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Can anyone please answer the below questions?

  1. Can I use logical operator over enum values? For example: 

    enum Days { MONDAY(1), TUESDAY(2), WEDNESDAY(3), THURSDAY(4), FRIDAY(5), SATURDAY(6), SUNDAY(7) }

    now can I use if(Days.SUNDAY > Days.MONDAY) ....?

  2. Is there any process to specify a range of values for enum? For example, I want to specify the valid numbers for an exam should be between 1 - 100. So if I want to declare an enum, then it would be like this -> enum Validno{ONE(1),TWO(2),....,HUNDRED(100)} Now is there any option to declare an enum containing the each values and specify them like a range instead of declaring each one seperately?

    • Thanks in advance.
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  • 5
    Possible and possible. Commented Mar 16, 2014 at 15:15
  • 8
    For #1, couldn't you just have tried it? Commented Mar 16, 2014 at 15:16
  • For #2, it's not clear what you want. Are you asking whether there's a way to generate the enum ONE(1), TWO(2), ... HUNDRED(100) without actually typing it all in to your source code? Commented Mar 16, 2014 at 15:17
  • 1
    With not just use an int for #2? It's not the best use of enums. Commented Mar 16, 2014 at 15:19
  • You better use enums for a small set. 100 values I would say it's too big to use as an enum. Commented Mar 16, 2014 at 15:24

3 Answers 3

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For #1, you can use ordinal method as below

enum Day { MON, TUE, WED, THU, FRI, SAT, SUN } public class EnumExample { public static void main(String[] args) { System.out.println(Day.MON.ordinal() < Day.TUE.ordinal()); // Prints true System.out.println(Day.MON.ordinal() > Day.TUE.ordinal()); // Prints false } }

for #2: why do you want to use enums? You can simple comparison. Like for eg: 

if(marks > 0 && marks < 100)
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You can also use Day.MON.compareTo(Day.TUE) > 0. Enums automatically implement Comparable.
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For #1, yes it's possible using compareTo method.

You could do something like this:

enum Days { Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday } public static void main(String[] args) { System.out.println(Days.Monday.compareTo(Days.Sunday)); // Returns negative value System.out.println(Days.Thursday.compareTo(Days.Tuesday)); // Returns positive value System.out.println(Days.Tuesday.compareTo(Days.Tuesday)); // Returns zero }

For #2, I don't think there's a way to declare enums programatically. You will have to list down ONE to HUNDRED, if you want to use enum.

Instead, why don't you just declare a function that checks if a given score is valid or not? It could be something like this:

public boolean isValid(int score){ return score>=0 && score<=100; }
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As an alternative for your second problem, you can simply use a regular class:

public final class Score implements Comparable<Score> { private final int value; public Score(int value) { if (value < 0 || value > 100) { throw new IllegalArgumentException("score value must be between 0 and 100"); } this.value = value; } public int getValue() { return value; } // equals, hashCode and compareTo omitted, but should be there }

This gives you the type safety of an enum, without the need to declare every of the 101 values independantly. No one will ever be able to create a score with an incorrect value.

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Thanks for ur suggestion ... actually I want to assign a pririty for the objects of a certain class. Now the priority should be in between 1-100 ... that's why I am thinking of using enum... but while I am writing code, I have to type ONE to HUNDRED ... that's the problem ...

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