JAVA] A와 B 날짜 차이 계산하기

JAVA JDK 1.8에서 테스트 했습니다.

 

 

A 2020년 7월 7일, B 2020년 7월 9일 두 개의 날짜 차이 계산

 

package com.main;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.concurrent.TimeUnit;

public class DateTest {

	public static void main(String[] args) {
		try {
			String a = "20200707";
			String b = "20200709";
			String format = "yyyyMMdd";
			SimpleDateFormat sdf = new SimpleDateFormat(format, Locale.ENGLISH);
			Date firstDate  = sdf.parse(a);
			Date secondDate = sdf.parse(b);
			
			long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
			long diff = TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
			System.out.println(String.format("A %s , B %s Diff %s Days", a, b, diff));
			
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}
}

 

실행 결과

---

응용 

A 일자와 B일자 개월 및 일수 차이 계산 하기

 

package com.main;

import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.Date;
import java.util.Locale;

public class DateTest {

	public static void main(String[] args) {
		String logFormat = "%s-%s-%s, %s-%s-%s Diff Momth %s, Diff Days %s";
//		String dateFormat = "yyyy-MM-dd";
		String strA = "2020-06-15";
//        LocalDate a = LocalDate.of(2020, 6, 15);
		LocalDate a = LocalDate.parse(strA);
        LocalDate b = LocalDate.of(2020, 7, 14);
        long monthDiff = ChronoUnit.MONTHS.between(a, b);
//        long dayDiff = getDayDiff(strA, "2020-07-14", dateFormat);
        long dayDiff = getDayDiff2(strA, "2020-07-14");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), b.getYear(), b.getMonthValue(), b.getDayOfMonth() , monthDiff, dayDiff));
        System.out.println("----");
        
        LocalDate c = LocalDate.of(2020, 7, 15);
        long monthDiff2 = ChronoUnit.MONTHS.between(a, c);
//        long dayDiff2 = getDayDiff(strA, "2020-07-15", dateFormat);
        long dayDiff2 = getDayDiff2(strA, "2020-07-15");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), c.getYear(), c.getMonthValue(), c.getDayOfMonth() , monthDiff2, dayDiff2));
        System.out.println("----");
        
        LocalDate d = LocalDate.of(2020, 7, 16);
        long monthDiff3 = ChronoUnit.MONTHS.between(a, d);
//        long dayDiff3 = getDayDiff(strA, "2020-07-16", dateFormat);
        long dayDiff3 = getDayDiff2(strA, "2020-07-16");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), d.getYear(), d.getMonthValue(), d.getDayOfMonth() , monthDiff3, dayDiff3));
        System.out.println("----");
        
        
        LocalDate e = LocalDate.of(2020, 8, 14);
        long monthDiff4 = ChronoUnit.MONTHS.between(a, e);
//        long dayDiff4 = getDayDiff(strA, "2020-08-14", dateFormat);
        long dayDiff4 = getDayDiff2(strA, "2020-08-14");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), e.getYear(), e.getMonthValue(), e.getDayOfMonth() , monthDiff4, dayDiff4));
        System.out.println("----");
        
        LocalDate f = LocalDate.of(2020, 8, 15);
        long monthDiff5 = ChronoUnit.MONTHS.between(a, f);        
//        long dayDiff5 = getDayDiff(strA, "2020-08-15", dateFormat);
        long dayDiff5 = getDayDiff2(strA, "2020-08-15");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), f.getYear(), f.getMonthValue(), f.getDayOfMonth() , monthDiff5, dayDiff5));
        System.out.println("----");
        
        LocalDate g = LocalDate.of(2020, 8, 16);
        long monthDiff6 = ChronoUnit.MONTHS.between(a, g);        
//        long dayDiff6 = getDayDiff(strA, "2020-08-16", dateFormat);
        long dayDiff6 = getDayDiff2(strA, "2020-08-16");
        System.out.println(String.format(logFormat, a.getYear(), a.getMonthValue(), a.getDayOfMonth(), g.getYear(), g.getMonthValue(), g.getDayOfMonth() , monthDiff6, dayDiff6));
        System.out.println("----");
	}
	
	private static long getDayDiff2(String dayA, String dayB) {
		LocalDate a = LocalDate.parse(dayA);
		LocalDate b = LocalDate.parse(dayB);
		long dayDiff = ChronoUnit.DAYS.between(a, b);
		return dayDiff;
	}

	private static long getDayDiff(String a, String b, String format) {
		long diff = 0;
		try {
			SimpleDateFormat sdf = new SimpleDateFormat(format, Locale.ENGLISH);
			Date firstDate  = sdf.parse(a);
			Date secondDate = sdf.parse(b);
			
			long diffInMillies = Math.abs(secondDate.getTime() - firstDate.getTime());
//			diff = TimeUnit.DAYS.convert(diffInMillies, TimeUnit.MILLISECONDS);
//			System.out.println(String.format("A %s , B %s Diff %s Days", a, b, diff));
		} catch (Exception e) {
			e.printStackTrace();
		}
		return diff;
	}
}

 

 

실행 결과