java中字符串 切割为 字符数组 并连接

切割

String s = "adsndsdns";
char[] char1 = s.toCharArray();
System.out.println(char1[0]); // a;
System.out.println(char1[2]); // s; 

连接

StringBuilder sb = new StringBuilder();
for(int i = char1.length - 1; i >= 0; i--){
  sb.append(char1[i]);
}
System.out.println(sb); // sndsdnsda;(倒序遍历)

将StringBuilder转为String类型

String hh = sb.toString();