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  • Static property references non-static method

    - by rhj4
    How can a static property reference a nonstatic method? Example: public static int UserID { get { return GetUserID(); } } private int GetUserID() { return 1; } When I try to compile this, I get the error: "An object reference is required for he non-static field, method or property "GetUserID()"

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  • [C++]Advantage of using a static member function instead of an equivalent non-static member function

    - by jonathanasdf
    I was wondering whether there's any advantages to using a static member function when there is a non-static equivalent. Will it result in faster execution (because of not having to care about all of the member variables), or maybe less use of memory (because of not being included in all instances)? Basically, the function I'm looking at is an utility function to rotate an integer array representing pixel colours an arbitrary number of degrees around an arbitrary centre point. It is placed in my abstract Bullet base class, since only the bullets will be using it and I didn't want the overhead of calling it in some utility class. It's a bit too long and used in every single derived bullet class, making it probably not a good idea to inline. How would you suggest I define this function? As a static member function of Bullet, of a non-static member function of Bullet, or maybe not as a member of Bullet but defined outside of the class in Bullet.h? What are the advantages and disadvantages of each?

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  • Why can't you call a non-static method from a static method?

    - by VoodooChild
    I have a static method [Method1] in my class, which calls another method [Method2] in the same class and is not a static method. But this is a no-no. I get this error: An object reference is required for the non-static field, method, or property "ClassName.MethodName()" Can someone please briefly describe why? including other things that might be related to this.

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  • Syntactic sugar in PHP with static functions

    - by Anna
    The dilemma I'm facing is: should I use static classes for the components of an application just to get nicer looking API? Example - the "normal" way: // example component class Cache{ abstract function get($k); abstract function set($k, $v); } class APCCache extends Cache{ ... } class application{ function __construct() $this->cache = new APCCache(); } function whatever(){ $this->cache->add('blabla'); print $this->cache->get('blablabla'); } } Notice how ugly is this->cache->.... But it gets waay uglier when you try to make the application extensible trough plugins, because then you have to pass the application instance to its plugins, and you get $this->application->cache->... With static functions: interface CacheAdapter{ abstract function get($k); abstract function set($k, $v); } class Cache{ public static $ad; public function setAdapter(CacheAdapter $a){ static::$ad = $ad; } public static function get($k){ return static::$ad->get($k); } ... } class APCCache implements CacheAdapter{ ... } class application{ function __construct(){ cache::setAdapter(new APCCache); } function whatever() cache::add('blabla', 5); print cache::get('blabla'); } } Here it looks nicer because you just call cache::get() everywhere. The disadvantage is that I loose the possibility to extend this class easily. But I've added a setAdapter method to make the class extensible to some point. I'm relying on the fact that I won't need to rewrite to replace the cache wrapper, ever, and that I won't need to run multiple application instances simultaneously (it's basically a site - and nobody works with two sites at the same time) So, am doing it wrong?

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  • Why use link classes in oql instead of classes that contain links

    - by Isaac
    itop abstracts its very complex database design with an object query language (oql). For this there are classes definded, like 'Ticket' and 'Server'. Now a Ticket usually is linked to a Server. In my naive way I would give the Ticket class an attribute 'affected_server_list', where I could reference the affected servers. itop does it different: neither Servers nor Tickets know of each other. Instead there is a class 'linkTicketToServer', which provides the link between the two. The first thing I noticed is that it makes oql queries more complex. So I wondered why they designed it this way. One thing that occured to me is that it allows for more flexiblity, in that I can add links without modifying the original classes. Is this allready why one would implement it this way, or are there other reasons for this kind of design?

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  • non-static variable cannot be referenced from a static context (java)

