Output the required palindrome date
·During the Spring Festival in 2020, a special date has attracted everyone's attention: February 2, 2020. Because if this date is written as an 8-digit number in the format of "yyyymmdd", it is 20200202, which is exactly a palindrome number. We call such a date palindromic date. Some people say that 20200202 is a special day of "once in a thousand years". Xiaoming doesn't agree with this, because the next palindrome date will be less than two years later: 20211202, that is, December 2, 2021. Others said that 20200202 is not only a palindrome date, but also an ABABBABA palindrome date. Xiaoming doesn't agree with this either, because the next ABABBABA palindrome date will come about in about 100 years: 21211212, that is, December 12, 2121. It is not "once in a thousand years", but "twice in a thousand years" at most.
·Given an 8-digit date, please calculate the next palindrome date and the next ABABBABA palindrome date after the date.
·Input Description: the input contains an eight digit integer N, indicating the date. For all evaluation cases, 10000101 ≤ N ≤ 89991231, ensure that N is 8 digits of a legal date
·Output Description: output two lines, each with one eight digit. The first line represents the next palindrome date, and the second line represents the next ABABBABA palindrome date.
(1) Programming implementation
At p03 Create PalindromicDate class in T06 package
1. Judge whether the input date is legal
Create a static method isLegalDate(String strDate)
package p03.t06;
/**
* Function: output the required palindrome date
* Author: Li Yue
* Date: May 19, 2022
*/
public class PalindromicDate {
/**
* Judge whether the date is legal
*
* @param strDate
* @return true-Legal, false illegal
*/
private static boolean isLegalDate(String strDate) {
int year, month, day;
year = Integer.parseInt(strDate.substring(0, 4));
month = Integer.parseInt(strDate.substring(4, 6));
day = Integer.parseInt(strDate.substring(6));
// Use reverse thinking to deal with
if (year < 1000 || year > 8999) return false;
if (month < 1 || month > 12) return false;
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
if (day < 1 || day > 31) return false;
} else if (month == 2) {
if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) { // Leap year judgment
if (day < 1 || day > 29) return false;
} else {
if (day < 1 || day > 28) return false;
}
} else {
if (day < 1 || day > 30) return false;
}
return true;
}
}
2. Create a main method to test whether the input date is legal
·Judge whether the input date is legal and give corresponding prompt
public static void main(String[] args) {
String strDate;
int year, month, day;
Scanner sc = new Scanner(System.in);
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
System.out.print("Enter an 8-digit date:");
strDate = sc.next();
if (isLegalDate(strDate)) {
System.out.println("[" + strDate + "]Is a legal date~");
} else {
System.out.println("[" + strDate + "]Is an illegal date~");
}
}
3. Judge whether the date is the palindrome date
·Define the static method isPalindromicDate() method
/**
* Judge whether to reply
*
* @param strDate
* @retrun true-Palindrome, false non palindrome
*/
private static boolean isPalindromicDate(String strDate) {
for (int i = 0; i<4; i++) {
if (strDate.charAt(i) != strDate.charAt(7 - i)) return false;
}
return true;
}
}
4. Modify the main method to output the first palindrome date after this date
·Complete the first task: output the first palindrome date after this date
//User entered date as starting point
year = Integer.parseInt(strDate.substring(0, 4));
month = Integer.parseInt(strDate.substring(4, 6));
day = Integer.parseInt(strDate.substring(6));
calendar.set(Calendar.YEAR,year);
calendar.set(Calendar.MONTH,month - 1);
calendar.set(Calendar.DAY_OF_MONTH,day);
//Enter the first palindrome date after this date
while (true) {
calendar.add(calendar.DAY_OF_MONTH, 1); //One day later
strDate = sdf.format(calendar.getTime());
if(isPalindromicDate(strDate)) {
break;
}
·View run results
5. Judge whether it is ABABBABA palindrome date
·Define static method isabababapalindromicdate()
/**
* Judge whether it is ABABBABA palindrome date
*
* @param strDate
* @return true-ABABBABA Type palindrome date, false- non ABABBABA type palindrome date
*/
private static boolean isABABBABAPalindromicDate(String strDate) {
if (isPalindromicDate(strDate)) {
if (strDate.charAt(0) == strDate.charAt(2) && strDate.charAt(1) == strDate.charAt(3)) return true;
}
return false;
}
6. Modify the main method to output the first ABABBABA palindrome date after this date
·Complete the second task: output the first ABABBABA palindrome date after this date
//Output the first ABABBABA palindrome date after this date
String strDate2 = strDate;
Calendar calendar2 = calendar;
while (true) {
calendar2.add(Calendar.DAY_OF_MONTH, 1); // 1 day later
strDate2 = sdf.format(calendar2.getTime());
if (isABABBABAPalindromicDate(strDate2)) {
break; //Find a palindrome date and jump out of the loop
}
}
System.out.println("First after this date ABABBABA Type palindrome date:" + strDate2);
7. View full source code
8. Run the program to view the results
·Enter a valid date
package p03t06;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Scanner;
import java.util.regex.Pattern;
/**
* Function:
* Author: Li Yue
* Date: May 19, 2022
*/
public class PalindromicDate {
