为什么这个程序报错 LocalDate cannot be resolved to a type？

代码是

import java.time.LocalDate;
 public class TodayDate {
        public static void main(String[] args) {
            LocalDate today=LocalDate.now();
        System.out.println(today);
        }
    }

错误是

Exception in thread "main" java.lang.Error: Unresolved compilation problems:
LocalDate cannot be resolved to a type
LocalDate cannot be resolved
at TodayDate.main(TodayDate.java:5)

我用的是jdk11，eslipse也是18年9月的，应该不是版本问题吧？

https://blog.csdn.net/testcs_dn/article/details/39643119/