Lets say I've this code:
public class MyClass { public final static int valueA = 0; public final static int valueB = 1; private int parameter = -1; public MyClass(int parameter) { if(parameter != valueA && parameter != valueB) { throw new IllegalArgumentException("Exception description here"); } this.parameter = parameter; } } Is this a best practice? Or is there a better way to grantee that whatever the value passed on the constructor it has the same value as one of those variables?
The Java API contains many classes that throw exceptions in their constructors, so there's nothing wrong with that.
Example :
In java.net.URI class :
public URI(String str) throws URISyntaxException { new Parser(str).parse(false); } In java.util.ArrayList class :
public ArrayList(int initialCapacity) { super(); if (initialCapacity < 0) throw new IllegalArgumentException("Illegal Capacity: "+ initialCapacity); this.elementData = new Object[initialCapacity]; } 
Maybe you should look into Enums.
public enum MyEnum { A(0), B(1); private int parameter; public MyEnum(int parameter) { this.parameter = parameter; } } Basically, this forces that you can only have the object with the parameter = 0,or parameter = 1. However, this also only allows ONE instance of each type (0, 1, etc...), so this may not work depending on your use case.
