为什么在为父项定义的 TreeMap 中输入子项类时会出现错误？

Question

在我的程序中，我有一个抽象 class TelephoneEntry，它包含一个 TelephoneNumber（它实现了 Comparable）和一个地址，然后我有子 classes Person 和 Company 扩展了 TelephoneEntry class.

abstract class TelephoneEntry {
    protected TelephoneNumber number;
    protected String address;

    public abstract void description();

    public TelephoneNumber getNumber() {
        return number;
    }

    public void setNumber(TelephoneNumber number) {
        this.number = number;
    }
}

class Person extends TelephoneEntry {
    protected String name;
    protected String surname;

    public Person(String name, String surname, String address, int code, long number) {
        this.name = name;
        this.surname = surname;
        this.address = address;
        this.number = new TelephoneNumber(code, number);
    }

    @Override
    public void description() {
        System.out.println("Name: " + name);
        System.out.println("Surname: " + surname);
        System.out.println("Address: " + address);
        System.out.println("TelephoneNumber: " + number.toString());
        }
    }

class Company extends TelephoneEntry {
    protected String name;

    public Company(String name, String address, int code, long number) {
        this.name = name;
        this.address = address;
        this.number = new TelephoneNumber(code, number);
    }

    @Override
    public void description() {
        System.out.println("Name: " + name);
        System.out.println("Address: " + address);
        System.out.println("TelephoneNumber: " + number.toString());
    }
}

public class TelephoneNumber implements Comparable<TelephoneNumber> {
    private int countryCode;
    private long localNumber;

    public TelephoneNumber(int code, long number) {
        countryCode = code;
        localNumber = number;
    }


    @Override
    public int compareTo(TelephoneNumber otherNumber) {
        if (Integer.compare(getCountryCode(), otherNumber.getCountryCode()) != 0) {
        return Long.compare(getLocalNumber(), otherNumber.getLocalNumber());
    } else
        return Integer.compare(getCountryCode(), otherNumber.getCountryCode());

    }

    public String toString() {
        String out = "";
        out += ("+" + countryCode + " " + localNumber);
        return out;
    }
}

但是当我尝试将它们传递给定义为

的树图时

TreeMap<TelephoneNumber,  TelephoneEntry> map = new TreeMap<>();

我收到一条错误消息：

"The method add(TelephoneNumber, Person) is undefined for the type TreeMap<TelephoneNumber,TelephoneEntry>"
"The method add(TelephoneNumber, Company) is undefined for the type TreeMap<TelephoneNumber,TelephoneEntry>"

我不确定这个错误的原因是什么，因为它们都从 TelephoneEntity 继承了使用的密钥。

Answer 1

地图有 put() 方法，而不是 add() 方法，用于添加条目。

将您的代码更改为：

myMap.put(myTelephoneNumber, myTelephoneEntry);

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