JSP Simple Examples Posted on: February 27, 2008 at 12:00 AM
# Creating a String
In jsp we create a string as we does in a java. In jsp we can declare it inside the declaration directive or a scriptlet directive.
JSP Simple Examples
Creating a String
In jsp we create a string as we does
in a java. In jsp we can declare it inside the declaration directive
or a scriptlet directive.
In java, Strings are
objects that belong to class java.lang.String. A string is a
sequence of simple characters. We can get the length of the string by
using the method length() of java.lang.String.
Declaring string array in java
An array is the collection of same data type. Suppose
if we have a declare an array of type String, then it will store only
the String value not any other data type. When we have a closely
related data of the same type and scope, it is better to declare it in
Multidimensional array java
A two dimensional array can be thought as a grid of rows and
columns. The first array will reflect to a row and the second one is
Array is a collection of same
data type. Suppose if we have declared an array of type int then the
array will take only the int values and not any other data types. We
can find find out the length of the variable by using the
JSP string array
String array cannot hold numbers
or vice- versa. Arrays can only store the type of data specified at
the time of declaring the array variable.
Custom Exception inherits the properties from the Exception
class. Whenever we have declare our own exceptions then we call it
Throwing an exception
All methods use the throw
statement to throw an exception. The throw statement requires a
single argument a throwable object. Here is an example of a throw
ArrayIndexOutOfBoundException is thrown when we have to
indicate that an array has been accessed with an illegal index.
printStackTrace in jsp
printStackTrace is a method of the Throwable class. By
using this method we can get more information about the error process
if we print a stack trace from the exception.
Errors are arised when there is
any logic problem with the logic of the program.
Try catch in jsp
In try block we write those code which can throw exception
while code execution and when the exception is thrown it is caught
inside the catch block.
Multiple try catch
We can have more than one try/catch block. The most specific
exception which can be thrown is written on the top in the catch block
following by the less specific least.
Nested try catch
We can declare multiple try blocks inside the try block. The
most specific exception which can be thrown is written on the top in
the catch block following by the less specific least.
kilometers per liter to miles per gallon
Kilometers per liter : The distance traveled by a vehicle
which is running on gasoline or diesel fuel in a kilometer.
Miles per Gallon: The distance traveled by a vehicle which is
running on gasoline or diesel fuel in a mile.
Ascii values table
ASCII stands for American Standard Code for Information
Interchange. Computers can only understand numbers, so an ASCII
code is the numerical representation of a character such as @, #, $,
and so on. ASCII was developed when non- printing characters were
life cycle of a jsp page
Life of the the jsp page is just same as the servlet life
cycle. After get translated the jsp file is just like a servlet.
Page directive attributes
A directive is a way to give special instructions to the
container at page translation time. The page directive is
written on the top of the jsp page.
Html tags in jsp
In this example we have used the
html tag inside the println() method of the out implicit
object which is used to write the content on the browser.
In this program we are going to
know how the server determines whether the password entered by the
user is correct or not. This whole process is controlled on the server
Multiple forms in jsp
The form tag creates a form for
user input. A form can contain checkboxes, textfields, radio- buttons
and many more. Forms are used to pass user- data to a specified URL
which is specified in the action attribute of the form tag.
Interface in jsp
In interface none of its methods
are implemented. All the methods are abstract. There is no code
associated with an interface. In an interface all the instance methods
are public and abstract. Interfaces are always implemented in the
class. They add extra behaviors to the class.
Inheritance in java with example
Inheritance is one of the concept of the Object- Oriented
programming. It allows you to define a general class, and later more
specialized classes by simply adding some new details.
Constructors are used to create objects from the class.
Constructor declaration are just like method declaration, except that
they do not have any return type and they use the name of the class.
The compiler provides us with a default constructor to the class
having no arguments.
We does not make a object of the abstract class. This class
must be inherited. Unlike interface the abstract class may implement
some of the methods defined in the class, but in this class at least
one method should be abstract.
After going through this example
you will be understand how you can calculate the factorial by using
recursion in jsp. To make a program on factorial, firstly it must be
clear what is recursion.
Celsius is a unit to measure
temperature scale on which water freezes at 0 degree and boiling point
is 100 degree. This unit is discovered by Celsius in 1742, a Swedish
astronomer and physicist, he has invented the centigrade, or Celsius
thermometer divided between the freezing and boiling points of water
into 100 parts.
comment in jsp
In a jsp we should always try to
use jsp- style comments unless you want the comments to appear in the
HTML. Jsp comments are converted by the jsp engine into java comments
in the source code of the servlet that implements the Jsp page.
