apache common包下的StringUtils的join方法

apache common包下的StringUtils的join方法:

关键字：java string array join

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();
    }