class StringBufferDemo

 {

     public static void main(String[] args)

     {

         method_get();

     }

     //获取指定位置的字符

     public static void method_get()

     {

         StringBuffer sb = new StringBuffer("abcde");

         char[] chs = new char[4];

         sb.getChars(1,4,chs,1);

         for(int x=0;x<chs.length;x++)

         {

         sop("chs["+x+"]="+chs[x]+";");

         }

     }

     //替换指定字符

     public static void method_update()

     {

         StringBuffer sb = new StringBuffer("abcde");

         //sb.replace(1,4,"java");

         sb.setCharAt(2,'a');

         sop(sb.toString());

     }

     //删除指定的字符

     public static void method_del()

     {

         StringBuffer sb = new StringBuffer("abcde");

         //sb.delete(2,4);

         sb.deleteCharAt(3);

         sop(sb.toString());

     }

     //添加功能字符串

     public static void method_add()

     {

         StringBuffer sb = new StringBuffer();

         sb.append("abc").append(true);

         //sop(sb.toString());

     }

     public static void sop(String str)

     {

             System.out.println(str);

     }

 }