Enum class using constants

[Clay Chow]

My Code :

public enum ExpenseCategory1 { NECESSITY(0,rangeIncrement), LUXURY(1000001, 2000000);

static final int rangeIncrement = 1000000;

private int startRange;
private int endRange;

ExpenseCategory1(int a, int b) {
this.startRange = a;
this.endRange = b;
}

public int getStartRange() {
return startRange;
}

public int getEndRange() {
return endRange;
}

}


Error: Illegal Forward Reference when I attempt to refer to 'illegal forward reference'


Question: how would I implement this (using a constant in the enum declaration? )


thanks

[marc weber]

Welcome to JavaRanch!

I don't know the "best" way to handle this. There's probably a pattern that would apply nicely, so perhaps another rancher will offer a more elegant solution.

In the meantime, one thing you could do is define a nested interface for your constants...

public enum ExpenseCategory1 {
  NECESSITY(0, ExpenseConstants.RANGE_INCREMENT), 
  LUXURY(1000001, 2000000);
  
  interface ExpenseConstants {
    int RANGE_INCREMENT = 1000000;
  }
  //...

[Rob Spoor]

public enum ExpenseCategory1
{
    NECESSITY(0, getRangeIncrement()),
 
    LUXURY(1000001, 2000000);
 
    static final int rangeIncrement = 1000000;
 
    static int getRangeIncrement()
    {
        return rangeIncrement;
    }
 
    private int startRange;
 
    private int endRange;
 
    ExpenseCategory1(int a, int b)
    {
        this.startRange = a;
        this.endRange = b;
    }
 
    public int getStartRange()
    {
        return startRange;
    }
 
    public int getEndRange()
    {
        return endRange;
    }
 
    public static void main(String[] args)
    {
        for (ExpenseCategory1 cat: values())
        {
            System.out.printf("%d - %d%n", cat.getStartRange(), cat.getEndRange());
        }
    }
}

Output:

0 - 1000000
1000001 - 2000000

[Clay Chow]

Cool

thanks


Haven't checked back for a while

[Clay Chow]

Actually got another question about enums:

say I have an enum declared as:

enum LETTER {A,B,C}

does each value have a corresponding int value ? (like A = 1, B= 2).

I'm asking because I want to convert an int to the enum type, such that the following will compile:

LETTER opt = (LETTER) 2;
switch (opt) {
CASE A:
CASE B:
}

thanks

[Clay Chow]

I found one way, not sure if there is a more elegant way to do it.

LETTER opt = LETTER.values()[2];
 
switch (opt) {
CASE A:
CASE B:
}

It does seem a bit silly, but I have a method that receives user input (in the form of an int).

Originally posted by Clay Chow:
Actually got another question about enums:

say I have an enum declared as:

enum LETTER {A,B,C}

does each value have a corresponding int value ? (like A = 1, B= 2).

I'm asking because I want to convert an int to the enum type, such that the following will compile:


thanks

[Rob Spoor]

That seems to be the best way to do it. I didn't even think of that - I was about to suggest getting values() and then iterating over it. But that's completely unnecessary of course

And next time, instead of creating several posts below each other with just a few minutes in between, could you please use the edit button () the next time to edit your last post?