在main方法中调用超类

class SuperClass {
    int num;

    SuperClass(int num) {
        this.num = num;
    }

    void display() {
        System.out.println("SuperClass: " + num);
    }
}

class SubClass extends SuperClass {
    int num;

    SubClass(int num1, int num2) {
        super(num1); // 调用父类的构造方法
        this.num = num2;
    }

    void display() {
        super.display(); // 调用父类的成员方法
        System.out.println("SubClass: " + num);
    }
}

public class Main {
    public static void main(String[] args) {
        SubClass obj = new SubClass(10, 20);
        obj.display(); // 调用子类的成员方法
    }
}

SuperClass: 10
SubClass: 20