String[] elements = new String[] {"a","b","c"}; //数组
String str= " " ; //拼接之后的字符串
for (int i = 0; i < elements.length; i++) {
if (i < elements.length - 1){
str+= elements[i] + "," ; //加上特定符号
}
else {
str+= elements[i];
}
}
System.out.println(str);
//输出结果为： a,b,c