Calendar Class and dateformat class of Java Foundation

User 8211341 2021-04-16 18:10:29
calendar class dateformat class java


Hello everyone , I am a Java Initiate , Today, Xiao Bian will take you to study together Java Technology base !

One 、Calendar class

1.Calendar It literally means calendar , stay java in Calendar Class can set and read the display year through methods 、 month 、 Japan 、 when , branch 、 Seconds, etc . When creating a Calendar Can't use new keyword , because Calendar Class, which is an abstract class , You need to call static methods getInstance() Method to get a Calendar The object of , Call other methods .

2.Calendar Class methods are shown in the following figure :

The picture above is quoted from 《 Novice tutorial 》

3. How to pass Canledar Class to get the current month, month, day, week, hour, minute and second of the computer :

import java.util.Calendar;
public class p1 {
public static void main(String[] args) {
// TODO Auto-generated method stub
Calendar c = Calendar.getInstance();// obtain Calendar object
// Get the current year
int year = c.get(c.YEAR);
// Get the current month
int month = c.get(c.MONDAY)+1;
// Get the current day
int day = c.get(c.DATE);
// When getting
int hour = c.get(c.HOUR);
// Get points
int minute = c.get(c.MINUTE);
// Get seconds
int second = c.get(c.SECOND);
// Get the current day of the week ( It starts on Sunday )
int week = c.get(c.DAY_OF_WEEK)-1;
// Set the date , Time, minute and second is the default current value
Calendar c1 = Calendar.getInstance();
c1.set(2020, 5, 20);
System.out.println(" The current time is : "+year+" year "+month+" month "+day+" Japan "+"\t week "+week);
System.out.println(" The current time is : "+hour+" when "+minute+" branch "+second+" second ");
System.out.println(" The set date is : "+c1.getTime());
}
}

The result of the operation is :

From the above code , You can find when to get the current month , The reason we need to add one is that its month is from 0 At the beginning , So we need to add one . And the day of the week is the same , Because it's from Sunday for the first day .

Two 、DateFormat class

1.DateFormat Class is to format the date into a string . stay Date Class represents the date and time , When printing, the date and time will be output in English format by default , When converting to Chinese format, you need DateFormat class .DateFormat Classes are also abstract classes , You can't instantiate . You can get it statically DateFormat class .

2.DateFormat The common methods of class are :

The picture is quoted from 《C Chinese language network Java course 》

3.DateFormat Class to pass as parameters to these methods , It includes FULL Represents the complete format 、LONG A long format 、MEDIUM Represents the normal format 、SHORT An example of a short format :

import java.text.DateFormat;
import java.util.Date;
public class p2 {
public static void main(String[] args) {
// TODO Auto-generated method stub
Date d=new Date();
// Define four formats
DateFormat f,l,m,s;
//Full Format
f=DateFormat.getDateInstance(DateFormat.FULL);
//Long Format
l=DateFormat.getDateInstance(DateFormat.LONG);
//medium Format
m=DateFormat.getDateInstance(DateFormat.MEDIUM);
//short Format
s=DateFormat.getDateInstance(DateFormat.SHORT);
// Format date
System.out.println("Full Format :"+f.format(d));
System.out.println("Long Format :"+l.format(d));
System.out.println("medium Format :"+m.format(d));
System.out.println("short Format :"+s.format(d));
}
}

The output is zero :

3、 ... and 、 Enter a year , Determine if it's a leap year

1. The solution is : Nothing can be denied 100 Divisible, but can be 4 Divisible year , Or can be 400 An integer year is a leap year , The rest of the year is not a leap year .

2. Code :

import java.util.Scanner;
public class p3 {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print(" Please enter the year :");
Scanner scan = new Scanner(System.in);
int year = scan.nextInt();
if(year%4==0&&year%100!=0||year%400==0){
System.out.println(" What you entered "+year+" Year is a leap year ");
}else{
System.out.println(" What you entered "+year+" It's not a leap year ");
}
}
}

Four 、 summary

This paper mainly introduces Calendar class 、DateFormat class 、 How to judge leap year .

This paper introduces Calendar Class to display and set the date and time .DateFormat Class is mainly used to convert date format into string form , English to Chinese format .

Through the example of how to judge whether the year entered by the user is a leap year, we can help you understand .

I am a Java Initiate , I hope you can learn from this article , It helps you ! Welcome to WeChat , If you have any problems, you can help us solve them at any time , It's good to make a friend ~

This article is from WeChat official account. - Java Advanced learning communication (java_xianghong) , author :Java Initiate

The source and reprint of the original text are detailed in the text , If there is any infringement , Please contact the [email protected] Delete .

Original publication time : 2021-04-04

Participation of this paper Tencent cloud media sharing plan , You are welcome to join us , share .

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