

Step 3.
Implement a method named getKeyMethodMap() in the subclass of the
LookupDispatchAction. The method returns a java.util.Map. The
keys used in the Map should be also used as keys in Message Resource
Bundle.

public class EmpAction extends LookupDispatchAction {

public Map getKeyMethodMap()
{
Map map = new HashMap();
map.put("button.add", "add");
map.put("button.delete", "delete");
map.put("button.update", "update");
}


public ActionForward add(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception
{
//your logic
mapping.findForward("add-success");
}

public ActionForward delete(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception
{
//your logic
mapping.findForward("delete-success");
}

public ActionForward update(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception
{
//your logic
mapping.findForward("update-success");
}

}

in struts-config.xml

<action path="/empaction"
input="/empform.jsp"
type="list.EmpAction"
parameter="step"
scope="request"
validate="false">
<forward name="add-success"
path="addEmpSuccess.jsp"
redirect="true"/>
<forward name="delete-success"
path="deleteEmpSuccess.jsp"
redirect="true"/>
<forward name="update-success"
path="updateEmpSuccess.jsp"
redirect="true"/>
</action>

for every form submission, LookupDispatchAction does the
reverse lookup on the resource bundle to get the key and then gets the method
whose name is associated with the key from
getKeyMethodmap().


Flow of LookupDispatchAction:
a) Form the button name "Add" get the key "button.add" fro resource bundle.
b) then in the Map getKeyMethodMap() find the value associated with the key "button.add".
c) value from the Map is "add" . then call add() method of the same action class.
12. what design patterns u have implemented in u r project(n singleton and factory, mvc)

Ans: Mvc architecture

13. wap to demonstrate table per class or table per concrete class or table per subclass in hibernate

One Table Per Class Hierarchy example
Suppose we have a class Person with subclass Employee. The properties of each class are:
* class Person
            - firstname
            - lastname

* class Employee
            - joining_date
            - department_name
In One Table per Class Hierarchy scheme, we store all the class hierarchy in a single SQL table. A discriminator is a key to uniquely identify the base type of the class hierarchy.
Following are the advantages and disadvantages of One Table per Class Hierarchy scheme.
Advantage
This hierarchy offers the best performance even for in the deep hierarchy since single select may suffice.
Disadvantage
Changes to members of the hierarchy require column to be altered, added or removed from the table.
Create Database Table to persist Class Hierarchy
CREATE TABLE `person` (
    `person_id` BIGINT(10) NOT NULL AUTO_INCREMENT,
    `firstname` VARCHAR(50) NULL DEFAULT NULL,
    `lastname` VARCHAR(50) NULL DEFAULT NULL,
    `joining_date` DATE NULL DEFAULT NULL,
    `department_name` VARCHAR(50) NULL DEFAULT NULL,
    `discriminator` VARCHAR(20) NOT NULL,
    PRIMARY KEY (`person_id`)
)
The PERSON table will store both Employee and Person objects.
Hibernate Inheritance: XML Mapping
Following is the example where we map Employee and Person entity classes using XML mapping.
File: Person.java
package net.viralpatel.hibernate;

public class Person {

    private Long personId;
    private String firstname;
    private String lastname;

    // Constructors and Getter/Setter methods,
}
File: Employee.java
package net.viralpatel.hibernate;

import java.util.Date;

public class Employee extends Person {

    private Date joiningDate;
    private String departmentName;

    // Constructors and Getter/Setter methods,
}
File: Person.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="net.viralpatel.hibernate">

    <class name="Person" table="PERSON" discriminator-value="P">
        <id name="personId" column="PERSON_ID">
            <generator class="native" />
        </id>

        <discriminator column="DISCRIMINATOR" type="string" />

        <property name="firstname" />
        <property name="lastname" column="lastname" />

        <subclass name="Employee" extends="Person" discriminator-value="E">
                <property name="departmentName" column="department_name" />
                <property name="joiningDate" type="date" column="joining_date" />
        </subclass>
    </class>
</hibernate-mapping>

Note that we have defined only one hibernate mapping (hbm) file Person.hbm.xml. Both Person and Employee model class are defined within one hbm file.
<discriminator> tag is used to define the discriminator column.
<subclass> tag is used to map the subclass Employee. Note that we have not used the usual <class> tag to map Employee as it falls below in the hierarchy tree.
The discriminator-value for Person is defined as “P” and that for Employee is defined “E”, Thus, when Hibernate will persist the data for person or employee it will accordingly populate this value.


