java 获取月份多少天 java获取日期的月份

1、获取年份列表示例如下

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class Main {
    public static void main(String[] args) {
        String date1 = "2017-01-01";
        String date2 = "2021-12-01";

        DateFormat formater = new SimpleDateFormat("yyyy");

        Calendar beginCalendar = Calendar.getInstance();
        Calendar finishCalendar = Calendar.getInstance();

        try {
            beginCalendar.setTime(formater.parse(date1));
            finishCalendar.setTime(formater.parse(date2));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        while (beginCalendar.before(finishCalendar) || beginCalendar.equals(finishCalendar)) {
            String date = formater.format(beginCalendar.getTime()).toUpperCase();
            System.out.println(date);
            beginCalendar.add(Calendar.YEAR, 1);
        }
    }
}

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2、获取月份列表示例如下

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MainYearMonth {
  public static void main(String[] args) {
        String date1 = "2017-01-01";
        String date2 = "2021-12-01";

        //注意：这里的MM一定是大写，小写计算出的月份列表是错误的
        DateFormat formater = new SimpleDateFormat("yyyy-MM");

        Calendar beginCalendar = Calendar.getInstance();
        Calendar finishCalendar = Calendar.getInstance();

        try {
            beginCalendar.setTime(formater.parse(date1));
            finishCalendar.setTime(formater.parse(date2));
        } catch (ParseException e) {
            e.printStackTrace();
        }
        while (beginCalendar.before(finishCalendar) || beginCalendar.equals(finishCalendar)) {
            String date = formater.format(beginCalendar.getTime()).toUpperCase();
            System.out.println(date);
            beginCalendar.add(Calendar.MONTH, 1);
        }
    }
}

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