Java 如何在将子类中的对象放入类型为super class的数组后调用subclass方法？_Java

Java 如何在将子类中的对象放入类型为super class的数组后调用subclass方法？

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Java 如何在将子类中的对象放入类型为super class的数组后调用subclass方法？,java,Java,我有两个班——“学生”和“员工”，这两个班都扩展到了班级人员。所有3个类中都有方法。在我的演示类中，我必须从每个类（Student、Employee和Person）创建2个对象，并将它们放入Person类型的数组中。然后我必须遍历数组，根据对象是来自Student、Employee还是Person，我必须在这个类/子类中调用一个方法。问题是，一旦这些对象进入Person数组，只有类Person中的.methods才可见。如果我的数组[I].“方法”来自学生或员工（数组[I].showStud

我有两个班——“学生”和“员工”，这两个班都扩展到了班级人员。所有3个类中都有方法。在我的演示类中，我必须从每个类（Student、Employee和Person）创建2个对象，并将它们放入Person类型的数组中。然后我必须遍历数组，根据对象是来自Student、Employee还是Person，我必须在这个类/子类中调用一个方法。问题是，一旦这些对象进入Person数组，只有类Person中的.methods才可见。如果我的数组[I].“方法”来自学生或员工（数组[I].showStudentInfo（）和数组[I].ShowEmployeInfo（）），如何才能找到它提前谢谢你

public class Person {
    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    void showPersonInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }
}

public class Student extends Person {
    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }
    public void showStudentInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }
}

public class Employee extends Person {
double daySallary;
double extraSum;
Employee(String name, int age, boolean isMan, double daySallary){
    super(name, age, isMan);
    this.daySallary=daySallary;
}
    double calculateOvertime(double hours) {
        if (this.age< 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }
    public void showEmployeeInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

public class Demo {
    public static void main(String[] args) {
        Person ivan = new Person("Ivan Georgiev", 27, true);
        Person nikola = new Person("Nikola Ivanov", 30, true);
        Student iskra = new Student("Iskra Dimitrova", 21, false, 4.5);
        Student georgi = new Student("Georgi Kazakov", 19, true, 5.5);
        Employee neli = new Employee("Anelia Stoicheva", 35, false, 50);
        Employee monika = new Employee("Monika Petrova", 42, false, 80);

        Person[] array = new Person[10];
        array[0] = ivan;
        array[1] = nikola;
        array[2] = iskra;
        array[3] = georgi;
        array[4] = neli;
        array[5] = monika;


        for (int i = 0; i < 6; i++) {
            if (array[i].getClass().equals(ivan.getClass())) {
                array[i].showPersonInfo();
            }
            if (array[i].getClass().equals(iskra.getClass())) {

                array[i].showStudentInfo();
            }
            if (array[i].getClass().equals(neli.getClass())) {

                array[i].showEmployeeInfo();
            }
        }

公共类人物{
字符串名；
智力年龄；
布尔伊斯曼；
Person（字符串名称、整数年龄、布尔isMan）{
this.name=名称；
这个。年龄=年龄；
this.isMan=isMan；
}
void showPersonInfo（）{
System.out.println（“|カ：”+this.name+“カ”+“+this.age+“カ”+“+this.isMan”）；
}
}
公营班级学生人数{
双倍得分；
学生（字符串名、整数、布尔isMan、双倍分数）{
超级（姓名、年龄、isMan）；
这个分数=分数；
}
公共空间显示学生信息（）{
System.out.println（“|カ：”+super.name+“カ”+“Γカカカ：”+super.age+“カ”+“Мъжカ”
+super.isMan+“|”+“öццаа”（+this.score）；
}
}
公共类雇员扩展个人{
双日制；
双倍外加费；
Employee（字符串名称、整数年龄、布尔isMan、双daySallary）{
超级（姓名、年龄、isMan）；
this.daySallary=daySallary；
}
双倍计算时间（双倍小时）{
如果（该年龄<18岁）
外和=0；
其他的
额外费用=（this.daySallary/8）*小时*1.5；
返回额外金额；
}
public void showEmployeeInfo（）{
System.out.println（“|カ：”+super.name+“カ”+“Γカカカ：”+super.age+“カ”+“Мъжカ”
+super.isMan+“|”+“此项额外费用）；
}
}
公开课演示{
公共静态void main（字符串[]args）{
人物伊万=新人（“伊万·乔治耶夫”，27岁，真实）；
人物尼古拉=新人（“尼古拉·伊万诺夫”，30岁，真实）；
学生iskra=新学生（“iskra Dimitrova”，21，假，4.5）；
学生georgi=新生（“georgi Kazakov”，19，正确，5.5）；
员工neli=新员工（“Anelia Stoicheva”，35，假，50）；
员工monika=新员工（“monika Petrova”，42，假，80）；
Person[]数组=新的Person[10]；
数组[0]=ivan；
数组[1]=尼古拉；
数组[2]=iskra；
数组[3]=georgi；
数组[4]=neli；
数组[5]=monika；
对于（int i=0；i<6；i++）{
if（数组[i].getClass（）.equals（ivan.getClass（）））{
数组[i].showPersonInfo（）；
}
if（数组[i].getClass（）.equals（iskra.getClass（）））{
数组[i]。showStudentInfo（）；
}
if（数组[i].getClass（）.equals（neli.getClass（）））{
数组[i].showEmployeeInfo（）；
}
}

