Rookie question: what does "delegate" mean?

in api explanation, it is sometimes mentioned that, 'A currently delegates to B",
like "DefaultListModel" delegates to "Vector", what does it mean exactly? Forgive me, my English is really bad.
is it saying that wherever A was previously used, use B instead now?
thanks

Basically when a request is made to Object A (for example a method is called), Object A forwards the request to Object B (the delegate). Object B then does some work to handle the request.
public class A {
private B delegate = new B();
public int getSize() {
return B.size();
}This is actually not "true" delegation, rather "forwarding" since true delegation would require A to be forwarded to B as well as the request.

Similar Messages

Probably a stupid question - what does '256' mean in response to a command

Hi,
I.m just learning PHP (I mean at the very beginning). The tutorial I'm following was running through how to start and stop the apache server via terminal.
When I entered the commands, I received the following error"
/usr/sbin/apachectl: line 82: ulimit: open files: cannot modify limit: Invalid argument
So I poked around and found out that I needed to modify the apachectl script to remove "ulimit -S -n `ulimit -H -n`" from the line ULIMITMAXFILES="ulimit -S -n `ulimit -H -n`"
So created a backup, opened nano and modifed the script. So far so good. So I went to try the command again and....
sudo apachectl graceful
256
Can someone please enlighten this poor beginner as to what I've done?
Many thanks

Can someone please enlighten this poor beginner as to what I've done?
Sure. You edited the file incorrectly (or, at least, pointlessly )
modify the apachectl script to remove "ulimit -S -n `ulimit -H -n`" from the line ULIMITMAXFILES="ulimit -S -n `ulimit -H -n`"
Well, sorta, kinda.
To understand what is happening now it's useful to understand what the original command did.
ULIMITMAXFILES="ulimit -S -n `ulimit -H -n`"
This command has three components:
ULIMITMAXFILES=
"ulimit -S -n "
and
`ulimit -H -n`
Note that the last component is surrounded by back ticks. This indicates that it's a subcommand that should be executed and the result of which inserted in its place.
So in effect, this line tells the shell to first go away and run `limit -H -n`.
This command determines the maximum limits available for a process and would normally return the string 'unlimited'.
This has the effect of turning the full line into:
ULIMITMAXFILES="ulimit -S -n unlimited"
(since the subcommand has been executed and its result inserted in the command).
So now the shell can run the command 'ulimit -S -n unlimited', the result of which is stuffed into ULIMITMAXFILES
Your mistake is that you simply omitted the subcommand that determines the maximum process limit on this system so now the command looks like:
ULIMITMAXFILES="ulimit -S -n"
which simply determines the current process limit (which is normally 256).
In other words, since you nixed the last parameter to the command you're now just asking it for the current limits (256) rather than setting a new limit value.
That's why you get '256' - it's what you asked for.
As for what to do about it? Well, nothing would be one option - it shouldn't prevent apache from running, you just get additional output when you run apachectl. If it bothers you, delete (or comment out) the entire line rather than just the subcommand. Unless I'm mistaken it's not going to make and significant difference to Apache's operation either way.

Question What does that mean?

- my iphone keep saying waiting for activation under iMessage?

It could be a couple of things, a HD failure or it could be the system forgot where the startup volume is. Please read Flashing question mark appears when you start your Mac.
BTW you posted in the wrong forum, this is a forum for Intel Based iMacs, you should either post in Mac Pro forum or the forum for the version of OS X you are running.

What does synchronisation mean? What data is being synchronised?

On my 80GB IpoD classic I replace music several times. After successful transfer of imported CDs from the mediathek onto the Ipod I finally clean up the mediathek; that means:
Mediathek and IpoD can never be synchron because of a clompletely different contents. (I manually administer my IpoD)
Synchron to me means: 2 or more different parts do exactly the same thing.
my question:
What does synchronsation mean in this context? What info has to be synchronized between Ipod and mediathek?
Thanks for answering

You are correct that the common meaning of synchronise is to make two things the same. iTunes uses this term slightly loosely but if you set your device to sync with selections from your iTunes library, e.g, certain playlists, podcasts, TV shows etc. then changes in those part of your library can be automatically reflected on the device. For iTunes syncronisation is one way - from iTunes to the device - although it can also transfer purchased items from the device back to iTunes. When automatically syncing it can also update play counts & last played dates both from iTunes to the device and from the device to iTunes.
If you manually manage your iPod then it will still have data that needs to be copied to it or deleted at some point. Whenever data is being modified on the device it will display the "syncronising" screen.
tt2

My MacBookPro has a white screen with a grey file folder in the center of the screen with a white question mark blinking in it. What does this mean? And how can I get my computer back up and running normal?

