Date类.随机数类

java.util包中的常用类

Date  日期类
SimpleDateformat 日期格式化类

Calendar  日历类
获得日历对象  Calendar rightNow = Calendar.getInstance();
int year = c.get(Calendar.YEAR);
int month = c.get(Calendar.MONTH);
int day = c.get(Calendar.DAY_OF_MONTH);
int dayWeek = c.get(Calendar.DAY_OF_WEEK);
int h = c.get(Calendar.HOUR_OF_DAY);
int m = c.get(Calendar.MINUTE);
int s = c.get(Calendar.SECOND);
int ms = c.get(Calendar.MILLISECOND);

随机数类
Random rd  = new Random();
int t = rd.nextInt(100);
int t = rd.nextInt(100)+200;