ArrayList不会在控制台中打印

Question

I have an Employee class with one method named addEmployee which manipulates an ArrayList to add employees. My following code won't print the list on the console screen. I can't find out what's wrong with my code.

package com.sib.Tmanager;

import java.util.ArrayList;
import java.util.Scanner;

public class Employee {
    private String EmpFName;
    private String EmpLName;

    public Employee(String empFName, String empLName) {
        super();
        EmpFName = empFName;
        EmpLName = empLName;
    }
    public String getEmpFName() {
        return EmpFName;
    }
    public void setEmpFName(String empFName) {
        EmpFName = empFName;
    }
    public String getEmpLName() {
        return EmpLName;
    }
    public void setEmpLName(String empLName) {
        EmpLName = empLName;
    }

    public static void addEmployee()
    {
        ArrayList<Employee> Emplist= new ArrayList<Employee>();

        Scanner s=new Scanner(System.in) ;

        System.out.println("Enter the Firstname of the employee");
        String Fname= s.next();
        System.out.println("Enter the Lastname of the employee");
        String Lname= s.next();

        Employee emp = new Employee(Fname, Lname);
        Emplist.add(emp);

        //System.out.println(emp.EmpFName +" "+ emp.EmpLName);

        System.out.println(Emplist);
    }

}

I tried to change my code by overriding the ToString() method and I still have the same following output.

Enter employee's Firstname

jason

Enter employee's Lastname

karl

[com.sib.Tmanager.Employee@1a758cb]

Answer 1

This may not be an answer, but a bit of advice about class design.

1. Think about an Employee as a physical object.
   • Should an Employee have a first name? Yes.
   • Should an Employee have a last name? Yes.
   • Should an Employee be filled with other Employyes ? Absolutley not.
2. If the above third point doesn't make sense, what should you do?
   • Create a class called something like EmployeeList . Should an EmplpoyeeList have Employees ? Why, of course!
   • The above class is the class you want to have the Employee ArrayList
   • Also, this is where you want to have the addEmployee method, so you can add the Employee the EmployeeList

Here's a example

public class EmployeeList {
    ArrayList<Employee> employees;

    public EmployeeList() {
        employees = new ArrayList<Employee>();
    }

    public void addEmployee(Employee employee) {
        employees.add(employee);
    }

    public void printEmployees() {
        for (Employee e : employees) {
            System.out.println(e);
        }
    }
}

So in the main , you first will create an EmployeeList then add Employee s to it.

public static void main(String[] args) {
    EmployeeList list = new EmployeeList();
    list.addEmployee(new Employee("Jim", "Bo");
    list.addEmployee(new Employee("Foo", "Bar");
    list.addEmployee(new Employee("First", "Last");

    list.printEmployees();
}

Note: to get the Employee object to print out as String representation, you should override the toString() method as others have suggested.

Answer 2

You can use Arrays.toString(empList.toArray(new Employee[0])) or empList.toString() in order to print the contents of an ArrayList . This will print nicely if you override toString() in Employee .

Answer 3

call AddEmployee() from public static void main()

System.out.println(Emplist)

you are trying to print Emplist object

you have to iterate the arraylist to show it's content

Answer 4

You should assign the ArrayList in the class fields and initialize it in the Constructor

public class Employee {
private String EmpFName;
private String EmpLName;
private ArrayList<Employee> Emplist;
.
.
.
}

public Employee(String empFName, String empLName) {
    super();
ArrayList<Employee> Emplist= new ArrayList<Employee>();
    EmpFName = empFName;
    EmpLName = empLName;
}

Now when you need to add you only do :

this.Emplist.add(x);

in the addEmployee method