Home Jsp Simple-jsp-example Using Super class Variables With Sub-classed Objects

Using Super class Variables With Sub-classed Objects
Posted on: March 11, 2008 at 12:00 AM

One of the strong features of java is that it is follows a OOPs concept, and one of the feature of OOP in java is that, we can assign a subclass object or variable to the variable of the superclass type.

Using Super class Variables With Sub-classed Objects

In this example we have a class named Rectangle which is the superclass of class Square, and Square is a superclass of Triangle. We can assign the object references of class Square to the variable of Rectangle, as well as the object references of class Rectangle.

The code of the program is given below:

<head>
        <title>To Use Superclass Variables With Subclassed Objects</title>
    </head>
    <body>
        <h1>To Use Superclass Variables With Subclassed Objects</h1>

        <%!
            javax.servlet.jsp.JspWriter pw;
            class Rectangle
            {
                public void areaOfRectangle() throws java.io.IOException 
                {
                    pw.println("Starting...<br>");
                }
            }
            class Square extends Rectangle
            {
                public void area() throws java.io.IOException 
                {
                    pw.println("Creating...<br>");
                }
            }
            class Triangle extends Square
            {
                public void area() throws java.io.IOException 
                {
                    pw.println("Creating...<br>");
                }
            }
        %>     
        <%
            pw = out;     
            out.println();
            out.println("Creating an Area...<br>");
            Rectangle p = new Triangle();
            p.areaOfRectangle();
        %>
    </body>
</html>

The output of the program is given below:

Download this example.

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