StringBuffer用法

 public class StringBufferTest {
     public static void main(String[] args) {
         StringBuffer sb=new StringBuffer();
         sb.append("aaa");
         sb.append("bbb");
         sb.append(123);
         sb.append(false);
         sb.insert(3, "tt");
         sb.insert(3,true);
         System.out.println(sb.toString());
     }
 }