public class Day
{  private int y, m, d;
   private Date date;
   public Day(int year, int month, int date)
   {  y = year -1900;
      m = month - 1;
      d = date;
      date = new Date(y, m, d);
   }
   public int dayBetween(Day day)
   {  }
}
上面是你的程序
public class Day
{  private int y, m, d;
   private Date date;
   public Day(int year, int month, int day1)
   {  y = year -1900;
      m = month - 1;
      d = day1;
      date = new Date(y, m, d);//这个Date类的构造方法是被反对的
   }
   public int dayBetween(Day day)
   { retrun 0; }
}
以下是java 文档中对这个构造方法的说明
Date()(int year, int month, int date)           Deprecated. As of JDK version 1.1, replaced by Calendar.set(year + 1900, month, date) or GregorianCalendar(year + 1900, month, date).