Substringing single characters in Java

Question

I am attempting to create a method in Java which will recognize non alphanumeric symbols in a line of text and remove them. However, I am limited in the tools that I can use. I have to use a loop and a scanner to read through the text, and only using the charAt and substring methods to remove the offending characters. Here is the code that I came up with

public String sanitize2(){
        Scanner sanitizer = new Scanner(input.getText());
        String toBeSanitized = sanitizer.nextLine();
        int length = toBeSanitized.length();
        for (int i=0;i < toBeSanitized.length(); i++){
            if ((toBeSanitized.charAt(i) >= 'a' && toBeSanitized.charAt(i) <= 'z') ||
                (toBeSanitized.charAt(i) >= 'A' && toBeSanitized.charAt(i) <= 'Z') ||
                (toBeSanitized.charAt(i) >= '0' && toBeSanitized.charAt(i) <= '9')) 
            {
                   toBeSanitized = toBeSanitized.substring(0,i) + toBeSanitized.substring(i+1);
            }
        }
        input.setText(toBeSanitized);
        return toBeSanitized;
    }

However it completely gives the wrong answer when i insert text into the input field. Can anyone shed light on what i'm doing wrong here?

Check this post. It's duplicated. http://stackoverflow.com/questions/1805518/replacing-all-non-alphanumeric-characters-with-empty-strings — Tran Ho, Apr 08 '16 at 01:05
@kimdung Not really of duplicate of your linked Question. That one is about regex, this one is not. This one is about single character Unicode number. — Basil Bourque, Apr 08 '16 at 01:08
I had looked at that as well, but i don't think it helps my situation as i'm limited by what methods I can use — Gee Boughuski, Apr 08 '16 at 01:09
You're removing characters when they're in the alphanumeric range — jack3694078, Apr 08 '16 at 01:12
Your code looks like it's trying to only remove alphanumeric characters, not keep them. Also, use a `while` loop instead of `for`, and only increment `i` when you find a valid character. You're currently always increment long `i` so you'll skip some bad characters — Krease, Apr 08 '16 at 01:12
can you give us any sample input along with the actual output and the desired output? — JanLeeYu, Apr 08 '16 at 01:16

score 1 · Accepted Answer · answered Apr 08 '16 at 01:28

If you are not required to use all the given tools, then I think this might Help solve your problem.

    String toBeSanitized = "(*this*)* text is ^0nly for t3st!ng!";
    String sanitizedStr = "";
    int length = toBeSanitized.length();
    for (int i=0;i < toBeSanitized.length(); i++){
        if ((toBeSanitized.charAt(i) >= 'a' && toBeSanitized.charAt(i) <= 'z') ||
        (toBeSanitized.charAt(i) >= 'A' && toBeSanitized.charAt(i) <= 'Z') ||
        (toBeSanitized.charAt(i) >= '0' && toBeSanitized.charAt(i) <= '9') || 
        toBeSanitized.charAt(i) == ' ') // optional
        {
            sanitizedStr += toBeSanitized.charAt(i);
        }
    }

    System.out.println(sanitizedStr);

I also included the spaces just incase but can just remove it if you want. Hope it helps.

Thanks, this seems to be working well. If i'm reading this right, instead of removing unwanted characters, it makes a new string consisting only of the accepted characters? — Gee Boughuski, Apr 08 '16 at 01:35

Substringing single characters in Java

1 Answers1