初学者，关于list

import java.util.ArrayList;

class Employee {
    private String name;
    private float salary;
    private String idno;
//    public Object getIdno;

    public Employee(String name, float salary, String idno) {
        this.name = name;
        this.salary = salary;
        this.idno = idno;
    }

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

    public String getName() {
        return name;
    }

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

    public float getSalary() {
        return salary;
    }

    public void setIdno(String idno) {
        this.idno = idno;
    }

    public String getIdno() {
        return idno;
    }

}

class Employer {
    // ArrayList al = new ArrayList();
    ArrayList<Employee> al = null;


    public Employer() {
        al = new ArrayList<Employee>();
    }

    public void addemp(Employee emp) {
        al.add(emp);
    }

    public void show_info(String idno) {
        for (int i = 0; i < al.size(); i++) {
            Employee employee =  al.get(i);
            if (employee.getIdno().equals(idno)) { //这里进行了修改
                System.out.println("该员工的信息是：" + employee.getName() + " "
                        + employee.getIdno() + " " + employee.getSalary());
            }
        }
    }
}

public class Array_List {

    public static void main(String[] args) {
        Employee emp1 = new Employee("maozedong", 1000, "SB001");
        Employer eeeee = new Employer();
        eeeee.al.add(emp1);
        eeeee.show_info("SB001");
        System.out.println("第1个人的信息：" + emp1.getName() + " ;" + emp1.getIdno()
                + " ;" + emp1.getSalary());

    }

}