如何让一个数组（字符串数组，有值）转换为将数组值用逗号隔开的字符串？

Question

如下：String [] str ={“aa”,“bb”,“cc”};

^&%*$#@!D
经过上述将其变为字符串如下：

String ss=“aa,bb,cc,”;

Answer 1

String[] str={"aa","bb","cc"};
String str1="";
for (int i = 0; i < str.length; i++) {
str1+=str[i]+",";
}
System.out.println(str1);