What is Reflection in a nutshell?

Is it simply how the JVM can determine at runtime what methods a class has or what ?

That's a part of it. In general it's about finding out all kinds of information about classes and objects at runtime, not just methods.
http://java.sun.com/docs/books/tutorial/reflect/
Starts off by saying:
The reflection API represents, or reflects, the classes, interfaces, and objects in the current Java Virtual Machine. You'll want to use the reflection API if you are writing development tools such as debuggers, class browsers, and GUI builders. With the reflection API you can:
Determine the class of an object.
Get information about a class's modifiers, fields, methods, constructors, and superclasses.
Find out what constants and method declarations belong to an interface.
Create an instance of a class whose name is not known until runtime.
Get and set the value of an object's field, even if the field name is unknown to your program until runtime.
Invoke a method on an object, even if the method is not known until runtime.
Create a new array, whose size and component type are not known until runtime, and then modify the array's components.

Similar Messages

What is reflection used for in RMI

hi,
I have a doubt regarding the use of reflection in RMI. why it is used and for what purpose?

Just generally, I would say, it is used for the same things its used for throughout java - to discover at runtime details of classes in the JVM, by examining their internals.
If you want a more specific answer, ask a more specific question.

What is reflection good for?

i heard people use reflection with rmi, but what it is good for?
if i use reflection to figure out what methods etc a class has, how do i know what they do?

Oh cool, you just gave me an idea!
Storing bean class names in a db and upon retrieval of any name, a single utility can construct an entire GUI editor panel for any variety of java bean conforming to the Java Bean specifications. This way, if ever I want to add a new Panel to an application for a new module or set of features, all I would hypothetically have to do is create the bean and add the name to the db and load up my app without even having to create the new GUI interface for editing it.
thanks!
Oh and one other additional thing reflection is good for, is interfacing with XML config files using the attribute names as identifiers for locating the setters (E.g., Spring Framework) as well as a bunch of other related XML things.
Your imagination is your only limit. I would excercise caution in where and how you use it though. Usually best to use in initialization routines rather than runtime functions or during exhaustive processes.

Errors With App Updates: Heres's what the "Apple Guy" said

Ever since the app store opened and updates to applications became available I have never been able to get an update without jumping through hoops. Those hoops would be deleting the application from iTunes and the iPhone as well as deleting any files from the application from my computer. Then after all this I have to re-download the application from iTunes.
I realize these apps don't have to be paid for again, but I find it very frustrating to have to go through this process just to get an update. My biggest issue is that I lose any and all data stored in that application because I had to delete it.
After searching these forums and seeing multiple people with the same problem, and no solution, I figured I'd go to the source and just call Apple support for iPhone and here's what they said in a nutshell.
Apple is totally aware that you can't get any updates without deleting the application. The guy was actually surprised when I told him that I have several updates per week. He said her personally only has 2 or 3 apps on his phone and he's never seen an update and thought maybe there was something wrong with my phone that I have so many updates. I told him I have about 30 apps and several of them have had several updates. This isn't a phone issue, it's an issue with iTunes being unable to load the new application without errors.
The gist of it is that there is NO way to fix this at this time. Apple fully expects us to delete the entire application every time there's an update and they don't really care that we're losing all our data. I don't think Apple had any idea that there would be as many updates as there are and so were completely unprepared. He actually told me that they are just now "getting back on our feet" after the big crash on the 11th when the 3G came out and they're doing the best they can. I'm sure this is true, but updates to applications were expected so why was this not forseen?
Disappointing!! Has anyone had any luck with updating applications without deleting everything first??? If so, how did you do it. I have tried since the middle of July with total failure. The Apple support guy was NO help so I'm turning to you guys!

Aha - interesting. Up until a few days ago, I was 'happily' updating apps virtually every day (bar the unhappiness caused by how long it took and the fact it moved the app to a different page from where I'd carefully moved it previously). I had a crash during an app update at the end of last week, after which I had to do a recovery restore. Since then... I'm seeing no updates available on the phone, even when I know they're in the store.
As of today I'd worked that could be because the App Store on the phone doesn't seem to know I've got most of my software installed, even though I clearly have (it marks only a few apps as 'Installed' on their page, whereas I've probably got 20-30). And now, checking iTunes, it's found updates for some apps, but not others. Who knows whether they'll be updated at the next sync...
Bottom line seems to be that as of 2.0.2, there are some serious issues with this aspect of the iPhone experience... along with endless backups (which to me seemed associated partly with the most recent iTunes update)... I really hope that the next update straightens things out!

