为什么找不到LocalDate变量？

Question

我是Java的新手...我创建这个类来从java.util.Date计算年龄但是编译器给了我错误“找不到符号”的LocalDate实例变量...可以任何一个解释原因并纠正它？ [找不到符号] [1]

this is the code:
import java.util.Date;
public class TimeAndAge extends CheckDate 
{
private LocalDate birthDate;
private LocalDate now;
private LocalDate age;

public TimeAndAge (int theYear,int theMonth,int      
     theDay,LocalDatebirthdate,LocalDate now,Years age)             
   {
    super(theYear,theMonth,theDay);
    this.birthDate = birthDate;
    this.now = now;
    this.age=age;
}


 public void setBirthDate(LocalDate birthdate)   
 {
    birthdate = new    
   LocalDate(super.getYear(),super.getMonth(),super.getDay());
  }
 public LocalDate getBirthDate()
  {
   return birthDate;
  }
  public void setNow(LocalDate now)
  {
    now = new LocalDate();
  }
  public LocalDate getNow()
  {
    return now;
   }
   public void setAge(Years age)    
  {
    age = Years.yearsBetween(birthdate, now);
  } 
  public Years getAge()
    {
    return age;
   }        
  }