java - 你能将枚举类传递给方法吗(java)

Question

我想将特定的枚举类传递给方法。这可能吗？该方法将接受任何枚举。我正在尝试创建一个函数，该函数将采用一种枚举类型并从中创建一个菜单，返回所选的枚举。

枚举类示例

  public enum METHODOFTRANSPORTATION {
        CAR("car"), BUS("bus"), COMMUTTER_RAIL("commuter rail"),MAINMENU("GO TO MAIN MENU");

        private String choice;

        METHODOFTRANSPORTATION(String choice){
            this.choice = choice;
        }

        public String getMethodOfTransportation(){
            return choice;
        }
    }

我的示例类实现了枚举

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;


public class Ticket{

    private static HashMap<Integer, Ticket> hm= new HashMap<>();
    private int ticketID = 0;

    private METHODOFTRANSPORTATION methodOfTransportation;

    Ticket(){
        //Call method of Transportation to create ticket
        //GETTING ERROR HERE!
        this.methodOfTransportation = createMethodOfTransportation(METHODOFTRANSPORTATION);
    }

    Ticket(METHODOFTRANSPORTATION methodOfTransportation){
        this.methodOfTransportation = methodOfTransportation;
    }

    public Enum<?> getMethodOfTransportation() {
        return methodOfTransportation;
    }   

    public Enum<?> createMenuChoice(Enum<?> e) {
        System.out.println("**************************");

        Scanner s = new Scanner(System.in);
        int input = 0;
        boolean intFlag = false;
        Enum<?> mot;

        //Validate user input for menu selection
        do{
            //Print our Enums allowed variables
            for(int i=0; i< e.getDeclaringClass().getEnumConstants().length; i++){
                System.out.printf("%d. %s",i,e.getDeclaringClass().getEnumConstants()[i]);
            }

            System.out.println("Please enter a valid menu entry (");
            for(int i = 0; i< e.getDeclaringClass().getEnumConstants().length; i++){
                if(i == e.getDeclaringClass().getEnumConstants().length){
                    System.out.println(i);
                }
                else{
                    System.out.print(i + ",");
                }
            }
            System.out.print("> ");

            if(s.hasNextInt()){
                input = s.nextInt();
                for(int i = 0; i< e.getDeclaringClass().getEnumConstants().length; i++){
                    if(input == i){
                        //*********************************************
                        //HOW DO I RETURN THE CORRESPONDING VALUE HERE?
                        //*******************************************
                        mot =  ;
                    }
                }
            }
            else{
                s.next();
            }
        }
        while(false);

        //WHAT SHOULD I RETURN HERE??
        return METHODOFTRANSPORTATION.CAR;
    }


}

这可能吗？我只想要一种可以接受任何枚举类并返回枚举值的方法。有更好的方法吗？

基本上我的驱动程序类看起来像

public class Driver {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Ticket t = new Ticket();

        Enum<?> mot = t.getMethodOfTransportation();
        if(mot == METHODOFTRANSPORTATION.CAR){
            //....
        }
        //...

        //OR
        /*
         * switch(mot){
         *      case(METHODOFTRANSPORTATION.CAR): ...
         *      ...
         *      ...
         * }
         */
    }


}

Answer 1

在 Java 中引用类的正确方法是 ClassName.class。所以你的行将是:

this.methodOfTransportation = createMethodOfTransportation(METHODOFTRANSPORTATION.class);

METHODOFTRANSPORTATION.class 返回一个 Class 类型对象。然后，您可以使用反射来检查其名称、可能的值等。 Here is more info on enum reflection.

名称 createMethodOfTransportation 但并不合适，因为它与特定枚举 METHODOFTRANSPORTATION 没有任何关系。