/**
* Joins array elements to string.
*
* @param arr Array.
* @return String.
*/
@Nullable
public static String compactArray(Object[] arr) {
if (arr == null || arr.length == 0) return null;
String sep = ", ";
StringBuilder sb = new StringBuilder();
for (Object s : arr) sb.append(s).append(sep);
if (sb.length() > 0) sb.setLength(sb.length() - sep.length());
return U.compact(sb.toString());
}
