Simplicity
Information coded in XML is easy to read and understand, plus it can be processed easily by computers.
Openness
XML is a W3C standard, endorsed by software industry market leaders.
Extensibility
There is no fixed set of tags. New tags can be created as they are needed.
Self-description
In traditional databases, data records require schemas set up by the database administrator. XML documents can be stored without such definitions, because they contain meta data in the form of tags and attributes.
XML provides a basis for author identification and versioning at the element level. Any XML tag can possess an unlimited number of attributes such as author or version.
Contains machine-readable context information
Tags, attributes and element structure provide context information that can be used to interpret the meaning of content, opening up new possibilities for highly efficient search engines, intelligent data mining, agents, etc.
This is a major advantage over HTML or plain text, where context information is difficult or impossible to evaluate.
Separates content from presentation
XML tags describe meaning not presentation. The motto of HTML is: "I know how it looks", whereas the motto of XML is: "I know what it means, and you tell me how it should look." The look and feel of an XML document can be controlled by XSL style sheets, allowing the look of a document (or of a complete Web site) to be changed without touching the content of the document. Multiple views or presentations of the same content are easily rendered.
Supports multilingual documents and Unicode
This is important for the internationalization of applications.
Facilitates the comparison and aggregation of data
The tree structure of XML documents allows documents to be compared and aggregated efficiently element by element.
Can embed multiple data types
XML documents can contain any possible data type - from multimedia data (image, sound, video) to active components (Java applets, ActiveX).
Can embed existing data
Mapping existing data structures like file systems or relational databases to XML is simple. XML supports multiple data formats and can cover all existing data structures and
Provides a 'one-server view' for distributed data
XML documents can consist of nested elements that are distributed over multiple remote servers. XML is currently the most sophisticated format for distributed data - the World Wide Web can be seen as one huge XML database.
Rapid adoption by industry
Software AG, IBM, Sun, Microsoft, Netscape, DataChannel, SAP and many others have already announced support for XML. Microsoft will use XML as the exchange format for its Office product line, while both Microsoft's and Netscape's Web browsers support XML. SAP has announced support of XML through the SAP Business Connector with R/3. Software AG supports XML in its Natural product line and provides Tamino, a native XML database.
Sunday, June 6, 2010
Sunday, May 2, 2010
JAVA QA?
1) Which of the following statements hold true in the following program?
package generics;
import java.util.ArrayList;
import java.util.List;
public class Ques04 {
public static void main(String[] args) {
List allInstruments = new ArrayList();
// -->X
allInstruments.add(new Guitar());
allInstruments.add(new Violin());
}
}
interface Instrument {
public void play();
}
class Guitar implements Instrument {
public void play(){
System.out.println("Playing Guitar.");
}
}
class Violin implements Instrument {
public void play(){
System.out.println("Playing Violin.");
}
}
1. The program will not compile.
2. The program will compile but will throw run-time exception.
3. The statement 'X' manifests that objects of type Instrument as well as sub-types can be
added to the list 'allInstruments'.
4. It is not possible to add any type of objects to the list 'allInstruments'.
5. The only possible element that can be added to the list 'allInstruments' is 'null'.
Answers
1) 1,5.
The declaration 'allInstruments' manifests a list, whose reference can point to a similar
declaration of list holding Instrument objects or sub-class of Instrument objects. It is not
possible to add elements into the list 'allInstruments'. The only permissible allowed type is
'null'.
2) What will be the output of the following program?
package enums;
public enum Color {
RED("Red Color"),
GREEN("Blue Color"),
BLUE("Blue Color");
private String displayName;
Color(String displayName){
this.displayName = displayName;
}
public String toString(){
return displayName;
}
}
class ColorTest{
public static void main(String[] args) {
Color redColor = Color.RED;
System.out.println(redColor);
Color blueColor = Color.BLUE;
System.out.println(blueColor);
}
}
1. The program will compile and the output will be 'Red Color' followed by 'Blue Color'.
2. The program will compile and throw a run-time exception.
3. The program won't compile as it is not possible to define methods within an Enum.
Answer
2)1
The above program defines a Enum called Color and the Enum constants within are
parameterized by defining a constructor for holding the display name of each constants. The
method toString() is defined at the declaration level which means that when an Enum object
is printed, this method will get called.
