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Search found 50247 results on 2010 pages for 'base class'.

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• Constructors in Inner classes (implementing Interfaces)

  - by thepandaatemyface

  Hi, How would I go about writing a constructor for an inner class which is implementing an interface? I know I could make a whole new class, but I figure there's got to be a way to do something along the line of this: JButton b = new JButton(new AbstractAction() { public AbstractAction() { super("This is a button"); } public void actionPerformed(ActionEvent e) { System.out.println("button clicked"); } }); When I enter this it doesn't recognize the AbstractAction method as a constructor (compiler asks for return type). Anyone have an idea? Thanks

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• Counter variable for class

  - by George

  I am having problem getting this piece of code to run. The class is Student which has a IdCounter, and it is where the problem seems to be. (at line 8) class Student: def __init__(self): # Each student get their own student ID idCounter = 0 self.gpa = 0 self.record = {} # Each time I create a new student, the idCounter increment idCounter += 1 self.name = 'Student {0}'.format(Student.idCounter) classRoster = [] # List of students for number in range(25): newStudent = Student() classRoster.append(newStudent) print(newStudent.name) I am trying to have this idCounter inside my Student class, so I can have it as part of the student's name (which is really an ID#, for example Student 12345. But I have been getting error. Traceback (most recent call last): File "/Users/yanwchan/Documents/test.py", line 13, in <module> newStudent = Student() File "/Users/yanwchan/Documents/test.py", line 8, in __init__ idCounter += 1 UnboundLocalError: local variable 'idCounter' referenced before assignment I tried to put the idCounter += 1 in before, after, all combination, but I am still getting the referenced before assignment error, can you explain to me what I am doing wrong? Thank you Edit: Provided the full code I have

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• Pass variable number of variables to a class in PHP

  - by user325282

  I need to pass a variable number of strings to instantiate different classes. I can always do a switch on the size of the array: switch(count($a)) { case 1: new Class(${$a[0]}); break; case 2: new Class(${$a[0]}, ${$a[1]}); break; etc... There has to be a better way to do this. If I have an array of strings ("variable1", "variable2", 'variable3", ...), how can I instantiate a Class without manually accounting for every possibility?

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• call method from main class, gives error

  - by user557039

  try to call method ss from class from it return me error, Blockquote Exception in thread "main" java.lang.NullPointerException at teste1.exp.ss(exp.java:16) at teste1.Main.main(Main.java:64) Java Result: 1 Blockquote <pre> public class Main { public static void main(String[] arguments) { ................... private static String[] ff; exp mega = new exp(); mega.ss(ff); } class exp { public void ss (String gvanswer[]){ String answer[] = new String[3]; answer[0] = "pacific "; answer[1] = "everest"; answer[2] = "amazon "; if (gvnswer[0].equals("pacific")) {System.out.println("eeeeeeeeeeeeee ");} if (gvanswer[1].equals(answer[1])){System.out.println("l ");} }

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• Why isn't the new() generic constraint satisfied by a class with optional parameters in the construc

  - by Joshua Flanagan

  The following code fails to compile, producing a "Widget must be a non-abstract type with a public parameterless constructor" error. I would think that the compiler has all of the information it needs. Is this a bug? An oversight? Or is there some scenario where this would not be valid? public class Factory<T> where T : new() { public T Build() { return new T(); } } public class Widget { public Widget(string name = "foo") { Name = name; } public string Name { get; set; } } public class Program { public static void Main() { var widget = new Widget(); // this is valid var factory = new Factory<Widget>(); // compiler error } }

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• Abstract class get parameter from implementing subclass?

  - by soren.qvist

  I'm wondering if there is way to do this without breaking encapsulation, I want the abstract class to rely on parameters defined in the implementing subclass. Like so: public abstract class Parent { private int size; private List<String> someList; public Parent() { size = getSize(); someList = new ArrayList<String>(size); } public abstract int getSize(); } public class Child extends Parent { @Override public int getSize() { return 5; } } Is this ugly? Is there a better way? And perhaps more importantly, is this even a good idea?

