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  • can we write this in C++ switch ?

    - by jellly
    #include <iostream> using namespace std; int main(){ char i; cin >>i; switch (i){ case ('e'||'i'||'o'||'u'||'a'): cout<<"Vowel"; break; case ('+'||'-'||'/'||'*'||'%'): cout<<"Op"; break; } return 0; } if not than how can we use comparison or logical operators in switch ? & why cant we declare and initialize variable in single case without using scope ?

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  • Java using enum with switch statement

    - by MisterSquonk
    I've looked at various Q&As on SO similar to this question but haven't found a solution. What I have is an enum which represents different ways to view a TV Guide... static enum guideView { GUIDE_VIEW_SEVEN_DAY, GUIDE_VIEW_NOW_SHOWING, GUIDE_VIEW_ALL_TIMESLOTS } ...when the user changes the view an event handler receives an int from 0-2 and I'd like to do something like this... // 'which' is an int from 0-2 switch (which) { case NDroid.guideView.GUIDE_VIEW_SEVEN_DAY: ... break; } I'm used to C# enums and select/case statements which would allow something like the above and I know Java does things differently but I just can't make sense of what I need to do. Am I going to have to resort to if statements? There will likely only ever be 3 choices so I could do it but I wondered how it could be done with switch-case in Java.

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  • Need help diagnosing network performance issues

    - by tokes
    I am currently working in a developing country as a system analyst for a government department. My area of expertise is software projects, but I've come across a few issues with the network setup in my office. (Unfortunately, being a developing country, there's not a lot of professional help available for this sort of thing.) Most recently, I am trying to diagnose a problem with slowness on the network. Our office is connected to the internet via an ADSL wireless modem/router (called Router). The modem is connected via ethernet to a switch (called Switch). The modem also acts as a wireless access point (called Wireless1), though because it is in a room at the end of the floor, it's range is limited. There are ethernet ports installed around the office. The cables of these all lead back to the same switch. In closer vicinity to the bulk of the client computers, there is another wireless router that acts as an access point for those clients (called Wireless2). That router is connected via ethernet to a wall port, and therefore to Switch. There is also a Windows server which acts as a DNS server (called DNSBox) which is located in the same room and is connected directly to Switch. ---Internet----------| Router/Wireless1 192.168.10.1 ---------------| |----|=========| DNSBox | |-------------------- 192.168.10.4 --------------------| Switch |---Other clients---- | |-------------------- |----|=========| Wireless2 ------------------| 192.168.10.198 One final thing to mention about the network setup. All clients are configured with manual IP addresses. Their router/gateway is set to the IP address of Router, and their DNS server is set to the IP address of DNSBox (with a secondary IP set to an external IP - that of our ISP's DNS server). Here are the symptoms we are experiencing: Clients connected to Wireless2 AP experience slow and unstable connections to the internet. (Slow here is defined as speeds of ~1KB/s, though ping response times seem to be as normal.) Clients connected via ethernet to Switch also experience the same slowness. Clients connected to Wireless1 AP (i.e. connecting via wireless directly to the ADSL modem) experience normal connections to the internet. Clients connected via ethernet to Router (i.e. connecting via ethernet directly to the ADSL modem) also experience normal connections to the internet. I also tried to gauge the connection performance between two machines on the network via ethernet: A file transfer between two clients who were both directly connected to Switch was the fastest; A file transfer between one client directly connected to Switch, and one client directly connected to Router (which is directly connected to Switch) performed much slower; A file transfer between two clients directly connected to Router also performed slowly. Things I have attempted to diagnose the problem: Restarted Switch -- no change. We tried unplugging ethernet jacks from Switch 4 at a time and testing the internet connection. The thought here was that perhaps a client on the network has contracted a virus, and is possibly spamming the network with traffic? (Not very technical, I know.) Unfortunately we couldn't get any significant increases in performance using this method. There were a couple of times when it seemed to be better, but then the connection speed quickly dropped back to slow/dead pace. I didn't want to unplug all jacks from Switch because I was concerned that users might be affected or that I would re-plug in the jacks incorrectly (should I even be worried about that? a port is a port on a switch, right?) I tried swapping the ethernet cable used to connect Router to Switch -- no change in performance. I tried swapping the port used on Switch for Router -- no change in performance. Anyone got any ideas on what this could be? Should I be mentioning specific brand names/models of the hardware used? Virii outbreaks are common in this country/office -- what could I be doing to figure out if a virus is at fault? If it is a virus, it doesn't seem to be generating a lot of traffic to/from the internet, because a) I can still get a good speed if I am directly connected to Router / Wireless1 and b) our ISP data usage has not risen suspiciously. Thanks for your help! Update #1 Here are the specs of some of the hardware: Switch is an Edimax ES3132RL 32-Port 10/100 Rackmount Switch Router is a D-Link DSL-G604T Update #2 I just tried unplugging everything except a laptop and Router from Switch. Speeds are still slow. I guess that means that Router / Switch are not being flooded? It seems more and more likely that the cause is something to do with the interaction between Router and Switch. However, I still can't find any useful resources on setting the LAN speed for either (and I'm not well-versed in these advanced networking configurations).

