Question

I’m learning Java as I complete CodingBat exercises, and I want to start using regular expressions to solve some level 2 String problems. I’m currently trying to solve this problem:

Return the number of times that the string “code” appears anywhere in the given string, except we’ll accept any letter for the ‘d’, so “cope” and “cooe” count.

countCode("aaacodebbb") → 1
countCode("codexxcode") → 2
countCode("cozexxcope") → 2

And here is the piece of code I wrote (which doesn’t work, and I’d like to know why):

public int countCode(String str) {
 int counter = 0;

 for (int i=0; i<str.length()-2; i++)
       if (str.substring(i, i+3).matches("co?e"))
        counter++;

 return counter;
}

I’m thinking that maybe the matches method isn’t compatible with substring, but I’m not sure.

Answer 1

Try using this in the if statement. Unless I’m mixing up Java rules with PHP, then it needs to be +4 rather than +3.

str.substring(i, i+4)