What's the Java equivalent of a .dll file?

If any?

Actually, DLL for Windows. Where as in java,
It's doesn't dynamically link.
It's some what like Reflection classes.

Reflect the class that implements Runnable

Hi,
I am implementing the reflection of the class that implements Runnable. In order to start a new thread I am trying to invoke "start()" method ( which is obviously not defined my class ) and I therefore I am getting "java.lang.NoSuchMethodException".
I am wondering is it possible at all to start a new thread on a reflected class?
thanks in advance.
{ Class refClass = Class.forName(className);
String methodName = "start";
Class[] types = new Class[1];
types[0] = Class.forName("java.util.HashMap");
Constructor cons = refClass.getConstructor(types);
Object[] params = new Object[5];
params[0] = new HashMap();
Method libMethod = refClass.getMethod(methodName, null);
libMethod.invoke(objType, null); }

Well, if we knew what it meant to "start a thread on a class" we could probably figure out how to "start a thread on a reflected class". If we knew what a "reflected class" was, that is.
In other words, it would help if you rephrased your question using standard terminology (and also explained why you want to do whatever it is you want to do).
But let's guess for now: If you have an object which implements Runnable then you start a thread to run that object like this:
Runnable r = // some object which implements Runnable
new Thread(r).start();Not what you wanted? Go ahead and clarify then.

Create angle, reflected, diamond gradient using actionscript

Hi,
As you know, in Graphics class there is beginGradientFill
method to draw
gradient:
beginGradientFill(type:String, colors:Array, alphas:Array,
ratios:Array, matrix:Matrix = null, spreadMethod:String = "pad",
interpolationMethod:String = "rgb", focalPointRatio:Number =
0):void
I saw that the first parameter "type:String" only have two
values: "linear" or "radial". In photoshop, beside theses there are
"angle", "reflected", "diamond" gradient type also.
So which class (or libraries etc) I can use in order to
create "angle", "reflected", "diamond" gradient using fully
actionscript?
Or "angle", "reflected", "diamond" gradient type can not be
implemented using AS?
Could anyone point me to the right direction?
many thanks and best regards

gghfh,
you can get your gradient set to a different angle (not just
horizontal/vertical) by using the matrix argument you mention, eg:
graphics.beginGradientFill("linear", fill_colors,
fill_alphas, fill_ratios,
rotated_matrix (0, 0, actual_w, actual_h, gradient_angle));
where rotated_matrix is a function like
private function rotated_matrix(x:Number, y:Number,
w:Number, h:Number, rot:Number):Matrix
var tempMatrix:Matrix;
tempMatrix = new Matrix();
tempMatrix.createGradientBox(w, h, rot*Math.PI/180, x, y);
return tempMatrix;
I don't know what the "reflected" or "diamond" patterns look
like but maybe this would solve the "angle" one?
Richard

What is EasyVPN Client? on my Cisco 877.

Hi, I see EasyVPN client and server on my Cisco 877 SDM, what is this in a nutshell?

Hi Andy,Easy VPN Server feature on your router is for providing remote users the ability to VPN to your network using IPsec. The Easy VPN client allows for Lan-to-LAN VPN whereby you could statblish an IPsec encripted tunnel to either a router, pix, asa, or vpn concentrator at a remote site-network.
Some more details on Easy VPN Server
http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a008055c37a.html#wp1276737
Easy VPN client - for Lan-to-LAN vpns etc.. read here for more details
http://www.cisco.com/en/US/docs/routers/access/800/850/software/configuration/guide/vpnezvpn.html
To learn more about your router and its features refer to this page.
http://www.cisco.com/en/US/products/hw/routers/ps380/products_data_sheet0900aecd8028a976.html
pls rate any helpful post if it helps
HTH
Jorge

Will Apple help us with ATT rate hikes? Who do I contact?