3) What will be the output of the following program?
package var_arg;
public class VarArgTest1 {
public static void main(String[] args) {
acceptMultipleArguments(1);
acceptMultipleArguments(1, 2);
}
static void acceptMultipleArguments(var_arg int nums){
System.out.println(nums.length);
}
}
1. The program will compile to produce the output 1 2.
2. The program will not compile
3. The program will compile but throw a run-time exception.
4. The program will output 1 1.
Answer
3) 2
The program won't compile as there is no keyword called 'var_arg' in Java
4) Imagine that you have directory called test1 in C drive containing some files,
within which there is a directory called test2 (sub-directory of test1) containing
some other set of files. Considering this, what statements are true about the
following program?
package io;
import java.io.File;
import java.io.FileFilter;
public class DirLister {
public static void main(String[] args) {
String path = "C:\\test1";
list(path);
}
static void list(String path){
File fileObject = new File(path);
if (fileObject.exists()){
if (fileObject.isDirectory()){
System.out.println("Dir-->" + fileObject.getAbsolutePath());
File allFiles[] = fileObject.listFiles(new MyFileLister());
for (File aFile : allFiles){
list(aFile.getAbsolutePath());
}
}else{
System.out.println("File-->" + fileObject.getAbsolutePath());
}
}
}
}
class MyFileLister implements FileFilter{
@Override
public boolean accept(File pathname) {
return pathname.getAbsolutePath().endsWith(".bmp");
}
}
1. The program will list down all the files within the directory test1 and test2
2. The program will list down only the files in directory test1
3. The program will list down only the files in directory test2
4. The program will run infinitely.
Answer
4)1
The program recursively traverses over the directories and the files. Hence answer 1 holds
good.
5) What will be the output of the following program?
package wrapper_boxing;
public class WrapperTest2 {
public static void main(String[] args) {
Boolean bool1 = new Boolean(true);
Boolean bool2 = new Boolean(false);
Boolean bool3 = new Boolean("false");
Boolean bool4 = new Boolean(bool1);
System.out.println(bool1.equals(bool4));
System.out.println(bool2 == bool3);
System.out.println(bool1 == bool4);
}
}
1. The program will not compile because the creation of bool4 object will cause
compilation error.
2. The program will produce the output 'true false false'.
3. The program will produce the output 'true true true'.
4. The program will output 'true false true'.
Answer
5)2
The first comparison statement compares the value of two objects and hence will return
true. Whereas the second and the third comparison verfires whether the references are
pointing to the same object, in which case both the comparisons will fail.
6) What will be the output of the following program?
package misc_apis;
import java.util.Scanner;
public class ScannerTest3 {
public static void main(String[] args) {
Scanner scanner = new Scanner("hello 1 2.00 false");
scanner.useDelimiter(" ");
String str = scanner.next();
int anInt = scanner.nextInt();
float aFloat = scanner.nextFloat();
boolean booleanValue = scanner.nextBoolean();
System.out.println(str + ":" + anInt + ":" + aFloat + ":" + booleanValue);
}
}
1. The program will output 'hello:1:2.0:false'
2. The program will throw Input Mismatch exception at the run-time
3. The program will output nothing.
4. The program will ouput ':1:2.0:false'
Answer
6) 1
The output will be 'hello:1:2.0:false'.
7) Which of the following statements are true about the new enhanced for loop?
1. The enhanced for loop eliminates the need for Iterator objects.
2. The enhanced for loop simplifies the process of iterating over a collection of
elements
3. The introduction of enhanced for loop will bring performance bottle-necks in an
Application
4. It is not possible to mix the older for loops as well as enhanced for loop in java
source code of version 5.0
Answer
7)1,2
The program recursively traverses over the directories and the files. Hence answer 1 holds
good.
8)Assume that in the current directory test.txt file is already exist. What will
happen when you execute the following code?
import java.io.*;
class Test
{
public static void main(String args[])
{
try
{
File file = new File("test.txt");
file.createNewFile();
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
}
a)text.txt will be created and overwrite the old file
b)file will not be created
c)exception will be thrown
d)none of the above.
Answer
8)c)file will not be created.
New file cannot be created,when the File object refers to an actual file name that already
exists in the file system
9)What is the output of the following program?
public class Gen
{
G g;
Gen(G g)
{
this.g =g;
}
public static void main(String[] args)
{
Gen arr[] = new Gen[5]; //line 1
arr[0] = new Gen("Java"); //line 2
arr[1] = new Gen(1); //line 3
arr[2] = (Gen)new Gen(1); //line 4
arr[3] = (Gen)new Gen(1); //line 5
for(Gen o:arr)
{
System.out.println(o);
}
}
}
a)Compile time Error at line 1
b)Compile time Error at line 3
c)Compile time Error at line 4
d)Compile time Error at line 5
e)Run Time Error
Answer
9) d.
