为什么我的构造函数无法解析为＆＃39;错误？

Question

Assignment4.java

import java.util.Scanner;
import java.text.DecimalFormat;
import java.text.NumberFormat;
public class Assignment4 {
public static void main(String[] args){
    int flightNum = 2399;
    String deptCity = "Phoenix";
    String arriCity = "Boston";
    double price = 473.50;
    Scanner in = new Scanner(System.in);
    DecimalFormat fmt = new DecimalFormat("$0.00");
    Flight flightOne = new Flight(flightNum, deptCity, arriCity, price);
    char choice = ' ';
    String caseD = new String("D");
    String caseA = new String("A");
    String caseI = new String("I");
    String caseR = new String("R");
    String caseS = new String("S");
    String caseM = new String("?");
    String caseQ = new String("Q");
    String letter;
    do{
    System.out.println("\tChoose an Action\n----------------------------------");
    System.out.println("D\tChange Departure City.");
    System.out.println("A\tChange Arrival City.");
    System.out.println("I\tIncrease The Price.");
    System.out.println("R\tReduce The Price.");
    System.out.println("S\tShow Flight Info.");
    System.out.println("?\tDisplay The Menu.");
    System.out.println("Q\tQuit.");
    letter = in.nextLine();
    if(letter.equals(caseD)){
        choice = 'D';
    }
     if(letter.equals(caseA)){
        choice = 'A';
     }
     if(letter.equals(caseI)){
         choice = 'I';
     }
     if(letter.equals(caseR)){
         choice = 'R';
        }
     if(letter.equals(caseS)){
         choice = 'S';
     }
     if(letter.equals(caseM)){
         choice = '?';
     }
     if(letter.equals(caseQ)){
         choice = 'Q';
     }

    // switch statement runs one of the choices based on
    // the user input, specifically the value of int choice
    switch(choice)
    {
        case 'D':
            System.out.println("Enter the new departure city");
            String newDeptCity = in.nextLine();
            flightOne.setDeptCity(newDeptCity);
            System.out.println("The departure city has been changed from Phoenix to " + deptCity + ".");
        break;
        case 'A':
            System.out.println("Enter the new arrival city");
            String newArriCity = in.nextLine();
            flightOne.setArriCity(newArriCity);
            System.out.println("The departure city has been changed from Boston to " + arriCity + ".");
        break;
        case 'I':
            System.out.println("Enter the increase rate (0.08):");
            double raiseRate = in.nextDouble();
            flightOne.raisePrice(raiseRate);
            System.out.println("Price was increased by " + (raiseRate * 100) + "%, the new price is " + fmt.format(price) + ".");
        break;
        case 'R':
            System.out.println("Enter the increase rate (0.05):");
            double reduceRate = in.nextDouble();
            flightOne.raisePrice(reduceRate);
            System.out.println("Price was increased by " + (reduceRate * 100) + "%, the new price is " + fmt.format(price) + ".");
        break;
        case 'S':
            flightOne.toString();
        break;
        case '?':

        break;
    }
    // exits the loop when the user enters '4'
    // (exit program) for their choice
    }while(choice != 'Q');
    in.close();
}
}

Flight.java

public class Flight {
private int flightNum = 2399;
private String deptCity = "Phoenix";
private String arriCity = "Boston";
private double price = 473.50;
public Flight(int newId, String newDepCity, String newArriCity, double newPrice){
    flightNum = newId;
    deptCity = newDepCity;
    arriCity = newArriCity;
    price = newPrice;
}
public int getFlightNum(){
    return flightNum;
}
public String getDeptCity(){
    return deptCity;
}
public String getArriCity(){
    return arriCity;
}
public double getPrice(){
    return price;
}
public void setFlightNum(int newFlightNum){
    flightNum = newFlightNum;
}
public void setDeptCity(String newCity){
    deptCity = newCity;
}
public void setArriCity(String newCity){
    arriCity = newCity;
}
public void raisePrice(double raiseRate){
    double newPrice = (price * raiseRate) + price;
    price = newPrice;
}
public void reducePrice(double reduceRate){
    double newPrice = price - (price * reduceRate);
    price = newPrice;
}
public String toString(){
    String result;
    result = "\nFlight No:\t" + flightNum + "\nDeparture:\t" + deptCity + "\nArrival:\t\t" + arriCity + "\nPrice:\t\t" + price + "\n\n";
    return result;
}
}

我在Assignment4.java第12行尝试编码构造函数时遇到错误：

Flight flightOne = new Flight(flightNum, deptCity, arriCity, price);

错误状态＆＃34;航班无法解析为某种类型。＆＃34;为什么我的Assignment4.java文件找不到我的Flight.java文件？我一直在谷歌上搜索这个问题并且在过去的3个小时里盯着我的电脑找不到任何帮助我的东西！我认为这可能是一个关于文件保存位置的问题，但我真的不确定。任何帮助将不胜感激！