11.Area of triangle,circle,rectangle

import java.util.*;
import java.lang.*;
abstract class shape
{
    int dim1,dim2;
    void read()
    {
        Scanner t = new Scanner (System.in);
        System.out.println("enter dim1 and dim2");
        dim1 = t.nextInt();
        dim2 = t.nextInt();
        int z = dim1*dim2;
        System.out.println("default area is "+z);
    }
    abstract void area();
}
class circle extends shape
{
    double area1;
    void area()
    {
        Scanner t = new Scanner (System.in);
        System.out.println("enter radius of circle");
        int r = t.nextInt();
        area1 = 3.142*r*r;


        System.out.println("Area of circle is"+area1);
    }
}
class rectangle extends shape
{
    int area2;
    void area()
    {
        Scanner t = new Scanner(System.in);
        System.out.println("enter lenght and breadth");
        int l = t.nextInt();
        int b = t.nextInt();
        area2 = l*b;
        System.out.println("Area of rectangle is"+area2);
    }
}
class triangle extends shape
{
    int area3;
    void area()
    {
        Scanner t = new Scanner(System.in);
        System.out.println("enter height and base");
        int h = t.nextInt();
        int b = t.nextInt();
        area3 = h*b/2;
        System.out.println("Area of triangle is"+area3);
    }
}
class test
{
    public static void main(String args[])
    {
        circle c = new circle ();
        c.read();
        c.area();
        rectangle r = new rectangle();
        r.area();
        triangle t = new triangle();
        t.area();
    }
}