public static void main(String[] args) {
String strDate;
int year, month, day;
Scanner sc = new Scanner(System.in);
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
System.out.print("Enter an 8-digit date:");
strDate = sc.next();
if (isLegalDate(strDate)) {
System.out.println("[" + strDate + "]Is a legal date~");
// Take the legal date entered by the user as the starting point of the date cycle
year = Integer.parseInt(strDate.substring(0, 4));
month = Integer.parseInt(strDate.substring(4, 6));
day = Integer.parseInt(strDate.substring(6));
Calendar calendar = Calendar.getInstance();
calendar.set(year, month - 1, day);
// Task 1. Output the first palindrome date after this date
String strDate1 = strDate;
Calendar calendar1 = calendar;
while (true) {
calendar1.add(Calendar.DAY_OF_MONTH, 1); // 1 day later
strDate1 = sdf.format(calendar1.getTime());
if (isPalindromicDate(strDate1)) {
break; // Find a palindrome date and jump out of the loop
}
}
System.out.println("The first palindrome date after this date:" + strDate1);
// Task 2. Output the first ABABBABA palindrome date after this date
String strDate2 = strDate;
Calendar calendar2 = calendar;
while (true) {
calendar2.add(Calendar.DAY_OF_MONTH, 1); // 1 day later
strDate2 = sdf.format(calendar2.getTime());
if (isABABBABAPalindromicDate(strDate2)) {
break; // Find a palindrome date and jump out of the loop
}
}
System.out.println("First after this date ABABBABA Type palindrome date:" + strDate2);
} else {
System.out.println("[" + strDate + "]Is an illegal date~");
}
}
/**
* Judge whether the date is legal
*
* @param strDate
* @return true-Legal, false illegal
*/
private static boolean isLegalDate(String strDate) {
int year, month, day;
year = Integer.parseInt(strDate.substring(0, 4));
month = Integer.parseInt(strDate.substring(4, 6));
day = Integer.parseInt(strDate.substring(6));
// Use reverse thinking to deal with
if (year < 1000 || year > 8999) return false;
if (month < 1 || month > 12) return false;
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
if (day < 1 || day > 31) return false;
} else if (month == 2) {
if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) { // Leap year judgment
if (day < 1 || day > 29) return false;
} else {
if (day < 1 || day > 28) return false;
}
} else {
if (day < 1 || day > 30) return false;
}
return true;
}
/**
* Judge whether it is palindrome date
*
* @param strDate
* @return true-Palindrome date, false non palindrome date
*/
private static boolean isPalindromicDate(String strDate) {
for (int i = 0; i < 4; i++) {
// Use reverse thinking
if (strDate.charAt(i) != strDate.charAt(7 - i)) return false;
}
return true;
}
/**
* Judge whether it is ABABBABA palindrome date
*
* @param strDate
* @return true-ABABBABA Type palindrome date, false- non ABABBABA type palindrome date
*/
private static boolean isABABBABAPalindromicDate(String strDate) {
if (isPalindromicDate(strDate)) {
if (strDate.charAt(0) == strDate.charAt(2) && strDate.charAt(1) == strDate.charAt(3)) return true;
}
return false;
}
}
Case: calculate the number of days since the founding of the people's Republic of China
package p03t06;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
/**
* Function:
* Author: Li Yue
* Date: May 19, 2022
*/
public class LifeiOfPRC {
public static void main(String[] args) {
// Create a simple date format object
SimpleDateFormat sdf = new SimpleDateFormat("yyyy year MM month dd day hh:mm:ss");
// Method 1: use Date class
Date foundDate = new Date(1949, 9, 1, 8, 0, 0 );
System.out.println("Date of establishment:" + sdf.format(foundDate));
Date currentDate = new Date();
System.out.println("Current date:" + sdf.format(currentDate));
long interval = 0;//Time interval (milliseconds)
interval = currentDate.getTime() - foundDate.getTime();
System.out.println("The people's Republic of China was founded" + interval + "millisecond");
System.out.println("The people's Republic of China was founded" + (interval / 1000) + "second");
System.out.println("The people's Republic of China was founded" + (interval / 1000 / 60) + "branch");
System.out.println("The people's Republic of China was founded" + (interval /1000 / 60 / 60)+ "hour");
System.out.println("The people's Republic of China was founded" + (interval /1000 / 60 / 24) + "day");
// Method 2: use the Calendar class
Calendar calendar1 = Calendar.getInstance();
calendar1.set(Calendar.YEAR, 1949);
calendar1.set(Calendar.MONDAY, 10);
calendar1.set(Calendar.DAY_OF_MONTH, 1);
calendar1.set(Calendar.HOUR, 8);
calendar1.set(Calendar.MINUTE, 0);
calendar1.set(Calendar.SECOND, 0);
System.out.println("Date of establishment:" + sdf.format(calendar1.getTime()));
Calendar calendar2 =Calendar.getInstance();
System.out.println("Current date:" + sdf.format(calendar2.getTime()));
interval = calendar2.getTime().getTime() - calendar1.getTime().getTime();
System.out.println("The people's Republic of China was founded" + interval + "millisecond");
System.out.println("The people's Republic of China was founded" + (interval / 1000) + "second");
System.out.println("The people's Republic of China was founded" + (interval / 1000 / 60) + "branch");
System.out.println("The people's Republic of China was founded" + (interval /1000 / 60 / 60)+ "hour");
System.out.println("The people's Republic of China was founded" + (interval / 1000 / 60 / 24) + "day");
}
}
·View run results
