如何显示借记和贷记交易的数量?

Question

我正在做一个简单的事务项目，这是我第一次用Java编写，所以这是代码片段:

private static void loadHistory(List<Transaction> transactions) {
double totalDebitCount = calculateTotalCountByType(transactions, TransactionType.DEBIT);
double totalCreditCount = calculateTotalCountByType(transactions, TransactionType.CREDIT);
System.out.println("There are " + totalCreditCount + "transactions in the database");
System.out.println();
for (Transaction transaction : transactions) {
System.out.println(transaction.toString());
}
System.out.println();
System.out.println("Total count for all debit transactions is" + totalDebitCount);
System.out.println("Total count for all credit transactions is " + totalCreditCount);
}

和第二个:

public static double calculateTotalCountByType(List<Transaction> transactions, TransactionType type) {
double total = 0;
for (Transaction transaction : transactions) {
if (transaction.type == type) {
total = total + transaction.quantity * transaction.exchangeRate;
}
}
return total;
}

顺便说一下，我根本不需要exchangeRate*数量，所以可以直接删掉

Answer 1

您的代码当前计算和交易金额

total = total + transaction.quantity; // Ignoring exchange rate

如果你想要的是计数，这应该是

total = total + 1

，返回值应该是int，而不是double。

旁注:永远不要在财务金额中使用浮点数。浮点数在某些操作中会失去精度。始终使用无损格式，如BigDecimal。