My MacBookPro has a white screen with a grey file folder in the center of the screen with a white question mark blinking in it. What does this mean? And how can I get my computer back up and running normal?

Start up in Safe Mode.
http://support.apple.com/kb/PH14204?viewlocale=en_US
Repair Disk.
http://support.apple.com/kb/PH5836
Reset PRAM.
http://support.apple.com/kb/PH14222

I can't log in to my computer- when it turns on it has a white/gray screen with a flashing folder with a question mark in it. What does this mean and how can I get it to stop to log in?

Hi
I dropped my macbook yesterday and it turned itself off. When I tried to turn it back on all I got was a white/gray screen with a flash folder with a ? in the middle of it? What does this mean and how do I get it to stop so I can log onto my laptop?

Deev
Normally the question mark on the gray screen means it can't find the operating system. Have you tried booting up from the installation DVD? Do that, and when you come to the screen where it wants to begin a system installation you'll notice in the menubar where it say's utilites. Click on that and choose disk utility. from there choose your disk and try to verify and repair the disk. If you can you may want to also try and new install of the system. I don't know how much critical data you have, but reinstalling is an option. did you purcahse you from an Apple store? If you did you may want them to look at it. Hope this helps.
Regards,
Joseph

What does it mean when I start my computer and there is a file folder with a question mark?

What does it mean if I start my computer and there is a file folder with a question mark blinking?

That Disk 1/ Mac OS is the install DVD not the hard drive. Your hard drive is not recognized which would mean it's probably dead.
For a new hard drive try Newegg.com http://www.newegg.com/Store/SubCategory.aspx?SubCategory=380&name=Laptop-Hard-Dr ives&Order=PRICE
Or OWC http://eshop.macsales.com/shop/hard-drives/2.5-Notebook/
Here are instructions on replacing the hard drive in a MacBook with a removable battery. http://creativemac.digitalmedianet.com/articles/viewarticle.jsp?id=45088
Here are video instructions on replacing the hard drive on the Aluminum Unibody http://eshop.macsales.com/installvideos/macbookpro_13_unibody_hd/
Here are video instructions on replacing the hard drive on the White Unibody http://eshop.macsales.com/installvideos/macbook_13_09_unibody_hd/
If you don’t have the tools to open up the MacBook OWC has a set for $5
http://eshop.macsales.com/item/OWC/TOOLKITMHD/

My iMac has a white screen with a flashing file folder with a question mark in the middle. What does that mean?

My iMac is completely unresponsive. Whenever I restart it, it's just a white screen with a flashing file folder with a question mark in the middle. What does this mean?

this means the mac cannot find the startup disc. which more times than not means you need a hdd replacement.
try starting holding the option key, then using utilities try to repair the disc.

My macbook pro displays a folder with a question mark on it when it turns on. What does this mean and how do I fix it?

My macbook pro displays a folder with a question mark and won't open. What does this mean and how can I fix it?

it means your HD and the software can't find each other, the following article tells how to troubleshoot this issue:
https://support.apple.com/kb/TS1440
hopefully you have backup of your data since sometimes this means the HD is crashing.
if the article doesn't resolve the issue i would take the mac to apple store or service provider and have it looked at, the following link tells how to find one close to you:
https://locate.apple.com
good luck!!

What does it mean when I see the file with the question mark on my screen?

What does it mean when I see a file with a question mark on the screen?

Means no bootable system can be found or required system files are missing or damaged. Reinstall OS X.
Reinstall OS X without erasing the drive
1. Repair the Hard Drive and Permissions
Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Reinstall Snow Leopard
If the drive is OK then quit DU and return to the installer. Proceed with reinstalling OS X. Note that the Snow Leopard installer will not erase your drive or disturb your files. After installing a fresh copy of OS X the installer will move your Home folder, third-party applications, support items, and network preferences into the newly installed system.
Download and install Mac OS X 10.6.8 Update Combo v1.1.