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• C++ destructor issue with std::vector of class objects

  - by Nigel

  I am confused about how to use destructors when I have a std::vector of my class. So if I create a simple class as follows: class Test { private: int *big; public: Test () { big = new int[10000]; } ~Test () { delete [] big; } }; Then in my main function I do the following: Test tObj = Test(); vector<Test> tVec; tVec.push_back(tObj); I get a runtime crash in the destructor of Test when I go out of scope. Why is this and how can I safely free my memory?

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• C# Different class objects in one list

  - by jeah_wicer

  I have looked around some now to find a solution to this problem. I found several ways that could solve it but to be honest I didn't realize which of the ways that would be considered the "right" C# or OOP way of solving it. My goal is not only to solve the problems but also to develop a good set of code standards and I'm fairly sure there's a standard way to handle this problem. Let's say I have 2 types of printer hardwares with their respective classes and ways of communicating: PrinterType1, PrinterType2. I would also like to be able to later on add another type if neccessary. One step up in abstraction those have much in common. It should be possible to send a string to each one of them as an example. They both have variables in common and variables unique to each class. (One for instance communicates via COM-port and has such an object, while the other one communicates via TCP and has such an object). I would however like to just implement a List of all those printers and be able to go through the list and perform things as "Send(string message)" on all Printers regardless of type. I would also like to access variables like "PrinterList[0].Name" that are the same for both objects, however I would also at some places like to access data that is specific to the object itself (For instance in the settings window of the application where the COM-port name is set for one object and the IP/port number for another). So, in short something like: In common: Name Send() Specific to PrinterType1: Port Specific to PrinterType2: IP And I wish to, for instance, do Send() on all objects regardless of type and the number of objects present. I've read about polymorphism, Generics, interfaces and such, but I would like to know how this, in my eyes basic, problem typically would be dealt with in C# (and/or OOP in general). I actually did try to make a base class, but it didn't quite seem right to me. For instance I have no use of a "string Send(string Message)" function in the base class itself. So why would I define one there that needs to be overridden in the derived classes when I would never use the function in the base class ever in the first place? I'm really thankful for any answers. People around here seem very knowledgeable and this place has provided me with many solutions earlier. Now I finally have an account to answer and vote with too. EDIT: To additionally explain, I would also like to be able to access the objects of the actual printertype. For instance the Port variable in PrinterType1 which is a SerialPort object. I would like to access it like: PrinterList[0].Port.Open() and have access to the full range of functionality of the underlaying port. At the same time I would like to call generic functions that work in the same way for the different objects (but with different implementations): foreach (printer in Printers) printer.Send(message)

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• Rotation in a Vector2d class in Java

  - by wanstein

  I've been working on this for one hour, just can't get it. I have a Vector2d class: public class Vector2d { public double x = 0.0; public double y = 0.0; .... } This vector class has a rotate() method which is causing me trouble. The first snippet seems to make the x and y values smaller and smaller. The second one works just fine! Am I missing something simple here? public void rotate(double n) { this.x = (this.x * Math.cos(n)) - (this.y * Math.sin(n)); this.y = (this.x * Math.sin(n)) + (this.y * Math.cos(n)); } This works: public void rotate(double n) { rx = (this.x * Math.cos(n)) - (this.y * Math.sin(n)); ry = (this.x * Math.sin(n)) + (this.y * Math.cos(n)); x = rx; y = ry; } I just can't spot any difference there

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• Apply a class to a <h1> based on the site url

  - by user1870639

  I'm new to PHP and want to apply a specific class to the title of my page depending on what part of the site the viewer is browsing. For instance, I want to apply the class "blog" to the if the viewer is at domain.com/blog OR domain.com/blog/post-1 so on and so forth BUT apply the class "pics" if they're viewing domain.com/pics or domain.com/pics/gallery-1 etc etc. I found something that could be modified to serve my needs using javascript here but I figured seeing as I'm using PHP already, it'd make more sense to keep this sort of thing server side. As I say, I'm new to PHP. I've experimented with some regular expressions, but to no avail.

