java 父类访问子类,Java继承：在超类中调用子类方法

I'm very new to java and would like to know whether calling a subclass method in a superclass is possible. And if doing inheritance, where is the proper place to set public static void main.

Superclass

public class User {

private String name;

private int age;

public User() {

//Constructor

}

//Overloaded constructor

public User(String name, int age) {

this.name = name;

this.age = age;

}

public String getName() {

return this.name;

}

public static void main(String []args) {

User user1 = new Admin("Bill", 18, 2);

System.out.println("Hello "+user1.getName());

user1.getLevel();

}

}

Subclass

public class Admin extends User {

private int permissionLevel;

public Admin() {

//Constructor

}

//Overloading constructor

public Admin(String name, int age, int permissionLevel) {

super(name, age);

this.permissionLevel = permissionLevel;

}

public void getLevel() {

System.out.println("Hello "+permissionLevel);

}

}

解决方案

I'm very new to java and would like to know whether calling a subclass

method in a superclass is possible.

A superclass doesn't know anything about their subclasses, therefore, you cannot call a subclass instance method in a super class.

where is the proper place to set public static void main.

I wouldn't recommend putting the main method in the Admin class nor the User class for many factors. Rather create a separate class to encapsulate the main method.

Example:

public class Main{

public static void main(String []args) {

User user1 = new Admin("Bill", 18, 2);

System.out.println("Hello "+user1.getName());

user1.getLevel();

}

}