Software School Projects | Academic Students Projects | Source Codes | Tablets header
Please use our contact us form or send email to Support@srishtis.com.

An Email Address Finder Example
This example, named email, stores names and email addresses in a map file based on the java.util.TreeMap class defined in the JDK 1.2. The TreeMap class creates a data structure called a red-black tree. In the tree, data is stored with a key and a value. In this example, the name is the key and the email address is the value.

When you add an entry to the map file, you enter both a name (the key) and an email address (the value). You can look up or delete an email address by entering just a name. The name cannot be null because it is a key. If a user tries to enter a null name, the application throws an exception and displays an error page.

conditions are: Every node has two children or is a leaf. Every node is colored red or black. Every leaf node is colored black. If a node is red, then both of its children are black. Every path from the root to a leaf contains the same number of black nodes.

The email example has three pages with HTML forms, two response files, one error page, and one JavaBeans component. 

 
Adding a Name and Email Address (email.jsp) ________________________________________________________ <%@ page language="java" % >
<HTML <%@ include file="copyright.html" %>
<%@ page isThreadSafe="false" import="java.util.*, email.Map" errorPage="error.jsp" %>
<jsp:useBean id="mymap" scope="session" class="email.Map" />
<jsp:setProperty name="mymap" property="name" param="name" />
<jsp:setProperty name="mymap" property="email" param="email" />
<% mymap.setAction( "add" ); %>
<html>
<head>
<title>
Email Finder</title>
</head>
<body bgcolor="#ffffff" background="background.gif" link="#000099">
<!-- the form table -->
<form method="get">
<table border="0" cellspacing="0" cellpadding="5">
<tr>
<td width="120">
  </td>
<td align="right">
<h1>
Email Finder</h1>
</td>
</tr>
<tr>
<td width="120" align="right">
<b>
Name</b>
</td>
<td align="left">
<input type="text" name="name" size="35">
</td>
</tr>
<tr>
<td width="120" align="right">
<b>Email Address</b>
</td>
<td align="left">
<input type="text" name="email" size="35">
</td>
</tr>
<tr>
<td width="120">
  </td>
<td align="right">
Please enter a name and an email address. </td>
</tr>
<tr>
<td width="120">   </td>
<td align="right">
<input type="submit" value="Add">
</td>
</tr>
<!-- here we call the put method to add the name and email address to the map file -->
<% String rname = request.getParameter( "name" ); String remail = request.getParameter( "email" ); if ( rname != null) { mymap.put( rname, remail ); } %>
<tr>
<td width="120">
  </td>
<td align="right">
The map file has <font color="blue">
<%= mymap.size() %>
</font> entries. </font>
</td>
</tr>
<tr>
<td width="120">
  </td>
<td align="right">
<a href="lookup.jsp">
Lookup</a>
  |   <a href="delete.jsp">
Delete</a>
</td>
</tr>
</table> </form> </body>
</html> __________________________________________________ Looking Up a Name in the Map File (lookup.jsp)
<%@ include file="copyright.html" %>
<%@ page isThreadSafe="false" import="java.util.*, email.Map" errorPage="error.jsp" %>
<jsp:useBean id="mymap" scope="session" class="email.Map" />
<jsp:setProperty name="mymap" property="name" param="name" />
<% mymap.setAction( "lookup" ); %>
<html>
<head>
<title>
Email Finder </title>
</head>
<body bgcolor="#ffffff" background="background.gif" link="#000099">
<form method="get">
<table border="0" cellspacing="0" cellpadding="5">
<tr>
<td width="120">
  </td>
<td align="right">
<h1>
Email Finder</h1>
</td>
</tr>
<tr>
<td width="120" align="right">
<b>Name</b>
</td>
<td align="left">
<input type="text" name="name" size="35">
</td>
</tr>
<tr>
<td width="120">
  </td>
<td align="right">
Please enter a name for which <br>

you'd like an email address. </td>

</tr>
<tr>
<td width="120">
  </td>
<td align="right">
The map file has <font color="blue">
<%= mymap.size() %>
</font>
entries. </td>

</tr>

<tr>
<td width="120">
  </td>
<td align="right">
<input type="submit" value="Lookup">
</td> </tr>
<% if ( request.getParameter( "name" ) != null ) { %>
<%@ include file="lookupresponse.jsp" %> <% } %> <tr> <td width="120">   </td> <td align="right">
<a href="email.jsp">
Add</a>   |   <a href="delete.jsp">
Delete</a> </td>
</tr>
</table>
</body>
</html> _______________________________________________________
Displaying the Lookup Response (lookupresponse.jsp) <%@ page import="java.util.*, email.Map" %>
<tr>
<td width="120">
  </td>
<td align="right">
<b>
Success! </b>
</td> </tr>
<tr>
<td width="120">
  </td>
<td align="right">
<jsp:getProperty name="mymap" property="name" />
<br>
<jsp:getProperty name="mymap" property="email" />
</td>
</tr>
______________________________________________________
Deleting an Email Address (delete.jsp)
<%@ include file="copyright.html" %>
<%@ page isThreadSafe="false" import="java.util.*, email.Map" errorPage="error.jsp" %>
<jsp:useBean id="mymap" scope="session" class="email.Map" />
<jsp:setProperty name="mymap" property="name" param="name" />
<!-- tags the JSP page so that we can display the right exception message later -->
<% mymap.setAction( "delete" ); %>
<html>
<head>
<title>
Email Finder </title>
</head>
<body bgcolor="#ffffff" background="background.gif" link="#000099">
<form method="get">
<table border="0" cellspacing="0" cellpadding="5">
<tr>
<td width="120">
  </td>
<td align="right">
<h1>
Email Finder</h1>
</td>
</tr>

