Question

我创建了一个类employee.it有四个变量名称，id，salary，city.i已经创建了一个雇员类对象的数组列表。当我运行该文件时，它只显示默认值。但我想要在我的数组列表中添加多个值。我该怎么办？请帮我解决这个问题，这是我的代码

 import java.util.*;
    public class arraylist {

     public static void main(String[] args) {
        new arraylist();
       }

    public arraylist() {

        List<Employee > listOfEmp = new ArrayList<Employee >();
        Employee  bk1 = new Employee ();
        listOfEmp .add(bk1);

        System.out.println("   emp = " + bk1);
        System.out.println("listOfEmployee(0) = " + listOfEmp.get(0));

    }

    public class Employee {

        String name="sarah";
        int id =102;
        String city="orny";
        int salary=13000;

       // @Override
        public String toString() {
            return "Employee: name = " + name + "; Id = " + id + "; City = " + city + "; Salary = " + salary + "; hashCode = " + hashCode();
        }

    }
}

Answer 1

您已使用字段的默认值创建了Employee类。

您还没有定义任何参数化的构造函数或setter来保存新的Employee。看看如何做到这一点：

使用构造函数添加Employee;迭代并打印员工名单：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

if([self checkForSelectedRow:indexPath]){
//change the title of button

}
else{
 //default of button
}

在Employee类中添加参数化构造函数：

List<Employee> listOfEmp = new ArrayList<Employee>();

// Add employee to list
listOfEmp.add(new Employee("sarah1", 101, "orny", 13000));
listOfEmp.add(new Employee("sarah2", 102, "orny", 13000));
listOfEmp.add(new Employee("sarah3", 103, "orny", 13000));

// Iterate and print employee list
for (Employee employee : listOfEmp)
    System.out.println(employee);

您还可以在[Employee类]中定义setter方法来保存实例变量的值。

Answer 2

当您需要使用不同的值创建该类的更多对象时，类的默认设置属性不是一个好习惯。相反，

在对象初始化时传递构造函数参数中的信息，或
使用setter-getter

使用setter和getter撰写您的员工课程，如下所示：

public class Employee {

    String name;
    int id;
    String city;
    int salary;

    public Employee() {
        // do something if u want
    }

    public Employee(String name, int id, String city, int salary) {
        this.name = name;
        this.id = id;
        this.city = city;
        this.salary = salary;
    }

    public String toString() {
        return "Employee: name = " + name + "; Id = " + id + "; City = " + city
                + "; Salary = " + salary + "; hashCode = " + hashCode();
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

}

然后您可以轻松地轻松添加更多员工，

import java.util.*;

public class Arraylist {

    public static void main(String[] args) {
        new Arraylist();
    }

    public Arraylist() {

        List<Employee> listOfEmp = new ArrayList<Employee>();
        Employee bk2 = new Employee(); //will set attribute later
        Employee bk1 = new Employee("sarah", 102, "orny",13000);// attributes set here

        listOfEmp.add(bk1);

        bk2.setCity("City");
        bk2.setId(12345);
        bk2.setName("Name");
        bk2.setSalary(123456);

        listOfEmp.add(bk2);

        System.out.println("   emp = " + bk1);
        System.out.println("listOfEmployee(0) = " + listOfEmp.get(0));

        System.out.println("   emp = " + bk2);
        System.out.println("listOfEmployee(1) = " + listOfEmp.get(1));

    }
}

目前，我得到以下输出：

emp =员工：name = sarah; Id = 102; City = orny;薪水= 13000;   hashCode = 27134973

listOfEmployee（0）=员工：name = sarah; Id =   102; City = orny;薪水= 13000; hashCode = 27134973

emp =员工：name = Name; Id = 12345;城市=城市;薪水=   123456; hashCode = 1284693

listOfEmployee（1）=员工：name = Name;   Id = 12345; City = cityName;薪水= 123456; hashCode = 1284693

在数组列表中添加多个值

2 个答案: