首先 Date类的构造方法

Date nowdate = new Date();

Date afterdate = new Date(1411122441L);

方法、判断是否是成立

System.out.println(nowdate.after(afterdate));

System.out.println(nowdate.before(afterdate));

克隆

Date thirddate = new Date();

Date thirdDate = (Date) afterdate.clone();

System.out.println(thirdDate);

其次 Calendar 类

Calendar rightNow = Calendar.getInstance();

初始化一个

Calendar rightNow = Calendar.getInstance();

System.out.println(Calendar.DATE);

当你调用静态方法的时候就要用类来生成Calendar.APRIL

方法

System.out.println(rightNow);

System.out.println(rightNow.APRIL);

System.out.println(rightNow.ERA);

System.out.println(rightNow.YEAR);

System.out.println(rightNow.MONTH);

System.out.println(rightNow.DST_OFFSET);

System.out.println(rightNow.HOUR);

rightNow.add(Calendar.MONTH, 2);//这个无返回值

System.out.println(rightNow.get(Calendar.MONTH));

rightNow.add(Calendar.YEAR, 2);

System.out.println(rightNow.get(Calendar.YEAR));

rightNow.set(Calendar.HOUR , 41);

System.out.println(rightNow.get(Calendar.HOUR));

Random

这个没在么练习-- 呵呵===

但是都差不多的规则

生成一个对象

Random firstRand = new Random(System.currentTimeMillis());

以上的用法都要在之前调用系统集成的类

才能实现方法和函数，

就是必须import那个包

分别是：

import java.util.Date;

import java.util.Calendar; import java.util.Random;