小编use*_*825的帖子

我有一个子类声明我的抽象超类中的所有方法,但它仍然给我一个错误,说明我的类不是抽象的.我无法弄清楚为什么会抛出这个错误.

我得到的具体错误是

PhoneBookEntry.java:1:错误:PhoneBookEntry不是抽象的,并且不会覆盖Comparable中的抽象方法compareTo(Object)

我的代码有问题:

public abstract class PhoneNumber implements Comparable
{
   protected String firstName, lastName;
   protected int number;

   public PhoneNumber(String firstName, String lastName, int number)
   {
      this.firstName = firstName;
      this.lastName = lastName;
      this.number = number;
   }

   public abstract String getLastName();
   public abstract String getFirstName();
   public abstract int getNumber();

   public int compareTo(PhoneNumber other)
   {
      int last = other.lastName.compareTo(lastName);
      int first = other.firstName.compareTo(firstName);
      int num = other.number - number;
      if(last > 0)
         return 1;
      else if(last < 0)
         return -1;
      else
         if(first …