Best Loop Idiom for special casing the last element

Question

I run into this case a lot of times when doing simple text processing and print statements where I am looping over a collection and I want to special case the last element (

Answer 1

I think it is easier to think of the first element as the special case because it is much easier to know if an iteration is the first rather than the last. It does not take any complex or expensive logic to know if something is being done for the first time.

public static String prettyPrint(String[] items) {
    String itemOutput = "[";
    boolean first = true;

    for (int i = 0; i < items.length; i++) {
        if (!first) {
            itemOutput += ", ";
        }

        itemOutput += items[i];
        first = false;
    }

    itemOutput += "]";
    return itemOutput;
}