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  • Java: If vs. Switch

    - by _ande_turner_
    I have a piece of code with a) which I replaced with b) purely for legibility ... a) if ( WORD[ INDEX ] == 'A' ) branch = BRANCH.A; /* B through to Y */ if ( WORD[ INDEX ] == 'Z' ) branch = BRANCH.Z; b) switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A; break; /* B through to Y */ case 'Z' : branch = BRANCH.Z; break; } ... will the switch version cascade through all the permutations or jump to a case ? EDIT: Some of the answers below regard alternative approaches to the approach above. I have included the following to provide context for its use. The reason I asked, the Question above, was because the speed of adding words empirically improved. This isn't production code by any means, and was hacked together quickly as a PoC. The following seems to be a confirmation of failure for a thought experiment. I may need a much bigger corpus of words than the one I am currently using though. The failure arises from the fact I did not account for the null references still requiring memory. ( doh ! ) public class Dictionary { private static Dictionary ROOT; private boolean terminus; private Dictionary A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z; private static Dictionary instantiate( final Dictionary DICTIONARY ) { return ( DICTIONARY == null ) ? new Dictionary() : DICTIONARY; } private Dictionary() { this.terminus = false; this.A = this.B = this.C = this.D = this.E = this.F = this.G = this.H = this.I = this.J = this.K = this.L = this.M = this.N = this.O = this.P = this.Q = this.R = this.S = this.T = this.U = this.V = this.W = this.X = this.Y = this.Z = null; } public static void add( final String...STRINGS ) { Dictionary.ROOT = Dictionary.instantiate( Dictionary.ROOT ); for ( final String STRING : STRINGS ) Dictionary.add( STRING.toUpperCase().toCharArray(), Dictionary.ROOT , 0, STRING.length() - 1 ); } private static void add( final char[] WORD, final Dictionary BRANCH, final int INDEX, final int INDEX_LIMIT ) { Dictionary branch = null; switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A = Dictionary.instantiate( BRANCH.A ); break; case 'B' : branch = BRANCH.B = Dictionary.instantiate( BRANCH.B ); break; case 'C' : branch = BRANCH.C = Dictionary.instantiate( BRANCH.C ); break; case 'D' : branch = BRANCH.D = Dictionary.instantiate( BRANCH.D ); break; case 'E' : branch = BRANCH.E = Dictionary.instantiate( BRANCH.E ); break; case 'F' : branch = BRANCH.F = Dictionary.instantiate( BRANCH.F ); break; case 'G' : branch = BRANCH.G = Dictionary.instantiate( BRANCH.G ); break; case 'H' : branch = BRANCH.H = Dictionary.instantiate( BRANCH.H ); break; case 'I' : branch = BRANCH.I = Dictionary.instantiate( BRANCH.I ); break; case 'J' : branch = BRANCH.J = Dictionary.instantiate( BRANCH.J ); break; case 'K' : branch = BRANCH.K = Dictionary.instantiate( BRANCH.K ); break; case 'L' : branch = BRANCH.L = Dictionary.instantiate( BRANCH.L ); break; case 'M' : branch = BRANCH.M = Dictionary.instantiate( BRANCH.M ); break; case 'N' : branch = BRANCH.N = Dictionary.instantiate( BRANCH.N ); break; case 'O' : branch = BRANCH.O = Dictionary.instantiate( BRANCH.O ); break; case 'P' : branch = BRANCH.P = Dictionary.instantiate( BRANCH.P ); break; case 'Q' : branch = BRANCH.Q = Dictionary.instantiate( BRANCH.Q ); break; case 'R' : branch = BRANCH.R = Dictionary.instantiate( BRANCH.R ); break; case 'S' : branch = BRANCH.S = Dictionary.instantiate( BRANCH.S ); break; case 'T' : branch = BRANCH.T = Dictionary.instantiate( BRANCH.T ); break; case 'U' : branch = BRANCH.U = Dictionary.instantiate( BRANCH.U ); break; case 'V' : branch = BRANCH.V = Dictionary.instantiate( BRANCH.V ); break; case 'W' : branch = BRANCH.W = Dictionary.instantiate( BRANCH.W ); break; case 'X' : branch = BRANCH.X = Dictionary.instantiate( BRANCH.X ); break; case 'Y' : branch = BRANCH.Y = Dictionary.instantiate( BRANCH.Y ); break; case 'Z' : branch = BRANCH.Z = Dictionary.instantiate( BRANCH.Z ); break; } if ( INDEX == INDEX_LIMIT ) branch.terminus = true; else Dictionary.add( WORD, branch, INDEX + 1, INDEX_LIMIT ); } public static boolean is( final String STRING ) { Dictionary.ROOT = Dictionary.instantiate( Dictionary.ROOT ); return Dictionary.is( STRING.toUpperCase().toCharArray(), Dictionary.ROOT, 0, STRING.length() - 1 ); } private static boolean is( final char[] WORD, final Dictionary BRANCH, final int INDEX, final int INDEX_LIMIT ) { Dictionary branch = null; switch ( WORD[ INDEX ] ) { case 'A' : branch = BRANCH.A; break; case 'B' : branch = BRANCH.B; break; case 'C' : branch = BRANCH.C; break; case 'D' : branch = BRANCH.D; break; case 'E' : branch = BRANCH.E; break; case 'F' : branch = BRANCH.F; break; case 'G' : branch = BRANCH.G; break; case 'H' : branch = BRANCH.H; break; case 'I' : branch = BRANCH.I; break; case 'J' : branch = BRANCH.J; break; case 'K' : branch = BRANCH.K; break; case 'L' : branch = BRANCH.L; break; case 'M' : branch = BRANCH.M; break; case 'N' : branch = BRANCH.N; break; case 'O' : branch = BRANCH.O; break; case 'P' : branch = BRANCH.P; break; case 'Q' : branch = BRANCH.Q; break; case 'R' : branch = BRANCH.R; break; case 'S' : branch = BRANCH.S; break; case 'T' : branch = BRANCH.T; break; case 'U' : branch = BRANCH.U; break; case 'V' : branch = BRANCH.V; break; case 'W' : branch = BRANCH.W; break; case 'X' : branch = BRANCH.X; break; case 'Y' : branch = BRANCH.Y; break; case 'Z' : branch = BRANCH.Z; break; } if ( branch == null ) return false; if ( INDEX == INDEX_LIMIT ) return branch.terminus; else return Dictionary.is( WORD, branch, INDEX + 1, INDEX_LIMIT ); } }

