Thursday, March 13, 2014
Wednesday, March 12, 2014
Wednesday, November 20, 2013
Hcl 21 nov walk-in
| Job Description: | HCL Technologies Off-Campus for Freshers : 2011 / 2012 / 2013 Passout : Trainee : On 21st Nov 2013 for Hyderabad location. Apply on or before Thursday, November 21, 2013 | |
| Skill Sets: | Trainees - Good Written and Verbal Communication Skills | |
| Education: | BE / B.Tech (CS, IT, ECE, EEE) / BCA / B.Sc / Arts & Graduate | |
| Experience: | Freshers (2011 / 2012 / 2013 Passout) | |
| Job Location: | Hyderabad | |
| Address: | Sree Dattha Institute of Engg. and Science. Nagarjuna Sagar Road, Sheriguda, Ibrahimpatnam, Hyderabad. | ||||||||||||
| Other Details | Walk-in Date: 21th November 2013 Time: 9AM | ||||||||||||
| Job Last Date: | Thursday, November 21, 2013 | ||||||||||||
core java questions
What is the difference between Assignment and Initialization?- Assignment can be done as many times as desired whereas initialization can be done only once.
What is the difference between constructor and method?- Constructor will be automatically invoked when an object is created whereas method has to be called explicitly.
What is the difference between an argument and a parameter?- While defining method, variables passed in the method are called parameters. While using those methods, values passed to those variables are called arguments.
What is the difference between overloading and overriding?- a) In overloading, there is a relationship between methods available in the same class whereas in overriding, there is relationship between a superclass method and subclass method. b) Overloading does not block inheritance from the superclass whereas overriding blocks inheritance from the superclass. c) In overloading, separate methods share the same name whereas in overriding, subclass method replaces the superclass. d) Overloading must have different method signatures whereas overriding must have same signature.
What is the difference between this() and super()?- this() can be used to invoke a constructor of the same class whereas super() can be used to invoke a super class constructor.
What is the difference between superclass and subclass?- A super class is a class that is inherited whereas sub class is a class that does the inheriting.
What is the difference between String and String Buffer?- a) String objects are constants and immutable whereas StringBuffer objects are not. b) String class supports constant strings whereas StringBuffer class supports growable and modifiable strings.
What is the difference between Array and vector?- Array is a set of related data type and static whereas vector is a growable array of objects and dynamic.
What is the difference between exception and error?- The exception class defines mild error conditions that your program encounters. Exceptions can occur when trying to open the file, which does not exist, the network connection is disrupted, operands being manipulated are out of prescribed ranges, the class file you are interested in loading is missing. The error class defines serious error conditions that you should not attempt to recover from. In most cases it is advisable to let the program terminate when such an error is encountered.
What is the difference between process and thread?- Process is a program in execution whereas thread is a separate path of execution in a program.
What is the difference between abstract class and interface?- a) All the methods declared inside an interface are abstract whereas abstract class must have at least one abstract method and others may be concrete or abstract. b) In abstract class, key word abstract must be used for the methods whereas interface we need not use that keyword for the methods. c) Abstract class must have subclasses whereas interface can’t have subclasses.
What is the difference between Integer and int?- a) Integer is a class defined in the java. lang package, whereas int is a primitive data type defined in the Java language itself. Java does not automatically convert from one to the other. b) Integer can be used as an argument for a method that requires an object, whereas int can be used for calculations.
What is the difference between choice and list?- A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices and only one item may be selected from a choice. A List may be displayed in such a way that several list items are visible and it supports the selection of one or more list items.
What is the difference between scrollbar and scrollpane?- A Scrollbar is a Component, but not a Container whereas Scrollpane is a Conatiner and handles its own events and perform its own scrolling.
What is the difference between applications and applets?- a)Application must be run on local machine whereas applet needs no explicit installation on local machine. b)Application must be run explicitly within a java-compatible virtual machine whereas applet loads and runs itself automatically in a java-enabled browser. d)Application starts execution with its main method whereas applet starts execution with its init method. e)Application can run with or without graphical user interface whereas applet must run within a graphical user interface.
What is the difference between set and list?- Set stores elements in an unordered way but does not contain duplicate elements, whereas list stores elements in an ordered way but may contain duplicate elements.
What is the difference between an applet and a servlet?- a) Servlets are to servers what applets are to browsers. b) Applets must have graphical user interfaces whereas servlets have no graphical user interfaces.
What is the difference between doPost and doGet methods?- a) doGet() method is used to get information, while doPost() method is used for posting information. b) doGet() requests can’t send large amount of information and is limited to 240-255 characters. However, doPost()requests passes all of its data, of unlimited length. c) A doGet() request is appended to the request URL in a query string and this allows the exchange is visible to the client, whereas a doPost() request passes directly over the socket connection as part of its HTTP request body and the exchange are invisible to the client.
What is the difference between TCP/IP and UDP?- TCP/IP is a two-way communication between the client and the server and it is a reliable and there is a confirmation regarding reaching the message to the destination. It is like a phone call. UDP is a one-way communication only between the client and the server and it is not a reliable and there is no confirmation regarding reaching the message to the destination. It is like a postal mail.
Java Frequently Asked Questions & Answers
Polymorphism is the feature that allows one interface to be used for general class actions.
What is OOPs?- Object oriented programming organizes a program around its data, i. e. , objects and a set of well defined interfaces to that data. An object-oriented program can be characterized as data controlling access to code.
What are Class, Constructor and Primitive data types?- Class is a template for multiple objects with similar features and it is a blue print for objects. It defines a type of object according to the data the object can hold and the operations the object can perform. Constructor is a special kind of method that determines how an object is initialized when created. Primitive data types are 8 types and they are: byte, short, int, long, float, double, boolean, char.
