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  • class array variable initialization error in java

    - by trinity
    Hello I am trying to write a java program that reads an input file consisting of URLs , extracts tokens from these , and accordingly insert into : class Tokens { String name ; int count ; } , where name is the name of every unique token , and count is the frequency of that token in the URLs file..I've written the following code : import java.io.*; import java.net.*; public class Main { static class Tokens { String name; int count; } public static void main(String[] args) { String url_str,host; String htokens[]; URL url; boolean found=false; Tokens t[]; int i,j,k; try { File f=new File("urlfile.txt"); FileReader fr=new FileReader(f); BufferedReader br=new BufferedReader(fr); while((url_str=br.readLine())!=null) { url=new URL(url_str); host=url.getHost(); htokens=host.split("\\.|\\-|\\_|\\~|[0-9]"); for(i=0;i<htokens.length;i++) { if(!htokens[i].isEmpty()) { for(j=0;j<t.length;j++) { if(htokens[i].equals(t[j].name)) { t[j].count++; found=true; } } if(!found) { k=t.length; t[k].name=htokens[i]; t[k].count=1; } } } System.out.println(t.length + "class tokens :"); for(i=0;i<t.length;i++) { System.out.println("name :"+t[i].name+" frequency :"+t[i].count); } } br.close(); fr.close(); } catch(Exception e) { System.out.println(e); } } } But when i run it , it says : variable t not initialized.. What should i do to set it right ?

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  • WinForms Load Event / Static Initialization Strangeness

    - by Eric J.
    Background I'm troubleshooting an WinForms 2.0 program that's already been burned to CD for distribution to an internet-challenged target audience. Some users are experiencing a fatal error that I can reproduce locally. Reproducing the Error I get the fatal error when I log into my Vista box using a standard user that I just created, even if I run the program as administrator. I do not get the fatal error when I log in as local administrator. I'm not sure that being administrator is necessarily the trigger (since runas did not help). I have reproduced this half a dozen times under each account with consistent results. The faulty code Base.cs (base class for several user controls, only one of which is shown on first screen) private void BaseWindow_Load(object sender, EventArgs e) { // This message shown once in both cases MessageBox.Show("BaseWindow_Load for " + this.GetType().FullName); SkinManager.ApplySkin(this); } SkinManager.cs private static Skin skin = null; public static void ApplySkin(UserControl applyTo) { if (skin == null) { skin = new Skin(SkinsDirectory, "Default"); } } Skin.cs internal Skin(string skinPath, string skinName) { config = SkinConfig.Load(path); } SkinConfig.cs public static SkinConfig Load(string path) { // This message shown only once running as Admin but twice running as standard user System.Windows.Forms.MessageBox.Show("@1"); // !!! LOCK path HERE !!! } A user control loads on the first form, which triggers a call to SkinManager.ApplySkin, which checks if skin is null and, if so assigns it (without thread synchronization or recursion protection), which ultimately causes a file to be opened. When logged in as local admin, that sequence completes just fine. When logged in as my test standard user, ApplySkin is always called a second time while skin is still null, causing a second attempt to load, causing the file to be locked on the second attempt. The error handling is draconian at this point and the program terminates. The Question While this code can be easily fixed, I would like to understand why the error is happening only in some cases.

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  • Java: define terms initialization, declaration and assignment

    - by HH
    I find the defs circular statements, the subjects are defined by their verbs but the verbs are undefined! So how do you define them? The question is central to understand the term final, related. The Circular Definitions itialization: to initilise a variable. It can be can be done at the time of declaration. assignment: to assign value to a variable. It can be done anywhere. declaration: to declare value to a variable.

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  • iPhone -- initialization partly by NSKeyedUnarchiver and partly by other means

    - by William Jockusch
    I have an object myObj, which is an instance of a class MyClass. Some of its instance variables always have their initial values passed in by the calling code. Other instance variables will be initialized in one of two ways. For an instanceArray of type NSMutableArray, the possibilities are either instanceArray = [[NSMutableArray alloc]init]; or instanceArray = [someKeyedUnarchiver decodeObjectForKey: kInstanceArrayKey]; The calling code should determine which of the above will be used. Any particular design pattern I should prefer?

