charat

That is sadly true, but at least for the Basic Multilingual Plane, charAt() and codePointAt() return correct results in constant time.

For example, I don't think it's particularly bad that array[-1] and array.charAt(-1) return different values.

Linear-time indexing: operations like charAt require character indexing to be fast.

Or am I misinterpreting we have passed the burden of proof onto users of charAt?

Imagine if String.charAt(int index) was a virtual call inside of strlen().

String.length() and String.charAt() use utf-16 units, meaning surrogate pairs are double-counted.

Consider these examples: List<String> list = getListofStrings(); List<String> capitalized = new ArrayList<String>(); for(String st: list) if(Character.isUpperCase(st.charAt(0))) capitalized.add(st); Or...

- In the presence of surrogates, charAt() and length() give wrong answers.

If you have a longer list of N swears (say 256 because it's the size of a byte, making encoding easier), you could produce a more efficient base-N encoding, e.g.: var bytes = atob(base64msg), swearsMsg = ''; for (var i = 0; i < bytes.length; i++) { newMsg += swears[bytes[i].charAt(0)] + ' '; } Of course, it's still less efficient than base64, but it's an improvement.

However, for backward-compatibility reasons "charAt()" is defined to return a UTF-16 code-unit (regardless of whether or not it's a useless half-a-code-point) so effectively it's O(1) indexing.

The String#charAt() Javadoc is not really useful, unless you fully understand the implications of: "If the char value specified by the index is a surrogate, the surrogate value is returned." Also, if you are handling CJK strings, is there actually a need to split them by charAt()?

No, function InstructionParsing(instruction) { var separator = instruction.charAt(0) var instructionSplit = instruction.split(separator) this.clickSelector = instructionSplit[1] this.classBehavior = instructionSplit[2].trim().split(" ")[0] this.classValue = instructionSplit[3] this.targetSelector = instructionSplit[5] } is not "self-documenting." Tool is not useful but it is a cool study in writing a limited DSL.

I realize this is a straw man, but with heavy reliance on deep (3+ levels) of immutable relationships, it is not uncommon to find crap that is the equivalent of this: String foo = "hello"; Character bar = foo.charAt(0);...