java strings concat

Question

I have got a list of string and now I want to take the list into a String with comma(,) separation is concat method the only way or there is some easy and good way

StringBuilder s = null;
List<String> listObjs (5 strings in it)
for(String listObj : listObjs)
s.append(listObj);
s.append(",");

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Answer 1

You can do

StringBuilder sb = new StringBuilder();
String sep = "";
for (String s : listObjs) {
    sb.append(sep).append(s);
    sep = ", ";
}
System.out.println(sb);