double[] features3 = {1,2,3};//如果是基本類型需先轉為對象 <span style="font-family:Arial;font-size:14px;">commons-lang3包可用</span> Double[] features4 = ArrayUtils.toObject(features3); 

public String listToString(List list, char separator) {  return org.apache.commons.lang.StringUtils.join(list.toArray(),separator);  }