Main_cal.java

"extends" function of point,line,area and cylinder

class Pointtt{
    public double cal(){
    return 0;
    }
}

class Lineee extends Pointtt{
    private double m,n;
    public Lineee(double m,double n){
        this.m = m;
        this.n = n;
    }
    public double cal(){
        return Math.abs(m-n);
    }
}

class Circleee extends Lineee {
    private double R;
    final double pi=3.14;
    public Circleee(double m,double n){
        super(m, n);
        R = super.cal()/2;
    }
    public double cal(){
        return pi*R*R;
    }
}

class Cylinderrr extends Circleee{
    private double H;
    private double A;
    public Cylinderrr(double m,double n,double H){
        super(m, n);
        A = super.cal();
        this.H = H;
    }
    public double cal(){
        return A*H;
    }
}

public class Main_cal {
    public static void main(String[] args) {
        Lineee p = new Lineee(20, 32);
        System.out.println("length_line="+p.cal());
        Circleee q = new Circleee(20, 32);
        System.out.println("area_circle="+q.cal());
        Cylinderrr r = new Cylinderrr(20, 32, 10);
        System.out.println("volume_cylinder="+r.cal());
    }
}

/*output*/

length_line=12.0
area_circle=113.03999999999999
volume_cylinder=1130.3999999999999