jdb dont dont print value of variables and objects

[Manuel Martin Martin]

I cant dysplay value of objects and variables in jdb.What happend?
How can i solve this ?
this is my session in jdb:

Copyright � 1995-1999 Technische Universit�t Braunschweig, Germany.
Copyright � 1999-2001 Universit�t Passau, Germany.
Initializing jdb...
> load ejemplo
> stop at ejemplo:10
Deferring breakpoint ejemplo:10.
It will be set after the class is loaded.
> run
run ejemplo
> 
VM Started: Set deferred breakpoint request ejemplo:10

Breakpoint hit: thread="main", ejemplo.main(), line=10, bci=47
  10            p.multiplicacion(p1).visualizar();

main[1] step

Step completed: main[1] thread="main", Polinomio.multiplicacion(), line=78, 
bci=0
  78            resul=new Polinomio();

main[1] java.lang.NullPointerException: 
        at com.sun.tools.jdi.MirrorImpl.validateMirrors(MirrorImpl.java:86)
        at 
com.sun.tools.jdi.ObjectReferenceImpl.getValues(ObjectReferenceImpl.java:113)
        at 
com.sun.tools.jdi.ObjectReferenceImpl.getValue(ObjectReferenceImpl.java:108)
        at 
com.sun.tools.example.debug.expr.LValue$LValueInstanceMember.getValue(LValue.java:274)
        at 
com.sun.tools.example.debug.expr.ExpressionParser.evaluate(ExpressionParser.java:44)
        at com.sun.tools.example.debug.tty.Commands.evaluate(Commands.java:65)
        at 
com.sun.tools.example.debug.tty.Commands.doPrint(Commands.java:1376)
        at com.sun.tools.example.debug.tty.Commands$3.run(Commands.java:1409)
main[1] main[1] print resul
Name unknown: resul
main[1] print i
Name unknown: i


the code of program is :

ejemplo.java

import Polinomio;
public class ejemplo{
        public static void main(String[] args){
                Polinomio p=new Polinomio();
                p.anadir_monomio(new Monomio(1,'x',1));
                p.anadir_monomio(new Monomio(1,'x',0));
                //p.anadir_monomio(new Monomio(3,'x',3));
                Polinomio p1=new Polinomio(p);

                p.multiplicacion(p1).visualizar();
                //p.visualizar();
        }
}

Polinomio.java

import Monomio;
import java.util.Vector;

class Polinomio{
        private Vector vectormonomios;

        public Polinomio(){
                vectormonomios=new Vector();
        }

        public Monomio get_monomio(int i){
                return (Monomio)vectormonomios.elementAt(i);
        }

        public Polinomio(Polinomio p){
                int i;

                vectormonomios=new Vector();
                for (i=0;i<p.grado();i++){
                        vectormonomios.addElement(p.get_monomio(i));
                }
        }

        public void anadir_monomio(Monomio m){
                int i;
                Monomio aux,aux2;
                i=0;
                while 
((i<vectormonomios.size())&&(m.get_exponente()<((Monomio)vectormonomios.elementAt(i)).get_exponente()))
                        i++;
                if (i==grado()){
                        vectormonomios.insertElementAt(m,i);
                }else{
                aux=get_monomio(i);
                if (aux.semejante(m)){
                        aux2=new 
Monomio(aux.get_coeficiente()+m.get_coeficiente(),m.get_indeterminada(),m.get_exponente());
                        vectormonomios.removeElementAt(i);
                        vectormonomios.insertElementAt(aux2,i);
                } else  vectormonomios.insertElementAt(m,i);
                }
        }



        public void visualizar(){
                int i;
                for (i=0;i<vectormonomios.size();i++){
                        ((Monomio)vectormonomios.elementAt(i)).visualizar();
                }
                System.out.println("");
        }

        public int grado(){
                return vectormonomios.size();
        }

        public Polinomio suma_resta(Polinomio p2){
                int i,max_grado;
                Monomio mp1,mp2;
                Polinomio aux=new Polinomio();


                max_grado=grado();
                if (p2.grado()>grado()) max_grado=p2.grado();
                for (i=0;i<max_grado;i++){
                        mp1=get_monomio(i);
                        mp2=get_monomio(i);
                        if (mp1.semejante(mp2)) aux.anadir_monomio(new 
Monomio(mp1.get_coeficiente()+mp2.get_coeficiente(),mp1.get_indeterminada(),mp1.get_exponente()));
                        else aux.anadir_monomio(new 
Monomio(mp1.get_coeficiente(),mp1.get_indeterminada(),mp1.get_exponente()));
                }
                return aux;
        }

        public Polinomio multiplicacion(Polinomio p2){
                int i,j;
                Monomio mp1,mp2;
                Polinomio resul;

                resul=new Polinomio();
                for (i=0;i<grado();i++){
                        mp1=get_monomio(i);
                        for (j=0;j<p2.grado();j++){
                                mp2=p2.get_monomio(j);
                                resul.anadir_monomio(mp1.multiplicacion(mp2));
                        }
                }
                return resul;
        }
}

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--o00o-------o00o--
 Manuel Martin Martin       
  [EMAIL PROTECTED] 
 Linux User:  250918
----------------


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