package cn.zxg.PackgeUse; /**  * 测试StringBuilder,StringBuffer可变字符序列  */ public class TestStringBuilder {
      public static void main(String[] args) {
          String str;         //StringBuilder 线程不安全，效率高（一般使用它）         //StringBuffer 线程安全，效率低         StringBuilder sb=new StringBuilder("abcdf");         StringBuffer sb1=new StringBuffer();         System.out.println(Integer.toHexString(sb.hashCode()));     } }