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• How to set a value from another class

  - by Ram

  Its said that property should not be "Set" only and it should be "Get" as well. What should i do if I need to set value to a variable from some other class? The will keep changing so I cannot pass it through constructor. Shall I create a function for this as shown below? class A { public void SetValue() { b = new B(); b.SetTest(10); } } class B { int test; public void SetTest(int value) { test = value; } } What are the other alternatives?

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• Reflection alternative for switch on enum in order to select namespace/class

  - by Am

  Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks. I will give my 2 cents of why I want to change this. There several people writing harvesters, I want them to focus only on building more harvesters, without ever needing to update the enum, or at worst, update only the enum.

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• "Inconsistent accessibility" on class definition

  - by TWood

  I'm adding some bindable CLR properties to my ongoing WPF application in my App class and I can't compile because of this inconsistent accessibility error. Inconsistent Accessibility: Property type 'SomeProj.Error' is less accessible than property 'SomeProj.App.LatestError' To fix this error I had to change class Error to public class Error. In VB, classes were assumed public and most of the time omitted that access modifier. Is this not the case in C# as well? I only recently made the vb-c# jump and little nuances like this in the syntax slow me down.

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• Getting Reference to Calling Activity from AsyncTask (NOT as an inner class)

  - by stormin986

  Is it at all possible, from within an AsyncTask that is NOT an inner class of the calling Activity class, to get a reference to the instance of Activity that initiated execution of the AsyncTask? I am aware of this thread, however it doesn't exactly address how to reference the calling Activity. Some suggest passing a reference to the Activity as a parameter to the AsyncTask constructor, however, it's reported that doing so will always result in a NullPointerException. So, I'm at a loss. My AsyncTask provides robust functionality, and I don't want to have to duplicate it as an inner class in every Activity that wants to use it. There must be an elegant solution.

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• Java generics: actual class as a generic parameter.

  - by user554916

  What do I write instead of "TheClass" to make this work? Or is there an alternative way to do it (possibly without making WithName and WithAge generic)? class Item { NeigborList<TheClass> neighbors; } class WithName extends Item { // here I want neighbors to be a NeighborList<WithName> String name; void someMethod() { System.out.println(neighbors.nearestTo(this).name); } } class WithAge extends Item { // here I want neighbors to be a NeighborList<WithAge> int age; void someOtherMethod() { System.out.println(neighbors.nearestTo(this).age); } }

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• javascript : make a new safe class constructor

  - by guilin ??

  sometimes we loss the new keyword when define new object, obj = new Clazz(); //correct obj = Clazz(); //wrong, but no syntax error, hard to debug. I want to write a function to help me create Class and make it new safe. var Class = function(constructor){ //when constructor // if not call by new return new constructor(); // else constructor(); } var MyClazz = Class(function(name){ this.name = name }, SuperClazz1, SuperClass2 ) MyClazz.extend({ show: function(){console.log(this.name)} }) obj1 = new MyClazz(); obj2 = MyClazz(); // obj1 should same as obj2 Is it possible, any exists module?

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• JQuery - Find the first identical class after a specific class.

  - by WEBProject

  Hi guys, lets say I have this divs: <div class="item current"><strong>Example 1</strong></div> <div class="item"><strong>Example 2</strong></div> Im have this code: var News = { init : function(){ $('#news-content') .find('.item:first-child') .addClass('current') .show('slide',{direction:"up"},500); $('#news-content') .find('.item:first-child') .addClass('current') .delay(1000) .hide('slide',{direction:"down"},500); this.show() }, show : function() { // ... } } $(document).ready(News.init) After the init - I want to catch the next "item" after "current" class and make the same operation as "init" on it. how can I do it with jquery?

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• Differences in variable declarations in C++

  - by Sachin Chourasiya

  Class A { }; What is the difference between A a , A *a and A a = new A().