Just a few months ago - and at the time I entered into my 2 year contract - unlimited textings was avaialble for less that 5 dollars more. But that is now gone and what has taken its place is just Dick Channey crazy!
Wasnt the whole point of APPLE insisting that phone plans all come with unlimited internet so that this would encourage the owners to fully integrate the iphone in to their daily lives? Does having huge rate increases in texting help that cause ?
MY QUESTION TO APPLE and its user forums - WHO do I contact at apple or at ATT for help on this issue??
Thats what I want in a nutshell. If you want, I can tell ya more.
Harry
iphone, ipod and shuffle owner
MORE is this...........................
I do understand the nature of big business and partnerships etc.
I do understand that Apple would like to not be involved in disputes between ATT and its customers.
I GET THAT. But can Apple help me anyway just for the reason that I WANT TO KEEP MY IPHONE?!?!?
ATT has implemented monsterous rate hikes and LIMITATIONS on package combinations so that iphone users will pay as much or more for Texting than they do for unlimited internet.
We had to live with unlimited internet not including unlimited texting. OK fine, thats how it was when we signed up and you have to take it or leave it. But now with the new changes in rates - here is what the iphone user has as their options.
200 included texts for free
or
$5 - get 200 more - 400 texts total
or
THE NEXT OPTION - $20 MORE, for not unlimited but 1500 texts.
Does having to keep an eye on your text totals or paying at least $85 / month sound like the vision that apple wanted for the iphone users?
if it doesnt, WILL YOU HELP US?

I didnt forget that - its I dont know that statement to be true.
I have been with ATT since Cingular and I've had internet,text and MMS combo packages for some time now; that Includes shopping around for the right phone and plans combo. And I know for a fact that there were MANY combos of unlimited and they were FAR from 50 bucks.
There certainly might be a webpage or two with some ancient pricing plans offered. And I am sure that any one of those would be superceeded by another new price offer on the same plan.
so I didnt forget that; I knew it to be not on point.

Just upgraded to vista and now can't open itunes

I just upgraded to vista (what a pain) I have uninstalled itunes and then reinstalled itunes but I still can't open it. This is what happens. When I click on the itunes icon I get the licence agareement which I check agree and when it goes away I get an error message which says: "The folder Itunes is on a locked disk or you do not have write permissions for this folder." I have tried clicking on the Itunes icon and have gone to itunes properties control panel and clicked on security and tried to get permission many times. After reading post's on this fourm I went to the itunes folder on my c drive and went to the same control panel and tried again but to no avail. I had no trouble with itunes on XP and have used it for years. Btw I can open Quicktime player but it will not play my video files (I don't care because quicktime is not my default player). but I can open it.
I have an Ipod nano and I want to use it to listen to audio books but I can't load them onto it without itunes.
Thanks for any help in advances
tiger8384

Yes I still have a problem. This is what it is in a nutshell. With User Account Control on in vista I can't open itunes. I am not sure what happens when I try but here goes. First I have installed itunes into my computer and have an icon on my desktop. When I click on that icon the first thing that happens is that I get a licenses agreement which I accept. As soon as I accept the agreement it goes away and I get an error message that says “The folder Itunes is on a locked disk or you do not have write permissions for this folder." The only option that the error message gives me is to say “OK”. When I click on the OK button on the error message it goes away and nothing else happens. Because of this problem I have uninstalled and installed itunes at least 5 times.
I have tried to read as many post in this forum as I can trying to find a solutions to this problem but to no avail. I have also gone to the vista forum and have read as many posts as I can about itunes problems that are there but to no avail. I have tried many fixes that have not work except one. And that was “to turn off the User Account Control.” When I turned off this control I was able to open itunes for the first times. Since then I have opened itunes many times and use it to load my ipod. But when I turn on User Account Control I have the same problem and I can’t open itune. I am open to suggestions on how to fix this problem and at this time I am not sure what is wrong. I have tried my things trying to fix this problem but for all I know I might have does something wrong. So at point I will try anything that you suggest.