I use picasa for my photos..currently there is a question mark imposed over the icon on the dock aand it won't open...what does this mean?

I use picasa for my photos..currently there is a question mark imposed over the icon on the dock and it won't open...what does this mean?
Thanks for any help.

The icon in the dock is a shortcut to the app itself.....for some reason the icon has lost contact with the app.......go to your Applications folder and drag Picasa back to the dock....a new alias (shortcut) will be created.....

What does it mean when there is a flashing file folder with a question mark when trying to start computer?

When I try to start my computer a flashing file folder with a question mark is on the screen. I can't open anything up. What does this mean?

There are four general causes of this issue:
1. The computer's PRAM no longer contains a valid startup disk setting when there aren't any problems with the disk itself. This can be checked for by pressing the Option key and seeing if the drive appears.
2. The internal drive's directory structure has become damaged. This requires usage of an alternate bootable system to perform the repair.
3. Critical system files have been deleted. This requires usage of an alternate bootable system to reinstall them.
4. The internal drive has died or become unplugged. This is the most likely case if the computer took a sharp impact or there are unusual sounds coming from its location.
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TS2094 After resetting the pram, the screen only shows a folder with a question mark inside. What does this mean?

I followed the initial steps in this post and reset pram. After restarting, the screen just shows a folder with a question mark. What does this mean?

Thanks Niel, I tried using Option and nothing happened so I next tried inserting the Leopard disc and rebooting while holding C. Nothing happened until the disc was ejected and then the folder with question mark reappeared. I inserted the disc again and at this point and it booted OSX. I tried to acess disc utility to repair but my harddrive wasn't listed, only the CD drive and the OS disc. Does this mean I'm lost everything?

DFS question: What does "Set Active" mean on the DFS tab in windows server 2008

When I logged into server and went to the DFS tab to check and see if it was replicating between two of the different shares. I saw one share marked as "Active" What does that mean?
I also seen a button that said "Set Active" I am guessing its related to my above question.
I am guessing its the root? The directory that others pull from or something? I tried to google that all over and could not find anything specific to this question which I found very odd.

If you have multiple folder targets in the namespace then the 'Set Active' button is how you change the current referral (at a client level). Only enabled folder targets will be listed. Users can choose a different server if they wish (maybe
for performance reasons).

What does it mean when you computer crashes and when you turn it back on it shows you a blank blue screen with a little folder and a question mark in the middle?

What does it mean when you computer crashes and when you turn it back on it shows you a blank blue screen with a little folder and a question mark in the middle? It's a old imac from 1997.

I don't have original discs that it came with.
Then you still can use the second option with the keyboard combo I posted, called "resetting the PRAM."
Also when you way hold the c key down do you mean turn computer off and turn back on holding the c key?
Yes, or you can simply restart. As you don't have the CDs, this isn't on the plate any more.
The internal backup battery is not expensive and, in most iMacs is user-replacable. If yours has a tray-loading optical drive like this one:
it takes a major teardown to replace the internal battery. If this is the case, you'd be better off to leave the computer plugged in all the time; that eliminates the main reason for having a working battery.
If it has a slot-loading optical drive like this one:
things are much easier. The battery is visible through the RAM access door on the bottom of the computer case. The manual:
http://manuals.info.apple.com/en_US/iMacG3_2000UserManual.PDF
has sketches of how to access the RAM and therefore the backup battery. Unfortunately, the pdf on the manual goes up sideways on-screen and the RAM instructions are pretty deep into the manual. It's probably easier to scroll (for a while) to the section on adding RAM and print the applicable pages.
When you work on the battery, some sort of non-conductive pliers or large tweezer or forceps help unless you have tiny fingers. Make sure to note the polarity of the old battery and install the new one in the same orientation.
The battery itself is readily available. If price is no oblect, you can get it for a small rasom from Radio Shack Store ("Tandy" outside the US) as part number 23-026.
Online, they are dirt-cheap even after adding shipping. I buy backup batteries form this outfit:
3.6v Newer Technology Lithium 1/2 AA PRAM Computer Clock Battery

Rookie question: what does "delegate" mean?

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