我已经搜索了一个解决方案,但我仍然不明白在这里要做什么。这个程序应该模仿一个atm机器,它会从支票中扣除余额并为存款添加资金。从父类的对象的数组列表中调用子类的方法
我有这个父类:
public class Transaction
{
private int transNumber;
private int transId;
private double transAmt;
public Transaction(int number, int id, double amount)
{
transNumber = number;
transId = id;
transAmt = amount;
}
public int getTransNumber()
{
return transNumber;
}
public int getTransId()
{
return transId;
}
public double getTransAmount()
{
return transAmt;
}
}
我具有存储事务的对象,每戒断/存款阵列列表(transList)。
子类:
public class Check extends Transaction
{
private int checkNumber; // check number for each check transaction
public Check(int tId, double tAmt, int tCount, int checkNumber) {
super(tCount, tId, tAmt);
this.checkNumber = checkNumber;
}
public int getCheckNumber() {
return checkNumber;
}
public void setCheckNumber(int checkNumber) {
this.checkNumber = checkNumber;
}
}
我需要做的是打印出的JOptionPane的支票号码,如果用户要求他们。
在主,我有:
checkNumStr = JOptionPane.showInputDialog("Enter check number:");
checkNum = Integer.parseInt(checkNumStr);
checkAmtStr = JOptionPane.showInputDialog("Eneter check amount:");
checkAmt = Double.parseDouble(checkAmtStr);
Check c = new Check(1, checkAmt, acctCheck.gettransCount(), checkNum);
acctCheck.addTrans(c);
我不知道我是否已经足够清晰。我以前没有在这里提过一个问题。我需要知道的是如何从父类Transaction的对象的数组列表中调用Check.getCheckNumber()。
编辑:transList位于另一个类:支票帐户:
public class CheckingAccount extends Account
{
private double totalServiceCharge;
private static ArrayList<Transaction> transList;
// keeps a list of Transaction objects for the account
private int transCount = 0;
// the count of Transaction objects and used as the ID for each transaction
NumberFormat fmt = NumberFormat.getCurrencyInstance();
public CheckingAccount()
{
transList = new ArrayList<Transaction>();
totalServiceCharge = 0;
}
public double getServiceCharge()
{
return totalServiceCharge;
}
public void setServiceCharge(double currentServiceCharge)
{
totalServiceCharge += currentServiceCharge;
}
// adds a transaction object to the transList
public void addTrans(Transaction newTrans)
{
transList.add (newTrans);
transCount++;
}
//returns the current value of transCount;
public int gettransCount()
{
return transCount;
}
}
答案是 - 不要这样做。你的Transaction类不应该拥有这个ArrayList,因为它属于其他地方,而不是父类。 –