14. difference between load and get in hibernate
Ans:
Actually, both functions are use to retrieve an object with different mechanism, of course.

1. session.load()
It will always return a “proxy” (Hibernate term) without hitting the database. In Hibernate, proxy is an object with the given identifier value, its properties are not initialized yet, it just look like a temporary fake object.
If no row found , it will throws an ObjectNotFoundException.
2. session.get()
It always hit the database and return the real object, an object that represent the database row, not proxy.
If no row found , it return null.
It’s about performance
Hibernate create anything for some reasons, when you do the association, it’s normal to obtain retrieve an object (persistent instance) from database and assign it as a reference to another object, just to maintain the relationship. Let’s go through some examples to understand in what situation you should use session.load().

1. session.get()
For example, in a Stock application , Stock and StockTransactions should have a “one-to-many” relationship, when you want to save a stock transaction, it’s common to declared something like below

               Stock stock = (Stock)session.get(Stock.class, new Integer(2));
           StockTransaction stockTransactions = new StockTransaction();
           //set stockTransactions detail
           stockTransactions.setStock(stock);       
           session.save(stockTransactions);
Output
Hibernate:
    select ... from mkyong.stock stock0_
    where stock0_.STOCK_ID=?
Hibernate:
    insert into mkyong.stock_transaction (...)
    values (?, ?, ?, ?, ?, ?)
In session.get(), Hibernate will hit the database to retrieve the Stock object and put it as a reference to StockTransaction. However, this save process is extremely high demand, there may be thousand or million transactions per hour, do you think is this necessary to hit the database to retrieve the Stock object everything save a stock transaction record? After all you just need the Stock’s Id as a reference to StockTransaction.

2. session.load()
In above scenario, session.load() will be your good solution, let’s see the example,

               Stock stock = (Stock)session.load(Stock.class, new Integer(2));
           StockTransaction stockTransactions = new StockTransaction();
           //set stockTransactions detail
           stockTransactions.setStock(stock);       
           session.save(stockTransactions);
Output
Hibernate:
    insert into mkyong.stock_transaction (...)
    values (?, ?, ?, ?, ?, ?)
In session.load(), Hibernate will not hit the database (no select statement in output) to retrieve the Stock object, it will return a Stock proxy object – a fake object with given identify value. In this scenario, a proxy object is enough for to save a stock transaction record.

Exception
In exception case, see the examples

session.load()
Stock stock = (Stock)session.load(Stock.class, new Integer(100)); //proxy

 //initialize proxy, no row for id 100, throw ObjectNotFoundException
System.out.println(stock.getStockCode());
It will always return a proxy object with the given identity value, even the identity value is not exists in database. However, when you try to initialize a proxy by retrieve it’s properties from database, it will hit the database with select statement. If no row is found, a ObjectNotFoundException will throw.

org.hibernate.ObjectNotFoundException: No row with the given identifier exists:
[com.mkyong.common.Stock#100]
session.get()
//return null if not found
Stock stock = (Stock)session.get(Stock.class, new Integer(100));
System.out.println(stock.getStockCode()); //java.lang.NullPointerException
It will always return null , if the identity value is not found in database.

Conclusion
There are no always correct solution, you have to understand the differential in between, and decide which method is best fix in your application.

15. write a join operation in HQL
Ans:


16 write a criteria query to retrieve the elements from the pojo classes
17 explain and write a rpogram to demonstrate the constructor, setter and method injection in spring.
18 what is auto wiring in spring
19 write a program to demonstrate bean inheritance and bean factory inheritance
20 what are the various scopes of spring bean
21 explain the integration of spring and hibernate with a program
22 explain spring mvc architecture well
23 explain about abstract constroller and simple form controller in spring with a program


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