Customizing MSS reporting selection period dropdown list

We have diffrent ABAP programs that uses the PNP logical database and we want to customize the period selection dropdown list on the MSS reporting iview. In same scenarios we want to display only 'Today'. In these scenarios we use the report together with a variant.
When the user execute the report, the selection period on the variant is used and that is 100% correct. The problem is that the user change the selection period on the frontend (on the Iview) and this is not what is reflected on the output of the report, becasue the report uses a variant.
Therefore we want to customize the period selection dropdown list on the Iviewin the scenarios where a report uses a variant.
I know that we cannot customize the perido selction on the Iview, beacue we cannot set the properties on the Iview.
Is anybody familiar with how we can accomplish this.
Regards
Margariet
<< moved by moderator - check out the list of other forums on top of portal forum >>
http://forums.sdn.sap.com/thread.jspa?threadID=1239838&tstart=0
Edited by: Anja Engelhardt on Feb 9, 2012 11:42 AM

Hi Darren,
We do have a property in the iview for which you can set the period. You need to know the name of the property. Give us the iview name so that we can have a look.
Cheers,
Sathya

Premiere / Media Encoder CS5 and deinterlacing

Maybe it's just me, but I'm not at all happy with the deinterlacing results from Premiere CS5 and Media Encoder. I've been using Premiere since CS3 and hoped for improvement in CS4, but no. And now with CS5, it's still just not good...
This is what I do in an nutshell: I edit 1080i HDV video in Premiere (using 1080i timelines) and export it to several formats, including 720p for Youtube. Now, whatever I do, I alway get some staircasing / aliasing on deinterlaced output. Not really bad and hardly noticable on video, but very noticable on logo's (which - ironically - are progressive to start with). Preview in Premiere looks fine, but as soon as I put the content through media encoder: staircasing. Even with the new "Use maximum render quality" option enabled.
When I output my 1080i timeline as 1080i MPEG2 video everything looks pristine (motion adaptive deinterlacing is then done upon playback by my nVidia graphics card). When I leave all rendering options the same and export 1080p or 720p - leaving deinterlacing to media encoder - staircasting is easily visible on logo's and detail is lost in the video compared to real-time deinterlaced output by my graphics card.
I guess my main question is: Why can't Adobe get this right? nVidia and ATI can do it very well and in realtime on their graphics cards (and have been able to do so for several years now) and freeware filters such as the ones used by ffdshow do a far better job too.
Why can't a high-end and expensive video editing solution like CS5 get this right? Hugely disappointing

Hi Todd, Steve,
I'm running CS5 a Cuda enabled system (Intel Core i7 965, 12 GB DDR3, MSI GeForce GTX 285 with 2GB memory and a secondary GeForce 9400GT 1GB, running Windows 7 Ultimate 64 bit).
Cuda support is enabled in premiere CS5, as my timelines are yellow even when I enable cuda accelerated effects such as color correction. So no problems there.
I work with 1080i50 HDV and AVCHD files, which I normally use in a HDCAM EX 50i timeline (I use HDCAM EX because that enables me to render all effects and graphics in 1920x1080, instead of a HDV timeline which renders everyting in 1440x1080). I have tried using native HDV timelines too, but that reduces horizontal sharpness on our logo and on sceen graphics, while the deinterlacing problems I encounter are exactly the same.
The problem is that when I export an HDCAM EX timeline to 720p, I get noticable degradation in image sharpness and visible jaggies on our on-screen logo. The same applies when I export to 1080p. When I export to 1080i (so no deinterlacing is done by Premiere or Media Encoder), the file looks great on playback (deinterlacing done in real time by my nVidia card).
For the last few weeks I've been working a round the problem in a way which is not ideal for me, but which does seem to provide better results:
I now work with HDCAM EX 25p timelines instead of 50i, and I set the 'field options' flag for all my clips to 'always deinterlace'. This results in a loss of temporal resolution on my timelines (which I don't really want, since I also export to PAL 50i) but it results in noticably better sharpness and less aliasing on 720p output.
I'd love to share my on-screen logo title if you wish to have a look at it. Our logo contains a circle which shows easily visible jaggies when deinterlaced incorrectly. Please let me know how to get the files to you.
Thanks,
Eric

Permanent end to Unlimited data.

