練習目標－使用有返回值的方法：在本練習里，將修改withdraw方法以返回一個布爾值來指示交易是否成功。

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任務

1．修改Account類
a.修改deposit 方法返回true（意味所有存款是成功的）。
b.修改withdraw方法來檢查提款數目是否大于余額。如果amt小于balance,則從余額中扣除提款數目并返回true，否則余額不變返回false。

2．在exercise2主目錄編譯并運行TestBanking程序，將看到下列輸出;

Creating the customer Jane Smith.
Creating her account with a 500.00 balance.
Withdraw 150.00: true
Deposit 22.50: true
Withdraw 47.62: true
Withdraw 400.00: false
Customer [Smith, Jane] has a balance of 324.88

//Account類

package banking;

public class Account {
private double balance;
public Account(double i)
{
balance=i;

}
public double getBalance()
{

return balance;
}
public boolean deposit(double i)
{
balance+=i;
System.out.print("Deposit "+i);
return true;
}
public boolean withdraw(double i)
{
if(balance>=i)
{
balance-=i;
System.out.print("Withdraw "+i);
return true;
}
else
{
System.out.print("余額不足");
return false;
}
}
}

//Testbanking類

package banking;

public class TestBanking {

public static void main(String[] args) {
Account a=new Account(500.00);
System.out.println("Creating an account with a "+a.getBalance()+"balance");
a.withdraw(150.00);
a.deposit(22.50);
a.withdraw(47.62);
System.out.println("The account has a balance of "+a.getBalance());
Customer c=new Customer("Jane", "Smith");
Account b=new Account(500.00);
c.setAccount(b);
a=c.getAccount();
System.out.println("Creating her account with a "+a.getBalance()+"balance");
System.out.println(":"+a.withdraw(150.00));
System.out.println(":"+a.deposit(22.50));
System.out.println(":"+a.withdraw(47.62));
System.out.println("Customer ["+c.getFirstName()+","+c.getLastName()+"] has a balance of "+a.getBalance());

}
}

//運行

Creating an account with a 500.0balance
Withdraw 150.0Deposit 22.5Withdraw 47.62The account has a balance of 324.88
Creating the customer Jane Smith
Creating her account with a 500.0balance
Withdraw 150.0:true
Deposit 22.5:true
Withdraw 47.62:true
Customer [Jane,Smith] has a balance of 324.88

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轉載于:https://www.cnblogs.com/smile-dream/p/5915467.html

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