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Thread: StringIndexOutOfBoundsException

  1. #1
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    Default StringIndexOutOfBoundsException

    Ok so basically this code finds all the numbers in a string then prints out how many digits they have...
    The code works fine but if the string has a number at the end it prints out "StringIndexOutOfBoundsException" and as u see I threw that exception in the class but with no use... I don't understand why it gives me that message every time there is a number at the end of the string...


    //Number Finder
    import java.io.*;
    public class pas4{
    	public static void main (String args []) throws IOException, StringIndexOutOfBoundsException{
    		InputStreamReader instream = new InputStreamReader(System.in);
    		BufferedReader br = new BufferedReader(instream);
    		System.out.println("Please insert a passage");
    		String psg = br.readLine();
    		int i = 0;
    		String tmp = "";
    		while (i < psg.length()){
    			while (((psg.charAt(i)) >= 48) && ((psg.charAt(i)) <= 57) && (i < psg.length())){
    				tmp = tmp + psg.charAt(i);
    				i = i + 1;
    			}
    			if (tmp.equals("")){
    				i = i + 1;
    			}else{
    				int z = Integer.parseInt(tmp);
    				int digits = 0;
    				while (z != 0){
    					z = z / 10;
    					digits = digits + 1;
    				}
    				System.out.print(tmp + " has ");
    				System.out.println(digits + " digits ");
    				tmp = "";
    				i = i + 1;
    			}
    		}		
    	}
    }

    Example input: I'll live till 42
    Output: Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 17
    at java.lang.String.charAt(String.java:686)
    at pas4.main(pas4.java:34)
    Last edited by Medo Almasry; July 14th, 2011 at 07:15 AM.

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: StringIndexOutOfBoundsException

    You need to test that the value of the arg to charAt() is not past the end of the String before you use it:
    (psg.charAt(i)) <= 57) && (i < psg.length())

    Here you use it BEFORE you test it.
    Swap those tests.

    What is the value 57? It would be more readable code if you used the char: '9'

  3. #3
    Super Moderator Norm's Avatar
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    Default Re: StringIndexOutOfBoundsException

    You need to test that the value of the arg to charAt() is not past the end of the String before you use it:
    (psg.charAt(i)) <= 57) && (i < psg.length())

    Here you use it BEFORE you test it.
    Swap those tests.

    What is the value 57? It would be more readable code if you used the char: '9'

  4. #4
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    Default Re: StringIndexOutOfBoundsException

    Thanks a LOT NORM...
    Never thought java takes care of conditions sequence...

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