Adding delimiter has any elegant way?

Question

This is a simple java coding question. I have a List of String [Say "hello" "how" "are" "you?"]. I need to insert a delimiter [-] between each element of the list so that my output is hello-how-are-you?

One simple way of doing this is as below:

private static String addDelim(List<String> a)
{
    String s = "";
    for(int i=0; i<a.size(); i++)
    {
        if(i != 0) // don't add if first element
        {
            s += "-";
        }

        s += a.get(i);
    }
    return s;
}

Is there any elegant way of doing this?

You can use a third-party library, such as Apache Commons, which contain utility methods for this kind of task. However, I doubt it has any code different from what you wrote. Maybe you could use `StringBuilder` for performance if your list has a lot of elements. — Mauren, Oct 07 '13 at 14:58

score 5 · Answer 1 · edited Oct 07 '13 at 14:59

5

If you can include Guava (highly recommended), then the solution would be:

 return Joiner.on("-").join(s);

edited Oct 07 '13 at 14:59

Joachim Sauer

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answered Oct 07 '13 at 14:57

Luke Usherwood

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score 2 · Accepted Answer · answered Oct 07 '13 at 14:57

2

From Apache Commons Lang:

String out = StringUtils.join(yourList, '-');

answered Oct 07 '13 at 14:57

sp00m

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StringUtils is in the JDK? – Jose Oct 07 '13 at 14:57
My mistake, I didn't see the commons link above your answer :) – Jose Oct 07 '13 at 15:00

score 1 · Answer 3 · answered Oct 07 '13 at 14:59

1

If you don't want to use external libraries, you better use StringBuilder:

private static String addDelim(List<String> a) {
    StringBuilder sb = new StringBuilder();
    for(int i=0; i < a.size(); i++) {
        if(i != 0) 
            sb.append("-");
        sb.append(a.get(i));
    }
    return sb.toString();
}

answered Oct 07 '13 at 14:59

Maroun

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Indexing via `get(i)` can have pretty bad performance numbers, for example on a `LinkedList`. – Joachim Sauer Oct 07 '13 at 15:05
@JoachimSauer Yes, but I don't want to change all of his code. – Maroun Oct 07 '13 at 15:33

score 1 · Answer 4 · answered Oct 07 '13 at 15:15

1

StringBuilder sb = new StringBuilder();
for(String str: a){
    sb.append(str).append('-');
}
sb.deleteCharAt(sb.length() -1);

answered Oct 07 '13 at 15:15

Andrey Gorelov

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2

Adding delimiter has any elegant way?

4 Answers4