Inheritance is probably the back bone of OOPS.
I have done it so many times in Java, C++, even python also. But this is my first time in JSP. Alas I am not writing any servlet!. This is just a JavaServer Page.
And this is how I did it. Use this code, build your own JSP. Just remember one thing that when you write your class do it within <%! %> instead of <% %>. Copy paste the code and save it with .jsp extension.
//---------------------------------------------------------------------------------------------------------------------
<html>
<head>
<%@ page language="java" import ="java.lang.*,java.io.*" %>
<%!
class Shape
{
int Radius;
int Width;
int Height;
Shape()
{
this.Width=0;
this.Height=0;
this.Radius=0;
}
Shape(int Radius)
{
this.Radius=Radius;
}
Shape(int Width,int Height)
{
this.Width=Width;
this.Height=Height;
}
}
class Circle extends Shape
{
Circle()
{
super();
}
Circle(int Radius)
{
super(Radius);
}
double Area()
{
return Math.round(Math.PI*Radius*Radius * 100.00)/100.00;
}
}
class Rectangle extends Shape
{
Rectangle()
{
super();
}
Rectangle(int Width,int Height)
{
super(Width,Height);
}
double Area()
{
return Math.round(Width*Height * 100.00)/100.00;
}
}
%>
</head>
<body>
<form action="classexample.jsp" method="post">
<select id="choice" onchange="displayelement()">
<option>Circle</option>
<option>Rectangle</option>
</select>
<div id="inputdiv"></div>
<script>
function displayelement()
{
obj=document.getElementById("choice");
if(obj.value=="Circle")
inputdiv.innerHTML="Enters Radius : <input name='rad1' type=text value='' /><br><input type='submit' value='Calculate' />";
else if(obj.value=="Rectangle")
inputdiv.innerHTML="Enter Width : <input name='width1' type=text value='' /><br>Enter Height : <input name='height1' type=text value='' /><br><input type='submit' value='Calculate' />";
}
</script>
</form>
<form>
<%
if(request.getParameter("rad1")!=null)
{
int rad=Integer.parseInt(request.getParameter("rad1"));
Circle c = new Circle(rad);
%><div><%= c.Area() %></div> <%
}
else if(request.getParameter("height1")!=null&&request.getParameter("width1")!=null)
{
int width=Integer.parseInt(request.getParameter("width1"));
int height=Integer.parseInt(request.getParameter("height1"));
Rectangle r = new Rectangle(width,height);
%><div><%= r.Area() %></div> <%
}
%>
</form>
</head>
