Java根据年月打印出当月日期

先看图

image.png

代码如下：

    public void printByYearAndMonth(int year, int month) {
        System.out.println();
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

        List<Integer> headerList = null;
        List<Integer> endList = null;

        String firstday, lastday;
        // 获取前月的第一天
        Calendar cale = Calendar.getInstance();
        cale.set(Calendar.YEAR, year);
        cale.set(Calendar.MONTH, month);

        cale.add(Calendar.MONTH, 0);
        cale.set(Calendar.DAY_OF_MONTH, 1);
        int dayOfWeek = cale.get(Calendar.DAY_OF_WEEK);
        if (dayOfWeek != Calendar.SUNDAY) {
            headerList = new ArrayList<>();
            for (int i = 1; i < dayOfWeek; i++) {
                headerList.add(0);
            }
        }
        firstday = format.format(cale.getTime());
        // 获取前月的最后一天
//        cale = Calendar.getInstance();
        cale.add(Calendar.MONTH, 1);
        cale.set(Calendar.DAY_OF_MONTH, 0);
        int lastDayOfMonth = cale.get(Calendar.DAY_OF_MONTH);
        lastday = format.format(cale.getTime());
        System.out.println("本月第一天和最后一天分别是 ： " + firstday + " and " + lastday);

        List<Integer> totalList = new ArrayList<>();
        if (headerList != null) {
            totalList.addAll(headerList);
        }
        for (int i = 1; i <= lastDayOfMonth; i++) {
            totalList.add(i);
        }

        for (int i = 0; i < totalList.size(); i++) {
            if (i != 0 && i % 7 == 0) {
                System.out.println();
            }
            System.out.print("   " + totalList.get(i));
        }

    }