Java-StringBuffer比對內容是否對稱

public class Play3{
 public static void main(String[] args) {
      StringBuffer sb = new StringBuffer("123345");
      System.out.println(sb);
      System.out.println("長度"+sb.length());
      System.out.println("等下要比對次數"+sb.length()/2);
      int f=0;
      int l=sb.length()-1;
      for(int i= 0 ; i<sb.length()/2;i++)
        {
         if(sb.toString().charAt(f) == sb.toString().charAt(l))
        {
            System.out.print("第"+(i+1)+"個跟後面數來第"+(i+1)+"個有一樣");
            break;
         }
         f++;
           l--;
        }
    }
}