Question

I would like to find an efficient way (not scanning the String 10,000 times, or creating lots of intermediary Strings for holding temporary results, or string bashing, etc.) to write a method that accepts a String and determine if it meets the following criteria:

• It is at least 2 characters in length
• The first character is uppercased
• The remaining substring after the first character contains at least 1 lowercased character

Here’s my attempt so far:

private boolean isInProperForm(final String token) {
    if(token.length() < 2)
        return false;

    char firstChar = token.charAt(0);
    String restOfToken = token.substring(1);
    String firstCharAsString = firstChar + "";
    String firstCharStrToUpper = firstCharAsString.toUpperCase();

    // TODO: Giving up because this already seems way too complicated/inefficient.
    // Ignore the '&& true' clause - left it there as a placeholder so it wouldn't  give a compile error.
    if(firstCharStrToUpper.equals(firstCharAsString) && true)
        return true;

    // Presume false if we get here.
    return false;
}

But as you can see I already have 1 char and 3 temp strings, and something just doesn’t feel right. There’s got to be a better way to write this. It’s important because this method is going to get called thousands and thousands of times (for each tokenized word in a text document). So it really really needs to be efficient.

Thanks in advance!

Answer 1

This function should cover it. Each char is examined only once and no objects are created.

public static boolean validate(String token) {
  if (token == null || token.length() < 2) return false;
  if (!Character.isUpperCase(token.charAt(0)) return false;
  for (int i = 1; i < token.length(); i++)
    if (Character.isLowerCase(token.charAt(i)) return true;
  return false;