将int转换为枚举类型

Question

Hello I seem to be having trouble with a project that I am working on. I have created an enum type named Shift for breakfast lunch dinner swing), I then have a switch with 4 cases to choose which one it is.

However when I try to create an object without any user input, and set the value to a random number from 1-4, there is a message that appears saying "incompatible types : int can not be converted to Shift"

any help would be appreciated!

EDIT* I currently have this

private void getShiftAsInput()

{

  Scanner cin = new Scanner(System.in);
  System.out.print(" Please enter " + getName()
           + "'s Shift by Number:\n"
                   + "1.  Breakfast\n"
                   + "2.  Lunch\n"
                   + "3.  Dinner\n"
                   + "4.  Swing ========> ");
  String inShift = cin.nextLine();
  switch(inShift){
      case "1": shift = Shift.breakfast; break;
      case "2": shift = Shift.lunch; break;
      case "3": shift = Shift.dinner; break;
      case "4": shift = Shift.swing; break;
      default: getShiftAsInput(); break;
  }
}

public enum Shift { breakfast, lunch, dinner, swing }

and in the main classs am trying to do this:

   RestaurantWorker[] arr;
   arr = new RestaurantWorker[6];

   arr[0] = new Manager();
   arr[1] = new Manager("John Edelman", "8521100900", 3, 10, 1000, 40000);
   arr[2] = new WaitStaff();
   arr[3] = new WaitStaff("Kelsey Green", "5662902901", 3, 36, 10.25, 40, 10, 2 );
   arr[4] = new KitchenStaff();
   arr[5] = new KitchenStaff("Jeff Brown", "8596042909", 2, 30, 10, 30, 0);

but am getting an error for the argument after the phone number.

Answer 1

You have to provide a way to convert int to your target Enum .

This is my way to do that:

public enum Shift {
   BREAKFAST(1), LUNCH(2), DINNER(3), SWING(4);

   private final int value;

   public Shift(int value) {
      this.value = value; 
   }

   private static final Map<Integer, Shift> SHIFT_MAP = new HashMap<>();
   static {
      Arrays.stream(Shift.values()).forEach(s -> SHIFT_MAP.put(s.getValue(), s));
   }

   public static Shift of(Integer value) {
       return SHIFT_MAP.getOrDefault(value, BREAKFAST); // Here you provide a default Shift value if input wrong value
   }
}

And in your switch statement:

Shift shift = Shift.of(value);
switch(shift) {
  case BREAKFAST:
 ... bla bla
}

Answer 2

This is how your code should be, the type mismatch is because you have to pass ENUM into the switch case.

public class Practise {
static enum SHIFT {
    BREAKFAST, LUNCH, DINNER
}

public static void main(String[] args) {
    SHIFT key = SHIFT.BREAKFAST; // hardcoded for example, but can be dynamic
    switch (key) {
    case BREAKFAST:

        break;

    default:
        break;
    }
}

}

When you generate random integer values, you can change your logic to assign an ENUM value to the variable. Something like,

SHIFT key = SHIFT.values()[getRandomIndex()];

Answer 3

You're setting an an int type to an Object Type, instead of "Shift = int" try "Shift.YourDataField = int"

"YourDataField" is whatever field you set in your object, and it should be an int type