Java: convert List to a String

Question

JavaScript has Array.join()

js>[\"Bill\",\"Bob\",\"Steve\"].join(\" and \")
Bill and Bob and Steve

Does Java have anything

Answer 1

EDIT

I also notice the toString() underlying implementation issue, and about the element containing the separator but I thought I was being paranoid.

Since I've got two comments on that regard, I'm changing my answer to:

static String join( List list , String replacement  ) {
    StringBuilder b = new StringBuilder();
    for( String item: list ) { 
        b.append( replacement ).append( item );
    }
    return b.toString().substring( replacement.length() );
}

Which looks pretty similar to the original question.

So if you don't feel like adding the whole jar to your project you may use this.

I think there's nothing wrong with your original code. Actually, the alternative that everyone's is suggesting looks almost the same ( although it does a number of additional validations )

Here it is, along with the Apache 2.0 license.

public static String join(Iterator iterator, String separator) {
    // handle null, zero and one elements before building a buffer
    if (iterator == null) {
        return null;
    }
    if (!iterator.hasNext()) {
        return EMPTY;
    }
    Object first = iterator.next();
    if (!iterator.hasNext()) {
        return ObjectUtils.toString(first);
    }

    // two or more elements
    StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
    if (first != null) {
        buf.append(first);
    }

    while (iterator.hasNext()) {
        if (separator != null) {
            buf.append(separator);
        }
        Object obj = iterator.next();
        if (obj != null) {
            buf.append(obj);
        }
    }
    return buf.toString();
}

Now we know, thank you open source