java 获取当前年份 月份,当月第一天和最后一天

获取当前年份 月份,当月第一天和最后一天，工作中会经常用到，下面是代码：

package basic.day01;

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

public class DateTest {
    public static void main(String[] args) {
        // 获取当前年份、月份、日期
        Calendar cal =  Calendar.getInstance();
        int year = cal.get(Calendar.YEAR);
        int month = cal.get(Calendar.MONTH) + 1;
        int day = cal.get(Calendar.DATE);
        int hour = cal.get(Calendar.HOUR_OF_DAY);
        int minute = cal.get(Calendar.MINUTE);
        int second = cal.get(Calendar.SECOND);
        int dow = cal.get(Calendar.DAY_OF_WEEK);
        int dom = cal.get(Calendar.DAY_OF_MONTH);
        int doy = cal.get(Calendar.DAY_OF_YEAR);  

        System.out.println("Current Date: " + cal.getTime());
        System.out.println("Year: " + year);
        System.out.println("Month: " + month);
        System.out.println("Day: " + day);
        System.out.println("Hour: " + hour);
        System.out.println("Minute: " + minute);
        System.out.println("Second: " + second);
        System.out.println("Day of Week: " + dow);
        System.out.println("Day of Month: " + dom);
        System.out.println("Day of Year: " + doy);  

        //当前季度 (当前月转换季度)
        String quarter = "";
        int m = cal.get(Calendar.MONTH) + 1;
        if (m >= 1 && m <= 3) {
            quarter = "1";
        } else if (m >= 4 && m <= 6) {
            quarter = "2";
        } else if (m >= 7 && m <= 9) {
            quarter = "3";
        } else {
            quarter = "4";
        }
        System.out.println("Quarter: " + quarter); 

        SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
        SimpleDateFormat format2 = new SimpleDateFormat("yyyy/MM/dd HH:mm");
        SimpleDateFormat format3 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        // 获取当前日期字符串
        Date d = new Date();
        System.out.println("当前日期字符串1：" + format1.format(d));
        System.out.println("当前日期字符串2：" + format2.format(d));
        System.out.println("当前日期字符串3：" + format3.format(d));

        //拼装日期字符串
        System.out.println("当前日期字符串4：" + year + "/" + month + "/" + day + " "
                + hour + ":" + minute + ":" + second);
    }

}

good luck!