Preferred Idiom for Joining a Collection of Strings in Java

Question

Given a Collection of Strings, how would you join them in plain Java, without using an external Library?

Given these variables:

Collection

        

Answer 1

Your proposition is a possible solution, another common one is:

for (String item: data) {
    sb.append(item)
    sb.append(separator);
}
String joined = sb.substring(0, sb.length() - separator.length())