We can cast raw type to specific type but we cannot type cast Integer type to String type
10) what is the output of compiling an running the following code?
import java.util.*;
class CheckTest {
public static void main(String [] args) {
Hashtable ht = new Hashtable();
ht.put("chec", "check");
ht.put(1000, "check"); // line 1
ht.put("check", 20.01); // line 2
System.out.print(ht.get("chec") + " ");
System.out.print(ht.get(1000) + " "); //line 3
System.out.print(ht.get("check")); //line 4
}
}
a) Compilation fails due to error at line 1,2,3,4
b) Compilation fails due to error at line 3,4
c) Compiles fine and exception is thrown at runtime.
d) Compiles fine and prints "check check 20.01"
e) Compilation fails due to error at line 1,2
Answers
10)d
d is the correct answer because even Hashtable reference is created with Generic type the
reference is stored in non-generic variable. So it act as an old collection.
package generics;
import java.util.ArrayList;
import java.util.List;
public class Ques04 {
public static void main(String[] args) {
List allInstruments = new ArrayList
// -->X
allInstruments.add(new Guitar());
allInstruments.add(new Violin());
}
}
interface Instrument {
public void play();
}
class Guitar implements Instrument {
public void play(){
System.out.println("Playing Guitar.");
}
}
class Violin implements Instrument {
public void play(){
System.out.println("Playing Violin.");
}
}
1. The program will not compile.
2. The program will compile but will throw run-time exception.
3. The statement 'X' manifests that objects of type Instrument as well as sub-types can be
added to the list 'allInstruments'.
4. It is not possible to add any type of objects to the list 'allInstruments'.
5. The only possible element that can be added to the list 'allInstruments' is 'null'.
Answers
1) 1,5.
The declaration 'allInstruments' manifests a list, whose reference can point to a similar
declaration of list holding Instrument objects or sub-class of Instrument objects. It is not
possible to add elements into the list 'allInstruments'. The only permissible allowed type is
'null'.
2) What will be the output of the following program?
package enums;
public enum Color {
RED("Red Color"),
GREEN("Blue Color"),
BLUE("Blue Color");
private String displayName;
Color(String displayName){
this.displayName = displayName;
}
public String toString(){
return displayName;
}
}
class ColorTest{
public static void main(String[] args) {
Color redColor = Color.RED;
System.out.println(redColor);
Color blueColor = Color.BLUE;
System.out.println(blueColor);
}
}
1. The program will compile and the output will be 'Red Color' followed by 'Blue Color'.
2. The program will compile and throw a run-time exception.
3. The program won't compile as it is not possible to define methods within an Enum.
Answer
2)1
The above program defines a Enum called Color and the Enum constants within are
parameterized by defining a constructor for holding the display name of each constants. The
method toString() is defined at the declaration level which means that when an Enum object
is printed, this method will get called.
3) What will be the output of the following program?
package var_arg;
public class VarArgTest1 {
public static void main(String[] args) {
acceptMultipleArguments(1);
acceptMultipleArguments(1, 2);
}
static void acceptMultipleArguments(var_arg int nums){
System.out.println(nums.length);
}
}
1. The program will compile to produce the output 1 2.
2. The program will not compile
3. The program will compile but throw a run-time exception.
4. The program will output 1 1.
Answer
3) 2
The program won't compile as there is no keyword called 'var_arg' in Java
4) Imagine that you have directory called test1 in C drive containing some files,
within which there is a directory called test2 (sub-directory of test1) containing
some other set of files. Considering this, what statements are true about the
following program?
package io;
import java.io.File;
import java.io.FileFilter;
public class DirLister {
public static void main(String[] args) {
String path = "C:\\test1";
list(path);
}
static void list(String path){
File fileObject = new File(path);
if (fileObject.exists()){
if (fileObject.isDirectory()){
System.out.println("Dir-->" + fileObject.getAbsolutePath());
File allFiles[] = fileObject.listFiles(new MyFileLister());
for (File aFile : allFiles){
list(aFile.getAbsolutePath());
}
}else{
System.out.println("File-->" + fileObject.getAbsolutePath());
}
}
}
}
class MyFileLister implements FileFilter{
@Override
public boolean accept(File pathname) {
return pathname.getAbsolutePath().endsWith(".bmp");
}
}
1. The program will list down all the files within the directory test1 and test2
2. The program will list down only the files in directory test1
3. The program will list down only the files in directory test2
4. The program will run infinitely.
Answer
4)1
The program recursively traverses over the directories and the files. Hence answer 1 holds
good.
5) What will be the output of the following program?
package wrapper_boxing;
public class WrapperTest2 {
public static void main(String[] args) {
Boolean bool1 = new Boolean(true);
Boolean bool2 = new Boolean(false);
Boolean bool3 = new Boolean("false");
Boolean bool4 = new Boolean(bool1);
System.out.println(bool1.equals(bool4));
System.out.println(bool2 == bool3);
System.out.println(bool1 == bool4);
}
}
1. The program will not compile because the creation of bool4 object will cause
compilation error.
