关于使用","拼接字符串

  方法一：

  String str[] = {"a","b","c"};
  String connect = "";  

  for(int i = 0; i < str.length; i++){
    connect  += str[i];
    if(i < str.length - 1){
        connect  += ",";
    }
   }

  方法二：

  String str[] = {"a","b","c"};
  String connect = "";  

  for(int i = 0; i < str.length; i++){
    connect += str[i] + ",";
   }
  connect = connect.substring(0,connect.length()-1);