字符串的翻转实现

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);
      }

}