java - 尽管显示值从方法 block 内部更改，但从 setter 设置私有(private)值 "balance"时出错

Question

制定提款方法，从有余额的活跃账户中提款。控制台显示提款值从 TestClass 正确传递到定义提款方法的帐户类。它还显示了提款方法内“余额”变化的值。

但是，当我在下一行代码中调用余额值时，它会给出我创建帐户时的初始余额值。

我将包括看起来相关的内容:

这是父类(super class)

public class Account {
//declares the variables
private double initialBalance;
private double credit;
private double balance;

//default constructor
public Account() {
    this(0.0, 0.0);
}

//constructs Account object
public Account(double initialBalance, double balance) {
        this.initialBalance = initialBalance;
        this.balance = initialBalance;
}

//gets initial balance
public double getInitialBalance() {
    return initialBalance;
}

//gets balance
public double getBalance() {
    return balance;
}

// Sets initial balance
public void setInitialBalance(double initialBalance) {
    if (initialBalance > 0){
        this.initialBalance = initialBalance;
        this.balance = initialBalance;
    }
    else noCrediting();
}

//crediting the account if the credit function gets a positive input
public double credit(double creditInput, double balance){
    if (creditInput>0)
    {
        balance = balance + creditInput;
    }   
    else
        noCrediting();
    return balance;
}


//tells the user no credit was added
public void noCrediting() {
    System.out.println("No credit was added because the deposit was not a positive double.");
}

//withdrawing from the account if the function gets a positive input
public void withdraw(double withdrawInput, double balance){
    if (withdrawInput>0 && withdrawInput<balance)
    {
        balance = balance - withdrawInput;
    }
    else
        noWithdrawing();
}

//tells the user no withdrawal was performed
public void noWithdrawing() {
    System.out.println("No amount was withdrawn because the deposit was not a positive double less than the balance.");
}

}

这是子类

public class CheckingAccount extends Account {

//declares the variables
private double feeChargedPerTransaction = 2.0;

//default constructor
public CheckingAccount() {
    this(0.0, 0.0, 2.0);
}

//constructs Account object
public CheckingAccount(double initialBalance, double balance, double feeChargedPerTransaction) {
    super(initialBalance,  balance);
    feeChargedPerTransaction = 2.0;
}

//withdrawing from the account if the function gets a positive input
public void withdraw(double withdrawInput, double balance){
    if (withdrawInput>0 && withdrawInput < balance)
    {
        System.out.println("The withdrawal amount from the checking account class is showing"+ withdrawInput); 
        balance = (balance - withdrawInput)*.98;
        System.out.println("Now The balance from the checking account class is showing: " + balance);

    }
    else
        noWithdrawing();
}

//gets fee
public double getFee() {
    return feeChargedPerTransaction;
}

public void noWithdrawing() {
    System.out.println("No amount was withdrawnnn because the deposit was not a positive double less than the balance.");
}

}

这是被调用的方法

//withdrawing from the account if the function gets a positive input
public void withdraw(double withdrawInput, double balance) {
    if (withdrawInput>0 && withdrawInput < balance) {
        System.out.println("The withdrawal amount from the checking account class is showing"+ withdrawInput); 
        balance = (balance - withdrawInput)*.98;
        System.out.println("Now The balance from the checking account class is showing: " + balance);
    }
    else
        noWithdrawing();
}

我已将 print 添加到控制台以跟踪发生的情况，因为它都是通过我的 testClass 中的 javaFX 打印的

String test = "current balance is: "
    + findCheckingAccountIndex(s, checkingsArray, nameListChecking).getBalance();
System.out.println(test);
test = "withdraw amount: " + Double.parseDouble(transactionField.getText());
System.out.println(test);

在这里找到帐户并使用提款(双倍提款，双倍余额)从帐户中提款

findCheckingAccountIndex(s, checkingsArray,           nameListChecking).withdraw(Double.parseDouble(transactionField.getText()),findCheckingAccountIndex(s, checkingsArray, nameListChecking).getBalance());

这是 getter 应该显示更改的地方!

test = "new balance is: " + findCheckingAccountIndex(s,checkingsArray,nameListChecking).getBalance();
    System.out.println(test);

现在假设我的账户余额为 12 美元。我输入提款金额 11，您会看到以下内容:

从测试类打印显示即将通过的提款以及获得余额所获得的值:

current balance is: 12.0   
withdraw amount: 11.0

在执行方法 block 时从相关子类打印:

The withdrawal amount from the checking account class is showing 11.0
Now The balance from the checking account class is showing: 0.98

太棒了!现在显示在withdraw方法之后调用的getter获得的值，因此该值应该是0.98:

new balance is: 12.0

正如您所看到的，新的余额并未在提款方式中设置。有任何想法吗？可能存在传值问题？也许与我的构造函数有关？真的输了。必须弄清楚这一点，以便我可以编写其他三个使用平衡的方法。

Answer 1

从方法中删除余额参数并使用类成员余额。否则更改将会丢失。