Java using enum with switch statement

I've looked at various Q&As on SO similar to this question but haven't found a solution.

What I have is an enum which represents different ways to view a TV Guide...

In the NDroid Application class

static enum guideView {
    GUIDE_VIEW_SEVEN_DAY,
    GUIDE_VIEW_NOW_SHOWING,
    GUIDE_VIEW_ALL_TIMESLOTS
}

...when the user changes the view an event handler receives an int from 0-2 and I'd like to do something like this...

In an Android Activity onClick(DialogInterface dialog, int which) event handler

// 'which' is an int from 0-2
switch (which) {
    case NDroid.guideView.GUIDE_VIEW_SEVEN_DAY:
    ...
    break;
}

I'm used to C# enums and select/case statements which would allow something like the above and I know Java does things differently but I just can't make sense of what I need to do.

Am I going to have to resort to if statements? There will likely only ever be 3 choices so I could do it but I wondered how it could be done with switch-case in Java.

EDIT Sorry I didn't completely expand on the issue as I was looking at it as being a generic Java issue. I've added to the question to explain a bit further.

There isn't anything that's Android specific which is why I didn't tag it as Android but the enum is defined in the Application class and the code where I wan't the switch is in an Activity. The enum is static as I need to access it from multiple Activities.


Solution 1:

The part you're missing is converting from the integer to the type-safe enum. Java will not do it automatically. There's a couple of ways you can go about this:

  1. Use a list of static final ints rather than a type-safe enum and switch on the int value you receive (this is the pre-Java 5 approach)
  2. Switch on either a specified id value (as described by heneryville) or the ordinal value of the enum values; i.e. guideView.GUIDE_VIEW_SEVEN_DAY.ordinal()
  3. Determine the enum value represented by the int value and then switch on the enum value.

    enum GuideView {
        SEVEN_DAY,
        NOW_SHOWING,
        ALL_TIMESLOTS
    }
    
    // Working on the assumption that your int value is 
    // the ordinal value of the items in your enum
    public void onClick(DialogInterface dialog, int which) {
        // do your own bounds checking
        GuideView whichView = GuideView.values()[which];
        switch (whichView) {
            case SEVEN_DAY:
                ...
                break;
            case NOW_SHOWING:
                ...
                break;
        }
    }
    

    You may find it more helpful / less error prone to write a custom valueOf implementation that takes your integer values as an argument to resolve the appropriate enum value and lets you centralize your bounds checking.

Solution 2:

If whichView is an object of the GuideView Enum, following works well. Please note that there is no qualifier for the constant after case.

switch (whichView) {
    case SEVEN_DAY:
        ...
        break;
    case NOW_SHOWING:
        ...
        break;
}