I've finally figured out how Verizon is going to end unlimited data. Forever.
(I had this epiphany when posting this as a reply to a post on VW's timeline. So if you see it there and here, you're not going crazy.)
Okay, about 15 months ago, Verizon announcing they were ending unlimited data plans for new customers. But not to worry, all current customers with unlimited data would be able to keep it as they would be "grandfathered" in. The reality is Verizon could not just up and take away their Unlimited data without voiding their contract and allowing the customers to walk away without having to pay expensive early termination fees. So under the false premise of graciously letting them keep their plans, it continued for a year, with everything going smoothly.
Then VW announced the end of Unlimited data plans. Again. How so? All users who were on unlimited plans would not be allowed to upgrade (IE sign a new 2 year agreement with VW) and get a discounted price on a new phone and keep their unlimited data. BUT, they say, you can keep your unlimited data as long as you want (*wink wink*) if you just pay full price for a new phone. You just can't "upgrade" and get a discount.
What they don't tell you is it's not about the phone's discount. It's about the contract. They don't want you locking in 2 more years of unlimited data. SO the cutoff this year to upgrade and keep unlimited data was June (or was it July?) 28th. If you upgraded after that, you HAD to move to a tiered plan or the new Share Everything plan.
And that leaves us where we are today. Many people with unlimited plans will look at their usage and say "Eh, I only use a gig or so a month anyway, might as well go to the tiered plan and get a new phone". That leaves everyone else. Everyone who wants to keep unlimited are now, slowly but surely, going to be edging toward the end of their contract date. After that, they can keep unlimited, BUT they'll be paying month-to-month, with no contract. (Do you see where I'm going with this?)
What do you think will happen next? I can guarantee that within the next year, VW is going to announce the end of unlimited data for everyone. Period. They'll give a date, and all people paying month-to-month will either have to switch to a tiered plan, or find service elsewhere. Everyone who upgraded this summer before the cutoff on June (July?) 28th will finish out the duration of their contract, and then have to move to a tiered plan, or their service will be terminated. It makes sense. With all the old unlimited users out of contract, VW will be free to change the terms of service at any time. You either agree to it, or go elsewhere, and there's nothing you can do.
Opinions?

I think one of the issues they are going to see (and we are already seeing some of it on these forums) is how Verizon calculated data. There are many posts in these forums about Verizon mimsrepresenting the data usage. My phone for example I have 2 different monitors on my phone plus the My Verizon Wireless app that monitors Data Usage. These 3 monitors will be within 100kb of usage at any given time of th emonth, yet the Verizon website shows almost 4 times the usage that these 3 monitors show, and the number posted in their website is what they use to calculate your usage and then the Overcharges.
Every month for the last 4 months I have called them about this and get 2 responses. the first is puzzling and is why does it matter, you have unlimited Data so it shouldn't matter what we reflect your usage as. and the other is, you are absolutely correct, there is a glitch in our measuring tool and it is not 100% accurate yet.
So for me, until I see that they are accurately reflecting the usage on their site etc... I will be sticking with my Unlimited plan as I do NOT plan on upgrading my phone anytime soon.
Now if they completely just say, Unlimited data is gone, then I will be forced to look at the Tiered plan, and keep accurate track of my usage with these monitors and escalate any differences to the correct people wither within Verizon or the PUC and or FTC.

When reporting "Spend" do you use PO Value, Invoice Amount or Goods Receipt

When reporting "Spend" do you use PO Value, Invoice Amount or Goods Receipt? I am trying to standardize reporting and would like feedback on what is the norm. The users cannot agree so I need to know what the standard is.

PO Value is what is budgeted for ,
Invoice is what is actually being paid for.
GR would give you the value of goods received. My take on this is that it should be Invoice value since this is what is reflected in the books and is actually being paid for...

Are itunes lps of the same quality as the analog

The question is this : an analog format weather a computer reel to reel or an anlog lp contains much more data then it's digital counterpart. how does itune LP compare to its
LP version.

Blu-Ray has better image quality. Apple TV only supports content up to 8Mbps for 1080p whereas Blu-Ray can go as high as 40Mbps.
What this means in a nutshell is that the content in iTunes is more compressed, which will have an impact with picture quality. I won't even go in to talking about sound.
At the end of the day I guess it really depends on your setup and what you're looking to get out of it. I've seen the newer content in iTunes (Sherlock Holmes: A Game of Shadows) and it looks really good. I've also downloaded Gladiator (1080p) and it looks mediocre at best.

What is Reflection in a nutshell?

Similar Messages

Maybe you are looking for