Java获取本周第一天，本月第一天，本季度第一天，本年第一天时间

梦里梦外; 2023-10-02 13:58 105阅读 0赞

import java.math.BigDecimal;
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.Date;
    
    public class Hello {
        
        public static void main(String[] args) {
        
            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Date date = new Date();
            Calendar calendar = Calendar.getInstance();
    
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_WEEK, 2);
            calendar.set(Calendar.HOUR_OF_DAY, 0);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.MILLISECOND, 0);
            String mon = dateFormat.format(calendar.getTime());
            System.out.println("获取本周第一天"+mon);
    
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_MONTH, 1);
            calendar.set(Calendar.HOUR_OF_DAY, 0);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.MILLISECOND, 0);
            String month = dateFormat.format(calendar.getTime());
            System.out.println("获取本月第一天"+month);
    
            calendar.setTime(date);
            int nowMonth = calendar.get(Calendar.MONTH) + 1;
            calendar.set(Calendar.MONTH, nowMonth - (nowMonth % 3));
            calendar.set(Calendar.DAY_OF_MONTH, 1);
            calendar.set(Calendar.HOUR_OF_DAY, 0);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.MILLISECOND, 0);
            String quarter = dateFormat.format(calendar.getTime());
            System.out.println("获取本季度第一天"+quarter);
    
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_YEAR, 1);
            calendar.set(Calendar.MONTH, 0);
            calendar.set(Calendar.DAY_OF_MONTH, 1);
            calendar.set(Calendar.HOUR_OF_DAY, 0);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.MILLISECOND, 0);
            String year = dateFormat.format(calendar.getTime());
            System.out.println("获取本年第一天"+year);
        }
    
    }