Avoiding multiple else ifs
Hi,
I am accepting an argument from a method and I want to enforce the user to send only a particular list of arguments (say: "Dog", "Cat", "Monkey"). So, I have created an interface and stored these values as constants.
Ideally the user of this method will call this method like:
myClass.myMethod(AnimalInterface.CAT);
But I have to check whether the argument sent will equal any of the interface constants defined in the AnimalInterface inside of my method. If it doesn't match, then I have to throw an IllegalArgumentException.
But, my problem is in the AnimalInterface, let's if I have about 20 constants, writing 20else ifs seems to be very weird. Is there any other way to get around this problem.
Thank you!
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[778 byte] By [
sri1025a] at [2007-10-3 3:21:40]
Use 1.5 and make an Enum.
If that's not an option, you'll have to simulate an enum yourself (using String/int constants inside an interface is not the way to go) and pass an instance of that, instead of a String.
final class AnimalsEnum {
private AnimalsEnum(String name) { myName = name; }
private final String myName;
public static final AnimalsEnum DOG = new AnimalsEnum("Dog");
public static final AnimalsEnum CAT = new AnimalsEnum("Cat");
//etc...
//probably implement toString to return myName
}
//and you would declare the target method as
void myMethod(AnimalsEnum animal);
//instead of
void myMethod(String animal);
If you can't use 1.5 Enums, I think something like that is the best solution; no more need to check inside your method since the argument can't have any other value than the ones defined in your class.
Lokoa at 2007-7-14 21:14:01 >
Define your constants within an enum class instead of an interrface. Then you can call a static method within the enum to get your constant value.
public enum AnimalEnum {
// list your animals
...
public static AnimalEnum valueOf(String name) {
// find the defined constant matching the String
// maybe return null if there's no match
}
}
Method myMethod can then throw an llegalArgumentException if it is passed a null.
myClass.myMethod(AnimalEnum.valueOf(userString));
