[java] Java: Enum parameter in method

I have a method lets say:

private static String drawCellValue(
    int maxCellLength, String cellValue, String align) { }

and as you can notice, I have a parameter called align. Inside this method I'm going to have some if condition on whether the value is a 'left' or 'right'.. setting the parameter as String, obviously I can pass any string value.. I would like to know if it's possible to have an Enum value as a method parameter, and if so, how?

Just in case someone thinks about this; I thought about using a Boolean value but I don't really fancy it. First, how to associate true/false with left/right ? (Ok, I can use comments but I still find it dirty) and secondly, I might decide to add a new value, like 'justify', so if I have more than 2 possible values, Boolean type is definitely not possible to use.

Any ideas?

You can use an enum in said parameters like this:

public enum Alignment { LEFT, RIGHT }
private static String drawCellValue(
int maxCellLength, String cellValue, Alignment align) {}

then you can use either a switch or if statement to actually do something with said parameter.

switch(align) {
case LEFT: //something
case RIGHT: //something
default: //something
}

if(align == Alignment.RIGHT) { /*code*/}

I like this a lot better. reduces the if/switch, just do.

private enum Alignment { LEFT, RIGHT;

void process() {
//Process it...
} 
};    
String drawCellValue (int maxCellLength, String cellValue, Alignment align){
  align.process();
}

of course, it can be:

String process(...) {
//Process it...
} 

I am not too sure I would go and use an enum as a full fledged class - this is an object oriented language, and one of the most basic tenets of object orientation is that a class should do one thing and do it well.

An enum is doing a pretty good job at being an enum, and a class is doing a good job as a class. Mixing the two I have a feeling will get you into trouble - for example, you can't pass an instance of an enum as a parameter to a method, primarily because you can't create an instance of an enum.

So, even though you might be able to enum.process() does not mean that you should.

I like this a lot better. reduces the if/switch, just do.

private enum Alignment { LEFT, RIGHT;

void process() {
//Process it...
} 
};    
String drawCellValue (int maxCellLength, String cellValue, Alignment align){
  align.process();
}

of course, it can be:

String process(...) {
//Process it...
} 

Even cooler with enums you can use switch:

switch (align) {
   case LEFT: { 
      // do stuff
      break;
   }
   case RIGHT: {
      // do stuff
      break;
   }
   default: { //added TOP_RIGHT but forgot about it?
      throw new IllegalArgumentException("Can't yet handle " + align);

   }
}

Enums are cool because the output of the exception will be the name of the enum value, rather than some arbitrary int value.

Sure, you could use an enum. Would something like the following work?

enum Alignment {
    LEFT,
    RIGHT
}

private static String drawCellValue(int maxCellLength, String cellValue, Alignment alignment) { }

If you wanted to use a boolean, you could rename the align parameter to something like alignLeft. I agree that this implementation is not as clean, but if you don't anticipate a lot of changes and this is not a public interface, it might be a good choice.

You could also reuse SwingConstants.{LEFT,RIGHT}. They are not enums, but they do already exist and are used in many places.