Java Calendar before()方法
java.util.Calendar.before()是java.util包Calendar类中的方法。如果此Calendar表示的时间早于when对象表示的时间，则该方法返回true。如果不是这种情况，则返回false。
语法
public boolean before(Object when)
参数
when-何时是要比较的对象。
返回
此方法返回True或false值
抛出
NA
示例1
import java.util.Calendar;
import java.util.Date;
public class CalendarbeforeExample1 {
public static void main(String[] args) {
// create calendar objects.
Calendar cal = (Calendar) Calendar.getInstance();
Calendar past = (Calendar) Calendar.getInstance();
// print the current date
System.out.println("Current date: " + cal.getTime());
// change year in future calendar
past.set(Calendar.YEAR, 2015);
System.out.println("Year is " + past.get(Calendar.YEAR));
// check if calendar date is after current date
Date time = past.getTime();
if (past.before(cal)) {
System.out.println("Date " + time + " is before current date.");
}
}
}
输出:
Current date: Mon Jul 30 04:08:30 PDT 2018
Year is 2015
Date Thu Jul 30 04:08:30 PDT 2015 is before current date.
示例2
import java.util.Calendar;
import java.util.Date;
public class CalendarbeforeExample2 {
public static void main(String[] args) {
// create calendar objects.
Calendar cal = (Calendar) Calendar.getInstance();
Calendar cal2 = (Calendar) Calendar.getInstance();
// print the current date
System.out.println("Current date: " + cal.getTime());
// change year in future calendar
cal2.set(Calendar.MONTH, 4);
System.out.println("Year is " + cal2.get(Calendar.MONTH));
// check if calendar date is after current date
Date time = cal2.getTime();
if (cal2.before(cal)) {
System.out.println("Date " + time + " is before current date.");
}
}
}
输出:
Current date: Mon Jul 30 04:13:04 PDT 2018
Year is 4
Date Wed May 30 04:13:04 PDT 2018 is before current date.
示例3
import java.util.Calendar;
import java.util.Date;
public class CalendarbeforeExample3 {
public static void main(String[] args) {
// create calendar objects.
Calendar cal = (Calendar) Calendar.getInstance();
Calendar cal3 = (Calendar) Calendar.getInstance();
// print the current date
System.out.println("Current date: " + cal.getTime());
// change year in future calendar
cal3.set(Calendar.DAY_OF_MONTH, 23);
System.out.println("Year is " + cal3.get(Calendar.DAY_OF_MONTH));
// check if calendar date is after current date
Date time = cal3.getTime();
if (cal3.before(cal)) {
System.out.println("Date " + time + " is before current date.");
}
}
}
输出:
Current date: Mon Jul 30 06:19:04 PDT 2018
Year is 23
Date Mon Jul 23 06:19:04 PDT 2018 is before current date.
示例4
import java.util.Calendar;
import java.util.Date;
public class CalendarbeforeExample4 {
public static void main(String[] args) {
// create calendar objects.
Calendar cal = (Calendar) Calendar.getInstance();
Calendar cal3 = (Calendar) Calendar.getInstance();
// print the current date
System.out.println("Current date: " + cal.getTime());
// change year in future calendar
cal3.set(Calendar.HOUR, 30);
System.out.println("Now date is " + cal3.getTime());
cal3.set(Calendar.MINUTE, 60);
System.out.println("Now date is " + cal3.getTime());
cal3.set(Calendar.SECOND, 30);
System.out.println("Now date is " + cal3.getTime());
// check if calendar date is after current date
Date time = cal3.getTime();
if (cal3.before(cal)) {
System.out.println("Date " + time + " is after current date.");
}
}
}
输出:
Current date: Mon Jul 30 06:23:37 PDT 2018
Now date is Tue Jul 31 06:23:37 PDT 2018
Now date is Tue Jul 31 07:00:37 PDT 2018
Now date is Tue Jul 31 07:00:30 PDT 2018