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  • SD card initialization using SPI interface

    - by Tobias
    I get invalid response Codes from my SD Card(CMD8, CMD55, CMD41) Init routine: SDCS = 1; // MMC deaktiviert SPI1CON1bits.SMP = 0; SPI1CON1bits.CKE = 1; SPI1CON1bits.MSTEN = 1; SPI1CON1bits.CKP = 0; SPI1STATbits.SPIEN = 1; for(i=0;i<10;i++) SPI(0xFF); // RESET unsigned char rr=Command(CMD0,0); SDCS=1; // MMC deactivated /*OK response == 1*/ r=Command(CMD8,0); // check voltage SDCS=1; /* response == 0xC1 ?!? */ r = Command(CMD58,0); // READ_OCR unsigned char ocr1 = SPI(0xFF); unsigned char ocr2 = SPI(0xFF); unsigned char ocr3 = SPI(0xFF); unsigned char ocr4 = SPI(0xFF); unsigned char ocr5 = SPI(0xFF); /* r = 0xF8; ?!? ocr1 = 0x0F; ocr2 = 0xFF; ocr3 = 0xFF; ocr4 = 0xFF; ocr5 = 0xFF; */ SDCS=1; // INIT unsigned char rrr = 0; i=10000; do { rrr=Command(55,0); // Next is APP CMD SDCS=1; if(r) break; }while(--i>0); /* OK response == 1 */ // APP CMD 41 with OCR = 0x0F?? You can read the response codes in the comments. Is it possible the response code to CMD8 is 0xC1? Bit 7 should be 0, right? Is it a hardware error?

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  • Initialization of std::vector<unsigned int> with a list of consecutive unsigned integers

    - by Thomas
    I want to use a special method to initialize a std::vector<unsigned int> which is described in a C++ book I use as a reference (the German book 'Der C++ Programmer' by Ulrich Breymann, in case that matters). In that book is a section on sequence types of the STL, referring in particular to list, vector and deque. In this section he writes that there are two special constructors of such sequence types, namely, if Xrefers to such a type, X(n, t) // creates a sequence with n copies of t X(i, j) // creates a sequence from the elements of the interval [i, j) I want to use the second one for an interval of unsigned int, that is std::vector<unsigned int> l(1U, 10U); to get a list initialized with {1,2,...,9}. What I get, however, is a vector with one unsigned int with value 10 :-| Does the second variant exist, and if yes, how do I force that it is called?

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  • Java ArrayList initialization

    - by Jonathan
    I am aware that you can initialize an array during instantiation as follows: String[] names = new String[] {"Ryan", "Julie", "Bob"}; Is there a way to do the same thing with an ArrayList? Or must I add the contents individually with array.add()? Thanks, Jonathan

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  • Initialization of an ArrayList in one line.

    - by Macarse
    I am willing to create a list of options to test something. I was doing: ArrayList<String> places = new ArrayList<String>(); places.add("Buenos Aires"); places.add("Córdoba"); places.add("La Plata"); I refactor the code doing: ArrayList<String> places = new ArrayList<String>(Arrays.asList("Buenos Aires", "Córdoba", "La Plata")); Is there a better way of doing this? Thanks for reading!

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  • DRY Ruby Initialization with Hash Argument

    - by ktex
    I find myself using hash arguments to constructors quite a bit, especially when writing DSLs for configuration or other bits of API that the end user will be exposed to. What I end up doing is something like the following: class Example PROPERTIES = [:name, :age] PROPERTIES.each { |p| attr_reader p } def initialize(args) PROPERTIES.each do |p| self.instance_variable_set "@#{p}", args[p] if not args[p].nil? end end end Is there no more idiomatic way to achieve this? The throw-away constant and the symbol to string conversion seem particularly egregious.

