Java错误: constructor Transaction in class Transaction cannot be applied to given types

Question

我正在尝试回答以下提示:

编写一个具体类 ZeroBalance，它扩展了抽象类 Transaction，其 adjustAccount 方法会导致帐户余额设置为零。由于 ZeroBalance 类不使用金额参数，因此您的类应该有一个仅接受两个参数的构造函数，并且它应该重写 toString 方法，以免提及任何金额。

我对编码还很陌生，我对如何创建只需要两个参数的构造函数感到困惑。

这是迄今为止我的代码:

public class ZeroBalance extends Transaction
{
public ZeroBalance (String time, String date ) 
    {
        super(time, date);
    }



public boolean adjustAccount ( Account acc )
{
    acc.setBalance(0);
    return true;
}

}

这是帐户类:

public class Account {
private String myName;
private double myBalance;

public Account ( String name, double balance )
{
    myName = name;
    myBalance = balance;
}

public String getName()
{
    return myName;
}

public void setName ( String name )
{
    myName = name;
}

public double getBalance()
{
    return myBalance;
}

public void setBalance( double balance )
{
    myBalance = balance;
}

public String toString()
{
    return "Account holder: " + myName + "; Current balance: $" + 
    myBalance;
}
}

这是 Transaction 类:

public abstract class Transaction {
private double myAmount;
private String myTime;
private String myDate;

public Transaction ( double amount, String time, String date )
{
    myAmount = amount;
    myTime = time;
    myDate = date;
}

public double getAmount()
{
    return myAmount;
}

public String getTime ()
{
    return myTime;
}

public String getDate()
{
    return myDate;
}

public String toString()
{
    return getClass().getName() + " " + myAmount + " " + myTime + " " + 
    myDate;
}

public abstract boolean adjustAccount ( Account acc );
}

Answer 1

喜欢jb-nizet和 shahaf提到过，您在调用缺少参数的基类构造函数时遇到问题。您可以按如下方式解决此问题:

public class ZeroBalance extends Transaction
{

private static final double ZERO_BALANCE_AMOUNT = 0.0;    

public ZeroBalance (String time, String date ) 
    {
        super(time, date,ZERO_BALANCE_AMOUNT);
    }
// ....
// ....
}

但是

我实际上建议您向 Transaction 添加另一个构造函数，如下所示:

public abstract class Transaction {

private static final double ZERO_AMOUNT = 0.0;

private double myAmount;
private String myTime;
private String myDate;

public Transaction ( String time, String date )
{
    myAmount = ZERO_AMOUNT;
    myTime = time;
    myDate = date;
}

看起来更优雅，恕我直言，因为这允许 future 的交易扩展也从零余额开始。