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  • jQuery add() function and the context of jQuery objects

    - by patrick
    Given the following HTML example... <div id='div1'>div one</div> <div id='div2'>div two</div> ...I found that the following jQuery code... $('#div1').click(function() { var $d = $(this); // Using 'this' instead of '#div1' $d.add('#div2').remove(); }); ...would not add #div2 to the set referenced by $d, but this code... $('#div1').click(function() { var $d = $('#div1'); // Using '#div1' instead of 'this' $d.add('#div2').remove(); }); ...successfully added #div2. Upon consulting firebug, I found that using $(this) gave the jQuery object a context of #div1, but doing $('#div1') gave the object a context of document. Given this information I tried... var $d = $(this, document); ...and the add() function worked as expected. So here's the question. Could someone please explain to my why a different context is assigned when using $(this) vs $('#div1')? Thanks much!

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  • Visual Studio 2010/2012 Context Menus and a Keyboard

    - by SergeyPopov
    As a software developer, I spend a lot of time using Visual Studio. I have to say that I completely satisfied with Visual Studio generally. Nevertheless, sometimes Visual Studio starts annoying me. One issue which poisoned my existence for a long time is that context menu behavior in VS2010 is a little different than it was in VS2005/2008. Unfortunately, in VS2012 this behavior remains the same as in VS2010. So, what is the issue? Working with Visual Studio, I use the keyboard in most cases. I also use the Apps key on the keyboard to open context menus in the code editor. Moreover, long time ago I am got used to using some key sequences, and press the keys without even thinking. In VS2008, a mouse pointer position didn’t affect context menu navigation if I used the keyboard. Every time I opened a context menu I was sure that, for example, the "Apps, Down, Down, Enter, Up, Enter" key sequence always invoke "Organize Usings > Remove and Sort" function. But in VS2010, this behavior has been changed. If a mouse pointer is located over an opened context menu, the menu item under the mouse pointer becomes selected immediately! So, now the "Apps, Down, Down, Enter, Up, Enter" key sequence will not lead to expected results all the time. In some cases, the result may be a little scary. If you are using Visual SVN extension, this key sequence may invoke "Revert whole file" function. Of course, this is not a fatal problem because "Undo" function restores all the changes, but this behavior strongly annoys me. In Visual Studio 2012, context menu behavior is a little different than in VS2010, but a mouse pointer position still affects the keyboard navigation in the context menu, and this behavior is still annoying. I tried to find the way how to change this behavior, but I didn’t manage to find the answer quickly. Then I decided to go right though, so I wrote a small utility which fixes this issue. This utility watches for Apps key, and if the key is pressed in Visual Studio, the utility moves the mouse pointer to the top of the screen before opening the context menu. You can find binaries and the source code of this utility here: http://code.google.com/p/vs-ctx-menu-fix/downloads/list This utility works fine in Windows 7 and Windows 8 x64. I wrote the first version in January, 2011; now I just added Visual Studio 2012 support. I hope you will find this utility useful! :)

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  • How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS

    - by Vilx-
    The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally simply Evil. It should be avoided, right? On that note, if I'm writing the software from ground up anyway, I could go the extra mile and implement my own task-switching. Split each task in parts, save the state inbetween, and then switch among them within a single thread. Or, if I detect that there are multiple CPU cores, I could just give each task to a separate thread and all would be well. The second solution does have the advantage of adapting to the number of available CPU cores, but will the manual task-switch really be faster than the one in the OS core? Especially if I'm trying to make the whole thing generic with a TaskManager and an ITask, etc?

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  • How to (re)enable the "New" context menu items for an administrator when right-clicking in a folder and selecting New > X?

    - by Metro Smurf
    I just migrated from XP x86 to Win7 x64 (clean install). I had a couple of data drives in my XP x86 system that I physically moved to my Win7 x64 system. When browsing a directory in any of the transferred drives, the only option available in the 'new' context menu is "Folder", i.e., Right-Click inside a folder New Folder (this is similar behavior for Win7 when using the context menu in c:\Program Files): However, whenever creating a new folder within any of the directories, all the context menu new items are available within the new folder: Steps I've taken that have failed to add the new context menu items: Removing all security permissions from a directory and sub-directories. Replacing them with new permissions. As well as removing inheritable permissions from the parent. Taking explicit ownership of a directory and sub-directories. Combing the above two. Sample of Effective Permissions that do not work: Steps I've taken that have succeeded to add the new context menu items: Adding the "Everyone" group to the drive and giving the group explicit "Modify" privileges. Giving the "Everyone" group explicit privileges smells wrong. I'm an administrator on my system; why should I have to add the "Everyone" group as well? Adding my username to the drive and giving full permissions. Again, since I'm an administrator on my system and the administrators group already has full control of the drive/directories/folders, why should I have to explicitly add my user name to the security permissions? Finally, The Question: Is it possible to have the New Item context menu have all available options by default without having to explicitly add the everyone group or a specific user name to the security permissions? I'm suspecting that the option may not be available unless the username is explicitly added to the security permissions. Of note: I've seen the registry hacks for updating the new items context menu; my preference is to avoid such hacks and return the functionality to the expected behavior an administrator should have.