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  • Is this pointer initialization necessary?

    - by bstullkid
    Lets say I have the following: CHARLINK * _init_link(CHARLINK **link) { short i; (*link)->cl = (CHARLINK **) calloc(NUM_CHARS, sizeof(CHARLINK *)); for (i = 0; i < NUM_CHARS; i++) (*link)->cl[i] = NULL; return (*link); } Is the loop to initialize each element to NULL necessary or are they automatically NULL from calloc?

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  • Java: initialization problem, cannot print "assigned" values from arrayList

    - by HH
    $ javac ArrayListTest.java $ java ArrayListTest $ cat ArrayListTest.java import java.io.*; import java.util.*; public class ArrayListTest{ public static void main(String[] args) { try { String hello ="oeoaseu oeu hsoae sthoaust hoaeut hoasntu"; ArrayList<String> appendMe = null; for(String s : hello.split(" ")) appendMe.add(s+" "); for(String s : appendMe) System.out.println(s); //WHY DOES IT NOT PRINT? }catch(Exception e){ } } }

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  • Custom class object in Initialization list

    - by Michael
    I have a class Bar: class Bar { public: Bar(void); ~Bar(void); }; And a class Foo that gets a reference to Bar object as a constructor parameter and needs to save it in a private member bar_ : class Foo { private: Bar& bar_; public: Foo(Bar& bar) : bar_(bar) {} ~Foo(void) {} }; This doesn't compile : overloaded member function not found in 'Parser' missing type specifier - int assumed. Note: C++ does not support default-int Now i suspect couple of things that i need to assure, the second error is for Bar& bar_; declaration in Foo. Do i need to use an explicit constructor when declaring bar_ ? I am interested in learning how the compiler works regarding this matter, so a detailed explanation would be highly appreciated. Thanks.

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  • Characteristics of an Initialization Vector

    - by Jamie Chapman
    I'm by no means a cryptography expert, I have been reading a few questions around Stack Overflow and on Wikipedia but nothing is really 'clear cut' in terms of defining an IV and it's usage. Points I have discovered: An IV is pre-pended to a plaintext message in order to strengthen the encryption The IV is truely random Each message has it's own unique IV Timestamps and cryptographic hashes are sometimes used instead of random values, but these are considered to be insecure as timestamps can be predicted One of the weaknesses of WEP (in 802.11) is the fact that the IV will reset after a specific amount of encryptions, thus repeating the IV I'm sure there are many other points to be made, what have I missed? (or misread!)

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  • C++ Constructor initialization list strangeness

    - by Andy
    I have always been a good boy when writing my classes, prefixing all member variables with m_: class Test { int m_int1; int m_int2; public: Test(int int1, int int2) : m_int1(int int1), m_int2(int int2) {} }; void main() { Test t(10, 20); // Just an example } However, recently I forgot to do that and ended up writing: class Test { int int1; int int2; public: // Very questionable, but of course I meant to assign ::int1 to this->int1! Test(int int1, int int2) : int1(int1), int2(int2) {} }; Believe it or not, the code compiled with no errors/warnings and the assignments took place correctly! It was only when doing the final check before checking in my code when I realised what I had done. My question is: why did my code compile? Is something like that allowed in the C++ standard, or is it simply a case of the compiler being clever? In case you were wondering, I was using Visual Studio 2008 Thank you.

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  • Firefox extension js object initialization

    - by Michael
    Note: this is about Firefox extension, not a js general question. In Firefox extension project I need my javascript object to be initialized just once per Firefox window. Otherwise each time I open my window a new timers will be engaged, new properties will be used, so everything will start from scratch. hope example below will demystify my question :) var StupidExtension { statusBarValue: "Not Initialized Yet", startup: function () { ... // Show statusBarValue in Status Bar Panel }, initTimerToRetrieveStatusBarValueFromNetwork: function () { ... } } so each time you hit Ctrl+N a new window you will see "Not Initialized Yet" and then new timer will be fired, so after some time it retrieve data from network you will see value also on second window and so on. Ideally would be to have just a single timer function running and updating all status bar panels in all Firefox windows. Of course I can do some caching, like saving the value in prefs or some other storage, then show it from there. But I feel like this is artificial. So the question will be is there "native" technique of making static some parts of the object among all Firefox window instances?

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  • Automatic initialization routine in C++ library?

    - by Robert Mason
    If i have a header file foo.h and a source file foo.cpp, and foo.cpp contains something along the lines of: #ifdef WIN32 class asdf { asdf() { startup_code(); } ~asdf() { cleanup_code(); } }; asdf __STARTUP_HANDLE__ #else //unix does not require startup or cleanup code in this case #endif but foo.h does not define class asdf, say i have an application bar.cpp: #include "foo.h" //link in foo.lib, foo.dll, foo.so, etc int main() { //do stuff return 0; } If bar.cpp is compiled on a WIN32 platform, will the asdf() and ~asdf() be called at the appropriate times (before main() and at program exit, respectively) even though class asdf is not defined in foo.h, but is linked in through foo.cpp?

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  • static initialization confusion

    - by Happy Mittal
    I am getting very confused in some concepts in c++. For ex: I have following two files //file1.cpp class test { static int s; public: test(){s++;} }; static test t; int test::s=5; //file2.cpp #include<iostream> using namespace std; class test { static int s; public: test(){s++;} static int get() { return s; } }; static test t; int main() { cout<<test::get()<<endl; } Now My question is : 1. How two files link successfully even if they have different class definitions? 2. Are the static member s of two classes related because I get output as 7. Please explain this concept of statics.

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  • static initialization order fiasco

    - by Happy Mittal
    I was reading about SIOF from a book and it gave an example : //file1.cpp extern int y; int x=y+1; //file2.cpp extern int x; y=x+1; Now My question is : In above code..will following things happen ? 1. while compiling file1.cpp, compiler leaves y as it is i.e doesn't allocate storage for it. 2. compiler allocates storage for x, but doesn't initialize it. 3. While compiling file2.cpp, compiler leaves x as it is i.e doesn't allocate storage for it. 4. compiler allocates storage for y, but doesn't initialize it. 5. While linking file1.o and file2.o, now let file2.o is initialized first, so now: Does x gets initial value of 0? or doesn't get initialized?

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  • gluNewQuadric() before opengl's initialization

    - by Schrödinger's cat
    Hello, I'm working on a c++ code that uses SDL/opengl. Is this possible to create a pointer to a quadric with 'gluNewQuadric()' before having initialized opengl with 'SDL_SetVideoMode'? The idea is to create a class with a (pointer to a) quadric class member that has to be instantiate before the 'SDL_SetVideoMode' call. This pointer is initialized in the class' constructor with a 'gluNewQuadric()' call.

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  • Lazy coding is fun

    - by Anthony Trudeau
    Every once in awhile I get the opportunity to write an application that is important enough to do, but not important enough to do the right way -- meaning standards, best practices, good architecture, et al.  I call it lazy coding.  The industry calls it RAD (rapid application development). I started on the conversion tool at the end of last week.  It will convert our legacy data to a completely new system which I'm working on piece by piece.  It will be used in the future, but only the new parts because it'll only be necessary to convert the individual pieces of the data once.  It was the perfect opportunity to just whip something together, but it was still functional unlike a prototype or proof of concept.  Although I would never write an application like this for a customer (internal or external) this methodology (if you can call it that) works great for something like this. I wouldn't be surprised if I get flamed for equating RAD to lazy coding or lacking standards, best practice, or good architecture.  Unfortunately, it fits in the current usage.  Although, it's possible to create a good, maintainable application using the RAD methodology, it's just too ripe for abuse and requires too much discipline for someone let alone a team to do right. Sometimes it's just fun to throw caution to the wind and start slamming code.

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  • what's the alternative to readonlycollection when using lazy="extra"?

