java.lang.StringIndexOutOfBoundsException

Question

This a code for converting hex to string but it works fine until size of the string doesn't exceeds 62 characters?

public static String hexToString(String hex)
        {       
           StringBuilder output = new StringBuilder();
           for (int i = 0; i < hex.length(); i+=2)
           {
            String str = hex.substring(i, i+2);
            output.append((char)Integer.parseInt(str, 16));
           }
           return(output.toString());
        }

java.lang.StringIndexOutOfBoundsException: String index out of range: 62 at java.lang.String.substring(Unknown Source) at HEX.hexToString(HEX.java:36) at HEX.main(HEX.java:56)

String hex1 = "234c02ecbbfbafa3ed18510abd11fa724fcda2018a1a8342cf064bbde548d" — Ali Ahmad
– Ali Ahmad, Commented Sep 7, 2012 at 12:07
It's 61 characters and in last iteration of your for cycle you ask for characters 61+62.. That is the problem. What are you actually trying to achieve?? — Michal Klouda
– Michal Klouda, Commented Sep 7, 2012 at 12:08

gefei · Accepted Answer · 2012-09-07 12:04:19Z

3

i+2 in String str = hex.substring(i, i+2); is the problem. even if i < hex.length(), i+2 is too large if hex.length() is odd.

answered Sep 7, 2012 at 12:04

gefei

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Comments

Santosh · Accepted Answer · 2012-09-07 12:33:18Z

2

You will face this problem only when you have odd number of characters in your string. Fix your function as follows:

public static String hexToString(String hex)
    {       
       StringBuilder output = new StringBuilder();
       String str = "";
       for (int i = 0; i < hex.length(); i+=2)
       {

        if(i+2 < hex.length()){
            str = hex.substring(i, i+2);
        }else{
            str = hex.substring(i, i+1);
        }
        output.append((char)Integer.parseInt(str, 16));
       }
       return(output.toString());
    }

edited Sep 7, 2012 at 12:33

answered Sep 7, 2012 at 12:28

Santosh

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Comments

Andrei0427 · Accepted Answer · 2012-09-07 12:06:29Z

0

If youre using String.length in a for loop with i initiated at 0 then you need to -1 from the strings length

for (int i = 0; i < hex.length()-1; i+=2)

answered Sep 7, 2012 at 12:06

Andrei0427

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Comments

spolto · Accepted Answer · 2012-09-07 12:11:07Z

0

Fix your loop condition :

for (int i = 0; i < hex.length() - 3; i +=2)

edited Sep 7, 2012 at 12:11

spolto

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answered Sep 7, 2012 at 12:09

Drona

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1 Comment

gefei Over a year ago

that's too simple. i < hex.length()-3, then i+2 < hex.length()-1, that's not what the OP wants

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