    - by Greg
    I ask that you ignore all logic.. i was taught poorly at first and so i still dont understand everything about static crap and its killing me. My error is with every single variable that i declare then try to use later inside my methods... i get the non-static variable cannot~~ error I can simply put all the rough coding of my methods inside my cases, and it works but then i cannot use recursion... What i really need is someone to help on the syntax and point me on the right direction of how to have my methods recognize my variables at the top... like compareCount etc thanks public class MyProgram7 { public static void main (String[]args) throws IOException{ Scanner scan = new Scanner(System.in); int compareCount = 0; int low = 0; int high = 0; int mid = 0; int key = 0; Scanner temp; int[]list; String menu, outputString; int option = 1; boolean found = false; // Prompt the user to select an option menu = "\n\t1 Reads file" + "\n\t2 Finds a specific number in the list" + "\n\t3 Prints how many comparisons were needed" + "\n\t0 Quit\n\n\n"; System.out.println(menu); System.out.print("\tEnter your selection: "); option = scan.nextInt(); // Keep reading data until the user enters 0 while (option != 0) { switch (option) { case 1: readFile(); break; case 2: findKey(list,low,high,key); break; case 3: printCount(); break; default: outputString = "\nInvalid Selection\n"; System.out.println(outputString); break; }//end of switch System.out.println(menu); System.out.print("\tEnter your selection: "); option = scan.nextInt(); }//end of while }//end of main public static void readFile() { int i = 0; temp = new Scanner(new File("CS1302_Data7_2010.txt")); while(temp.hasNext()) { list[i]= temp.nextInt(); i++; }//end of while temp.close(); System.out.println("File Found..."); }//end of readFile() public static void findKey() { while(found!=true) { while(key < 100 || key > 999) { System.out.println("Please enter the number you would like to search for? ie 350: "); key = scan.nextInt(); }//end of inside while //base if (low <= high) { mid = ((low+high)/2); if (key == list[mid]) { found = true; compareCount++; }//end of inside if }//end of outside if else if (key < list[mid]) { compareCount++; high = mid-1; findKey(list,low,high,key); }//end of else if else { compareCount++; low = mid+1; findKey(list,low,high,key); }//end of else }//end of outside while }//end of findKey() public static void printCount() { System.out.println("Total number of comparisons is: " + compareCount); }//end of printCount }//end of class

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  • Regarding C Static/Non Static Float Arrays (Xcode, Objective C)

    - by user1875290
    Basically I have a class method that returns a float array. If I return a static array I have the problem of it being too large or possibly even too small depending on the input parameter as the size of the array needed depends on the input size. If I return just a float array[arraysize] I have the size problem solved but I have other problems. Say for example I address each element of the non-static float array individually e.g. NSLog(@"array[0] %f array[1] %f array[2] %f",array[0],array[1],array[2]); It prints the correct values for the array. However if I instead use a loop e.g. for (int i = 0; i < 3; i++) { NSLog(@"array[%i] %f",i,array[i]); } I get some very strange numbers (apart from the last index, oddly). Why do these two things produce different results? I'm aware that its bad practice to simply return a non static float, but even so, these two means of addressing the array look the same to me. Relevant code from class method (for non-static version)... float array[arraysize]; //many lines of code later if (weShouldStoreValue == true) { array[index] = theFloat; index = index + 1; } //more lines of code later return array; Note that it returns a (float*).

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  • Cannot make a static reference to the non-static type MyRunnable

    - by kaiwii ho
    Here is the whole code : import java.util.ArrayList; public class Test{ ThreadLocal<ArrayList<E>>arraylist=new ThreadLocal<ArrayList<E>>(){ @Override protected ArrayList<E> initialValue() { // TODO Auto-generated method stub //return super.initialValue(); ArrayList<E>arraylist=new ArrayList<E>(); for(int i=0;i<=20;i++) arraylist.add((E) new Integer(i)); return arraylist; } }; class MyRunnable implements Runnable{ private Test mytest; public MyRunnable(Test test){ mytest=test; // TODO Auto-generated constructor stub } @Override public void run() { System.out.println("before"+mytest.arraylist.toString()); ArrayList<E>myarraylist=(ArrayList<E>) mytest.arraylist.get(); myarraylist.add((E) new Double(Math.random())); mytest.arraylist.set(myarraylist); System.out.println("after"+mytest.arraylist.toString()); } // TODO Auto-generated method stub } public static void main(String[] args){ Test test=new Test<Double>(); System.out.println(test.arraylist.toString()); new Thread(new MyRunnable(test)).start(); new Thread(new MyRunnable(test)).start(); System.out.println(arraylist.toString()); } } my questions are: 1\ why the new Thread(new MyRunnable(test)).start(); cause the error: Cannot make a static reference to the non-static type MyRunnable ? 2\ what is the static reference refer to right here? thx in advanced

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  • Most scalable way of serving a small set of static HTTP content