<tr>

<td width="120" align="right">

<b>
Name</b>
</td>
<td align="left">
<input type="text" name="name" size="35">
</td>
</tr>
<tr>
<td width="120">
  </td>
<td align="right">
Please enter a name you would like to delete. </td> </tr>
<tr>
<td width="120">
  </td>
<td align="right">
The map file has <font color="blue">
<%= mymap.size() %>
</font>
entries. </td>
</tr>
<tr>
<td width="120">
  </td>
<td align="right">
<input type="submit" value="Delete">
</td>
</tr>
<!-- display the name and email address, then delete them from the map file -->
<% if ( request.getParameter( "name" ) != null ) { %>
<%@ include file="deleteresponse.jsp" %><
<% mymap.remove( request.getParameter("name") ) ; } %>
<tr>
<td width="120">
  </td>
<td align="right">
<a href="email.jsp">Add</a>
  |   <a href="lookup.jsp">
Lookup</a>
</td>
</tr>
</table>
</body>
</html> _____________________________________________________
Displaying the Delete Response (deleteresponse.jsp) <%@ page import="java.util.*, email.Map" %>
<tr>
<td width="120">
  </td>
<td align="right">
<b>Success!</b>
</td>
</tr> <tr>
<td width="120">
  </td>
<td align="right">
<jsp:getProperty name="mymap" property="name" />
<br>
<jsp:getProperty name="mymap" property="email" />
<br>
<p>
has been deleted from the map file. </td>
</tr> _______________________________________________________
Displaying Exception Messages (error.jsp)
<%@ include file="copyright.html" %>
<%@ page isErrorPage="true" import="java.util.*, email.Map" %>
<jsp:useBean id="mymap" scope="session" class="email.Map" />
<html>
<head><title>
Email Finder</title>
</head>
<body bgcolor="#ffffff" background="background.gif" link="#000099">
<table border="0" cellspacing="0" cellpadding="5">
<tr>
<td width="150" align="right">
  </td>
<td align="right" valign="bottom">
<h1>
Email Finder </h1>
</td>
</tr>
<tr>
<td width="150" align="right">
  </td>
<td align="right">
<b>
Oops! an exception occurred.</b>
</td>
</tr>
<tr>
<td width="150" align="right">
  </td>
<td align="right">
The name of the exception is <%= exception.toString() %>
. </td>
</tr>
<tr>
<td width="150" align="right">
  </td>
<td align="right">
  </td>
</tr>
<% if (mymap.getAction() == "delete" ) { %>
<tr>
<td width=150 align=right>
  </td>
<td align=right>
<b>
This means that ...</b>
<p>The entry you were trying to <font color="blue">
delete</font> is not in the map file <br>
<b>
<i>
or</i>
</b>
<br>
you did not enter a name to delete. <p>
Want to try <a href="delete.jsp">
again</a>
? </td>
</tr>
<% } else if (mymap.getAction() == "lookup" ) { %>
<tr>
<td width="150" align="right">
  </td>
<td align="right">
<b>
<i>This means that ...</b>
</i>
<p>
the entry you were trying to <font color="blue">vlook up</font>
is not in the map file, <b>
<i>
or</i>
</b>
<br> you did not enter a name to look up. <p>
Want to try <a href="lookup.jsp">
again</a>? </td>
</tr>
<% } else if (mymap.getAction() == "add" ) { %>
<tr>
<td width="150" align="right">
  </td>
<td align="right">
<b><i>
This means that ...</b>
</i>
<p>
You were trying to <font color="blue">
add</font>
an entry with a name of null. <br>
The map file doesn't allow this. <p>
Want to try <a href="email.jsp">
again</a>? </td>
</tr>
<% } %>
</table> __________________________________________________________
Creating the Map File (Map.java) package email; import java.util.*; public class Map extends TreeMap
{ // In this treemap, name is the key and email is the value private String name, email, action;
private int count = 0; public Map() {
} public void setName( String formName )
{ if ( formName != "" )
{ name = formName;
}
} public String getName() return name;
} public void setEmail( String formEmail )
{
if ( formEmail != "" )
{
email = formEmail;
System.out.println( name );
// for debugging only System.out.println( email );
// for debugging only
}
}
public String getEmail()
{
email = get(name).toString();
return email;
} public void setAction( String pageAction )
{ action = pageAction;
}
public String getAction()
{ return action;
}
}
 
Job or extra money for students

Search Engine Rank of your blog or websites