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Java Forum / First Aid / June 2005which data structure to use
Hi, I have data that I need to store in a data structure: key value === ===== name object What is a good data stucture to use if I need to sort the keys ( and the accompanied objects)? //mikael > Hi, > [quoted text clipped - 5 lines] > What is a good data stucture to use if I need to sort the keys ( and the > accompanied objects)? Seems like java.util.SortedMap is just what you need. Take a look at the API docs. ;) There, you'll also find a handy ready-made implementation  SignatureIn pioneer days they used oxen for heavy pulling, and when one ox couldn't budge a log, they didn't try to grow a larger ox. We shouldn't be trying for bigger computers, but for more systems of computers. --- Rear Admiral Grace Murray Hopper Stefan Schulz coughed up: ...[rip]... (quoted signature:) > In pioneer days they used oxen for heavy pulling, and when one ox > couldn't budge a log, they didn't try to grow a larger ox. We shouldn't > be trying for bigger computers, but for more systems of computers. > --- Rear Admiral Grace Murray Hopper Bah. {blowing raspberries with much spit} They always tried to grow the most powerful oxen possible. That quickly hit an upper limit, and they were left with no choice than to team them together. In the case of computers, people also try to make the most powerful systems possible. And they still get teamed together when it's cost effective to do so. SignaturePuzzle: You are given a deck of cards all face down except for 10 cards mixed in which are face up. If you are in a pitch black room, how do you divide the deck into two piles (may be uneven) that each contain the same number of face-up cards? Answer (rot13): Sebz naljurer va gur qrpx, qrny bhg gra pneqf naq syvc gurz bire. > Stefan Schulz coughed up: > [quoted text clipped - 15 lines] > possible. And they still get teamed together when it's cost effective to do > so. R.A. Grace Murray Hopper died in 1992 at the age of 85. Presuming she said that at 'retirement age' of 65, that places the statement at 1972 (but quite probably before that). 1972 was 33 years ago. If we had simply tied more computers together as from that point, we would need a ..lot more computers to service the needs of our current day computing needs. Taking Moore's law of a doubling in processor speed every 18 months, would lead to approximately 2^(33/1.5) ..or 2^22 or 4,194,304 computers for every current day machine. Not that I hav anything against running thousands of processors in parallel (I am over this entire 'You can have 1 ..or 2 processors!' deal) but R.A. G.M.H.'s suggestion seems rather impractical. SignatureAndrew Thompson http://www.PhySci.org/codes/ Web & IT Help http://www.PhySci.org/ Open-source software suite http://www.1point1C.org/ Science & Technology http://www.LensEscapes.com/ Images that escape the mundane >>Stefan Schulz coughed up: >> [quoted text clipped - 34 lines] > in parallel (I am over this entire 'You can have 1 ..or 2 > processors!' deal) but R.A. G.M.H.'s suggestion seems rather impractical. Once you put it that way, it *does* really sound rather ridiculous. (Imagine having roughly four million computers of the 1970's era on *your* desk ;-) However, it still doesn't prevent parallel processing from being an effective solution in some cases - SETI@home and similiar "donate you computer's spare processor time"-schemes for example. Signature-Aki "Sus" Laukkanen > R.A. Grace Murray Hopper died in 1992 at the age of 85. > [quoted text clipped - 9 lines] > would lead to approximately 2^(33/1.5) ..or 2^22 or 4,194,304 computers > for every current day machine. Taking today's processor speed as 3 GHz, the same calculation says the 1972 machine ran at about 715 Hz. (Geez, it sure seemed faster to me -- but I was young and impressionable back then, and probably *wanted* to believe the instruction timing numbers were in microseconds rather than their milliseconds. Hmmm: Anybody know how that 715 Hz machine kept pace with the card reader? ;-) SignatureEric.Sosman@sun.com > > Stefan Schulz coughed up: > > [quoted text clipped - 33 lines] > in parallel (I am over this entire 'You can have 1 ..or 2 > processors!' deal) but R.A. G.M.H.'s suggestion seems rather impractical. Great analysis, Andrew. I couldn't find a date of attribution for the quotation, but I did find that her official Navy retirement was in 1986 and she was still working as a consultant for DEC up until her death. (I'll skip jumping to a cynical conclusion there.) http://en.wikipedia.org/wiki/Grace_Hopper It's also true that parallel computing is much more effective for numerical analysis and hardware systems than for ordinary desktop applications, so we are making use of parallel processors today, just not in terms of general computing power. Cheers, Matt Humphrey matth@ivizNOSPAM.com http://www.iviz.com/ > "Andrew Thompson" <SeeMySites@www.invalid> wrote in message .. >> R.A. Grace Murray Hopper died in 1992 at the age of 85. >> >> Presuming she said that at 'retirement age' of 65, ... > Great analysis, Andrew. Except for the guess of the retirement age.. >..I couldn't find a date of attribution for the > quotation, but I did find that her official Navy retirement was in 1986 .. She retired from the services at 80(?!) (and that was involuntary). <sheepish grin> And there I was, about to set her retirement age at 60! </sheepish grin> > It's also true that parallel computing is much more effective for numerical > analysis and hardware systems than for ordinary desktop applications, so we > are making use of parallel processors today, just not in terms of general > computing power. It is a pity. I feel we are misapplying single and dual processor based machines where massive-parallelism would be a distinct advantage, especially in analysing 'real world' data. SignatureAndrew Thompson http://www.PhySci.org/codes/ Web & IT Help http://www.PhySci.org/ Open-source software suite http://www.1point1C.org/ Science & Technology http://www.LensEscapes.com/ Images that escape the mundane 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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