    - by Ekevoo
    The story: Hi guys. I'm among the people responsible for serving the results of the most anticipated (by number of people participating) annual entrance exam in my state. As such, when our results are published, the interest is overwhelming. In the past we delegated the responsibility of serving the results to the media, but that spoils a little the officialness of these results. This year we went with a little (long overdue) experiment of using lighttpd instead of Apache as well as other physical network optimizations I wasn't directly involved with. The results were very satisfactory. The server didn't choke even once, nor we saw any of the usual Twitter complaints on unavailability and/or slowness that were previously common. However, because we still delegated the first publication of the results to the media I'm still not 100% sure we can handle the load of actually publishing the results first. The question: Now because these files are like 14MB in total and a true lightweight Linux distribution isn't that big either, I'm thinking: what if next year we run full RAMdrive? Is there any? Is that useful? Is that worth it for a team that uses Debian almost exclusively? Are there other optimizations that I should be focusing on instead?

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  • Linux, static lib referring to other static lib within an executable

    - by andras
    Hello, I am creating an application, which consists of two static libs and an executable. Let's call the two static libs: libusefulclass.a libcore.a And the application: myapp libcore instantiates and uses the class defined in libusefulclass (let's call it UsefulClass) Now, if I link the application in the following way: g++ -m64 -Wl,-rpath,/usr/local/Trolltech/Qt-4.5.4/lib -o myapp src1.o src2.o srcN.o -lusefulclass -lcore The linker complains about the methods in libusefulclass not being found: undefined reference to `UsefulClass::foo()' etc. I found a workaround for this: If UsefulClass is also instantiated within the source files of the executable itself, the application is linked without any problems. My question is: is there a more clean way to make libcore refer to methods defined in libusefulclass, or static libs just cannot be linked against eachother? TIA P.S.: In case that matters: the application is being developed in C++ using Qt, but I feel this is not a Qt problem, but a library problem in general.

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  • Building iPhone static library for armv6 and armv7 that includes another static library

    - by Martijn Thé
    Hi, I have an Xcode project that has a "master" static library target, that includes/links to a bunch of other static libraries from other Xcode projects. When building the master library target for "Optimized (armv6 armv7)", an error occurs in the last phase, during the CreateUniversalBinary step. For each .o file of the libraries that is included by the master library, the following error is reported (for example, the FBConnectGlobal.o file): warning for architecture: armv6 same member name (FBConnectGlobal.o) in output file used for input files: /Developer_Beta/Builds/MTToolbox/MTToolbox.build/Debug-iphoneos/MTToolbox.build/Objects-normal/armv6/libMTToolbox.a(FBConnectGlobal.o) and: /Developer_Beta/Builds/MTToolbox/MTToolbox.build/Debug-iphoneos/MTToolbox.build/Objects-normal/armv7/libMTToolbox.a(FBConnectGlobal.o) due to use of basename, truncation and blank padding In the end, Xcode tells that the build has succeeded. However, when using the final static library in an application project, it won't build because it finds duplicate symbols in one part of build (armv6) and misses symbols in the other part of the build (armv7). Any ideas how to fix this? M

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  • Google Analytics setting cookies on static content despite being on entirely separate domain

    - by Donald Jenkins
    I recently decided to comply with the YSlow recommendation that static content is hosted on a cookieless domain. As I already use the root of my domain (donaldjenkins.com) to host my website—on which Google Analytics sets a few cookies—that meant I had to move the CNAME URL for the CDN serving the static files from cdn.donaldjenkins.com to an entirely separate, dedicated domain. I purchased cdn.dj (yes, it's a real Djibouti domain name), hosted the files on the root (which contains nothing else, other than a robots.txt file) and set a CNAME of e.cdn.dj for the CDN. This setup works, but I was rather surprised to find that YSlow was still flagging the static files for not being cookie-free: here's a screenshot: The cdn.djdomain was new, and was never used for anything other than hosting these static files. Running httpfox on the site shows the _utma and _utmz Google Analytics cookies are being set on the static files listed above—despite their being hosted on an entirely separate, dedicated domain. Here's my Google Analytics code: //Google Analytics tracking code var _gaq=[['_setAccount','UA-5245947-5'],['_trackPageview']]; (function(d,t){var g=d.createElement(t),s=d.getElementsByTagName(t)[0]; g.src=('https:'==location.protocol?'//ssl':'//www')+'.google-analytics.com/ga.js'; s.parentNode.insertBefore(g,s)}(document,'script')); // [END] Google Analytics tracking code I'm not obsessing about this issue—I know it's not really affecting server performance—but I'd like to just understand what is causing it not to go away...

