即使我在Java中有适当的构造函数，为什么我的子类对象始终为空？

如何解决即使我在Java中有适当的构造函数，为什么我的子类对象始终为空？

我有一个继承自超类的子类，并且我注意到，如果我尝试将其打印出来，则该子类的对象似乎为空。 我以前从未遇到过这样的问题，非常感谢您的帮助。

我有这个子类：

public class OnetimeAppointment extends Appointment {
    int year,month,day;
    private String description;



    public OnetimeAppointment(int year,int month,int day,String description)
    {
        super();
        System.out.println(this.year);
        System.out.println(year);
        this.year = year;
        this.month = month; 
        this.day = day;
        this.description = description;
        System.out.println(this.year);
    
        }

    public int getYear() 
    {
        return year;
    }
    public int getMonth() 
    {
        return month;
    }


    @Override
    public boolean occursOn(int year,int day) {
        // Todo Auto-generated method stub
        return false;
    
    }

    @Override
    public boolean equals(Object otherObject)
    {
        return false;
    }

}
}

这是超类：

public abstract class Appointment {
    private String description;

    
    public Appointment() {
        description = "";
    }
    
    public abstract boolean equals(Object otherObject);
    
    
    public void setDescription(String description) {
        this.description = description;
    }
    
    public String getDescription() {
        return description;
    }

    
    public abstract boolean occursOn(int year,int day);

    
    public String toString() {
        return description;
    }
    
    public static void main(String args[])
    {
        Appointment app = new OnetimeAppointment(2020,11,1,"Dentist");
        System.out.println(app);

}