我正在将证券交易所计划作为一个项目进行工作，到目前为止，我已经完成了大约 98% 的工作，我遇到的唯一问题是当我试图出售比当前持有量更多的股票时。例如，我在第 1 天以每股 30 美元的价格购买 20 股，在第 2 天以每股 20 美元的价格购买 40 股。然后我输入说我想以每股 20 美元的价格出售 30 股。代码应该做的是从第一天开始出售所有股票，然后从第 2 天开始出售 10 股。但是，我得到的是抛出 EmptyQueueException。我觉得我的 sellShares 方法在进入带有 while 循环的最终 else 语句时可能会出错。但是，我无法解决可能的错误。我已经盯着代码看了很长一段时间，但我似乎无法找到解决方案。对此提供一些帮助将不胜感激。以下代码来自我的主类和 CircleArrayQueue 类：
import java.util.Scanner;
import java.lang.Integer;
public class StockTran {
String command = "";
int gain = 0;
int totalPrice = 0; // totalPrice variable will keep of gain or loss of shares being sold
int shareTracker = 0; // shareTracker variable will keep track of shares being bought and sold
String[] stockParts = null;
CircleArrayQueue Q;
boolean quit = false;
public StockTran(String inputCommand) {
try {
Q = new CircleArrayQueue(32);
Scanner conReader = new Scanner(System.in);
this.command = inputCommand.toLowerCase();
this.stockParts = command.split("\\s"); // splits the input into three parts
while (quit == false) { // will loop until user says "q" to quit program
if (this.stockParts[0].equals("q")) { // ends transaction and terminates program
System.out.println("Share trading successfully terminated.");
quit = true;
System.exit(0); // exits the program
}
if (this.stockParts == null || this.stockParts.length > 3) {
System.out.println("That is an invalid input. Please try again.");
}
if (stockParts[0].equals("b")) { // checks to see if it is a buying of shares
int shares = Integer.parseInt(stockParts[1]); // stores share amount
int value = Integer.parseInt(stockParts[2]); // stores selling value
buyShares(shares, value); // calls buyShares method and adds share to queue
}
else if (stockParts[0].equals("s")) { // checks to see if it is a selling of shares
int shares = Integer.parseInt(stockParts[1]);
int value = Integer.parseInt(stockParts[2]);
sellShares(shares, value); // calls sellShares method
}
else if (stockParts[0].equals("c")) { // checks to see if it is capital gain
gain = capitalGain(); // calls capitalGain and calculates net gain
System.out.println("Capital gain is " + gain);
}
else {
System.out.println("That is an invalid input. Please try again."); // any other input is invalid
}
System.out.println("Enter your next command, or press 'q' to quit: ");
command = conReader.nextLine().toLowerCase();
stockParts = command.split("\\s");
}
} catch (Exception e) {
e.printStackTrace();
}
}
public void buyShares(int shareAmount, int sharePrice) { // takes in share total and values for each share
shareTracker = shareTracker + shareAmount; // adds to amount of shares bought
Node temp = new Node(shareAmount, sharePrice); // stores values into node
try {
Q.enqueue(temp); // enqueues the node into the CircularQueue
} catch (FullQueueException e) {
e.printStackTrace();
}
}
public void sellShares(int shareAmount, int sharePrice) throws Exception {
Node temp = new Node(); // stores values into node
int tempShare = 0;
try {
temp = Q.front(); // gets the first node from CircleArrayQueue and stores it in temporary node
int share = temp.getShare();
int price = temp.getPrice();
System.out.println(Q.size());
if (shareAmount > shareTracker) { // throws exception if trying to sell more shares than purchased
throw new Exception ("You don't have that many shares to sell.");
}
else if (share > shareAmount) { // checks to see if first node has a larger share amount or less
temp.setShare(share - shareAmount); // will decrease amount sold from the first days share
shareTracker = shareTracker - shareAmount;
totalPrice = shareAmount * (sharePrice - price) + totalPrice; // calculates total profit or loss
}
else if (share == shareAmount) {
Q.dequeue();
shareTracker = shareTracker - shareAmount; // updates shareTracker to show how many shares are remaining
totalPrice = shareAmount * (sharePrice - price) + totalPrice;
}
else {
while (shareAmount != tempShare) { // will loop until it sells total share amount user wanted
Node temp2 = Q.dequeue(); // removes another node from CircleArrayQueue
int newShare = temp2.getShare();
int newPrice = temp2.getPrice();
tempShare = tempShare + newShare; // adds the shares together to check if while loop condition still holds
totalPrice = shareAmount * (sharePrice - newPrice) + totalPrice;
sellShares(shareAmount - tempShare, sharePrice); // recursively calls sellShares on new amount of shares
}
}
} catch (EmptyQueueException e) {
e.printStackTrace();
}
}
public int capitalGain() { // returns the total net gain or loss in share trading
return totalPrice;
}
public static void main(String[] args) {
String inputCommand = "";
Scanner mainReader = new Scanner(System.in);
System.out.println("Enter 'b' to purchase share, 's' to sell share, 'c' for capital gain, or 'q' to quit: ");
inputCommand = mainReader.nextLine();
StockTran tran = new StockTran(inputCommand);
}
}
public class CircleArrayQueue implements Queue {
protected Node Q[]; // initializes an empty array for any element type
private int MAX_CAP = 0; // initializes the value for the maximum array capacity
private int f, r;
public CircleArrayQueue(int maxCap) {
MAX_CAP = maxCap;
Q = new Node[MAX_CAP]; // sets Q to be a specific maximum size specified
f = 0; // sets front value to be 0
r = 0; // sets rear value to be 0;
}
public int size() {
return (MAX_CAP - f + r) % MAX_CAP; // returns the size of the CircularArrayQueue
}
public boolean isEmpty() { // if front and rear are of equal value, Queue is empty
return f == r;
}
public Node front() throws EmptyQueueException { // method to get the front value of the CircularArrayQueue
if (isEmpty()) throw new EmptyQueueException("Queue is empty.");
return Q[f]; // returns object at front of CircularArrayQueue
}
public Node dequeue() throws EmptyQueueException { // method to remove from the front of the CircularArrayQueue
if (isEmpty()) throw new EmptyQueueException("Queue is empty.");
Node temp = Q[f]; // stores front object in local variable
Q[f] = null; // sets the value to be null in the array
f = (f + 1) % MAX_CAP; // sets the new front value to be this
return temp; // returns the object that was originally in the front
}
public void enqueue(Node element) throws FullQueueException { // method to add to the end of the CircualarArrayQueue
if (size() == MAX_CAP - 1) throw new FullQueueException("Queue has reached maximum capacity.");
Q[r] = element; // stores the new element at the rear of array
r = (r + 1) % MAX_CAP; // sets the new rear value to be the location after element insertion
}
}