在數組列表中添加多個值

Question

我創建了一個類employee.it，它有四個變量name，id，salary，city.i創建了一個僱員類對象的數組列表。當我運行該文件時，它只顯示defaullt values.But我想在我的數組list.what應該怎麼做添加一個以上的價值嗎？請幫我解決這個這裏是我的代碼

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

您已經創建Employee類採用默認值的字段。

您尚未定義任何參數化構造函數或setter來容納新員工。看到如何做到這一點：

使用構造函數添加員工;迭代和打印員工列表：

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); 

添加參數化的構造函數Employee類：

class Employee { 

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

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

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

您還可以定義setter方法[在Employee類]舉行的實例變量的值。

Answer 2

當您需要使用不同的值創建該類的更多對象時，類的默認設置屬性不是一個好習慣。相反，

• 傳遞在構造函數中的參數的信息時對象的初始化，或

• 使用setter-getter

撰寫您員工類setter和getter，像這樣：

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; 
    } 

} 

然後你就可以輕鬆添加更多員工容易，

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，我得到下面的輸出：

EMP =僱員：名稱=薩拉; Id = 102;城市= orny;薪酬= 13000; hashCode = 27134973

listOfEmployee（0）= Employee：name = sarah; Id = 102;城市= orny;薪酬= 13000; hashCode = 27134973

emp =員工：姓名=姓名; Id = 12345;城市=城市;薪酬= 123456; hashCode = 1284693

listOfEmployee（1）= Employee：name = Name; Id = 12345;城市= cityName;薪酬= 123456; hashCode = 1284693