package demo;    public class ReverseString {      public static void main(String[] args) {          String strs="12345ABCD";          StringBuffer sb = new StringBuffer(strs);          String temp = reverseIt(strs);          String temp2 = sb.reverse().toString();//调用StringBuffer自己的字符串反转方法          System.out.println("自己写的reverse后的串是："+temp);          System.out.println("StringBuffer反转后的串是："+temp2);                }      　　//方法一:倒序拼接的方法    public static String reverseIt(String str){          int i;          int len=str.length();          StringBuffer sb = new StringBuffer(len);          for(i=(len-1);i>=0;i--){              sb.append(str.charAt(i));          }          return sb.toString();      }    //方法二:字符串反向拼接的方法

public static String reverseIt2(String s){   int length = s.length();    String reverse = "";  //注意这是空串，不是null   for (int i = 0; i < length; i++)     reverse = s.charAt(i) + reverse;//在字符串前面连接，  而非常见的后面   return reverse;   }

//方法三：利用数组实现

public String reverse(String str) {          if ((null == str) || (str.length() <= 1)) {              return str;          }          char[] chars = str.toCharArray();          int right = chars.length - 1;          for (int left = 0; left < right; left++) {              char swap = chars[left];              chars[left] = chars[right];              chars[right--] = swap;          }          return new String(chars);      }

}