Why is Java String indexOf failing?

Question

Hi all, this must be quite simple but I am having great difficulty. You see I am trying to find a string within another string as follows.

            e = input.indexOf("-->");
            s = input.indexOf("<!--");
            input = input.replace(input.substring(s, e + 3), " ");

The integers e and s are returning -1 in that it was not found and this is causing the replace method to fail. The test string I am using is "Chartered Certified<!--lol--> Accountants (ACCA)". I tried to creat a new string object and pass in the string as an argument as follows

e=input.indexOf(new String("<!--"));

This yielded the same result. Any ideas ?

This is a stand alone piece of code I wrote and it works perfectly.

public static void main(String[] args) {
    int e = 0;
    int s = 0;
    while (e != -1) {
        //input.replace("\"", "\'");
        e = input.indexOf("-->");
        s = input.indexOf("<!--");
        input = input.replace(input.substring(s, e + 3), " ");
        e = input.indexOf("-->");
        System.out.println(input);
    }
}

But I cannot seem to see why it fails when i use this logic in my action class.

Answer 1

The string "Chartered Certified Accountants (ACCA)" does not contain "-->" or "<!--", so e and s will always be -1.

Answer 2

System.out.println("!Chartered Certified<!--lol--> Accountants (ACCA)".indexOf("-->"));

prints 27

So your input string must not be what you expect

Answer 3

 String input = "Chartered Certified<!--lol--> Accountants (ACCA)";
 int e = input.indexOf("-->");
 int s = input.indexOf("<!--");

 System.out.println(e+" "+s);

yields

26 19

so I think that there's an error somewhere else, is there other code in the middle?

Answer 4

Maybe you are obtaining the string from a sort of xml parser and hides the commented string on rendering. Check that the input string just before the indexOf call really has the '<!--' and '-->' strings inside.

Answer 5

I ran the test real quick using a command-line argument. It worked just fine. Here's the code/results:

public static void main(String[] args) {
    String input = args[0];
    System.out.println(input);
    int e = input.indexOf("-->");
    int s = input.indexOf("<!--");
    input = input.replace(input.substring(s, e + 3), "");
    System.out.println(input);
}

Output:

Chartered Certified<!--lol--> Accountants (ACCA)
Chartered Certified Accountants (ACCA)

If you were passing input as a command-line argument, make sure it is in quotes, or else input will be set to Chartered because of the spaces.

Answer 6

This code should work, there is some other problem. You should code it for safety though as shown below.

e = input.indexOf("-->");
s = input.indexOf("<!--");
if (e > -1 && s > -1 && e > s + 4) {
    input = input.replace(input.substring(s, e + "-->".length()), " ");
}

Answer 7

Your code seems OK. So if it fails. it may be that the string it parses is not what you think it is. Where does the string come from? Try printing the string just before parsing it to see what it actually is.