JAVA获取月份开始和月末最后一天

package com.swift.oa;

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

public class APP4 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String firstDay = getFirstDay(2022,12,"yyyy-MM-dd");
        String lastDay = getLastDay(2022,12,"yyyy-MM-dd");
        
        System.out.println(firstDay);
        
        System.out.println(lastDay);
        
        
    }
    
    
    /**
     * 根据年月获取月初第一天日期
     * @param year
     * @param month
     * @return
     */
    public static String getFirstDay(int year,int month,String format) {
        Calendar cale = Calendar.getInstance();
        
        
 
        cale.set(Calendar.YEAR,year);    //赋值年份
        cale.set(Calendar.MONTH, month-1);//赋值月份
        int lastDay = cale.getActualMinimum(Calendar.DAY_OF_MONTH);//获取月最大天数
        cale.set(Calendar.DAY_OF_MONTH, lastDay);//设置日历中月份的最大天数
        SimpleDateFormat sdf = new SimpleDateFormat(format);//格式化日期yyyy-MM-dd
        String lastDayOfMonth = sdf.format(cale.getTime());
        return lastDayOfMonth;
    }
    
    
    /**
     * 根据年月获取月末最后一天日期
     * @param year
     * @param month
     * @return
     */
    public static String getLastDay(int year,int month,String format) {
        Calendar cale = Calendar.getInstance();
        
        cale.set(Calendar.YEAR,year);//赋值年份
        cale.set(Calendar.MONTH, month-1);//赋值月份
        int lastDay = cale.getActualMaximum(Calendar.DAY_OF_MONTH);//获取月最大天数
        cale.set(Calendar.DAY_OF_MONTH, lastDay);//设置日历中月份的最大天数
        SimpleDateFormat sdf = new SimpleDateFormat(format);    //格式化日期yyyy-MM-dd
        String lastDayOfMonth = sdf.format(cale.getTime());
        return lastDayOfMonth;
    }

}