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  • Java: Switch statements with methods involving arrays

    - by Shane
    Hi guys I'm currently creating a program that allows the user to create an array, search an array and delete an element from an array. Looking at the LibraryMenu Method, the first case where you create an array in the switch statement works fine, however the other ones create a "cannot find symbol error" when I try to compile. My question is I want the search and delete functions to refer to the first switch case - the create Library array. Any help is appreciated, even if its likely from a simple mistake. import java.util.*; public class EnterLibrary { public static void LibraryMenu() { java.util.Scanner scannerObject =new java.util.Scanner(System.in); LibraryMenu Menu = new LibraryMenu(); Menu.displayMenu(); switch (scannerObject.nextInt() ) { case '1': { System.out.println ("1 - Add Videos"); Library[] newLibrary; newLibrary = createLibrary(); } break; case '2': System.out.println ("2 - Search Videos"); searchLibrary(newLibrary); break; case '3': { System.out.println ("3 - Change Videos"); //Change video method TBA } break; case '4': System.out.println ("4 - Delete Videos"); deleteVideo(newLibrary); break; default: System.out.println ("Unrecognized option - please select options 1-3 "); break; } } public static Library[] createLibrary() { Library[] videos = new Library[4]; java.util.Scanner scannerObject =new java.util.Scanner(System.in); for (int i = 0; i < videos.length; i++) { //User enters values into set methods in Library class System.out.print("Enter video number: " + (i+1) + "\n"); String number = scannerObject.nextLine(); System.out.print("Enter video title: " + (i+1) + "\n"); String title = scannerObject.nextLine(); System.out.print("Enter video publisher: " + (i+1) + "\n"); String publisher = scannerObject.nextLine(); System.out.print("Enter video duration: " + (i+1) + "\n"); String duration = scannerObject.nextLine(); System.out.print("Enter video date: " + (i+1) + "\n"); String date= scannerObject.nextLine(); System.out.print("VIDEO " + (i+1) + " ENTRY ADDED " + "\n \n"); //Initialize arrays videos[i] = new Library (); videos[i].setVideo( number, title, publisher, duration, date ); } return videos; } public static void printVidLibrary( Library[] videos) { //Get methods to print results System.out.print("\n======VIDEO CATALOGUE====== \n"); for (int i = 0; i < videos.length; i++) { System.out.print("Video number " + (i+1) + ": \n" + videos[i].getNumber() + "\n "); System.out.print("Video title " + (i+1) + ": \n" + videos[i].getTitle() + "\n "); System.out.print("Video publisher " + (i+1) + ": \n" + videos[i].getPublisher() + "\n "); System.out.print("Video duration " + (i+1) + ": \n" + videos[i].getDuration() + "\n "); System.out.print("Video date " + (i+1) + ": \n" + videos[i].getDate() + "\n "); } } public static Library searchLibrary( Library[] videos) { //User enters values to setSearch Library titleResult = new Library(); java.util.Scanner scannerObject =new java.util.Scanner(System.in); for (int n = 0; n < videos.length; n++) { System.out.println("Search for video number:\n"); String newSearch = scannerObject.nextLine(); titleResult.getSearch( videos, newSearch); if (!titleResult.equals(-1)) { System.out.print("Match found!\n" + newSearch + "\n"); } else if (titleResult.equals(-1)) { System.out.print("Sorry, no matches found!\n"); } } return titleResult; } public static void deleteVideo( Library[] videos) { Library titleResult = new Library(); java.util.Scanner scannerObject =new java.util.Scanner(System.in); for (int n = 0; n < videos.length; n++) { System.out.println("Search for video number:\n"); String deleteSearch = scannerObject.nextLine(); titleResult.deleteVideo(videos, deleteSearch); System.out.print("Video deleted\n"); } } public static void main(String[] args) { Library[] newLibrary; new LibraryMenu(); } }

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  • Android AsyncTask context problem, help!

    - by dnkoutso
    I've been working with AsyncTasks in Android and I am dealing with a strange issue. Take a simple example, an Activity with one AsyncTask. The task on the background does not do anything spectacular, it just sleeps for 8 seconds. At the end of the AsyncTask in the onPostExecute() method I am just setting a button visibility status to View.VISIBLE, only to verify my results. Now, this works great until the user decides to change his phones orientation while the AsyncTask is working (within the 8 second sleep window). I understand the Android activity life cycle and I know the activity gets destroyed and recreated. This is where the problem comes in. The AsyncTask is referring to a button and apparently holds a reference to the context that started the AsyncTask in the first place. I would expect, that this old context (since the user caused an orientation change) to either become null and the AsyncTask to throw an NPE for the reference to the button it is trying to make visible. Instead, no NPE is thrown, the asynctask thinks that the button reference is not null, sets it to visible. The result? Nothing is happening on the screen! I have tackled this by keeping and updating the context reference into the AsyncTask. This is cumbersome and prone to leaks. Here's the code: public class Main extends Activity { private Button mButton = null; private Button mTestButton = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mButton = (Button) findViewById(R.id.btnStart); mButton.setOnClickListener(new OnClickListener () { @Override public void onClick(View v) { new taskDoSomething().execute(0l); } }); mTestButton = (Button) findViewById(R.id.btnTest); } private class taskDoSomething extends AsyncTask<Long, Integer, Integer> { @Override protected Integer doInBackground(Long... params) { Log.i("LOGGER", "Starting..."); try { Thread.sleep(8000); } catch (InterruptedException e) { e.printStackTrace(); } return 0; } @Override protected void onPostExecute(Integer result) { Log.i("LOGGER", "...Done"); mTestButton.setVisibility(View.VISIBLE); } } } Try executing and while the AsyncTask is working change your phones orientation.

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  • When are references declared in a switch statement?

    - by sandis
    To my surprise this code works fine: int i = 2; switch(i) { case 1: String myString = "foo"; break; case 2: myString = "poo"; System.out.println(myString); } But the String reference should never be declared? Could it be that all variables under every case always are declared no matter what, or how is this resolved?

