java - 在Java中更改字段值时遇到麻烦

因此，作为免责声明，我对编程非常陌生，并且可能缺少明显的东西。现在，我尝试创建两个名为withdraw()和deposit()的方法，这些方法将允许我更改字段currentBalance的值，但是，每次尝试使用这两个方法更改currentBalance的值时，我都会检查我的方法getBalance()获得字段的值，并且始终保持不变。

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，并且正在“交互”面板中测试我的代码。这是我测试的结果。

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

我已经完成了我可以想象的所有工作来修复代码，但是我没有主意，并且我认为再花3个小时在我的代码中输入随机的内容并不会起到很大的作用。

感谢您抽出宝贵时间阅读我的问题。

最佳答案

类“Trader”看起来很好，可以为我工作。但是您有一个“Trader”类，它是“TradingService”类中的一个公共(public)类，我认为也许该类未在编译，并且您正在执行旧文件，因此可以像内部类一样使用“Trader”类进行尝试。

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());

    }
}