1.创建银行卡类，并分别设计两个储蓄卡和信用卡子类。

 import javax.swing.plaf.BorderUIResource;import java.util.Scanner;class Card {int Id;   //银行卡；int password;  //密码；double balance=2000; //账户存款金额；String AccountType;public boolean Login(String AccountType){boolean result=false;// String AccountType1="储蓄卡";// String AccountType2="信用卡";Scanner sc=new Scanner(System.in);for(int i=0;i<4;i++) {if (AccountType.equals("储蓄卡")) {System.out.println("请您输入储蓄卡密码：");password=sc.nextInt();if(result=(password==123456)){System.out.println("储蓄卡密码输入正确，正在加载中，请您耐心等待……");return result;}else if(i<2&&password!=123456){System.out.println("储蓄卡密码输入错误");}else{System.out.println("储蓄卡密码连续3次输入错误，您的账号已被锁定，请您24小时后重试");}} else if (AccountType.equals("信用卡")) {System.out.println("请您输入信用卡密码：");password=sc.nextInt();if(result=(password==234567)){System.out.println("信用卡密码输入正确，正在加载中，请您耐心等待……");return result;}else if(i<2&&password!=234567){System.out.println("信用卡密码输入错误");}else{System.out.println("信用卡密码连续3次输入错误，您的账号已被锁定，请您24小时后重试");}} else {System.out.println("本系统暂不支持此类银行卡的登陆！");}}return false;}//存款方法public  void Savemoney(){double money;Scanner m=new Scanner(System.in);System.out.println("请输入存款金额：");money=m.nextDouble();System.out.println("请确认存款金额："+money+"元。");balance=balance+money;//System.out.println("恭喜您存款成功，当前账户的存款金额为："+balance+"元。");System.out.println("恭喜您存款成功，当前账户的存款金额为："+balance+"元。");}}
class Card2 extends Card{double money;double maxOverdraf=20000;//最大透支额度；void Withdraw(){double money;Scanner m1=new Scanner(System.in);System.out.println("请输入取款金额：");money=m1.nextDouble();if(money<=balance+maxOverdraf){System.out.println("请您确认取款金额：" + money + "元。");double account=balance-money;System.out.println("account:"+account);if(account<=0){System.out.println("当前账户剩余金额为：" + 0+ "元。");maxOverdraf=maxOverdraf+account;
//                System.out.println("money:"+money);
//                System.out.println("balance:"+balance);
//                System.out.println("maxOverdraf:"+maxOverdraf);System.out.println("当前账户剩余透支金额为：" + maxOverdraf + "元。");}else{
//                System.out.println("money:"+money);
//                System.out.println("balance:"+balance);
//                System.out.println("maxOverdraf:"+maxOverdraf);System.out.println("当前账户剩余金额为：" + account + "元。");System.out.println("当前账户剩余透支金额为：" + maxOverdraf + "元。");}}else{double account=money-balance-maxOverdraf;System.out.println("您的账户已透支，透支金额为：" + account+ "元，您取款失败。");}}}class Card1 extends Card {  //储蓄卡double money;private void Withdraw() {double r;double money;Scanner m=new Scanner(System.in);System.out.println("请输入取款金额：");money=m.nextDouble();if (money <= balance) {System.out.println("请您确认取款金额：" + money + "元。");balance = balance - money;System.out.println("恭喜您取款成功，账户剩余金额为" + balance + "元。");} else {System.out.println("请确认取款金额："+money+"元。");r= money-balance;System.out.println("您的账户余额不足，还差"+r+"元。");}}
public static void main(String[] args){String yewu;String AccountType;  //银行卡账户类型；Card1 c1=new Card1();Card2 c2=new Card2();Scanner sc1=new Scanner(System.in);System.out.println("请您选择银行卡类型：");AccountType=sc1.nextLine();if(AccountType.equals("储蓄卡")){boolean cL=c1.Login(AccountType);if(cL) {System.out.println("请您选择业务类型：");yewu = sc1.nextLine();if(yewu.equals("取款")){// int money=sc1.nextInt();c1.Withdraw();}else if(yewu.equals("存款")){//int money=sc1.nextInt();c1.Savemoney();}else{System.out.println("本系统暂不支持此业务！");}}else{System.out.println("储蓄卡登陆失败。");}}else if(AccountType.equals("信用卡")){boolean cL1= c2.Login(AccountType);if(cL1) {System.out.println("请您选择业务类型：");yewu = sc1.nextLine();if(yewu.equals("取款")){// int money=sc1.nextInt();c2.Withdraw();}else if(yewu.equals("存款")){//int money=sc1.nextInt();c2.Savemoney();}else{System.out.println("本系统暂不支持此业务！");}}else{System.out.println("储蓄卡登陆失败。");}}else{System.out.println("本系统暂不支持此银行卡类型！");}}}储蓄卡子类效果：信用卡子类效果：