Java中如何使用Calendar类的before()、after()和equals()方法？

<code>@Test<br/>void 
testDateCompare3(
) throws ParseException {<br/>  SimpleDateFormat sdf = 
new SimpleDateFormat("yyyy-MM-dd");<br/>  Date date1 = sdf.parse("2009-12-31");<br/>  Date date2 = sdf.parse("2019-01-31");<br/><br/>  System.out.println("date1 : " + sdf.format(date1));<br/>  System.out.println("date2 : " + sdf.format(date2));<br/><br/>  Calendar cal1 = Calendar.getInstance();<br/>  Calendar cal2 = Calendar.getInstance();<br/>  cal1.setTime(date1);<br/>  cal2.setTime(date2);<br/><br/>  if (cal1.after(cal2)) {<br/>    System.out.println("Date1 时间在 Date2 之后");<br/>  }<br/><br/>  if (cal1.before(cal2)) {<br/>    System.out.println("Date1 时间在 Date2 之前");<br/>  }<br/><br/>  if (cal1.equals(cal2)) {<br/>    System.out.println("Date1 时间与 Date2 相等");<br/>  }<br/>}<br/></code>

<code>date1 : 2009-12-31<br/>date2 : 2019-01-31<br/>Date1 时间在 Date2 之前</code>