I need help with

[Sheiib]

Hey, I'm doing this program (it's very simple) and I can't find the error in the code!

import java.util.Random;
public class NúmerosEnteros{
private int []s;

public NúmerosEnteros (int n, Random azar){
s=new int [n]; int a=0;
for (int k=0; k<n; k++){
a=azar.nextInt(10); 
s[k]=a;}}

public boolean tieneReflejo(){
return (tr(0, s.length-1));}

public boolean tr(int a, int b){
if (b<=a) return false;
else
    if(s[a]==s[b]) return true;
    else return (tr(a++,b--));}
}

all it has to do, is see if the number has "a reflection" in the array.
it means that if the array is empty or has just one element, it doesn't have a reflection.
in other case:
you all know the array saves numbers like this
d0 d1 d2 d3... d(n-1) dn

so, if d0=dn, or d1=d(n-1), or d2=d(n-2), etc., then it has a reflection.
else, it doesn't.

can someone tell me where the error is? I can't find it.

EDIT: Moved post to this thread

[Norm]

Why do you think there is an error?
Can you post the output from when the program executes and add some comments saying what the output should be. Show the input and the output.

Create a complete test program that will execute and show the problem. I don't see a main method so what you posted will not execute.

[Sheiib]

Because when I run the tester it says that's the error, java.lang.StackOverflowError

the tester is this:

import java.util.Random;
public class Tester
{

public static void main(String[] args) {
NúmerosEnteros ne;
Random aleatorio = new Random();
ne= new NúmerosEnteros(7, aleatorio);
String mostrar=ne.toString();
System.out.println(" ");
System.out.println("Original: "+mostrar);


System.out.println(" ");
System.out.println("Tiene reflejo: ");
if (ne.tieneReflejo()) System.out.print("Sí");
else System.out.print("No");
}


that's it. it compiles, but then when I run it, if the number doesn't have a reflection it doesnt work.

[Norm]

Your error message does give you a line number. Did you look at that line to see why the code is calling itself?

[Norm]

Try debugging your code by adding printlns to show the values of the variables as they change and to show the execution flow.
You need to see why your logic doesn't stop calling the tr() method.

[Solarsonic]

As Norm said you need to give us the exact error message, and the code that's causing it.

[Sheiib]

PROGRAM


import java.util.Random;
public class NúmerosEnteros{
private int []s;

public NúmerosEnteros (int n, Random azar){
s=new int [n]; int a=0;
for (int k=0; k<n; k++){
a=azar.nextInt(10);
s[k]=a;}}

public boolean tieneReflejo(){
return (tr(0, s.length-1));}

public boolean tr(int a, int b){
if (b<=a) return false;
else
if(s[a]==s[b]) return true;
else return (tr(a++,b--));}
}







TESTER


import java.util.Random;
public class Tester
{

public static void main(String[] args) {
NúmerosEnteros ne;
Random aleatorio = new Random();
ne= new NúmerosEnteros(7, aleatorio);
String mostrar=ne.toString();
System.out.println(" ");
System.out.println("Original: "+mostrar);


System.out.println(" ");
System.out.println("Tiene reflejo: ");
if (ne.tieneReflejo()) System.out.print("Sí");
else System.out.print("No");
}




ERROR MESSAGE

java.lang.StackOverflowError:
null


the part in red is the part that produces the error.

[Solarsonic]

PROGRAM

Looks like you have never-ending recursion; your method is stuck calling itself over and over.

This is happening because "if(s[a]==s[b])" never turns out to be true.

[Norm]

Try debugging your code by adding printlns to show the values of the variables as they change and to show the execution flow.
You need to see why your logic doesn't stop calling the tr() method.

[Sheiib]

No, it works when the number has a reflection.
It doesn't work when the number hasn't a reflection.

[Norm]

Have you tried debugging it?
Try debugging your code by adding printlns to show the values of the variables as they change and to show the execution flow.
You need to see why your logic doesn't stop calling the tr() method.

[Solarsonic]

No, it works when the number has a reflection.
It doesn't work when the number hasn't a reflection.

I explained your problem in my post above.