2. The program will produce the output 'true false false'.
3. The program will produce the output 'true true true'.
4. The program will output 'true false true'.
Answer
5)2
The first comparison statement compares the value of two objects and hence will return
true. Whereas the second and the third comparison verfires whether the references are
pointing to the same object, in which case both the comparisons will fail.
6) What will be the output of the following program?
package misc_apis;
import java.util.Scanner;
public class ScannerTest3 {
public static void main(String[] args) {
Scanner scanner = new Scanner("hello 1 2.00 false");
scanner.useDelimiter(" ");
String str = scanner.next();
int anInt = scanner.nextInt();
float aFloat = scanner.nextFloat();
boolean booleanValue = scanner.nextBoolean();
System.out.println(str + ":" + anInt + ":" + aFloat + ":" + booleanValue);
}
}
1. The program will output 'hello:1:2.0:false'
2. The program will throw Input Mismatch exception at the run-time
3. The program will output nothing.
4. The program will ouput ':1:2.0:false'
Answer
6) 1
The output will be 'hello:1:2.0:false'.
7) Which of the following statements are true about the new enhanced for loop?
1. The enhanced for loop eliminates the need for Iterator objects.
2. The enhanced for loop simplifies the process of iterating over a collection of
elements
3. The introduction of enhanced for loop will bring performance bottle-necks in an
Application
4. It is not possible to mix the older for loops as well as enhanced for loop in java
source code of version 5.0
Answer
7)1,2
The program recursively traverses over the directories and the files. Hence answer 1 holds
good.
8)Assume that in the current directory test.txt file is already exist. What will
happen when you execute the following code?
import java.io.*;
class Test
{
public static void main(String args[])
{
try
{
File file = new File("test.txt");
file.createNewFile();
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
}
a)text.txt will be created and overwrite the old file
b)file will not be created
c)exception will be thrown
d)none of the above.
Answer
8)c)file will not be created.
New file cannot be created,when the File object refers to an actual file name that already
exists in the file system
9)What is the output of the following program?
public class Gen
{
G g;
Gen(G g)
{
this.g =g;
}
public static void main(String[] args)
{
Gen
arr[0] = new Gen("Java"); //line 2
arr[1] = new Gen(1); //line 3
arr[2] = (Gen
arr[3] = (Gen
for(Gen o:arr)
{
System.out.println(o);
}
}
}
a)Compile time Error at line 1
b)Compile time Error at line 3
c)Compile time Error at line 4
d)Compile time Error at line 5
e)Run Time Error
Answer
9) d.
We can cast raw type to specific type but we cannot type cast Integer type to String type
10) what is the output of compiling an running the following code?
import java.util.*;
class CheckTest {
public static void main(String [] args) {
Hashtable ht = new Hashtable
ht.put("chec", "check");
ht.put(1000, "check"); // line 1
ht.put("check", 20.01); // line 2
System.out.print(ht.get("chec") + " ");
System.out.print(ht.get(1000) + " "); //line 3
System.out.print(ht.get("check")); //line 4
}
}
a) Compilation fails due to error at line 1,2,3,4
b) Compilation fails due to error at line 3,4
c) Compiles fine and exception is thrown at runtime.
d) Compiles fine and prints "check check 20.01"
e) Compilation fails due to error at line 1,2
Answers
10)d
d is the correct answer because even Hashtable reference is created with Generic type the
reference is stored in non-generic variable. So it act as an old collection.
What is a Package & Define it?
A Java package is a mechanism for organizing Java classes into namespaces similar to the modules of Module. Java packages can be stored in compressed files called JAR files, allowing classes to download faster as a group rather than one at a time. Programmers also typically use packages to organize classes belonging to the same category or providing similar functionality.
* A package provides a unique namespace for the types it contains.
* Classes in the same package can access each others package-access members.
Define a Package.
This keyword is usually the first keyword in source file.
package java.awt.event;
To use a package's classes inside a Java source file, it is convenient to import the classes from the package with an import statement.
import java.awt.event.*;
imports all classes from the java.awt.event package, while the next statement
import java.awt.event.ActionEvent;
imports only the ActionEvent class from the package.
ActionEvent myEvent = new ActionEvent();
Classes can also be used directly without an import statement by using the fully-qualified name of the class.
java.awt.event.ActionEvent myEvent = new java.awt.event.ActionEvent();
* A package provides a unique namespace for the types it contains.
