Java using enum with switch statement

Question

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.

Answer 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.

Answer 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; }