What is an Object and how do you allocate memory to it?- Object is an instance of a class and it is a software unit that combines a structured set of data with a set of operations for inspecting and manipulating that data. When an object is created using new operator, memory is allocated to it.
What are methods and how are they defined?- Methods are functions that operate on instances of classes in which they are defined. Objects can communicate with each other using methods and can call methods in other classes. Method definition has four parts. They are name of the method, type of object or primitive type the method returns, a list of parameters and the body of the method. A method’s signature is a combination of the first three parts mentioned above.
What is the use of bin and lib in JDK?- Bin contains all tools such as javac, appletviewer, awt tool, etc., whereas lib contains API and all packages.
What is casting?- Casting is used to convert the value of one type to another.
How many ways can an argument be passed to a subroutine and explain them?- An argument can be passed in two ways. They are passing by value and passing by reference. Passing by value: This method copies the value of an argument into the formal parameter of the subroutine. Passing by reference: In this method, a reference to an argument (not the value of the argument) is passed to the parameter.
What are different types of access modifiers?- public: Any thing declared as public can be accessed from anywhere. private: Any thing declared as private can’t be seen outside of its class. protected: Any thing declared as protected can be accessed by classes in the same package and subclasses in the other packages. default modifier : Can be accessed only to classes in the same package.
What is final, finalize() and finally?- final : final keyword can be used for class, method and variables. A final class cannot be subclassed and it prevents other programmers from subclassing a secure class to invoke insecure methods. A final method can’t be overridden. A final variable can’t change from its initialized value. finalize() : finalize() method is used just before an object is destroyed and can be called just prior to garbage collection. finally : finally, a key word used in exception handling, creates a block of code that will be executed after a try/catch block has completed and before the code following the try/catch block. The finally block will execute whether or not an exception is thrown. For example, if a method opens a file upon exit, then you will not want the code that closes the file to be bypassed by the exception-handling mechanism. This finally keyword is designed to address this contingency.
What is UNICODE?- Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other.
What is Garbage Collection and how to call it explicitly?- When an object is no longer referred to by any variable, java automatically reclaims memory used by that object. This is known as garbage collection. System. gc() method may be used to call it explicitly.
What is finalize() method?- finalize () method is used just before an object is destroyed and can be called just prior to garbage collection.
What are Transient and Volatile Modifiers?- Transient: The transient modifier applies to variables only and it is not stored as part of its object’s Persistent state. Transient variables are not serialized. Volatile: Volatile modifier applies to variables only and it tells the compiler that the variable modified by volatile can be changed unexpectedly by other parts of the program.
What is method overloading and method overriding?- Method overloading: When a method in a class having the same method name with different arguments is said to be method overloading. Method overriding : When a method in a class having the same method name with same arguments is said to be method overriding.
What is meant by Inheritance and what are its advantages?- Inheritance is the process of inheriting all the features from a class. The advantages of inheritance are reusability of code and accessibility of variables and methods of the super class by subclasses.
What modifiers may be used with top-level class?- public, abstract and final can be used for top-level class.
What are inner class and anonymous class?- Inner class : classes defined in other classes, including those defined in methods are called inner classes. An inner class can have any accessibility including private. Anonymous class : Anonymous class is a class defined inside a method without a name and is instantiated and declared in the same place and cannot have explicit constructors.
What is a package?- A package is a collection of classes and interfaces that provides a high-level layer of access protection and name space management.
What is a reflection package?- java. lang. reflect package has the ability to analyze itself in runtime.
Monday, November 18, 2013
Upload file one place to another place
FileUpload Application in Servlet
Here We are going to see,How to create a FileUploadApplication using Java Zoom API
Directory Structure
upload1.html
<form action="uplurl" method="post" enctype="multipart/form-data"> Select File1 <input type="file" name="file1" /> Select File2 <input type="file" name="file2" /> <input type="Submit" value="Upload" /> </form>
web.xml
<web-app> <servlet> <servlet-name>uplsrv</servlet-name> <servlet-class>UplSrv1</servlet-class> </servlet> <servlet-mapping> <servlet-name>uplsrv</servlet-name> <url-pattern>/uplurl</url-pattern> </servlet-mapping> </web-app>
UplSrv1.java
//UplSrv1.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javazoom.upload.*;
import java.util.*;
public class UplSrv1 extends HttpServlet {
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
PrintWriter pw = res.getWriter();
try {
// set location for saving uploded files
UploadBean upb = new UploadBean();
upb.setFolderstore("c:/store");
upb.setOverwrite(false);
MultipartFormDataRequest nreq = new MultipartFormDataRequest(req);
upb.store(nreq); // completes files uploding
// display names of the uploded files
pw.println("The uploded files are ");
Hashtable ht = nreq.getFiles();// gives all uploded files
Enumeration e = ht.elements();
while (e.hasMoreElements()) {
UploadFile file = (UploadFile) e.nextElement();
pw.println(file.getFileName() + " ");
}// while
}// try
catch (Exception e) {
pw.println(e);
}// catch
}// doPost ()
}// class
Jars required in classpath
servlet-api.jar
uploadbean.jar
uploadbean.jar
Jars required in lib Folder
(See the directory structure)
(See the directory structure)
Compile the ServletProgram
c:\JavaZoomUpload\WEB-INF\classes>javac *.java
Running the Application
Copy the JavaZoomUpload Application and paste it to web-apps folder of Tomcat
Executing the Application
Start tomcat server.and then give the following request from browser window
http://localhost:2012/JavaZoomUpload/upload1.html
You will get the screen
Select any two file,and click upload button.The file will be uploaded and stored in C:\store folder of the server.(in our case,It will be stored in our c:\store folder.
Upon successful upload,you will get the success screen
Hope,You like this tutorial.
Thank You
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