* Classes in the same package can access each others package-access members.
Define a Package.
- Package pkg;[here pkg is the name of package ]
- Package pkg1[.pkg2[.pkg3[.pkg4]]];
This keyword is usually the first keyword in source file.
package java.awt.event;
To use a package's classes inside a Java source file, it is convenient to import the classes from the package with an import statement.
import java.awt.event.*;
imports all classes from the java.awt.event package, while the next statement
import java.awt.event.ActionEvent;
imports only the ActionEvent class from the package.
ActionEvent myEvent = new ActionEvent();
Classes can also be used directly without an import statement by using the fully-qualified name of the class.
java.awt.event.ActionEvent myEvent = new java.awt.event.ActionEvent();
Saturday, May 1, 2010
Types of operators in Java?
There are several types of operators, but before we go into them, you should understand a little thing we in the biz call operator precedence. Precedence determines in which order operators execute.
Operator Type | Operator Precedence |
postfix | expr++ expr-- |
unary | ++expr –expr +expr -expr ~ ! |
multiplicative | * / % |
additive | + - |
shift | << >> >>> |
relational | < > <= >= instanceof |
equality | “==” != |
bitwise AND | & |
bitwise exclusive OR | ^ |
bitwise inclusive OR | | |
logical AND | && |
logical OR | || |
ternary | ? : |
assignment | “=” += -= *= /= %= &= ^= |= <<= >>= >>>= |
Java Tips
- The Default value of uninitialized int variable is Zero.
- Border layout or grid layout affected by the frame size this case with not apply flow layout.
- When a class is properly encapsulated it is possible to change the class implementation with out chnge it interface.
- Implementation change do not affect other class which aside by this interface.
- The Abstract Keywords must precede the method return type.
- A Java package is a naming context for classes and & Interface.
- A compilation unit is a java source code file.
- Package name or statement appear as the first line in a source code file.
- java.lang package is always imported by default.return type of a main method is void
- argument of main method is always string type.
Monday, April 26, 2010
Difference Between Servlet vs JSP ?
Servlets and Java Server Pages are complementary APIs, both providing a means for generating dynamic Web content. A servlet is a Java class implementing the javax.servlet.Servlet interface that runs within a Web or application server's servlet engine, servicing client requests forwarded to it through the server. A Java Server Page is a slightly more complicated beast. JSP pages contain a mixture of HTML, Java scripts (not to be confused with JavaScript), JSP elements, and JSP directives. The elements in a Java Server Page will generally be compiled by the JSP engine into a servlet, but the JSP specification only requires that the JSP page execution entity follow the Servlet Protocol.
The advantage of Java Server Pages is that they are document-centric. Servlets, on the other hand, look and act like programs. A Java Server Page can contain Java program fragments that instantiate and execute Java classes, but these occur inside an HTML template file and are primarily used to generate dynamic content. Some of the JSP functionality can be achieved on the client, using JavaScript. The power of JSP is that it is server-based and provides a framework for Web application development. Rather than choosing between servlets and Java Server Pages, you will find that most non-trivial applications will want to use a combination of JSP and servlets. In fact, the JSP 1.1 and Servlet 2.2 specifications are based around the concept of the Web application, combining the two APIs into a unified framework.
The advantage of Java Server Pages is that they are document-centric. Servlets, on the other hand, look and act like programs. A Java Server Page can contain Java program fragments that instantiate and execute Java classes, but these occur inside an HTML template file and are primarily used to generate dynamic content. Some of the JSP functionality can be achieved on the client, using JavaScript. The power of JSP is that it is server-based and provides a framework for Web application development. Rather than choosing between servlets and Java Server Pages, you will find that most non-trivial applications will want to use a combination of JSP and servlets. In fact, the JSP 1.1 and Servlet 2.2 specifications are based around the concept of the Web application, combining the two APIs into a unified framework.
JSP DEFINATION ?
Java Server Page (JSP) is a technology for controlling the content or appearance of Web pages through the use of servlets, small programs that are specified in the Web page and run on the Web server to modify the Web page before it is sent to the user who requested it. Sun Microsystems, the developer of Java, also refers to the JSP technology as the Servlet application program interface (API). JSP is comparable to Microsoft's Active Server Page (ASP) technology. Whereas a Java Server Page calls a Java program that is executed by the Web server, an Active Server Page contains a script that is interpreted by a script interpreter (such as VBScript or JScript) before the page is sent to the user.
An HTML page that contains a link to a Java servlet is sometimes given the file name suffix of .JSP.
An HTML page that contains a link to a Java servlet is sometimes given the file name suffix of .JSP.
Subscribe to:
Comments (Atom)
