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  • Can't get recursive function to work in Java

    - by Ahmed Salah
    I read docs about java recorsion and I thought I have understood it, but when I try to use it in the following example, it does not work as expected. I a class account, which has amount and can have forther subAccount. I would have implemented one method getSum, which has to return the summ of the amount of the account and amount of all of its subaccount. In the following code, the call of the method getSumm() should return 550, but it behaves strange. can somebody help please? public class Balance{ ArrayList<Balance> subAccounts = new ArrayList<Balance>(); String accountID = null; Double amount = null; double result=0; public double getSum(ArrayList<Balance> subAccounts){ if(subAccounts !=null && subAccounts.size()>0){ for (int i = 0; i < subAccounts.size(); i++) { result = result + getSum(subAccounts.get(i).subAccounts); } } else { return amount; } return result; } public static void main(String[] args) { Balance bs1 = new Balance(); Balance bs2 = new Balance(); Balance bs3 = new Balance(); bs1.amount=100.0; bs2.amount=150.0; bs3.amount=300.0; ArrayList<Balance> subAccounts1 = new ArrayList<Balance>(); bs2.subAccounts=null; bs3.subAccounts=null; subAccounts1.add(bs2); subAccounts1.add(bs3); bs1.subAccounts=subAccounts1; double sum= bs1.getSum(subAccounts1); System.out.println(sum); } }

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  • Parallel Classloading Revisited: Fully Concurrent Loading

