访问和修改数组列表的问题

Question

我想创建一个程序，允许用户删除员工与指定的工资单号码。

import java.util.*;

import personnelPackage.Personnel;

public class ArrayListTest
{
    static Scanner keyboard = new Scanner(System.in);

    public static void main(String[] args)
    {
        long searchQuery;

        ArrayList<Personnel> staffList = new ArrayList<Personnel>();
        Personnel[] staff =
            {new Personnel(123456,"Smith","John"),
             new Personnel(234567,"Jones","Sally Ann"),
             new Personnel(999999,"Black","James Paul")};

        for (Personnel person:staff)
            staffList.add(person);

        do
        {
            showDisplay(staffList);

            System.out.print("\nPlease enter a payroll number to search: ");
            searchQuery = keyboard.nextLong();

            searchForPayrollNumber(staffList, searchQuery);


        }while(!(searchQuery == 0));


    }

    private static void showDisplay(ArrayList<Personnel> staffList)
    {
        System.out.print("\n------------- CURRENT STAFF LIST -------------\n");
        for (Personnel person : staffList)
        {
            System.out.println("Payroll number: " + person.getPayNum());
            System.out.println("Surname: " + person.getSurname());
            System.out.println("First name(s): " + person.getFirstNames() + "\n");
        }
    }

    public static void searchForPayrollNumber(ArrayList<Personnel> staffList, long searchQuery)
    {
        long index = staffList.indexOf(searchQuery);;

        for (Personnel person: staffList)
        {
            if (person.getPayNum() == searchQuery)
            {               
                System.out.print("\n------------- Staff member found and removed! -------------");
                System.out.println("\n\nFirst Name(s): " + person.getFirstNames());
                System.out.println("\nSurname: " + person.getSurname());
                System.out.print("\n-----------------------------------------------");

                staffList.remove(index);
                return;
            }
        }

        System.out.print("\n------------- No staff members found. Program terminated -------------");
        return;

    }

}

java（在其名为PersonnelPackage的包中）

package personnelPackage;

public class Personnel
{
    private long payrollNum;
    private String surname;
    private String firstNames;

    public Personnel(long payrollNum, String surname, String firstNames)
    {
        this.payrollNum = payrollNum;
        this.surname = surname;
        this.firstNames = firstNames;
    }

    public long getPayNum()
    {
        return payrollNum;
    }

    public String getSurname()
    {
        return surname;
    }

    public String getFirstNames()
    {
        return firstNames;
    }

    public void setSurname(String newName)
    {
        surname = newName;
    }
}

当我输入工资单号码时，我的程序只识别第一个工作人员。任何其他工作人员都不会被‘发现’。我在哪里出了问题？如何从数组中删除特定的工资单号码并向用户请求另一个输入（直到数组为“空”）。

Answer 1

删除else块中的return语句。

    for (Personnel person: staff)
    {
        if (person.getPayNum() == searchQuery)
        {
            System.out.print("\n------------- Staff member found! -------------");
            System.out.println("\n\nFirst Name(s): " + person.getFirstNames());
            System.out.println("Surname: " + person.getSurname());
            return;
        }
        else
        {
            System.out.print("\n------------- No staff members found -------------");
            return;  // Remove this one.
        }
    }

通过在条件的每个分支中都有一个return语句，这个循环将只执行一次。

请注意，您可能还希望将els的内容移到循环之外，否则，对于每个检查的人员，您都将被告知“没有找到工作人员”。

    for (Personnel person: staff)
    {
        if (person.getPayNum() == searchQuery)
        {
            System.out.print("\n------------- Staff member found! -------------");
            System.out.println("\n\nFirst Name(s): " + person.getFirstNames());
            System.out.println("Surname: " + person.getSurname());
            return;
        }
    }
    System.out.print("\n------------- No staff members found -------------");

要进行有效的移除，需要使用迭代器；增强的for循环不起作用。粗略的实现如下所示：

Iterator<Personnel> it = staff.iterator();
while (it.hasNext()) {
  Personnel person = it.next();
  if (person.getPayNum() == searchQuery)

{//...打印等it.remove（）；return；}}