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Question

在一个学校项目中，我需要制作一个具有以下选项的菜单系统：

1. 加载员工数据 - 提示用户输入要加载的员工数量，然后提示输入每个员工的姓名、ID（5 位数字）和年薪
2. 添加新员工 - 提示用户输入员工数据、姓名、身份证和年薪
3. 显示所有员工 - 将每个员工的数据显示到控制台，每行一名员工
4. 检索特定员工的数据 - 提示用户输入员工 ID 并显示相应的员工数据：ID、姓名和薪水
5. 根据范围检索具有工资的员工 - 提示用户输入最低和最高工资，并显示所有工资在该范围内的员工。在单独的行上显示每个员工的所有信息 - 姓名、ID 和薪水
6. 退出

每个菜单选项都必须是它自己的方法，他更喜欢我们使用数组而不是列表，这就是我分配 100 个空格的原因。这是我到目前为止所拥有的。菜单选项 1、2 和 6 在不中断程序的情况下运行。但是任何必须展示的东西似乎都坏了。我最好的猜测是在所有方法之间传递和更新数组“员工”存在问题。

package practice;

import java.util.Arrays;
import java.util.Scanner;

public class Project {
    
    public static Employee[] loadData() {
        Scanner scanint = new Scanner(System.in);
        Scanner scanstr = new Scanner(System.in);
        
        System.out.println("How many employees would you like to add?"); //Determines how many employees to create
        Employee[] employees = new Employee[100];
        int numberEmployees = scanint.nextInt();
        for (int i = 0; i < numberEmployees; i++) {
            System.out.println("Enter name: ");
            String empName = scanstr.nextLine();
            System.out.println("Enter ID: ");
            int empID = scanint.nextInt();
            System.out.println("Enter Salary: ");
            int empSalary = scanint.nextInt();
            employees[i+1] = new Employee(empName, empID, empSalary); //Add employee to array
        }
        return employees;
    }
    
    public static Employee addEmployee() {
        Scanner scanint = new Scanner(System.in);
        Scanner scanstr = new Scanner(System.in);
        System.out.println("Enter name: ");
        String empName = scanstr.nextLine();
        System.out.println("Enter ID: ");
        int empID = scanint.nextInt();
        System.out.println("Enter salary: ");
        int empSalary = scanint.nextInt();
        return new Employee(empName, empID, empSalary);
    }
    
    public static void displayEmployees(Employee[] employees) {
        for (int i = 0; i < employees.length; i++) {
            if (employees[i] != null) {
                System.out.println(Arrays.toString(employees));
                //System.out.println("Employee Name: " + employees[i].name + " ID: " + employees[i].id + " Salary: " + employees[i].salary);
            }
        }
    }
    
    public static void specificEmployee(Employee[] employees, int id) {
        for (int i = 0; i < employees.length; i++) {
            if (employees[i].id == id) {
                System.out.println("Name: " + employees[i].name + " ID: " + employees[i].id + " Salary: " + employees[i].salary);
            }
            else {
                System.out.println("ID not recognized");
            }
        }
    }
    
    public static void salaryRange(Employee[] employees, int salaryMinimum, int salaryMaximum) {
        for (int i = 0; i < employees.length; i++) {
            if (employees[i].salary >= salaryMinimum && employees[i].salary <= salaryMaximum) {
                System.out.println("Name: " + employees[i].name + " ID: " + employees[i].id + " Salary: " + employees[i].salary);
            }
            else {
                System.out.println("No employees within salary range");
            }
        }
    }

    public static void main(String[] args) {
        
        Scanner scanint = new Scanner(System.in);
        Scanner scanstr = new Scanner(System.in);
        int menuChoice = 0;
        while (menuChoice != 6) {
            System.out.println("\tMenu:");
            System.out.println("1. Load Employee Data");
            System.out.println("2. Add New Employee");
            System.out.println("3. Display All Employees");
            System.out.println("4. Retrieve Specific Employee Data");
            System.out.println("5. Retrieve Employees Within Salary Range");
            System.out.println("6. Exit");
        
            menuChoice = scanint.nextInt();
            Employee[] employees = new Employee[100];
            int amountEmployees;
        
        
            
            if (menuChoice == 1) {
                employees = loadData();
            }
            else if (menuChoice == 2) {
                employees[0] = addEmployee();
            }
            else if (menuChoice == 3) {
                displayEmployees(employees);
            }
            else if (menuChoice == 4) {
                System.out.println("Enter 5 digit employee ID: ");
                int id = scanint.nextInt();
                specificEmployee(employees, id);
            }
            else if (menuChoice == 5) {
                System.out.println("Enter minimum of salary range: ");
                int salaryMinimum = scanint.nextInt();
                System.out.println("Enter maximum of salary range");
                int salaryMaximum = scanint.nextInt();
                salaryRange(employees, salaryMinimum, salaryMaximum);
            }
            else if (menuChoice == 6) {
                break;
            }
            else {
                System.out.println("Invalid Choice");
            }

        }
        scanint.close();
        scanstr.close();

    }

任何帮助将不胜感激！！！！！！

Answer 1

你的代码有几个问题：

while (menuChoice != 6) {
            System.out.println("\tMenu:");
            System.out.println("1. Load Employee Data");
            System.out.println("2. Add New Employee");
            System.out.println("3. Display All Employees");
            System.out.println("4. Retrieve Specific Employee Data");
            System.out.println("5. Retrieve Employees Within Salary Range");
            System.out.println("6. Exit");
        
            menuChoice = scanint.nextInt();
            **Employee[] employees = new Employee[100];**
            int amountEmployees;
        
        
            
            if (menuChoice == 1) {
                employees = loadData();
            }

您已在 while 循环中声明了 employees 数组，因此每次读取输入时，您都在创建一个新输入。这完全违背了将员工存储在数组中并稍后检索它们的目的，如果menuChoice == 1，这也会使分配变得多余。您必须考虑应该在哪里声明您的数组。

public static void specificEmployee(Employee[] employees, int id) {
        for (int i = 0; i < employees.length; i++) {
            if (employees[i].id == id) {
                System.out.println("Name: " + employees[i].name + " ID: " + employees[i].id + " Salary: " + employees[i].salary);
            }
            else {
                System.out.println("ID not recognized");
            }
        }
    }

当你声明一个数组时，默认值是空的，除非你给它们赋值。在这里，您正在迭代整个数组并检查员工 ID。您应该考虑如果数组中特定索引处的员工为空会发生什么。您必须对此类情况进行检查。

您创建的其他方法之一也存在类似问题。我会让你自己调试。

正如@NomadMaker 所建议的那样 - 您的第二个菜单项仅设置数组的元素 0。您不能添加两个或更多员工。

我建议，你尝试干运行你的代码，如果你觉得很难，尝试在 ide 中调试它。