    - by davidholmes
    Java 7 introduced support for parallel classloading. A description of that project and its goals can be found here: http://openjdk.java.net/groups/core-libs/ClassLoaderProposal.html The solution for parallel classloading was to add to each class loader a ConcurrentHashMap, referenced through a new field, parallelLockMap. This contains a mapping from class names to Objects to use as a classloading lock for that class name. This was then used in the following way: protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException { synchronized (getClassLoadingLock(name)) { // First, check if the class has already been loaded Class c = findLoadedClass(name); if (c == null) { long t0 = System.nanoTime(); try { if (parent != null) { c = parent.loadClass(name, false); } else { c = findBootstrapClassOrNull(name); } } catch (ClassNotFoundException e) { // ClassNotFoundException thrown if class not found // from the non-null parent class loader } if (c == null) { // If still not found, then invoke findClass in order // to find the class. long t1 = System.nanoTime(); c = findClass(name); // this is the defining class loader; record the stats sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0); sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); sun.misc.PerfCounter.getFindClasses().increment(); } } if (resolve) { resolveClass(c); } return c; } } Where getClassLoadingLock simply does: protected Object getClassLoadingLock(String className) { Object lock = this; if (parallelLockMap != null) { Object newLock = new Object(); lock = parallelLockMap.putIfAbsent(className, newLock); if (lock == null) { lock = newLock; } } return lock; } This approach is very inefficient in terms of the space used per map and the number of maps. First, there is a map per-classloader. As per the code above under normal delegation the current classloader creates and acquires a lock for the given class, checks if it is already loaded, then asks its parent to load it; the parent in turn creates another lock in its own map, checks if the class is already loaded and then delegates to its parent and so on till the boot loader is invoked for which there is no map and no lock. So even in the simplest of applications, you will have two maps (in the system and extensions loaders) for every class that has to be loaded transitively from the application's main class. If you knew before hand which loader would actually load the class the locking would only need to be performed in that loader. As it stands the locking is completely unnecessary for all classes loaded by the boot loader. Secondly, once loading has completed and findClass will return the class, the lock and the map entry is completely unnecessary. But as it stands, the lock objects and their associated entries are never removed from the map. It is worth understanding exactly what the locking is intended to achieve, as this will help us understand potential remedies to the above inefficiencies. Given this is the support for parallel classloading, the class loader itself is unlikely to need to guard against concurrent load attempts - and if that were not the case it is likely that the classloader would need a different means to protect itself rather than a lock per class. Ultimately when a class file is located and the class has to be loaded, defineClass is called which calls into the VM - the VM does not require any locking at the Java level and uses its own mutexes for guarding its internal data structures (such as the system dictionary). The classloader locking is primarily needed to address the following situation: if two threads attempt to load the same class, one will initiate the request through the appropriate loader and eventually cause defineClass to be invoked. Meanwhile the second attempt will block trying to acquire the lock. Once the class is loaded the first thread will release the lock, allowing the second to acquire it. The second thread then sees that the class has now been loaded and will return that class. Neither thread can tell which did the loading and they both continue successfully. Consider if no lock was acquired in the classloader. Both threads will eventually locate the file for the class, read in the bytecodes and call defineClass to actually load the class. In this case the first to call defineClass will succeed, while the second will encounter an exception due to an attempted redefinition of an existing class. It is solely for this error condition that the lock has to be used. (Note that parallel capable classloaders should not need to be doing old deadlock-avoidance tricks like doing a wait() on the lock object\!). There are a number of obvious things we can try to solve this problem and they basically take three forms: Remove the need for locking. This might be achieved by having a new version of defineClass which acts like defineClassIfNotPresent - simply returning an existing Class rather than triggering an exception. Increase the coarseness of locking to reduce the number of lock objects and/or maps. For example, using a single shared lockMap instead of a per-loader lockMap. Reduce the lifetime of lock objects so that entries are removed from the map when no longer needed (eg remove after loading, use weak references to the lock objects and cleanup the map periodically). There are pros and cons to each of these approaches. Unfortunately a significant "con" is that the API introduced in Java 7 to support parallel classloading has essentially mandated that these locks do in fact exist, and they are accessible to the application code (indirectly through the classloader if it exposes them - which a custom loader might do - and regardless they are accessible to custom classloaders). So while we can reason that we could do parallel classloading with no locking, we can not implement this without breaking the specification for parallel classloading that was put in place for Java 7. Similarly we might reason that we can remove a mapping (and the lock object) because the class is already loaded, but this would again violate the specification because it can be reasoned that the following assertion should hold true: Object lock1 = loader.getClassLoadingLock(name); loader.loadClass(name); Object lock2 = loader.getClassLoadingLock(name); assert lock1 == lock2; Without modifying the specification, or at least doing some creative wordsmithing on it, options 1 and 3 are precluded. Even then there are caveats, for example if findLoadedClass is not atomic with respect to defineClass, then you can have concurrent calls to findLoadedClass from different threads and that could be expensive (this is also an argument against moving findLoadedClass outside the locked region - it may speed up the common case where the class is already loaded, but the cost of re-executing after acquiring the lock could be prohibitive. Even option 2 might need some wordsmithing on the specification because the specification for getClassLoadingLock states "returns a dedicated object associated with the specified class name". The question is, what does "dedicated" mean here? Does it mean unique in the sense that the returned object is only associated with the given class in the current loader? Or can the object actually guard loading of multiple classes, possibly across different class loaders? So it seems that changing the specification will be inevitable if we wish to do something here. In which case lets go for something that more cleanly defines what we want to be doing: fully concurrent class-loading. Note: defineClassIfNotPresent is already implemented in the VM as find_or_define_class. It is only used if the AllowParallelDefineClass flag is set. This gives us an easy hook into existing VM mechanics. Proposal: Fully Concurrent ClassLoaders The proposal is that we expand on the notion of a parallel capable class loader and define a "fully concurrent parallel capable class loader" or fully concurrent loader, for short. A fully concurrent loader uses no synchronization in loadClass and the VM uses the "parallel define class" mechanism. For a fully concurrent loader getClassLoadingLock() can return null (or perhaps not - it doesn't matter as we won't use the result anyway). At present we have not made any changes to this method. All the parallel capable JDK classloaders become fully concurrent loaders. This doesn't require any code re-design as none of the mechanisms implemented rely on the per-name locking provided by the parallelLockMap. This seems to give us a path to remove all locking at the Java level during classloading, while retaining full compatibility with Java 7 parallel capable loaders. Fully concurrent loaders will still encounter the performance penalty associated with concurrent attempts to find and prepare a class's bytecode for definition by the VM. What this penalty is depends on the number of concurrent load attempts possible (a function of the number of threads and the application logic, and dependent on the number of processors), and the costs associated with finding and preparing the bytecodes. This obviously has to be measured across a range of applications. Preliminary webrevs: http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.hotspot/ http://cr.openjdk.java.net/~dholmes/concurrent-loaders/webrev.jdk/ Please direct all comments to the mailing list [email protected].

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  • Good practices for intialising properties ?

    - by Rubans
    HI, I have a class property that is a list of strings, List. Sometimes this property is null or if it has been set but the list is empty then count is 0. However elsewhere in my code I need to check whether this property is set, so currently my code check whether it's null and count is 0 which seems messy. if(objectA.folders is null) { if(objectA.folders.count == 0) { // do something } } Any recommendation on how this should be handled? Maybe I should always initialise the property so that it's never null? Appolgies if this is a silly question.