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  • Why do switch statements continue after case

    - by John W.
    After evaluating a case in a switch statement in Java (and I am sure other languages) the following case's are also evaluated unless a control statement like break, or return is used. I understand this is probably an implementation detail, but what is/are the reasons for having this functionality happen? Thanks!

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  • php switch statement error on int = 0

    - by Jagdeep Singh
    I am having a problem in php switch case. When i set $number=0 it should run very first case but here this code returns 10-20K that is in second case. I checked comparison operators, tested them in if else case they return correct values but here first case do not run on $number=0 Why is this happening ? php consider 0 as false or something wrong in code ? Link to codepad paste http://codepad.org/2glDh39K also here is the code <?php $number = 0; switch ($number) { case ($number <= 10000): echo "0-10K"; break; case ($number > 10000 && $number <= 20000): echo "10-20K"; break; case ($number > 20000 && $number <= 30000): echo "20-30K"; break; case ($number > 30000 && $number <= 40000): echo "30-40K"; break; case ($number > 40000 && $number <= 50000): echo "40-50K"; break; case ($number > 50000 && $number <= 60000): echo "50-60K"; break; case ($number > 60000 && $number <= 70000): echo "60-70K"; break; case ($number > 70000 && $number <= 80000): echo "70-80K"; break; case ($number > 80000 && $number <= 90000): echo "80-90K"; break; case ($number > 90000): echo "90K+"; break; default: //default echo "N/A"; break; } ?>

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  • Context module for block visibility

    - by calebthorne
    I have a site built in Drupal 6 that requires a number of blocks that are only visible to certain roles or on specific pages. Normally, I would use the block configuration settings to control page and role visibility. However I recently ran across the context module that effectively splits the site into "sections" or "groups" of related attributes. My question is: When is it appropriate to control block visibility from context rather than the block configuration settings? Should I only use one or the other or a combination of both?

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  • Best way to get an Application Context into a static method in Android

    - by Slapout
    I'm working on an Android application that has several Activities. In it I have a class with several static methods. I would like to be able to call these methods from the different Activities. I'm using the static methods to load data from an xml file via a XmlResourceParser. To create a XmlResourceParser requires a call on the Application Context. So my question is, what is the best way to get a reference to the Application Context into the static methods? Have each Activity get it and pass it in? Store it somehow in a global variable?

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  • Swapping switch-case in extra fle/data structure (Java)

    - by poeschlorn
    Hi guys, it may be a nooby question, but I've never needed it before: I have several strings and I want to compare them to given ones... At first glance it would lead to a switch/case construction in what every available entry is checked. Is there a more elegant way to swap those strings as key/value datas? greets, poeschlorn

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  • How to calculate required switch speed based on network usage?

    - by tobefound
    I have a 48 port HP Procurve Switch 2610 (J9088A) that can handle 13.0 million PPS (packets per second) and features wire speed switching capacity at 17.6Gbps. First off, what does that REALLY mean? Where do I start when trying to figure out if my office (with 70 employees) will be well setup with this switch? How to calculate through-put based on a user average load of X MB per day? 90% of the folks will only be sending email, access random websites, etc... the other 10% will be conducting heavier tasks like moving image files (10 MB) across network shares, constant external FTP streams through the switch to a server etc... Is this switch good enough?

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  • Spring - PropertiesPlaceholderConfigurer not finding properties file

    - by sat
    Not sure what could be wrong. I had an app that worked all along with this <context:property-placeholder location="classpath:my.properties"/> No problems finding the properties file and hooking things up. Now, I needed to encrypt some fields in the properties file. So I ended up writing the custom PropertiesPlaceholderConfigurer and tried to wire it up like this <bean class="com.mycompany.myapp.PropertiesPlaceholderConfigurer"> <property name="location" value="classpath:my.propeties"/> </bean> With this configuration, Spring complains that it cannot find the properties file. java.io.FileNotFoundException: class path resource [my.propeties] cannot be opened because it does not exist What in addition should be done? The custom placeholder configurer package com.mycompany.myapp; import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer; import org.springframework.util.ObjectUtils; import java.util.Enumeration; import java.util.Properties; public class PropertiesPlaceholderConfigurer extends PropertyPlaceholderConfigurer{ @Override protected void convertProperties(Properties props) { Enumeration<?> propertyNames = props.propertyNames(); while (propertyNames.hasMoreElements()) { String propertyName = (String) propertyNames.nextElement(); String propertyValue = props.getProperty(propertyName); if(propertyName.endsWith("encrypted")){ System.out.println("Decrypting the property " + propertyName); String convertedValue = decrypt(propertyValue); System.out.println("Decrypted the property value to " + convertedValue); if (!ObjectUtils.nullSafeEquals(propertyValue, convertedValue)) { props.setProperty(propertyName, convertedValue); } } } } } Update: Forget my custom placeholder configurer, even the spring provided one has trouble if I replace with this <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="location" value="classpath:my.propeties"/> </bean> What is context:property-placholder doing that the bean definition can't? Full stack trace java.lang.IllegalStateException: Failed to load ApplicationContext at org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContext(CacheAwareContextLoaderDelegate.java:99) at org.springframework.test.context.DefaultTestContext.getApplicationContext(DefaultTestContext.java:101) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75) at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:319) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:212) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:232) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:175) at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264) at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153) at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124) at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200) at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153) at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103) Caused by: org.springframework.beans.factory.BeanInitializationException: Could not load properties; nested exception is java.io.FileNotFoundException: class path resource [my.propeties] cannot be opened because it does not exist at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:89) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:265) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:162) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:609) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:121) at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:60) at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.delegateLoading(AbstractDelegatingSmartContextLoader.java:100) at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:250) at org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContextInternal(CacheAwareContextLoaderDelegate.java:64) at org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContext(CacheAwareContextLoaderDelegate.java:91) at org.springframework.test.context.DefaultTestContext.getApplicationContext(DefaultTestContext.java:101) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75) at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:319) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:212) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:232) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:175) at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264) at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153) at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124) at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200) at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153) at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103) Caused by: java.io.FileNotFoundException: class path resource [my.propeties] cannot be opened because it does not exist at org.springframework.core.io.ClassPathResource.getInputStream(ClassPathResource.java:158) at org.springframework.core.io.support.EncodedResource.getInputStream(EncodedResource.java:143) at org.springframework.core.io.support.PropertiesLoaderUtils.fillProperties(PropertiesLoaderUtils.java:98) at org.springframework.core.io.support.PropertiesLoaderSupport.loadProperties(PropertiesLoaderSupport.java:175) at org.springframework.core.io.support.PropertiesLoaderSupport.mergeProperties(PropertiesLoaderSupport.java:156) at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:80) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:265) at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:162) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:609) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:121) at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:60) at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.delegateLoading(AbstractDelegatingSmartContextLoader.java:100) at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:250) at org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContextInternal(CacheAwareContextLoaderDelegate.java:64) at org.springframework.test.context.CacheAwareContextLoaderDelegate.loadContext(CacheAwareContextLoaderDelegate.java:91) at org.springframework.test.context.DefaultTestContext.getApplicationContext(DefaultTestContext.java:101) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:109) at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75) at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:319) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:212) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:232) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:175) at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264) at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153) at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124) at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200) at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153) at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)

