Guava Joiner doesn't have ability to prefix and suffix [duplicate]

Question

I have requirement in Joiner to have the ability to prefix and suffix elements.

For example

String str[] = {"a", "b", "c"};
Joiner.on(",").prefix("'").suffix("'").join(str);

---

Expected output would be:

'a','b','c'

Do we have any alternative for this? As Guava doesn't do it (or I'm not aware of). With java 8 is there a better alternative?

Answer 1

You can use Guava's List#transform to make the transformation a --> 'a' and then use Joiner on the transformed list. transform only works on Iterable objects, though, not on arrays. The code will still be succinct enough:

List<String> strList = Lists.newArraylist(str); // where str is your String[]
Joiner.on(',').join(Lists.transform(str, surroundWithSingleQuotes));

where the transformation is as follows:

Function<String, String> surroundWithSingleQuotes = new Function<String, String>() {
    public String apply(String string) {
        return "'" + string + "'";
    }
};

One might say this is a long-winded way of doing this, but I admire the amount of flexibility provided by the transform paradigm.

Edit (because now there's Java 8)

In Java 8, all this can be done in a single line using the Stream interface, as follows:

strList.stream().map(s -> "'" + s + "'").collect(Collectors.joining(","));