1  import java.text.*;
 2   public class Gxjun
 3  {
 4     public static void main(String atgs[])
 5     {
 6        StringBuffer str= new StringBuffer(); 
 7        str.append("大家好");
 8        System.out.println("str:"+str);
 9        System.out.println("length:"+str.length());  
10        System.out.println("capacity:"+str.capacity());       
11        str.setCharAt(0,‘w‘);
12        str.setCharAt(1,‘e‘);
13        System.out.println(str);

14        str.insert(2, "are all");
15        System.out.println(str);
16        int index=str.indexOf("好");
17        str.replace(index, str.length(),"right");
18        System.out.println(str); 
19     }
20  }