    - by Kunjan
    I am trying to use lazy="extra" for the child collection of Trades I have on my Client object. The trades is an Iset<Trade Trades, exposed as ReadOnlyCollection<Trade because I do not want anyone to modify the collection directly. As a result, I have added AddTrade and RemoveTrade methods. Now I have a Client Search page where I need to show the Trade Count. and on the Client details page I have a tab where I need to show all the trades for the Client in paged gridview. What I want to achieve is, for the search when I say on the client object as client.Trades.Count, nHibernate should only fire a select count(*) query. Hence I am using lazy="extra". But because I am using a ReadOnlyCollection, nHibernate fires a count query & a separate query to load the child collection trades completely. Also, I cannot include the Trades in my initial search request as this would disturb the paging because a counterparty can have n trades which would result in n rows, when I am searching clients only. So the child collections have to be loaded lazily. The second problem is that on the client details page -- Trades grid view, I have enabled paging for performance reasons. But by nature nHibernate loads the entire collection of trades as the user goes from one page to another. Ideally I want to control this by getting only trades specific to the page the user is on. How can I achieve this? I came across this very good article. http://stackoverflow.com/questions/876976/implementing-ipagedlistt-on-my-models-using-nhibernate But I am not sure if this will work for me, as lazy=extra currently doesnt work as expected with the ReadOnlyCollection. So, if I went ahead and implemented the solution this way and further enhanced it by making the List/Set Immutable, will lazy=extra give me the same problem as with ReadOnlyCollections?

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  • Any way to define getters for lazy variables in Javascript arrays?

    - by LLer
    I'm trying to add elements to an array that are lazy-evaluated. This means that the value for them will not be calculated or known until they are accessed. This is like a previous question I asked but for objects. What I ended up doing for objects was Object.prototype.lazy = function(var_name, value_function) { this.__defineGetter__(var_name, function() { var saved_value = value_function(); this.__defineGetter__(var_name, function() { return saved_value; }); return saved_value; }); } lazy('exampleField', function() { // the code that returns the value I want }); But I haven't figured out a way to do it for real Arrays. Arrays don't have setters like that. You could push a function to an array, but you'd have to call it as a function for it to return the object you really want. What I'm doing right now is I created an object that I treat as an array. Object.prototype.lazy_push = function(value_function) { if(!this.length) this.length = 0; this.lazy(this.length++, value_function); } So what I want to know is, is there a way to do this while still doing it on an array and not a fake array?

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  • Lazy Processing of Streams

    - by Giorgio
    I have the following problem scenario: I have a text file and I have to read it and split it into lines. Some lines might need to be dropped (according to criteria that are not fixed). The lines that are not dropped must be parsed into some predefined records. Records that are not valid must be dropped. Duplicate records may exist and, in such a case, they are consecutive. If duplicate / multiple records exist, only one item should be kept. The remaining records should be grouped according to the value contained in one field; all records belonging to the same group appear one after another (e.g. AAAABBBBCCDEEEFF and so on). The records of each group should be numbered (1, 2, 3, 4, ...). For each group the numbering starts from 1. The records must then be saved somewhere / consumed in the same order as they were produced. I have to implement this in Java or C++. My first idea was to define functions / methods like: One method to get all the lines from the file. One method to filter out the unwanted lines. One method to parse the filtered lines into valid records. One method to remove duplicate records. One method to group records and number them. The problem is that the data I am going to read can be too big and might not fit into main memory: so I cannot just construct all these lists and apply my functions one after the other. On the other hand, I think I do not need to fit all the data in main memory at once because once a record has been consumed all its underlying data (basically the lines of text between the previous record and the current record, and the record itself) can be disposed of. With the little knowledge I have of Haskell I have immediately thought about some kind of lazy evaluation, in which instead of applying functions to lists that have been completely computed, I have different streams of data that are built on top of each other and, at each moment, only the needed portion of each stream is materialized in main memory. But I have to implement this in Java or C++. So my question is which design pattern or other technique can allow me to implement this lazy processing of streams in one of these languages.

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