这个方法定义出现错误，要怎么改才对呢？

Question

import java.io.InputStreamReader;
import java.util.Calendar;
import java.util.Date;
class JspCalendar {
        Calendar calendar=null;
        public JspCalendar()
        {
                calendar=Calendar.getInstance();
                Date trialTime=new Date();
                calendar.setTime(trialTime);
                
        }
                  
     public int getEra(){
           return calendar.get(Calendar.ERA);
   }
   public int getAMPM()
   {
           return calendar.get(Calendar.AM_PM);
   }
   public int getDSTOffset()
   {
           return calendar.get(Calendar.DST_OFFSET);
   }
   public int getZoneOffset()
   {
           return calendar.get(Calendar.ZONE_OFFSET);
   }
   public TimeZone getUSTimeZone()       //就是这个方法出现错误：E:\JAVA\aa1.java:89: 找不到符号
                                                              符号： 类 TimeZone
                                                                                             位置： 类 JspCalendar
                                                                                               public TimeZone getUSTimeZone()
                                                                                                         ^
                                                                                              1 错误  {
           return calendar.getTimeZone();
   }
   public static void main(String args[])
   {
           JspCalendar db=new JspCalendar();
           p("era:"+db.getEra());
           p("ampm:"+db.getAMPM());
           p("DST:"+db.getDSTOffset());
           p("ZONEOffset:"+db.getZoneOffset());
           p("TIMEZONE:"+db.getUSTimeZone());
   }
   private static void p(String x)
   {
        System.out.println(x);
   }
}谢谢！！