闰年

能被4整除并且不能被一百整除或者能被四百整除

    public boolean isLeapYear(){
        boolean flag = (year%4==0&&year%100!=0)||year%400==0;
        String msg = flag ?year+"是闰年":year+"不是闰年";
        System.out.println(msg);
        return flag;
    }