*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;
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!
*
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