1.出现：Exception in thread "main" java.lang.ClassCastException: class java.time.format.Parsed cannot be cast to class java.time.LocalDate (java.time.format.Parsed and java.time.LocalDate are in module java.base of loader 'bootstrap')
原因分析：不能直接将TemporalAccessor对象强转成localdate对象 ，应该用localdate.parse转换，
2.出现：Exception in thread "main" java.time.format.DateTimeParseException: Text '2020-11-24' could not be parsed: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2020-11-24 of type java.time.format.Parsed
原因分析：不能将"yyyy-MM-dd"转化为localdatetime的格式，因为缺少时分秒，应该用localdate

代码如下：

/**
 * @Auther:ThroneW
 * @Date:2020/11/24-11-24-9:36
 * @Description:使用localdate打印日历
 * @version:1.0
 */
public class TestLocalDatePro {
    public static void main(String[] args) {
        System.out.print("请输入你想要查看的日期：（提示：请按照例如2012-05-06的格式书写）");
        Scanner scanner=new Scanner(System.in);//接受键盘的输入
        String input = scanner.next();//接受输入的字符串
        //1.定义日期格式
        DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        //2.创建localdate的对象
        LocalDate now = LocalDate.now();

        //3.把字符串转变成localdatetime的对象
        /*TemporalAccessor parse = df.parse(input);
        LocalDate now1=(LocalDate) parse;*/
        /*LocalDateTime now1 = LocalDateTime.parse(input, df);*/
        LocalDate now1=LocalDate.parse(input,df);


        int count=0;
        System.out.println("日\t一\t二\t三\t四\t五\t六");
        /*DAY_OF_WEEK:星期日：1，星期一：2，星期二：3......*/

        //获取nowDay
        int nowDay = now1.getDayOfMonth();


        //设置时间到当月的第一天，返回相应的星期
        /*LocalDateTime now2 = now1.withDayOfMonth(1);*/
        LocalDate now2=now1.withDayOfMonth(1);
        DayOfWeek dayOfWeek = now2.getDayOfWeek();
        int firstDay = dayOfWeek.getValue();
        /*System.out.println("firstDay="+firstDay);测试代码，可以忽略*/
        firstDay%=7;
        for (int j = 1; j <= firstDay; j++) {
            System.out.print("\t");
            count++;
        }
        //没有偏移量
        /*getDayOfMonth()返回的是这个月的第几天
        *lengthOfMonth()返回这个月的长度
        * */
        for (int i = 1; i <= now1.lengthOfMonth(); i++) {
            count++;
            if (i==nowDay){
                System.out.print(i+"*\t");
            }else {
                System.out.print(i+"\t");
            }
            if (count%7==0){
                System.out.println();
            }
        }
    }
}

运行结果：

image.png