如何在java中从抽象类arraylist打印特定对象类型

Question

下面的班级是我的主要班级。我的arraylist是“Employee”类型，并且该arraylist包含多个对象的许多元素（多态性）。所以我想知道，当用户输入一个类名时，我应该从ArrayList中打印出那个特定类的employees。例如，当用户输入“Surgeon”时，程序应该能够从ArrayList中打印出所有Surgeon雇员的。请帮忙，提前谢谢。

 import java.util.*;


public class HospitalDatabase {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        String q;
        String w;
        ArrayList<Employee> e = new ArrayList<Employee>(); 
        Employee s = new Surgeon("Christian Barnard", 2113211, "Cardiac", "Cardiology",
                2000, "Yale University");
        Employee i = new ITSupport("Mickey Mouse", 11280, Department.IT, 26, "Mac OS");
        Employee n = new Nurse("Florence Nightingale", 54678, "Urgent Care", 
                "Emergency", false, HospitalWing.North);
        Employee p = new PatientAccountsManager("Donald Duck", 32465, Department.PatientSupport, 
                99, true); 
        Employee s1 = new Surgeon("Sanjay Gupta", 42171, "Neurosurgery", 
                "Neurology", 500, "Duke University"); 
        Employee n1 = new Nurse("Mary Breckinridge", 56536, "Gynecology", "Midwife",
                true, HospitalWing.West);


        e.add(s);
        e.add(i);
        e.add(n);
        e.add(p);
        e.add(s1);
        e.add(n1);

        System.out.println(e.toString()); 
        System.out.println(Employee.numEmployees);
        System.out.println("-------------******--------------");

        Scanner scan = new Scanner(System.in);
        System.out.println("Enter a name: ");
        q = scan.nextLine();
        boolean j = false; 
        System.out.println("***************");

        for(Employee v: e){
            if(v.name.contains(q)){
                System.out.println(v.name);
                j = true; 
            }
        } 
        if(j == false){
            System.out.println("Name not found");
        }  
        System.out.println("----------------**************---------------");

        Scanner f = new Scanner(System.in);
        System.out.println("Enter the class of employees: ");
        w = f.nextLine();
        System.out.println("***************************"); 

        //PLEASE SHOW THE CODE HERE
    } 
}

Answer 1

您可以使用反射API来完成此操作。例如：

String className1 = e.getClass().getSimpleName();
String className2 = e.getClass().getName();
String className3 = e.getClass().getCanonicalName();

选择一个最适合你的考虑这篇文章。