Have you ever found yourself writing a function to do something that seems pretty simple, then months or years later you find out there's a built-in function to accomplish exactly what you were doing? Maybe you didn't know where to look or the built-in function's name was confusing. I'd argue that Java's toUpperCase() does not fall in this category.

Somehow I imagine that if you were to reverse engineer the built-in method, it wouldn't look like this implementation (submitted anonymously):

private static String upperCaseIt(String Account) {
  String result = ""; int i = 0;
  while (Account.length() > i) {
    if (Account.substring(i,i+1).equals("a")) { 
      result = result + "A";} else {
      if (Account.substring(i,i+1).equals("b")) { 
        result = result + "B";} else {
        if (Account.substring(i,i+1).equals("c")) { 
          result = result + "C";} else {
          if (Account.substring(i,i+1).equals("d")) { 
            result = result + "D";} else {
            if (Account.substring(i,i+1).equals("e")) { 
              result = result + "E";} else {
              if (Account.substring(i,i+1).equals("f")) { 
                result = result + "F";} else {
                /* I'm sure you get the idea. */
              }
            }
          }
        }
      }
    }
    i++;
  }

  return result;
}