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Java Forum / General / February 2006What would you throw?
One of these "not gonna happen before the heat death of the Universe" questions that drive me nuts. Map.size() returns an int, so what should I throw if someone tries to add more than Integer.MAX_VALUE entries to my map -- which could happen on a 64-bit JVM? IllegalStateException? ArithmeticException? Thoughts?  Signature======================================================================== Ian Pilcher i.pilcher@comcast.net ======================================================================== > One of these "not gonna happen before the heat death of the Universe" > questions that drive me nuts. [quoted text clipped - 7 lines] > > Thoughts? IllegalArgumentException? Consistency is the key. How do you test your app? Do you want to look up every time to see what you throw? For this reason I like IllegalArgumentException -- Mike W There is nothing wrong with argument passed though, it is the data structure which cannot cope, so I say IllegalStateException Opalinski opalpa@gmail.com http://www.geocities.com/opalpaweb/ <opalpa@gmail.com> wrote in message news:1140828103.563105.266130@u72g2000cwu.googlegroups.com... > There is nothing wrong with argument passed though, it is the data > structure which cannot cope, so I say IllegalStateException Yes, of couirse, sorry reasonogjing p[oerwrs reduiced since quite drujnik. > add more than Integer.MAX_VALUE entries to my map -- which could happen > on a 64-bit JVM? Who told you that? The tooth fairy? It is untrue, which moots the remainder of your question. -- Tony Morris http://tmorris.net/ > One of these "not gonna happen before the heat death of the Universe" > questions that drive me nuts. [quoted text clipped - 7 lines] > > Thoughts? This is defined in the API spec for java.util.Map.size() "Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE." Alun Harford > This is defined in the API spec for java.util.Map.size() > "Returns the number of key-value mappings in this map. If the map contains > more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE." D'oh! Signature======================================================================== Ian Pilcher i.pilcher@comcast.net ======================================================================== > Map.size() returns an int, so what should I throw if someone tries to > add more than Integer.MAX_VALUE entries to my map Why should you care ? Leaving aside the observation that it's unrealisitic to worry about such things, it's the /map's/ job to determine its capacity not yours. If it can't accept another entry then it should throw something, it's not your responsibility to police /its/ limitations. OTOH, if you are creating your own implementation of Map, then either you really care about this situation, in which case I don't see why you should code your Map to have this limitation, or you don't and are just painting the lily, in which case do whatever seems convenient. Throw a custom exception, throw an ill-choosen exception (OutOfMemory ?), go into an infinite loop, whatever takes your fancy. -- chris On Sat, 25 Feb 2006 09:26:39 -0000, "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> wrote, quoted or indirectly quoted someone who said : >Throw a custom exception, throw an >ill-choosen exception (OutOfMemory ?), go into an infinite loop, whatever takes >your fancy. The one I end up using is IllegalArgumentException but that most of the time is not a very accurate name for what has happened. There should be standard one with a name like BadData or MalformedData to complate about the format of data in files. Maybe ProblemTooBigException.. It is easy to get carried away. SignatureCanadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. > There should be standard one with a name like BadData or > MalformedData to complate about the format of data in files. FWIW, IllegalStateException seems to fit Ian's requirements exactly. You have asked an object to perform an operation when that object is not in a state where it can comply. But, I stick by my earlier answer. -- chris > > Map.size() returns an int, so what should I throw if someone tries to > > add more than Integer.MAX_VALUE entries to my map [quoted text clipped - 5 lines] > accept another entry then it should throw something, it's not your > responsibility to police /its/ limitations. If you might put more than 2^31 entries into a map, you need to deal with the fact that the interface is badly defined so that size() return an int. > OTOH, if you are creating your own implementation of Map, then either you > really care about this situation, in which case I don't see why you should code > your Map to have this limitation, You don't have a choice. Map.size() returns an int. Clearly, because the map can contain more than Integer.MAX_SIZE elements, it _should_ return a long - and Sun have had to do a nasty hack to keep backwards compatibility. Alun Harford > You don't have a choice. Map.size() returns an int. Clearly, because the map > can contain more than Integer.MAX_SIZE elements, it _should_ return a long - > and Sun have had to do a nasty hack to keep backwards compatibility. Sun's nasty hack breaks every bit of code out there that relies on size returning a meaningful value, including their own AbstractSet. Demo at: http://home.comcast.net/~i.pilcher/IntegerSet.java Signature======================================================================== Ian Pilcher i.pilcher@comcast.net ======================================================================== Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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