public class BankCard

public class BankCard {
String cardNum;

public void saveMoney() {
    System.out.println("卡号为" + cardNum + "银行卡可以存钱。");
}

}

public class CreditCard extends BankCard{
public void drawMoney() {
System.out.println("卡号为" + cardNum + "银行卡可以取钱。");
}

public void borrowMoney() {
    System.out.println("卡号为" + cardNum + "银行卡可以借钱。");
}

}

public class SavingCard extends BankCard{
public void drawMoney() {
System.out.println("卡号为" + cardNum + "银行卡可以取钱。");
}
}

public class Test {
public static void main(String[] args) {
System.out.println("--------------银行卡的特点--------------");
BankCard bankCard = new BankCard();
bankCard.cardNum = "6224 4569 2421 3677";
bankCard.saveMoney();
System.out.println("--------------储蓄卡的特点--------------");
SavingCard savingCard = new SavingCard();
savingCard.cardNum = "6212 2636 0001 2739";
savingCard.saveMoney();
savingCard.drawMoney();
System.out.println("--------------信用卡的特点--------------");
CreditCard creditCard = new CreditCard();
creditCard.cardNum = "4013 7356 3380 0642";
creditCard.saveMoney();
creditCard.drawMoney();
creditCard.borrowMoney();
}
}