1.创建 banking 包 2． 在 banking 包下创建 Account 类。该类必须实现上述 UML 框图中的模型。 a. 声明一个私有对象属性：balance，这个属性保留了银行帐户的当前（或 即 时）余额。 b. 声明一个带有一个参数 （init_balance ）的公有构造器 ，这个参数为 balance 属性赋值。 c. 声明一个公有方法 geBalance，该方法用于获取经常余额。 d. 声明一个公有方法 deposit,该方法向当前余额增加金额。 e. 声明一个公有方法 withdraw 从当前余额中减去金额。 3．打开TestBanking.java文件，按提示完成编写，并编译 TestBanking.java 文件。 4． 运行 TestBanking 类。可以看到下列输出结果： Creating an account with a 500.00 balance Withdraw 150.00 Deposit 22.50 Withdraw 47.62 The account has a balance of 324.88
package banking; public class Account { private static double balance; //这个属性保留了银行账户的当前余额 private double amt; public Account(double init_balance){ this.balance=init_balance; } public double getBalance() { return this.balance; } public void deposit(double amt){ balance+=amt; System.out.println("Deposit "+amt+": true"); } public boolean withdraw(double amt){ if(amt<balance){ balance-=amt; System.out.println("Withdraw "+amt+": true"); return true; }else{ System.out.println("Withdraw "+amt+": false"); return false; } } } package banking; public class TestBanking { public static void main(String[] args) { Customer customer=new Customer("Jane","Smith"); //customer.setAccount(500.00); Account admin=new Account(500.00); System.out.println("Creating the customer "+customer.getFirstName()+" "+customer.getLastName()); System.out.println("Creating her account with a "+admin.getBalance()+" balance"); admin.withdraw(150.00); admin.deposit(22.50); admin.withdraw(47.62); admin.withdraw(400.00); System.out.println("Customer ["+customer.getLastName()+", "+customer.getFirstName()+"] has a balance of "+admin.getBalance()); } } package banking; public class Customer { private String firstName; private String lastName; private double account; public Customer(String f,String l){ this.firstName=f; this.lastName=l; } public String getFirstName(){ return this.firstName; } public String getLastName() { return this.lastName; } public void setAccount(double account){ this.account=account; } public double getAccount(){ return this.account; } }