第三知识单元

public class Main {
    public static void main(String [] args) {
        Campus201Card my201Card = new Campus201Card();
        my201Card.setCampusName();
        my201Card.performCharge();
        System.out.println(my201Card.getInfo());
    }
}
class Campus201Card extends PhoneCard {
    String campusName;
    void setCampusName() {
        campusName = "NCUT";
    }
    String getInfo() {
        // String s = "CampusName: " + campusName + ", Balance: " + balance;
        String s = "CampusName: " + campusName + ", " + super.getInfo();
        return s;
    }
}
class PhoneCard {
    double balance;
    void performCharge() {
        balance += 100.0;
    }
    String getInfo() {
        String s = "Balance: " + balance;
        return s;
    }
}