这里介绍Java比较两个日期类型三个例子：
Date.compareTo()
一个经典的方法比较两个日期类型。
the value 0 if the argument Date is equal to this Date; a value less than 0 if this Date is before the Date argument; and a value greater than 0 if this Date is after the Date argument.
public static void main(String[] args) throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date1 = sdf.parse("2009-12-31");
Date date2 = sdf.parse("2010-01-31");
System.out.println(sdf.format(date1));
System.out.println(sdf.format(date2));
if (date1.compareTo(date2) > 0) {
System.out.println("Date1 is after Date2");
} else if (date1.compareTo(date2) < 0) {
System.out.println("Date1 is before Date2");
} else if (date1.compareTo(date2) == 0) {
System.out.println("Date1 is equal to Date2");
} else {
System.out.println("How to get here?");
}
}
Date.before(), Date.after() and Date.equals()
这是一个对用户更友好的方法去比较两个日期
public static void main(String[] args) throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date1 = sdf.parse("2009-12-31");
Date date2 = sdf.parse("2010-01-31");
System.out.println(sdf.format(date1));
System.out.println(sdf.format(date2));
if (date1.after(date2)) {
System.out.println("Date1 is after Date2");
}
if (date1.before(date2)) {
System.out.println("Date1 is before Date2");
}
if (date1.equals(date2)) {
System.out.println("Date1 is equal Date2");
}
}
Calender.before(), Calender.after() and Calender.equals()
最常用的方法去比较两个日期java.util.Calendar类
public static void main(String[] args) throws ParseException {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date1 = sdf.parse("2009-12-31");
Date date2 = sdf.parse("2010-01-31");
System.out.println(sdf.format(date1));
System.out.println(sdf.format(date2));
Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);
if(cal1.after(cal2)){
System.out.println("Date1 is after Date2");
}
if(cal1.before(cal2)){
System.out.println("Date1 is before Date2");
}
if(cal1.equals(cal2)){
System.out.println("Date1 is equal Date2");
}
}