在您的情况下，由于您已经确认在循环的每个迭代过程中所处理的

人员的类型，您可以根据需要将人员
强制转换为员工
或学生
：
if (array[i].getClass().equals(iskra.getClass())) {
    ((Student)array[i]).showStudentInfo();
}


但是，更好的办法是遵循更标准的面向对象编程模型。因为从Person
扩展的所有类都有一个显示信息的方法，所以您应该在Person
类中声明该方法，并让子类重写它
通过在Person
类中声明showInfo（）
方法，您可以确保无论您使用的是哪种Person
循环都可以访问该方法

人员类别：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

学生班：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

员工类别：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

在您的情况下，由于您已经确认在循环的每次迭代期间您正在处理的人员的类型，您可以根据需要将人员
强制转换为员工
或学生
：
if (array[i].getClass().equals(iskra.getClass())) {
    ((Student)array[i]).showStudentInfo();
}


但是，更好的办法是遵循更标准的面向对象编程模型。因为从Person
扩展的所有类都有一个显示信息的方法，所以您应该在Person
类中声明该方法，并让子类重写它
通过在Person
类中声明showInfo（）
方法，您可以确保无论您使用的是哪种Person
循环都可以访问该方法

人员类别：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

学生班：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

员工类别：
public class Person {

    String name;
    int age;
    boolean isMan;

    Person(String name, int age, boolean isMan) {
        this.name = name;
        this.age = age;
        this.isMan = isMan;
    }

    public void showInfo() {
        System.out.println("Име: " + this.name + " | " + "години: " + this.age + " | " + "мъж ли е: " + this.isMan);
    }

    // SETTERS and GETTERS
}

public class Student extends Person {

    double score;

    Student(String name, int age, boolean isMan, double score) {
        super(name, age, isMan);
        this.score = score;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Оценка: " + this.score);
    }

    // SETTERS and GETTERS
}

public class Employee extends Person {

    double daySallary;
    double extraSum;

    Employee(String name, int age, boolean isMan, double daySallary) {
        super(name, age, isMan);
        this.daySallary = daySallary;
    }

    double calculateOvertime(double hours) {
        if (this.age < 18)
            extraSum = 0;
        else
            extraSum = (this.daySallary / 8) * hours * 1.5;
        return extraSum;
    }

    @Override
    public void showInfo() {
        System.out.println("Име: " + super.name + " | " + "години: " + super.age + " | " + "мъж ли е: " + " | "
                + super.isMan + " | " + "Допълнителна сума от оставане след работно време: " + this.extraSum);
    }
}

如果您知道正在使用的人的类型，则可以将对象强制转换为正确的类型：（（学生）数组[i]）。showStudentInfo（）
如果您有人
声明一个简单的showInfo（），则您的设计可能会更好
方法并在子类中重写它。从OOP的角度使用instanceOf
或更好的方法将showInfo
方法添加并抽象到超类，并在数组的每个元素上调用它。如果您知道正在处理的Person
的类型，则可以将对象强制转换为正确的类型：(（学生）数组[i]）。showStudentInfo（）
但是，如果您有Person
声明一个简单的showInfo（）
方法并在子类中重写它，您的设计可能会更好