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  • Add Multiple Types of Items to the Desktop Context Menu in Windows 7 or 8

    - by Lori Kaufman
    The context menu in Windows provides a convenient place to start programs, access websites, and open folders. There are several ways to add programs to the menu including a registry method and a free tool. We’ve found another free tool, called Right Click Context Menu Adder, that allows you to add more than just programs to the desktop context menu and the folders context menu. It allows you to add folders, web addresses, and files to the menus, as well as programs. Right Click Context Menu Adder is portable and doesn’t need to be installed. To run it, simply extract the .zip file you downloaded (see the link at the end of this article) and double-click on the .exe file. How to Banish Duplicate Photos with VisiPic How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It?

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  • C++: Calling class functions within a switch

    - by user1446002
    i've been trying to study for my finals by practicing classes and inheritance, this is what I've come up with so far for inheritance and such however I'm unsure how to fix the error occuring below. #include<iostream> #include<iomanip> #include<cmath> #include<string.h> using namespace std; //BASE CLASS DEFINITION class hero { protected: string name; string mainAttr; int xp; double hp; double mana; double armour; int range; double attkDmg; bool attkType; public: void dumpData(); void getName(); void getMainAttr(); void getAttkData(); void setAttkData(string); void setBasics(string, string, double, double, double); void levelUp(); }; //CLASS FUNCTIONS void hero::dumpData() { cout << "Name: " << name << endl; cout << "Main Attribute: " << mainAttr << endl; cout << "XP: " << xp << endl; cout << "HP: " << hp << endl; cout << "Mana: " << mana << endl; cout << "Armour: " << armour << endl; cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl << endl; } void hero::getName() { cout << "Name: " << name << endl; } void hero::getMainAttr() { cout << "Main Attribute: " << mainAttr << endl; } void hero::getAttkData() { cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl; } void hero::setAttkData(string attr) { int choice = 0; if (attr == "Strength") { choice = 1; } if (attr == "Agility") { choice = 2; } if (attr == "Intelligence") { choice = 3; } switch (choice) { case 1: range = 128; attkDmg = 80.0; attkType = 0; break; case 2: range = 350; attkDmg = 60.0; attkType = 0; break; case 3: range = 600; attkDmg = 35.0; attkType = 1; break; default: break; } } void hero::setBasics(string heroName, string attribute, double health, double mp, double armourVal) { name = heroName; mainAttr = attribute; hp = health; mana = mp; armour = armourVal; } void hero::levelUp() { xp = 0; hp = hp + (hp * 0.1); mana = mana + (mana * 0.1); armour = armour + ((armour*0.1) + 1); attkDmg = attkDmg + (attkDmg * 0.05); } //INHERITED CLASS DEFINITION class neutHero : protected hero { protected: string drops; int xpGain; public: int giveXP(int); void dropItems(); }; //INHERITED CLASS FUNCTIONS int neutHero::giveXP(int exp) { xp += exp; } void neutHero::dropItems() { cout << name << " has dropped the following items: " << endl; cout << drops << endl; } /* END OF OO! */ //FUNCTION PROTOTYPES void dispMenu(); int main() { int exit=0, choice=0, mainAttrChoice=0, heroCreated=0; double health, mp, armourVal; string heroName, attribute; do { dispMenu(); cin >> choice; switch (choice) { case 1: system("cls"); cout << "Please enter your hero name: "; cin >> heroName; cout << "\nPlease enter your primary attribute\n"; cout << "1. Strength\n" << "2. Agility\n" << "3. Intelligence\n"; cin >> mainAttrChoice; switch (mainAttrChoice) { case 1: attribute = "Strength"; health = 750; mp = 150; armourVal = 2; break; case 2: attribute = "Agility"; health = 550; mp = 200; armourVal = 6; break; case 3: attribute = "Intelligence"; health = 450; mp = 450; armourVal = 1; break; default: cout << "Choice invalid, please try again."; exit = 1; break; hero player; player.setBasics(heroName, attribute, health, mp, armourVal); player.setAttkData(attribute); heroCreated=1; system("cls"); cout << "Your hero has been created!\n\n"; player.dumpData(); system("pause"); break; } case 2: system("cls"); if (heroCreated == 1) { cout << "Your hero has been detailed below.\n\n"; **player.dumpData(); //ERROR OCCURS HERE !** system("pause"); } else { cout << "You have not created a hero please exit this prompt " "and press 1 on the menu to create a hero."; } break; case 3: system("cls"); cout << "Still Under Development"; system("pause"); break; case 4: system("cls"); exit = 1; break; default: cout << "Your command has not been recognised, please try again.\n"; system("pause"); break; } } while (exit != 1); system("pause"); return 0; } void dispMenu() { system("cls"); cout << "1. Create New Hero\n" "2. View Current Hero\n" "3. Fight Stuff\n" "4. Exit\n\n" "Enter your choice: "; } However upon compilation I get the following errors: 220 `player' undeclared (first use this function) Unsure exactly how to fix it as I've only recently started using OO approach. The error has a comment next to it above and is in case 2 in the main. Cheers guys.