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• class T in c++ (your definition)

  - by JohnWong

  The one advantage of using class T in c++ is to reduce the time to redefine data types in a function, if those data types are defined in other function, for example, in int main. template <class T> void showabs(T number) { if (number < 0 ) number = -number; cout << number << endl; return 0; } int main() { int num1 = -4; float num2 = -4.23f; showabs(num1); showabs(num2); return 0; } So in this case, without class T, for each data type, we have to add its corresponding data-type condition, that is, another set of if statement for int, and another one for float. Am I correct?

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• Get size of jar file loaded by urlclassloader

  - by Aliya

  Does anybody know a good way to find the file size that is dynamically loaded by urlclassloader? I am using the urlclassloader in the following manner, but need to keep track of how much bandwidth is being used. URLClassLoader sysloader = (URLClassLoader) ClassLoader .getSystemClassLoader(); Class<URLClassLoader> sysclass = URLClassLoader.class; Method method = sysclass.getDeclaredMethod("addURL", parameters); method.setAccessible(true); method.invoke(sysloader, (Object[]) urls); Thanks in advance!

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• Object directing to a property when accessed as an iterable

  - by ThE_JacO

  I'm trying to figure out if there's an elegant and concise way to have a class accessing one of its own properties when "used" as a dictionary, basically redirecting all the methods that'd be implemented in an ordered dictionary to one of its properties. Currently I'm inheriting from IterableUserDict and explicitly setting its data to another property, and it seems to be working, but I know that UserDict is considered sort of old, and I'm concerned I might be overlooking something. What I have: class ConnectionInterface(IterableUserDict): def __init__(self, hostObject): self._hostObject= hostObject self.ports= odict.OrderedDict() self.inputPorts= odict.OrderedDict() self.outputPorts= odict.OrderedDict() self.data= self.ports This way I expect the object to behave and respond (and be used) the way I mean it to, except I want to get a freebie ordered dictionary behaviour on its property "ports" when it's iterated, items are gotten by key, something is looked up ala if this in myObject, and so on. Any advice welcome, the above seems to be working fine, but I have an odd itch that I might be missing something. Thanks in advance.

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• Checking variable from a different class in C#

  - by Josh

  Greetings- I have 2 classes. One is called "Programs" and the other is called "Logs". The class called Programs has public const string m_sEnviron = ""; near the top and I need to check what the m_sEnviron variable is set to through my class called Logs. The variable m_sEnviron will get set from a scheduler called Tidal so how can I check its value from a different class. If this is not the best to do this then please let me know what the better ways are. Thanks in advance. Regards,

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• Simple C++ classes question

  - by Without me Its just Aweso

  Its been a long time since i've done C++ and I'm running into some trouble with classes referencing eachother. right now I have something like: a.h class a { public: a(); bool skeletonfunc(b temp); } ==================== b.h class b { public: b(); bool skeletonfunc(a temp); } since each one needs a reference to the other i've found I cant do a #include of eachother at the top or i end up in a weird loop of sorts with the includes. So how can I make it so that a can use b and vice versa with out making a cyclical #include problem. thanks!

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• How to set value from other class

  - by Ram

  Its said that property should not be "Set" only and it should be "Get" as well. What should i do if I need to set value to a variable from some other class? The will keep changing so I cannot pass it through constructor. Shall I create a function for this as shown below? class A { public void SetValue() { b = new B(); b.SetTest(10); } } class B { int test; public void SetTest(int value) { test = value; } } What are the other alternatives?

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• Similar Sub-Classes

  - by praks5432

  Lets say I have a class A that is fairly simple like this - public class A{ private int randomField = 0; protected int key; protected double dmg; } Now I want to write a number of sub-classes that inherit the protected fields and only differ based on the initial values that are assigned to those fields - for example, if I wrote two subclasses B and C, the only difference between those two sub-classes would be that the values key and dmg would have different values. They would share a method, set, which would be exactly the same, in that it would affect the same variable. I find when I'm writing these sub-classes I'm repeating myself, as I just change the constructor to set different initial values to key and dmg, and simply copy and paste the set method. Is there a 'good' way to do this?

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