Why is Java String indexOf failing?

Question

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 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.

There's no match to the strings you're looking for. Did the comments get parsed out in formatting your post? — Steve B.
– Steve B., Commented Mar 31, 2010 at 17:41
How should foo --> bar  foo --> bar <!-- foo be parsed? — BalusC
– BalusC, Commented Mar 31, 2010 at 17:47
To be clearer on BalusC point: You need to consider illegally formatted comments — Pyrolistical
– Pyrolistical, Commented Mar 31, 2010 at 17:51

Pyrolistical · Accepted Answer · 2010-03-31 17:42:54Z

3

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

prints 27

So your input string must not be what you expect

answered Mar 31, 2010 at 17:42

Pyrolistical

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Comments

Jack · Accepted Answer · 2010-03-31 17:43:39Z

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?

answered Mar 31, 2010 at 17:43

Jack

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2 Comments

BalusC Over a year ago

My cents on that < is actually an < and so on.

Pyrolistical Over a year ago

@Binaryrespawn see comment above

Matt Huggins · Accepted Answer · 2010-03-31 17:40:12Z

1

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

answered Mar 31, 2010 at 17:40

Matt Huggins

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7 Comments

Jacob Mattison Over a year ago

Actually, the string he posted did have them, but they were interpreted as HTML comments and not displayed. I added a code block to show them.

Faiyet Over a year ago

Basically I am trying to manually strip away any characters enclosed between these two comments in java. befoer even hitting the jsp. So its strictly java logic. The indexOf() method returns -1 because the string was not seen by java, but it is part of the string.

JeffH Over a year ago

@Binaryrespawn - Elaborate in your question on: "the string was not seen by java, but it is part of the string". Java appears to be working correctly.

Amir Afghani Over a year ago

It looks like you were flagged by the Smart Police too Matt.

Matt Huggins Over a year ago

@Jack - I would assume a coding site like StackOverflow would know how to convert less than and greater than signs to their escaped equivalents, no need to be a dick.

|

Diego Pereyra · Accepted Answer · 2010-03-31 17:50:50Z

0

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 '' strings inside.

answered Mar 31, 2010 at 17:50

Diego Pereyra

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Comments

Justin Ardini · Accepted Answer · 2010-03-31 17:56:45Z

0

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.

answered Mar 31, 2010 at 17:56

Justin Ardini

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Comments

fastcodejava · Accepted Answer · 2010-03-31 18:04:40Z

0

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()), " ");
}

answered Mar 31, 2010 at 18:04

fastcodejava

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Comments

nplatis · Accepted Answer · 2010-03-31 18:24:02Z

0

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.

answered Mar 31, 2010 at 18:24

nplatis

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