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  • java.lang.ExceptionInInitializerError Exception when creating Application Context in Spring

    - by cyotee
    I am practicing with Spring, and am getting a java.lang.ExceptionInInitializerError exception when I try to instantiate the context. The Exception appears below, with my code following it. I have simplified my experiment from before. The Exception Oct 17, 2012 5:54:22 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@570c16b7: startup date [Wed Oct 17 17:54:22 CDT 2012]; root of context hierarchy Exception in thread "main" java.lang.ExceptionInInitializerError at org.springframework.context.support.AbstractRefreshableApplicationContext.createBeanFactory(AbstractRefreshableApplicationContext.java:195) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:128) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:535) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:449) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83) at helloworld.HelloWorldTest.main(HelloWorldTest.java:13) Caused by: java.lang.NullPointerException at org.springframework.beans.factory.support.DefaultListableBeanFactory.<clinit>(DefaultListableBeanFactory.java:105) ... 7 more My configuration XML <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd"> <bean id="messageContainer" class="helloworld.MessageContainer"> <property name="message" value="Hello World"> </property> </bean> <bean id="messageOutputService" class="helloworld.MessageOutputService"> </bean> My test class. package helloworld; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class HelloWorldTest { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("HelloWorldTest-context.xml"); MessageContainer message = context.getBean(MessageContainer.class); MessageOutputService service = context.getBean(MessageOutputService.class); service.outputMessageToConsole(message); } }

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  • Converting switch statements to more elegant solution.

    - by masfenix
    I have a 9 x 9 matrix. (think of suduko). 4 2 1 6 8 1 8 5 8 3 1 5 8 1 1 7 5 8 1 1 4 0 5 6 7 0 4 6 2 5 5 4 4 8 1 2 6 8 8 2 8 1 6 3 5 8 4 2 6 4 7 4 1 1 1 3 5 3 8 8 5 2 2 2 6 6 0 8 8 8 0 6 8 7 2 3 3 1 1 7 4 now I wanna be able to get a "quadrant". for example (according to my code) the quadrant 2 , 2 returns the following: 5 4 4 2 8 1 6 4 7 If you've noticed, this is the matrix from the very center of the 9 x 9. I've split everything up in to pairs of "3" if you know what i mean. the first "ROW" is from 0 - 3, the second from 3 - 6, the third for 6 - 9.. I hope this makes sense ( I am open to alternate ways to go about this) anyways, heres my code. I dont really like this way, even though it works. I do want speed though beccause i am making a suduko solver. //a quadrant returns the mini 3 x 3 //row 1 has three quads,"1", "2", 3" //row 2 has three quads "1", "2", "3" etc public int[,] GetQuadrant(int rnum, int qnum) { int[,] returnMatrix = new int[3, 3]; int colBegin, colEnd, rowBegin, rowEnd, row, column; //this is so we can keep track of the new matrix row = 0; column = 0; switch (qnum) { case 1: colBegin = 0; colEnd = 3; break; case 2: colBegin = 3; colEnd = 6; break; case 3: colBegin = 6; colEnd = 9; break; default: colBegin = 0; colEnd = 0; break; } switch (rnum) { case 1: rowBegin = 0; rowEnd = 3; break; case 2: rowBegin = 3; rowEnd = 6; break; case 3: rowBegin = 6; rowEnd = 9; break; default: rowBegin = 0; rowEnd = 0; break; } for (int i = rowBegin ; i < rowEnd; i++) { for (int j = colBegin; j < colEnd; j++) { returnMatrix[row, column] = _matrix[i, j]; column++; } column = 0; row++; } return returnMatrix; }

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  • Unnecessary Java context switches

    - by Paul Morrison
    I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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  • Set Context User Principal for Customized Authentication in SignalR

