java - 在 Java 中更改字段值时遇到问题

Question

所以，作为免责声明，我对编程非常陌生，可能遗漏了一些明显的东西。现在，我正在尝试创建两个名为 withdraw() 和 deposit() 的方法，它们允许我更改字段 currentBalance 的值，但是，每次我尝试使用我的两个方法更改 currentBalance 的值时，我都会检查使用我的方法 getBalance() 获取该字段的值，它始终保持不变。

class TradingService{

   public class Trader {

      //This field stores the trader's name
      private String traderName;

      //This field stores the trader's current balance
      private double currentBalance;

      //A constructor to create a Trader
      public Trader(String traderName) {
        this.traderName = traderName;
      }

      //This method gets returns the trader's name
      public String getName() {
        return traderName;
      }

      //This method set's the trader's name
      public void setName(String traderName) {
        this.traderName = traderName;
      }

      //This method decreases the trader's balance
      public void withdraw(double withdrawAmount) {
        this.currentBalance = (currentBalance - withdrawAmount);
      }

      //This method increases the trader's balance
      public void deposit(double depositAmount) {
        this.currentBalance = (currentBalance + depositAmount);
      }

      //This method returns the trader's current balance
      public double getBalance() {
        return currentBalance;
      }

   }

}

我正在使用 DrJava 并在交互面板中测试我的代码。这是我的测试结果。

> Trader t1
> t1 = new Trader("Bill")
Trader@22e1cbe4
> t1.deposit(10.0)
10.0
> t1.getBalance()
0.0

我已尽我所能来修复代码，但我没有想法，而且我认为在我的代码中再输入 3 个小时的随机内容不会有多大作用。

感谢您花时间阅读我的问题。

Answer 1

“交易员”类看起来不错，适合我。但是你有一个“Trader”什么是“TradingService”类中的公共(public)类，我想也许这个类没有编译并且你正在执行一个旧文件，你可以像内部类一样用“Trader”类试试这个。

class Trader {

  //This field stores the trader's name
  private String traderName;

  //This field stores the trader's current balance
  private double currentBalance;

  //A constructor to create a Trader
  public Trader(String traderName) {
    this.traderName = traderName;
  }

  //This method gets returns the trader's name
  public String getName() {
    return traderName;
  }

  //This method set's the trader's name
  public void setName(String traderName) {
    this.traderName = traderName;
  }

  //This method decreases the trader's balance
  public void withdraw(double withdrawAmount) {
    this.currentBalance = (currentBalance - withdrawAmount);
  }

  //This method increases the trader's balance
  public void deposit(double depositAmount) {
    this.currentBalance = (currentBalance + depositAmount);
  }

  //This method returns the trader's current balance
  public double getBalance() {
    return currentBalance;
  }
}

public class TradingService{

    public static void main(String[] args)
    {

      Trader t = new Trader("test");
      t.deposit(10);
      System.out.print(t.getBalance());

    }
}