How can I improve this while loop code snippet?

#discuss

So, I have this code snippet.

while (!Character.isWhitespace(this.source.charAt(this.currentCharIndex))) {
    char c = this.source.charAt(this.currentCharIndex);
    // ...
}

What it does is just basically loops through a string until it hits a white space character.

However, I find the code a bit messy. How can I improve it?

I can try this code snippet instead.

char c = this.source.charAt(this.currentCharIndex);
while (!Character.isWhitespace(c)) {
    c = this.source.charAt(this.currentCharIndex);
}

It looks cleaner but this.source.charAt(this.currentCharIndex) seems redundant (the same as the previous snippet) so I need your opinion on how you would tackle this problem.

Thanks! :D

Top comments (8)

fabulous.yap • Apr 8 '18

maybe...

        char c;
        while (!Character.isWhitespace(c=source.charAt(currentCharIndex++))) {
            //do code magic here...
        }

        char c;
        while (!Character.isWhitespace(c=source.charAt(currentCharIndex))) {
            currentCharIndex++;
            //more code magic happen after this...
        }

but I know nothing of what happen next tho... I assume currentCharIndex will be increment somewhere in the loop...

Kasey Speakman • Apr 8 '18 • Edited

(I don't use Java, but) I'd probably use the Java Streams API.

Optional<int> whitespaceIndex =
    IntStream.range(0, this.source.length())
        .filter(i -> Character.isWhiteSpace(this.source.charAt(i)))
        .findFirst();
Optional<char> whitespaceChar = whitespaceIndex.map(i -> this.source.charAt(i));

Using Optional makes it obvious you have to handle when whitespace is not found.

Note: not guaranteed to compile.

Fabian Holzer • Apr 8 '18 • Edited

Well, you give very little context about your intentions.

If it is safe to assume that currentCharIndex is within the correct bounds, you might get rid of the assignment outside of the loop by using do { } while.

Or, you get rid of the imperative style by using Streams (you get an IntStream from a String using the chars() method in Java 8).

Sean Francis N. Ballais • Apr 8 '18

Interesting. I'm actually creating a tokenizer for a programming language we came up as part of our course curriculum.

edA‑qa mort‑ora‑y • Apr 8 '18

Use a find_first function, writing your own if it doesn't exist.

Alain Van Hout • Apr 9 '18

If you simply want the first instance of a certain character, and the context is not more complex, and it doesn't require hyper-optimisation, then just go with source.indexOf(" ")