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  • Script + template to generate static web site?

    - by user702
    After giving it more thought, I don't actually need a PHP-based CMS for a small, static web site. Does someone know of a good solution that can run on Windows that would take basic HTML pages and JPG pictures, combine those with a template, and generate a static site ready to be FTPed to an web server? Thank you. Edit: For those looking for the same information, here's some well-known tools to create a static site: http://get-simple.info/ http://gpeasy.com/How_Easy http://textpattern.com/features http://nanoc.stoneship.org/ http://www.movabletype.com/

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  • get static initialization block to run in a java without loading the class

    - by TP
    I have a few classes as shown here public class TrueFalseQuestion implements Question{ static{ QuestionFactory.registerType("TrueFalse", "Question"); } public TrueFalseQuestion(){} } ... public class QuestionFactory { static final HashMap<String, String > map = new HashMap<String,String>(); public static void registerType(String questionName, String ques ) { map.put(questionName, ques); } } public class FactoryTester { public static void main(String[] args) { System.out.println(QuestionFactory.map.size()); // This prints 0. I want it to print 1 } } How can I change TrueFalseQuestion Type so that the static method is always run so that I get 1 instead of 0 when I run my main method? I do not want any change in the main method. I am actually trying to implement the factory patterns where the subclasses register with the factory but i have simplified the code for this question.

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  • Call static properties within another class in php

    - by ali A
    I have problem about calling a static property of a class inside another class. Class A { public $property; public function __construct( $prop ) { $this->property = $prop; } public function returnValue(){ return static::$this->property; } } Class B extends A { public static $property_one = 'This is first property'; public static $property_two = 'This is second property'; } $B = new B( 'property_one' ); $B->returnValue(); I expect to return This is first property But the Output is just the name a parameter input in __construct; When I print_r( static::$this->property ); the output is just property_one

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  • Java - Class type from inside static initialization block

    - by DutrowLLC
    Is it possible to get the class type from inside the static initialization block? This is a simplified version of what I currently have:: class Person extends SuperClass { String firstName; static{ // This function is on the "SuperClass": // I'd for this function to be able to get "Person.class" without me // having to explicitly type it in but "this.class" does not work in // a static context. doSomeReflectionStuff(Person.class); // IN "SuperClass" } } This is closer to what I am doing, which is to initialize a data structure that holds information about the object and its annotations, etc... Perhaps I am using the wrong pattern? public abstract SuperClass{ static void doSomeReflectionStuff( Class<?> classType, List<FieldData> fieldDataList ){ Field[] fields = classType.getDeclaredFields(); for( Field field : fields ){ // Initialize fieldDataList } } } public abstract class Person { @SomeAnnotation String firstName; // Holds information on each of the fields, I used a Map<String, FieldData> // in my actual implementation to map strings to the field information, but that // seemed a little wordy for this example static List<FieldData> fieldDataList = new List<FieldData>(); static{ // Again, it seems dangerous to have to type in the "Person.class" // (or Address.class, PhoneNumber.class, etc...) every time. // Ideally, I'd liken to eliminate all this code from the Sub class // since now I have to copy and paste it into each Sub class. doSomeReflectionStuff(Person.class, fieldDataList); } }

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  • call function between classes [closed]

    - by aziz joh
    hello I have 3 classes class A, B, and C class A is the main class and content the main function also, i call class B and class C in the main as b1,b2 and c1. in class B there is a vector (V) has list of int. and 3 functions Add, get and delete delete. all the thing in the class is public. in class C i have function that need to (B::get) from b. what I want is that how I can make c1 call get of b1 to return the value of the V in b1 after that use add of b2 to add new item in V of b2. Thanks in advance This is an example class a{ int main(){ b b1,b2; c c1; b1.add(10); b1.add(20); c1.start(); }} class b{ vector<int> v; void add(int i){ v.push_back(i)} int get(){int i=v.at(0); return i;} } class c{// take something from b1 and add it to b2 void play(){ int i=b.get();//should take it from b1 b.add(i*2);//should add it to b2 }} please I need your help I been searching to solve this problem for days.

