Hello bulimic,this is that i do, please i am a new on java, but i believe that
now is more clear the code. What do you think?
public class Cilindro {
double pi = Math.PI;
double area;
double perimetro;
public Cilindro()
{
}
public double area(double r, double h){
area = (2*pi*r*h) + (2*pi*r*r);
return this.area;
}
public double perimetro(double r, double h){
perimetro = (4*pi*r)+(2*h);
return this.perimetro;
}
}
public class Circulo extends Cilindro{
public Circulo(){
}
public double area(double r){
area = pi*r*r;
return this.area;
}
public double perimetro(double r){
perimetro = 2*pi*r;
return this.perimetro;
}
}
public class Main {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
Circulo obj1 = new Circulo();
Cilindro obj2=new Cilindro();
double radio ,altura ;
Scanner input = new Scanner(System.in);
System.out.println("Ingresa Radio: ");
radio = input.nextFloat();
System.out.println("Ingresa Altura: ");
altura = input.nextFloat();
System.out.println("Area del circulo: " + obj1.area(radio));
System.out.println("Perimetro del circulo: " +
obj1.perimetro(radio));
System.out.println("Area del cilindro: " + obj2.area(radio,altura));
System.out.println("Perimetro del cilindro: " +
obj2.perimetro(radio,altura));
}
}
> Date: Mon, 30 Mar 2009 14:32:33 -0700
> Subject: [java programming] Re: Logic error!
> From: [email protected]
> To: [email protected]
>
>
> On Mar 31, 3:27 am, el mio uno y dos <[email protected]> wrote:
> > Hello bulimic, i think that circulo is not a inner class of cilindro. I
> > think that circulo is a subclass of cilindro. I send a copy of how i do it.
> > Please see it and tell me if is correct.
> Hello. I did not receive any copy. Anyway, we can discuss here.
>
> Circulo inherits cilindro is odd. I think it would be more efficient
> if cilindro extends circulo as it can take advantage of code re-use.
> For example:
> public class Circulo{
> public double area(double radius){
> }
> public double perimetro(double radius){
> }
> }
>
> public class Cilindro extends Circulo{
> public double area(double radius, double height){
> // Use circulo's methods to calculate cilindro's area. Then
> return.
> double areaCirculo=area(radius), perimetroCirculo=perimetro
> (radius);
> }
> }
> >
> >
> >
> > > Date: Mon, 30 Mar 2009 11:53:33 -0700
> > > Subject: [java programming] Re: Logic error!
> > > From: [email protected]
> > > To: [email protected]
> >
> > > On Mar 31, 1:36 am, jose luis garcia <[email protected]> wrote:
> > > > *Hello everybody... I have a problem. I wrote a code for a program that
> > > > have
> > > > 1 superclass and 1 class extends. the code it`s follow:*
> >
> > > > //Programa que realiza algunos calculos mediante las caracteristicas de
> > > > un
> > > > cilindro
> >
> > > > package cilindro;
> >
> > > > // @author louis
> >
> > > > import java.util.Scanner;
> >
> > > > public class Cilindro {
> > > > double pi = Math.PI;
> >
> > > > public Cilindro(){
> > > > // super();
> >
> > > > }
> >
> > > > public double areaCilindro(double r, double h){
> > > > double area = (2*pi*r*h) + (2*pi*r*r);
> >
> > > > return area;
> > > > }
> >
> > > > public double perimetroCilindro(double r, double h){
> > > > double perimetro = (4*pi*r)+(2*h);
> >
> > > > return perimetro;
> >
> > > > }
> >
> > > > public class Circulo extends Cilindro{
> >
> > > > Circulo(){
> > > > super();
> > > > }
> >
> > > > public double areaCirculo(double r){
> >
> > > > double area = pi*r*r;
> > > > return area;
> > > > }
> >
> > > > public double perimetroCirculo(double r){
> > > > double perimetro = 2*pi*r;
> >
> > > > return r;
> > > > }
> >
> > > > }
> >
> > > > public static void main(String[] args) {
> >
> > > > // Cilindro obj = null;
> > > > Circulo obj1 = null;
> > > I suspect the culprit is the inner class. If I remember correctly, an
> > > inner class type declaration should be like:
> > > Cilindro.Circulo obj1 = null;
> >
> > > > double radio = 0,altura = 0;
> > > > Scanner input = new Scanner(System.in);
> >
> > > > System.out.println("Ingresa Radio: ");
> > > > radio = input.nextFloat();
> >
> > > > /* System.out.println("Ingresa altura: ");
> > > > altura = input.nextFloat();
> > > > */
> > > > String resultado = "Area del circulo: " +
> > > > obj1.areaCirculo(radio);
> >
> > > > System.out.println(resultado);
> >
> > > > }
> >
> > > > }
> >
> > > > *Netbeans not generate any error. But at the moment that run the
> > > > program and
> > > > insert a float, Netbeans generate me this message:*
> >
> > > > run:
> > > > Ingresa Radio:
> > > > Exception in thread "main" java.lang.NullPointerException
> > > > at cilindro.Cilindro.main(Cilindro.java:66)
> > > > 2.23
> > > > Java Result: 1
> > > > GENERACIÓN CORRECTA (tiempo total: 3 segundos)
> >
> > > > *
> > > > I`m sure that is a logic error... help me please. Thanks!
> > > > *
> >
> > _________________________________________________________________
> > Descubre todas las formas en que puedes estar en contacto con amigos y
> > familiares.http://www.microsoft.com/windows/windowslive/default.aspx
>
> >
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