i have a program that converts a text string into a hash sequence using parseInt(). but parseInt() keeps throwing a NumberFormatException.

any ideas why? is it becuase i'm using <= instead of = in my for loop?

EDIT: ingnore r. it's not being used. sorry.

package test;

import java.util.Random;
import java.util.Scanner;

public class minecraft_check {

    public static void main(String[] args)
        String yn =  null;
        Random rand = new Random();
        String r = null;
        int hash = 0;
            System.out.print("Enter the Seed to be converted (max 30 chars.): ");
            r = new Scanner(System.in).nextLine();
            while(r.length() > 31);
            hash = getHashCode(r, rand);
            System.out.println("\nYour Hash code for " + r + " is: " + hash + "\n\n");
            System.out.println("Again? (y/n)");
            yn = new Scanner(System.in).nextLine();
        }while(yn != "n" && yn != "N");

    public static int getHashCode(String seed, Random rand)
        char[] split = seed.toCharArray();
        int generatornum = 0, r = 0;
        for(int i = 0; i <= seed.length();)
             r = rand.nextInt(256);
            if(!(r == 0 || r == 256))
                generatornum+=(Integer.parseInt(Integer.toString((int)split[i]), 256)) * Math.pow(31,seed.length()-i);
            }else continue;
        return generatornum;

What is the contents of th String you are trying to parse?
How is it getting non-numeric data?
If you can't see what the value being parsed is, assign it to a String first and print the value of the String so you can see it.

Does the full text of the error message show you the invalid String?

here is the layout

seed is the base string, and is got from imput from the main function.
seed s split into single chars. to get the proper hash, i have to get the value of each character seperately.

problem is though, parseInt does not accept Character. so i have to reinterpret the character as a String that contains an integral value by dynamically converting the character to an integer.

then finaly i can parse the string into a number based on the number of ascii characters and complete the calculation.

eclipse is showing that line 40, is causing a problem, along with line 20 of my program and line 426 of integer.class

What value are you trying to get from the single char value: split[i]? Can you give some examples: '?' to int value

What is the full text of the compiler's error message?

eclipse throws: Exception in thread "main" java.lang.NumberFormatException: radix 128 greater than Character.MAX_RADIX

That error seems clear. Where is the 128 coming from? I see 256 in the posted code.
What about my other question?

i tried a lower number to see if it would correct the problem earlier.

here is the formula:
s[i]31^(n-i) +s[i]31^(n-i) + s[i]*31^(n-i)... until i = n

where s[i] is the character and n is the length of the string.

What int value do you want to convert split[i] to? Can you give some examples?

sure. say split[1] = "A"

A -> 65 decimal

therfore: 65 *(30^1 * 1) = 65 * 30 = 1950

thefore the hash is 1950.

What was the purpose of this expression in your code:
Integer.parseInt(Integer.toString((int)split[i]), 256)
You wanted to use the value of split[i] to get an int.

in order to get the value of the character. 256 is the maximum number of characters in the ASCII table.

Can you show some examples? What values did you want that expression to return? What were the minimum and max values you wanted to get?

assumming that the user has entered character 0xFF (in hex. idk what it's represenation is) 30 times then.

255*(30^30-1) +.... (the eqaution is ver long) = ~5.5 * 10^46

the lowest number is 1 becasue entering 0x01 would result in:
1*(30^1-1) = 1 * 30^0 = 1

How does a user enter a character with the value: 0xFF?

You are not answering my question. what value did you want to get from split[i] using the expression I posted?
I'm not asking what you are going to do with the value AFTER you get it.

if a user on the keyboard press ALT+0+2+5+5 it will display 0xFF

if a user enters a character, say Q, it needs to read 81 then calculate.

i solved my problem now. i just rewrote the function.

You don't say how you re-wrote it, but for future reference, a Java char is a numeric value. If you get a single char (eg by converting a String to a char array) then you can just use that value in a numeric expression without any further conversion, eg

      String str = "QRS";
      char[] chars = str.toCharArray();
      System.out.println(chars[0] * 2); // prints 162 ('Q' == 81)