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  • How to create static method that evaluates local static variable once?

    - by Viet
    I have a class with static method which has a local static variable. I want that variable to be computed/evaluated once (the 1st time I call the function) and for any subsequent invocation, it is not evaluated anymore. How to do that? Here's my class: template< typename T1 = int, unsigned N1 = 1, typename T2 = int, unsigned N2 = 0, typename T3 = int, unsigned N3 = 0, typename T4 = int, unsigned N4 = 0, typename T5 = int, unsigned N5 = 0, typename T6 = int, unsigned N6 = 0, typename T7 = int, unsigned N7 = 0, typename T8 = int, unsigned N8 = 0, typename T9 = int, unsigned N9 = 0, typename T10 = int, unsigned N10 = 0, typename T11 = int, unsigned N11 = 0, typename T12 = int, unsigned N12 = 0, typename T13 = int, unsigned N13 = 0, typename T14 = int, unsigned N14 = 0, typename T15 = int, unsigned N15 = 0, typename T16 = int, unsigned N16 = 0> struct GroupAlloc { static const uint32_t sizeClass; static uint32_t getSize() { static uint32_t totalSize = 0; totalSize += sizeof(T1)*N1; totalSize += sizeof(T2)*N2; totalSize += sizeof(T3)*N3; totalSize += sizeof(T4)*N4; totalSize += sizeof(T5)*N5; totalSize += sizeof(T6)*N6; totalSize += sizeof(T7)*N7; totalSize += sizeof(T8)*N8; totalSize += sizeof(T9)*N9; totalSize += sizeof(T10)*N10; totalSize += sizeof(T11)*N11; totalSize += sizeof(T12)*N12; totalSize += sizeof(T13)*N13; totalSize += sizeof(T14)*N14; totalSize += sizeof(T15)*N15; totalSize += sizeof(T16)*N16; totalSize = 8*((totalSize + 7)/8); return totalSize; } };

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  • Static Variables in Overloaded Functions

    - by BSchlinker
    I have a function which does the following: When the function is called and passed a true bool value, it sets a static bool value to true When the function is called and passed a string, if the static bool value is set to true, it will do something with that string Here is my concern -- will a static variable remain the same between two overloaded functions? If not, I can simply create a separate function designed to keep track of the bool value, but I try to keep things simple.

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  • non static method cannot be referenced from a static context.

    - by David
    First some code: import java.util.*; ... class TicTacToe { ... public static void main (String[]arg) { Random Random = new Random() ; toerunner () ; // this leads to a path of methods that eventualy gets us to the rest of the code } ... public void CompTurn (int type, boolean debug) { ... boolean done = true ; int a = 0 ; while (!done) { a = Random.nextInt(10) ; if (debug) { int i = 0 ; while (i<20) { System.out.print (a+", ") ; i++; }} if (possibles[a]==1) done = true ; } this.board[a] = 2 ; } ... } //to close the class Here is the error message: TicTacToe.java:85: non-static method nextInt(int) cannot be referenced from a static context a = Random.nextInt(10) ; ^ What exactly went wrong? What does that error message "non static method cannot be referenced from a static context" mean?

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  • Inherit static properties in subclass without redeclaration?

    - by David
    Hi, I'm having the same problem as this guy with the application I'm writing right now. The problem is that static properties are not being inherited in subclasses, and so if I use the static:: keyword in my main class, it sets the variable in my main class as well. It works if I redeclare the static variables in my subclass, but I expect to have a large number of static properties and subclasses and wish to avoid code duplication. The top-rated response on the page I linked has a link to a few "workarounds", but it seems to have 404'd. Can anyone lend me some help or perhaps point me in the direction of said workarounds?

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  • Why and when should I make a class 'static'? What is the purpose of 'static' keyword on classes?

    - by Saeed Neamati
    The static keyword on a member in many languages mean that you shouldn't create an instance of that class to be able to have access to that member. However, I don't see any justification to make an entire class static. Why and when should I make a class static? What benefits do I get from making a class static? I mean, after declaring a static class, one should still declare all members which he/she wants to have access to without instantiation, as static too. This means that for example, Math class could be declared normal (not static), without affecting how developers code. In other words, making a class static or normal is kind of transparent to developers.

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