Tylor is correct that recursion is great on algorithms that deal with trees whether it is for sorting or searching or even writing or reading them from or to disk. A couple more reasons for them. 1) They can make rather large loops look really small and easy to upkeep at the cost of memory. Note how cheap memory is now days. 2) Some things are just easier to do with recursion for example the knights tour problem is not so easy to do with loops 3) Some weird languages don't have great looping structures and recursion can help you there. Now if you're in for a good joke just search for "recursion" on google. You will notice that the google programmers can be funny. Google will ask you. Did you mean recursion? Then you click on that and guess what it asks if you mean "recursion"? again. You can click that all day long if you like. Ken From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Stanzel, Susan - Kansas City, MO Sent: Thursday, April 07, 2011 1:45 PM To: programmingblind@xxxxxxxxxxxxx Subject: RE: Java Questions Again: What's So Great About Recursion Hi Listers, I have asked the Java teacher to enlighten me on this subject of recursion. I have wondered what it was for also, but it was just one of those things I didn't bother to ask. Susie From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Stanzel, Susan - Kansas City, MO Sent: Thursday, April 07, 2011 12:32 PM To: programmingblind@xxxxxxxxxxxxx Subject: RE: Java Questions Again: What's So Great About Recursion Hi Listers, Java has a serialization mechanism to do that kind of tracking. Susie From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Homme, James Sent: Thursday, April 07, 2011 12:16 PM To: programmingblind@xxxxxxxxxxxxx Subject: RE: Java Questions Again: What's So Great About Recursion Hi Ty, Is it done when it has finished reading the file? Thanks. Jim Jim Homme, Usability Services, Phone: 412-544-1810. Skype: jim.homme Highmark recipients, Read my accessibility blog <http://mysites.highmark.com/personal/lidikki/Blog/default.aspx> . Discuss accessibility here <http://collaborate.highmark.com/COP/technical/accessibility/default.aspx> . Accessibility Wiki: Breaking news and accessibility advice <http://collaborate.highmark.com/COP/technical/accessibility/Accessibility%2 0Wiki/Forms/AllPages.aspx> From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Littlefield, Tyler Sent: Thursday, April 07, 2011 12:59 PM To: programmingblind@xxxxxxxxxxxxx Subject: Re: Java Questions Again: What's So Great About Recursion Jim: Recursion has a limited number of applications where it is actually more useful than a loop, I'll give one I use it for. In my game engine, properties are stored in a tree setup with a root property and all other properties work from there. so, you could essentially have stats.health, stats.mana, etc. stats is the root node, health are the children nodes on stats. Now, here's where recursion comes in handy. when I serialize this tree, I write it all in xml. so I'll serialize the stats, then I'll serialize health. what I do is something like this: Serialize(XMLNode, property) so lets say that stats.health has two properties: stats.health.hp, and stats.health.max_hp. in order to serialize that I would have to loop through the properties of stats.health, then if hp were to have another property I'd have to loop through those, which could get messy. Rather than do that though, I use recursion. so the serialization setup calls serialize on stats, passing the root, then that function calls serialize on stats.health passing health. I hope I explained that properly. Essentially in summary, it allows me to keep passing in each node of the tree until I am finally done. I can recurse until I get done serializing a branch, at which point I will pop back to where i was because the recursion will return when it's done. On 4/7/2011 10:51 AM, Homme, James wrote: Hi, It's probably my ignorance coming out to bite me again, but I just was reading about recursion in my Java book and thinking that it isn't all that useful because you can do the same stuff with a loop. Maybe the book examples are so simple that I just don't see it's usefulness. They were even saying that recursion eats up more memory than loops do, so I'm wondering why I learned it in the first place, other than to know how it works and that it exists. Please help. Thanks. Jim Jim Homme, Usability Services, Phone: 412-544-1810. Skype: jim.homme Highmark recipients, Read my accessibility blog <http://mysites.highmark.com/personal/lidikki/Blog/default.aspx> . Discuss accessibility here <http://collaborate.highmark.com/COP/technical/accessibility/default.aspx> . Accessibility Wiki: Breaking news and accessibility advice <http://collaborate.highmark.com/COP/technical/accessibility/Accessibility%2 0Wiki/Forms/AllPages.aspx> This e-mail and any attachments to it are confidential and are intended solely for use of the individual or entity to whom they are addressed. If you have received this e-mail in error, please notify the sender immediately and then delete it. If you are not the intended recipient, you must not keep, use, disclose, copy or distribute this e-mail without the author's prior permission. The views expressed in this e-mail message do not necessarily represent the views of Highmark Inc., its subsidiaries, or affiliates. -- Thanks, Ty