我仍然在学习Java,所以请多多包涵。
建立以前的工作。因此,我有一个抽象的Stock类,其中包含ETF类和Dividend类,它们都扩展了Stock类。 ETF和股息从股票中覆盖了calculatePrice。在另一个StockManager类中,我可以输入一些信息,例如股票名称,股价以及ETF值或股息。以前我将这些输入存储到对象数组中
股票[] stk =新股票[STOCKLIMIT]
现在,由于Stock是一个抽象类,所以我不能再这样做了。如何存储这些值?或打印它们?
除此之外,您还可以在StockManager中添加,删除,打印或查找库存总成本。
删除了一些不必要的东西
只需添加,打印和总成本方面的帮助
StockManager类
public class StockManager
{
Scanner stdin = new Scanner(System.in);
final int STOCKLIMIT = 6;
int numberOfStocks = 0;
Stock[] stk = new Stock[STOCKLIMIT]; //before stock was abstract
String name;
Double namePrice;
int etfDividendVal;
public void run()
{
String command = stdin.next();
while (!command.equalsIgnoreCase("Q"))
{
if (command.equalsIgnoreCase("A"))
{
else
{
String commandTwo = stdin.next(); //either e for etf or d for dividend
if (commandTwo.equalsIgnoreCase("E"))
{
name = stdin.next();
namePrice = stdin.nextDouble();
etfDividendVal = stdin.nextInt();
//stk[numberOfStocks] = new Stock(name, namePrice); //object array when stock wasn't abstract
//store name, namePrice, and etfDividendVal somewhere now that stock is abstract
numberOfStocks++;
}
else if (commandTwo.equalsIgnoreCase("D"))
{
name = stdin.next();
namePrice = stdin.nextDouble();
etfDividendVal = stdin.nextInt();
//stk[numberOfStocks] = new Stock(name, namePrice);
//where to store name, namePrice, and etfDividendVal somewhere now that stock is abstract
Stock stk = new Dividend();
numberOfStocks++;
}
}
}
}
else if (command.equalsIgnoreCase("R")) //remove a stock
{
else
{
name = stdin.next();
namePrice = stdin.nextDouble();
for (int i = 0; i < numberOfStocks; i++)
{
if (stk[i].getTicker().equals(name))
{
for(int z = i; z < numberOfStocks; z++)
{
if (z + 1 == numberOfStocks)
stk[z] = null;
else
stk[z] = stk[z+1];
}
numberOfStocks--;
}
}
}
}
else if (command.equalsIgnoreCase("P"))
{
else
{
// print stock name, price, and etf/divident value
}
}
}
else if (command.equalsIgnoreCase("C"))
{
else
{
//print the total cost
}
}
}
}
}
抽象股票类
abstract public class Stock
{
protected String commandTwo;
protected String ticker;
protected Double price;
protected int etfDividendVal;
public Stock()
// default constructor
public Stock(String commandTwo, String ticker, Double price,
int etfDividendVal)
{
this.commandTwo = commandTwo;
this.ticker = ticker;
this.price = price;
this.etfDividendVal = etfDividendVal;
}
public String getTicker()
{
return ticker;
}
public String setTicker(String name)
{
ticker = name;
return ticker;
}
public Double getPrice()
{
return price;
}
public Double setPrice(Double namePrice)
{
price = namePrice;
return price;
}
@Override
public String toString()
{
return this.ticker + " " + this.price + "\t";
}
public abstract double calculatePrice();
}
ETF类别
public class ETF extends Stock
{
public float numberOfStocks;
@Override
public double calculatePrice()
{
return (price * numberOfStocks);
}
}
股利类别
public class Dividend extends Stock
{
public float yieldPercentage;
@Override
public double calculatePrice()
{
return (price * yieldPercentage);
}
}
它应该看起来像这样
Pick an option: A-Add R-Remove P-Print C-Total cost Q-Quit
A
E
AMD
30.45
10
Pick an option: A-Add R-Remove P-Print C-Total cost Q-Quit
A
D
FXAIX
100
3
Pick an option: A-Add R-Remove P-Print C-Total cost Q-Quit
P
AMD 30.45 10.0
FXAIX 100.0 0.03
Pick an option: A-Add R-Remove P-Print C-Total cost Q-Quit
C
The total cost is: 307.4999999329448
最佳答案
您仍然可以创建数组Stock[]
,因为ETF
和Dividend
都扩展了Stock
,因此可以将它们添加到数组中。要在从数组中检索的对象上使用在ETF
和Dividend
中声明的方法,必须像下面这样强制转换它们:ETF etf = (ETF) stk[someIndexHere];
。请注意,您不知道哪些对象实际上是ETF
,哪些对象实际上是Dividend
,如果将它们强制转换为实际上不是的类型,则会收到错误消息。您可以使用stk
运算符检查ETF
中的对象是Dividend
还是instanceof
:
Stock stock = stk[0]; // Provided that there is a Stock at stk[0]
if (stock instanceof ETF) {
ETF etf = (ETF) stock;
// Now you can use etf as an ETF object
} else if (stock instanceof Dividend) {
// The second if-statement is redundant since there are only
// two possibilities, but in the future there might be more
// classes extending Stock
Dividend div = (Dividend) stock;
// Now you can use div as a Dividend object
}
尽管由于
ETF
和Dividend
都未实现任何新方法,所以不需要强制转换。 instanceof
也是如此,除非您想告诉用户他们正在处理哪种类型的股票。