Java，似乎找不到我的继承问题

Question

我正在尝试找出我的问题。

出于某种原因，当我尝试设置销售人员的销售额时，它仅将第一个销售人员创建的销售额设置为最后一个销售人员的销售集合。

这里EmployeeDatabase保存着EmployeeList，它是Employee类型的容器对象。

我有其他类的代码，但我认为这就是所需要的......抱歉代码中缺少注释

我的输出:

John 12000.0
Set sales to: 12000.0
Joan 10000.0
Set sales to: 10000.0
Jack 5000.0
Set sales to: 5000.0
Name: John           Commision: 0.03 Sales: 5000.0
Name: Joan           Commision: 0.04 Sales: 0.0
Name: Jack           Commision: 0.02 Sales: 0.0

Payroll: 150.0

代码:员工数据库

public class EmployeeDatabase 
{

public static void main(String[] args) 
{
    EmployeeList emp = new EmployeeList();
    /*emp.enqueue(new SalesManager("Gee", 1000));
    emp.enqueue(new SalesManager("Gal", 1000));
    emp.enqueue(new SalesManager("Gem", 1000));*/
    emp.enqueue(new SalesPerson("John", 0.03));
    emp.enqueue(new SalesPerson("Joan", 0.04));
    emp.enqueue(new SalesPerson("Jack", 0.02));
    /*emp.enqueue(new Manager("Fred", 10000));
    emp.enqueue(new Manager("Frank", 5000));
    emp.enqueue(new Manager("Florence", 3000));
    emp.enqueue(new Programmer("Linda", 7));
    emp.enqueue(new Programmer("Larry", 5));
    emp.enqueue(new Programmer("Lewis", 3));*/

    /*emp.setHours("Linda", 35);
    emp.setHours("Larry", 23);
    emp.setHours("Lewis", 3);*/
    emp.setSales("John", 12000);
    emp.setSales("Joan", 10000);
    emp.setSales("Jack", 5000);
    /*emp.setSales("Gee", 4000);
    emp.setSales("Gal", 3000);
    emp.setSales("Gem", 2000);
    emp.setSalary("Gee", 1000);
    emp.setSalary("Gal", 2000);
    emp.setSalary("Gem", 3000);*/
    emp.display();
}
}

员工名单

import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;


public class EmployeeList 
{
Queue<Employee> empList = new LinkedList<Employee>();

Employee find(String nm)
{
    Iterator<Employee> it = empList.iterator();
    while(it.hasNext())
    {
        Employee em = (Employee)it.next();
        if(!em.name.equals(nm))
        {
            return em;
        }   
    }
    return null;
}

double payroll()
{
    double payroll = 0.0;
    Iterator<Employee> it = empList.iterator();
    while(it.hasNext())
    {
        Employee em = (Employee)it.next();
        payroll += em.computePay(); 
    }
    return payroll;
}

void display()
{
    Iterator<Employee> it = empList.iterator();
    while(it.hasNext())
    {
        Employee em = (Employee)it.next();
        em.display();   
    }
    System.out.println("\nPayroll: " + payroll());
}

void enqueue(Employee e)
{
    empList.add(e);
}

void setHours(String nm, int hrs)
{
    Employee em = find(nm);
    /*if(em == null)
        return;*/
    em.setHours(hrs);
}

void setSalary(String nm, float salary)
{
    Employee em = find(nm);
    /*if(em == null)
        return;*/
    em.setSalary(salary);
}

void setSales(String nm, double sales)
{
    System.out.println(nm + " " + sales);
    Employee em = find(nm);
    /*if(em == null)
        return;*/
    em.setSales(sales);
}
}

员工

abstract class Employee 
{
String name;

Employee() {}
Employee (String nm) { name = nm; }
abstract double computePay();
void display () {}
void setHours(double hrs) {}
void setSales(double sales) {}
void setSalary(double salary) { System.out.println("NO!"); }
 }

工资员工

public class WageEmployee extends Employee 
{
double rate;
double hours;

WageEmployee(String name)
{
    this.name = name;
    if(this.name.length() < 14)
    {
        while(this.name.length() < 14)
        {
            this.name += " ";
        }
    }
}
WageEmployee(String name, double rate)
{
    this.name = name;
    if(this.name.length() < 14)
    {
        while(this.name.length() < 14)
        {
            this.name += " ";
        }
    }
    this.rate = rate;
}

double computePay()
{
    return rate * hours;
}

void setHours(double hrs) 
{
    hours = hrs;
    System.out.println("Set Hours to: " + hours);
}

 void display () 
 {
     System.out.println("Name: " + name + " Hours: " + hours + " Rate: " + rate);
 }
}

销售人员

public class SalesPerson extends WageEmployee 
{
double comission;
double salesMade;

SalesPerson(String name, double commision) 
{
    super(name);
    this.comission = commision;
}

double computePay()
{
    return comission * salesMade;
}

void setSales(double sales) 
{
    salesMade = sales;
    System.out.println("Set sales to: " + salesMade);
}

void display () 
 {
     System.out.println("Name: " + name + " Commision: " + comission + " Sales: " + salesMade);
 }
}

Answer 1

这段代码有两个问题。

首先，有一个额外的!在 find 方法中。

if(!em.name.equals(nm)) 应为 if(em.name.equals(nm))。

第二个问题是在工资员工构造函数中创建的填充。

if(this.name.length() < 14)
{
    while(this.name.length() < 14)
    {
        this.name += " ";
    }
}`

这段代码使得您正在寻找的“John”实际上是“John”。注意间距。 (射击，Markdown 消除了大部分内容，但你会在最后得到额外的间距)。这会导致名称永远不会比较相等，从而在您尝试与不存在的员工一起工作时导致空指针异常。

对此有三种可能的解决方案。首先，在比较之前对 em.name 使用 String.trim 方法。其次，按照比较之前存储的方式填充搜索名称。第三，您也许可以完全删除填充(我不知道您的用例，但 String.format 可能允许您仅在输出时填充)。