    - by Shaun
    Originally posted on: http://geekswithblogs.net/shaunxu/archive/2014/05/27/set-context-user-principal-for-customized-authentication-in-signalr.aspxCurrently I'm working on a single page application project which is built on AngularJS and ASP.NET WebAPI. When I need to implement some features that needs real-time communication and push notifications from server side I decided to use SignalR. SignalR is a project currently developed by Microsoft to build web-based, read-time communication application. You can find it here. With a lot of introductions and guides it's not a difficult task to use SignalR with ASP.NET WebAPI and AngularJS. I followed this and this even though it's based on SignalR 1. But when I tried to implement the authentication for my SignalR I was struggled 2 days and finally I got a solution by myself. This might not be the best one but it actually solved all my problem.   In many articles it's said that you don't need to worry about the authentication of SignalR since it uses the web application authentication. For example if your web application utilizes form authentication, SignalR will use the user principal your web application authentication module resolved, check if the principal exist and authenticated. But in my solution my ASP.NET WebAPI, which is hosting SignalR as well, utilizes OAuth Bearer authentication. So when the SignalR connection was established the context user principal was empty. So I need to authentication and pass the principal by myself.   Firstly I need to create a class which delivered from "AuthorizeAttribute", that will takes the responsible for authenticate when SignalR connection established and any method was invoked. 1: public class QueryStringBearerAuthorizeAttribute : AuthorizeAttribute 2: { 3: public override bool AuthorizeHubConnection(HubDescriptor hubDescriptor, IRequest request) 4: { 5: } 6:  7: public override bool AuthorizeHubMethodInvocation(IHubIncomingInvokerContext hubIncomingInvokerContext, bool appliesToMethod) 8: { 9: } 10: } The method "AuthorizeHubConnection" will be invoked when any SignalR connection was established. And here I'm going to retrieve the Bearer token from query string, try to decrypt and recover the login user's claims. 1: public override bool AuthorizeHubConnection(HubDescriptor hubDescriptor, IRequest request) 2: { 3: var dataProtectionProvider = new DpapiDataProtectionProvider(); 4: var secureDataFormat = new TicketDataFormat(dataProtectionProvider.Create()); 5: // authenticate by using bearer token in query string 6: var token = request.QueryString.Get(WebApiConfig.AuthenticationType); 7: var ticket = secureDataFormat.Unprotect(token); 8: if (ticket != null && ticket.Identity != null && ticket.Identity.IsAuthenticated) 9: { 10: // set the authenticated user principal into environment so that it can be used in the future 11: request.Environment["server.User"] = new ClaimsPrincipal(ticket.Identity); 12: return true; 13: } 14: else 15: { 16: return false; 17: } 18: } In the code above I created "TicketDataFormat" instance, which must be same as the one I used to generate the Bearer token when user logged in. Then I retrieve the token from request query string and unprotect it. If I got a valid ticket with identity and it's authenticated this means it's a valid token. Then I pass the user principal into request's environment property which can be used in nearly future. Since my website was built in AngularJS so the SignalR client was in pure JavaScript, and it's not support to set customized HTTP headers in SignalR JavaScript client, I have to pass the Bearer token through request query string. This is not a restriction of SignalR, but a restriction of WebSocket. For security reason WebSocket doesn't allow client to set customized HTTP headers from browser. Next, I need to implement the authentication logic in method "AuthorizeHubMethodInvocation" which will be invoked when any SignalR method was invoked. 1: public override bool AuthorizeHubMethodInvocation(IHubIncomingInvokerContext hubIncomingInvokerContext, bool appliesToMethod) 2: { 3: var connectionId = hubIncomingInvokerContext.Hub.Context.ConnectionId; 4: // check the authenticated user principal from environment 5: var environment = hubIncomingInvokerContext.Hub.Context.Request.Environment; 6: var principal = environment["server.User"] as ClaimsPrincipal; 7: if (principal != null && principal.Identity != null && principal.Identity.IsAuthenticated) 8: { 9: // create a new HubCallerContext instance with the principal generated from token 10: // and replace the current context so that in hubs we can retrieve current user identity 11: hubIncomingInvokerContext.Hub.Context = new HubCallerContext(new ServerRequest(environment), connectionId); 12: return true; 13: } 14: else 15: { 16: return false; 17: } 18: } Since I had passed the user principal into request environment in previous method, I can simply check if it exists and valid. If so, what I need is to pass the principal into context so that SignalR hub can use. Since the "User" property is all read-only in "hubIncomingInvokerContext", I have to create a new "ServerRequest" instance with principal assigned, and set to "hubIncomingInvokerContext.Hub.Context". After that, we can retrieve the principal in my Hubs through "Context.User" as below. 1: public class DefaultHub : Hub 2: { 3: public object Initialize(string host, string service, JObject payload) 4: { 5: var connectionId = Context.ConnectionId; 6: ... ... 7: var domain = string.Empty; 8: var identity = Context.User.Identity as ClaimsIdentity; 9: if (identity != null) 10: { 11: var claim = identity.FindFirst("Domain"); 12: if (claim != null) 13: { 14: domain = claim.Value; 15: } 16: } 17: ... ... 18: } 19: } Finally I just need to add my "QueryStringBearerAuthorizeAttribute" into the SignalR pipeline. 1: app.Map("/signalr", map => 2: { 3: // Setup the CORS middleware to run before SignalR. 4: // By default this will allow all origins. You can 5: // configure the set of origins and/or http verbs by 6: // providing a cors options with a different policy. 7: map.UseCors(CorsOptions.AllowAll); 8: var hubConfiguration = new HubConfiguration 9: { 10: // You can enable JSONP by uncommenting line below. 11: // JSONP requests are insecure but some older browsers (and some 12: // versions of IE) require JSONP to work cross domain 13: // EnableJSONP = true 14: EnableJavaScriptProxies = false 15: }; 16: // Require authentication for all hubs 17: var authorizer = new QueryStringBearerAuthorizeAttribute(); 18: var module = new AuthorizeModule(authorizer, authorizer); 19: GlobalHost.HubPipeline.AddModule(module); 20: // Run the SignalR pipeline. We're not using MapSignalR 21: // since this branch already runs under the "/signalr" path. 22: map.RunSignalR(hubConfiguration); 23: }); On the client side should pass the Bearer token through query string before I started the connection as below. 1: self.connection = $.hubConnection(signalrEndpoint); 2: self.proxy = self.connection.createHubProxy(hubName); 3: self.proxy.on(notifyEventName, function (event, payload) { 4: options.handler(event, payload); 5: }); 6: // add the authentication token to query string 7: // we cannot use http headers since web socket protocol doesn't support 8: self.connection.qs = { Bearer: AuthService.getToken() }; 9: // connection to hub 10: self.connection.start(); Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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