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  • Problem with migrating a model in ruby

    - by Shreyas Satish
    I run script/generate model query edit query.rb in models.. class Query < ActiveRecord::Base #I even tried Migrations instead of Base def sef.up create table :queries do|t| t.string :name end end def self.down drop_table :queries end end ,run rake db:migrate. and what I see in db is this: mysql> desc queries; +------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------+----------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | created_at | datetime | YES | | NULL | | | updated_at | datetime | YES | | NULL | | +------------+----------+------+-----+---------+----------------+ Where is the "name" field? HELP ! Cheers !

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  • How do I apply a "template" or "skeleton" of code in C# here?

    - by Scott Stafford
    In my business layer, I need many, many methods that follow the pattern: public BusinessClass PropertyName { get { if (this.m_LocallyCachedValue == null) { if (this.Record == null) { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.PropertyId); } else { this.m_LocallyCachedValue = new BusinessClass( this.Database, this.Record.ForeignKeyName); } } return this.m_LocallyCachedValue; } } I am still learning C#, and I'm trying to figure out the best way to write this pattern once and add methods to each business layer class that follow this pattern with the proper types and variable names substituted. BusinessClass is a typename that must be substituted, and PropertyName, PropertyId, ForeignKeyName, and m_LocallyCachedValue are all variables that should be substituted for. Are attributes usable here? Do I need reflection? How do I write the skeleton I provided in one place and then just write a line or two containing the substitution parameters and get the pattern to propagate itself? EDIT: Modified my misleading title -- I am hoping to find a solution that doesn't involve code generation or copy/paste techniques, and rather to be able to write the skeleton of the code once in a base class in some form and have it be "instantiated" into lots of subclasses as the accessor for various properties. EDIT: Here is my solution, as suggested but left unimplemented by the chosen answerer. // I'll write many of these... public BusinessClass PropertyName { get { return GetSingleRelation(ref this.m_LocallyCachedValue, this.PropertyId, "ForeignKeyName"); } } // That all call this. public TBusinessClass GetSingleRelation<TBusinessClass>( ref TBusinessClass cachedField, int fieldId, string contextFieldName) { if (cachedField == null) { if (this.Record == null) { ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), typeof(int) }); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, fieldId }); } else { var obj = this.Record.GetType().GetProperty(objName).GetValue( this.Record, null); ConstructorInfo ci = typeof(TBusinessClass).GetConstructor( new Type[] { this.Database.GetType(), obj.GetType()}); cachedField = (TBusinessClass)ci.Invoke( new object[] { this.Database, obj }); } } return cachedField; }

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  • PHP String tokenizer not working correctly

    - by asdadas
    I have no clue why strtok decided to break on me. Here is my code. I am tokenizing a string by dollar symbol $. echo 'Tokenizing this by $: ',$aliases,PHP_EOL; if(strlen($aliases) > 0) { //aliases check $token = strtok($aliases, '$'); while($token != NULL) { echo 'Found a token: ',$token,PHP_EOL; if(!isGoodLookup($token)) { echo 'ERROR: Invalid alias found.',PHP_EOL; stop($db); } $goodAliasesList[] = $token; $token = strtok('$'); } if($token == NULL) echo 'Found null token, moving on',PHP_EOL; } And this is my output: Tokenizing this by $: getaways$aaa Found a token: getaways Found null token, moving on str tok is not supposed to do this!! where is my aaa token!!

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  • MySQL + MyISAM table size question

    - by alessandro ferrucci
    Hello, I have a test table. The test table is as follows: CREATE TABLE mytest ( num1 int(10) unsigned NOT NULL, KEY key1 (num1) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; I inserted 50 million rows in this table. When I do show table status the avg_row_length is 7. I was expecting to see 4 since mySQL uses 4 bytes for integers. Does the key have an effect on the avg_row_length? When I look at my .MYD file the size is 334 MB which is exactly what it should be given that the avg_row_length is 7, however I was really expecting to see 190 MB given that I only have an int. +----------------+--------+---------+------------+----------+----------------+-------------+------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-------------------+----------+----------------+---------+ | Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment | +----------------+--------+---------+------------+----------+----------------+-------------+------------------+--------------+-----------+----------------+---------------------+---------------------+------------+-------------------+----------+----------------+---------+ | mytest | MyISAM | 10 | Fixed | 50000000 | 7 | 350000000 | 1970324836974591 | 600518656 | 0 | NULL | 2010-05-22 09:15:06 | 2010-05-22 19:32:53 | NULL | latin1_swedish_ci | NULL | | | I have included the output of show table status for mytest table. Sorry about the formatting :D Thanks in advance! Alessandro Ferrucci

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  • getjson and servers

    - by gheil.apl
    Is getJSON only useful for those who control a server? Is there any other alternative for getting data from a file? i tried $.getJSON("good.json", function(data){ out=out+"good.json: "+data + ","; }); where good.json = {"a":"1","b":"2"} and got a result of 'null' for data. These all are valid JSON files, and all give null when used in the above: good.htm assoc.json assoc.js stub.json stub.js test.js test.txt and all get a null result... The above is in an interactive setting at http://jsbin.com/dbJSON/8/edit the output (of null) is to be had by clicking 'output'.

