java - 如何访问扩展类中的方法？

Question

我有以下内容:

main.java

public class main {
    public static  void main(String[] args){
        Player startingPitcher = new Player("Doug", "Mellon",
                "Pitcher", 29);

        startingPitcher.setThrowingArm("right");
    }
}

Player.java

class Player
{
    private String firstName, lastName, position;
    private int age;

    public Player(String firstName, String lastName, String position, int age)
    {
        this.firstName = firstName;
        this.lastName = lastName;
        this.position = position;
        this.age = age;
    }

    private String getFirstName(){
        return this.firstName;
    }

    private void setFirstName(String newFirstName){
        this.firstName = newFirstName;
    }

    private String getLastName(){
        return this.lastName;
    }

    private void setLastName(String newLastName){
        this.lastName = newLastName;
    }

    private String getPosition(){
        return this.position;
    }

    private void setPosition(String newPosition){
        this.position = newPosition;
    }

    private int getAge(){
        return this.age;
    }

    private void setAge(int newAge){
        this.age = newAge;
    }
}

投手.java

public class Pitcher extends Player{

    public String throwingArm;
    public int fastballMPH;


    public Pitcher(String firstName, String lastName, String position, int age,
                   String throwingArm, int fastballMPH) {
        super(firstName, lastName, position, age);
        this.throwingArm = throwingArm;
        this.fastballMPH = fastballMPH;
    }

    public String getThrowingArm(){
        return this.throwingArm;
    }

    public void setThrowingArm(String newThrowingArm){
        this.throwingArm = newThrowingArm;
    }

    private int getFastballMPH(){
        return this.fastballMPH;
    }

    private void setFastballMPH(int newFastballMPH){
        this.fastballMPH = newFastballMPH;
    }
}

我的主要抛出以下错误:

Error:(6, 24) java: cannot find symbol symbol: method setThrowingArm(java.lang.String) location: variable startingPitcher of type Player

我理解这个错误 - 我认为 - 但我认为如果您使用继承，您可以访问这些方法。

如何为主对象中的 Player 对象设置 throw 臂？

很抱歉，如果这个问题措辞不好。如果我可以添加任何内容来澄清我的问题，请随时提问。

非常感谢大家抽出宝贵的时间。

Answer 1

main 类的 main() 方法中的

变量 startingPitcher 是 Player 的实例，而不是Pitcher 的实例，因此它没有 setThrowingArm() 方法。

您需要创建一个 Pitcher 实例，即

Pitcher startingPitcher = new Pitcher("Doug", "Mellon", "pitcher", 29, "right", 90);

请注意，这是错误消息告诉您的内容，即变量 startingPitcher 是 Player 的实例(并且不是实例) 投手)。