Using Abstract Class

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. We can't instantiate the object of the abstract class but we can call its static method by its class name.

The code of the program is given below:

<html>
    <head>
        <title>Using Abstract Classes</title>
    </head>
          <body>
        <h1>Using Abstract Classes</h1>
        <%!
            javax.servlet.jsp.JspWriter pw;
            abstract class Rectangle
            {
		int length, breadth, area;
 abstract int getArea() throws java.io.IOException;
 public void setArea(int length, int breadth) throws java.io.IOException 
                {
			this.length = length;
			this.breadth = breadth;
			pw.println("Calculating the area of a rectangle...........<br>");
			pw.println("The area of rectangle is  ");
			pw.println(getArea());
                }
            }
            class Rectangle1 extends Rectangle
            {
                int getArea() throws java.io.IOException 
                {
	       	    area = length*breadth;
                    return(area);
                }
            }
        %>     
        <%
            pw = out;     
            Rectangle1 rect = new Rectangle1();
            rect.setArea(2,3);
        %>
    </body>
</html>

The output of the program is given below:

Download this example.

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