Html tag inside out implicit object
In this program we are going to
use a html tag inside a out object. out object is used to display the
content on the browser. To make this program run use out object inside
which define some html code along with the content you want to display
on the browser
In this example we are
going to show you how we can declare a method and how we can used it.
In this example we are making a method named as addNum(int i, int
b) which will take two numbers as its parameters and return
Jsp is used mainly for
presentation logic. In the jsp we can declare methods just like as we
declare methods in java classes. Methods can be declared in either
declaration directive or we can declare it in scriptlet. If we declare
method inside declaration directive, then the method is applicable in
the whole page.
Passing Array method Array is a collection of similar data type. It is one of
the simplest data structures. Arrays holds equally sized data elements
generally of the similar data type.
In this example we will show how we
can use two indexes in a for loop. We can solve this problem by using
for loop defined inside the scriptlet directive.
Date in JSP
To print a Date in JSP firstly we are importing a class named java.util.Date
of the package java.util. This package is imported in the jsp
page so that the Date class and its properties can accessed in
the JSP page.
If- Else Ladder
A ladder means a vertical set of steps. It is a computer generated
list of pairings used in eliminations.
We use the if condition to check if the particular condition is true
then it should perform a certain task, and if a particular condition
is not true then it should do some other tasks.
Quintessential means representing the perfect example of a class or
quality. It is pure and concentrated essence of a substance.
Include File JSP using directive and include action <%@ include file = " "%>: - This is include
directive. This directive has only one attribute named as file, which
is used to include a file in the jsp page at the translation time. <jsp:include page = " ">:- This is known as the
include standard action. This standard action is used to include a
file at run time. This standard action is evaluated at the run time.
Snoop in JSP
It mostly contains the request information, ServletContext
initialization parameters, ServetContext attributes, request headers,
response headers etc.
sendRedirect In JSP sendRedirect() method is a method of HttpServletResponse
interface. In sendRedirect() the object of request will be
generated again with the location of page which will perform the
request of the client.
Request Header in JSP
Whenever an http client sends a request, it sends the request in the
form of get or post method or any other HttpRequest methhods. It
can also sends the headers with it.
Specific request headers in JSP
Whenever an http client sends a request, it can also sends the headers
with it. All the headers are optional except Content-length, which is
required only for POST request.
Java class in JSP
To use the class inside the jsp page we need to create an object of
the class by using the new operator. At last use the instance of the
class to access the methods of the java file.
Setting Colors in JSP
In Jsp also we can set the background color which we want, the
font color can be changed. The table can be coloured . By using the
colors code we can give colors according to our wish.
Sine Table in JSP
Mathematically, the sine of an angle
is the ratio of the length of the opposite side to the length of the
hypotenuse of an imaginary right triangle having that angle in it.
Applet In Jsp
Applets are small programs or applications written in java.
These applets are those small programs that runs on web browsers,
usually written in java. We can use the applets in jee also. In jee it
runs on the context of web application on a client computer.
Creating a Local Variable in JSP
Consider a situation where we have to declare a variable as local,
then we should declare the methods and variables in tag except the
Method in Declaration Tag
Anything which will be declared inside declaration tag will be
applicable within the whole application. We call this tag a Declaration
Tag. The syntax of this tag is <%! --------- %>.
Forward a JSP Page
The request object goes to the controller then the
controller decides by which jsp or servlet this request will be
processed, then the request object is passed to that jsp or servlet
and the output is displayed to the browser by the response object.
Random in JSP
Random numbers are the numbers that
are determined entirely by chance. User does not have any control over
the working of random numbers. random() is a method of Math
class which extends java.lang package.
JSP include directive
By using the include tag the file will be included in the jsp page at
the translation time. In this example we have created a jsp file which
has to be included in the other jsp file by using the tag <%@
include file = " "%>.
Literals in JSP
Literals are the values, such as a number or a text string, that are
written literally as part of a program code. A literal is a expression
of a value, including a number or a text string.
Custom tags are usually distributed in the form of a tag
library, which defines a set of related custom tags and contains the
objects that implement the tags. Custom tag libraries allow the java
programmer to write code that provides data access and other services,
and they make those features available to the jsp author in a simple
to use XML- like fashion.
Expression Language In JSP
EL means the expression language , it is a simple
language for accessing data, it makes it possible to easily access
application data stored in JavaBeans components.
EL Basic Arithmetic
Addition (+), subtraction (-), multiplication (*), division (/ or
div), and modulus (% or mod) are all supported in Expression Language.
Error conditions, like division by zero are handled easily by the