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  • jQuery JSON .each problem

    - by Aran
    I have a JSON object that looks like this. [ { "id" : "23", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Under 1 day!", "content" : "It\\'s all hotting up and battle commences in under one day!", "link" : "" }, { "id" : "20", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Getting Exciting", "content" : "Less than two days till it all kicks off, with cricket....", "link" : "" }] and I am trying to get the details out of this JSON Object and prepend them to a <ul> the code that I am currently trying looks like this and is having problems var writeup_list = writeuplist; $.getJSON('../json/getWriteups.json', function(data) { $.each(data.items, function(i, item) { writeup_list.html(function() { var output; output = '<li><a href="/writeups/index.php#writeup_' + item.id + '">'; if(item.sport_title != null) { output += item.sport_title + ' - '; } output += item.title + '</a></li>'; return output; }); }); }); writeuplist is just the ul object. I am also worried about overriding information that is already in the list or just adding again. Don't want to keep adding the same data. What is a good way to avoid this? I seem to be having a problem in getting the data out of the JSON file I believe it has something to do with the way am trying to access it in the .each function. Can anyone spot where am going wrong?

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  • Repaint window problems

    - by nXqd
    #include "stdafx.h" // Mario Headers #include "GameMain.h" #define MAX_LOADSTRING 100 // Global Variables: HINSTANCE hInst; // current instance TCHAR szTitle[MAX_LOADSTRING]; // The title bar text TCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name // Mario global variables ================= CGameMain* gGameMain; HWND hWnd; PAINTSTRUCT ps; // ======================================== // Forward declarations of functions included in this code module: ATOM MyRegisterClass(HINSTANCE hInstance); BOOL InitInstance(HINSTANCE, int); LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM); // My unprocess function ===================================== void OnCreate(HWND hWnd) { } void OnKeyUp(WPARAM wParam) { switch (wParam) { case VK_LEFT: gGameMain->KeyReleased(LEFT); break; case VK_UP: gGameMain->KeyReleased(UP); break; case VK_RIGHT: gGameMain->KeyReleased(RIGHT); break; case VK_DOWN: gGameMain->KeyReleased(DOWN); break; } } void OnKeyDown(HWND hWnd,WPARAM wParam) { switch (wParam) { case VK_LEFT: gGameMain->KeyPressed(LEFT); break; case VK_UP: gGameMain->KeyPressed(UP); break; case VK_RIGHT: gGameMain->KeyPressed(RIGHT); break; case VK_DOWN: gGameMain->KeyPressed(DOWN); break; } } void OnPaint(HWND hWnd) { HDC hdc = BeginPaint(hWnd,&ps); RECT rect; GetClientRect(hWnd,&rect); HDC hdcDouble = CreateCompatibleDC(hdc); HBITMAP hdcBitmap = CreateCompatibleBitmap(hdc,rect.right,rect.bottom); HBITMAP bmOld = (HBITMAP)SelectObject(hdcDouble, hdcBitmap); gGameMain->SetHDC(&hdcDouble); gGameMain->SendMessage(MESSAGE_PAINT); BitBlt(hdc,0,0,rect.right,rect.bottom,hdcDouble,0,0,SRCCOPY); SelectObject(hdcDouble,bmOld); DeleteDC(hdcDouble); DeleteObject(hdcBitmap); DeleteDC(hdc); } void OnDestroy() { gGameMain->isPlaying = false; EndPaint(hWnd,&ps); } // My unprocess function ===================================== ATOM MyRegisterClass(HINSTANCE hInstance) { WNDCLASSEX wcex; wcex.cbSize = sizeof(WNDCLASSEX); wcex.style = CS_HREDRAW | CS_VREDRAW; wcex.lpfnWndProc = WndProc; wcex.cbClsExtra = 0; wcex.cbWndExtra = 0; wcex.hInstance = hInstance; wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_GDIMARIO)); wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); wcex.lpszMenuName = MAKEINTRESOURCE(IDC_GDIMARIO); wcex.lpszClassName = szWindowClass; wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL)); return RegisterClassEx(&wcex); } BOOL InitInstance(HINSTANCE hInstance, int nCmdShow) { hInst = hInstance; // Store instance handle in our global variable hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, WIDTH, HEIGHT, 0, NULL, hInstance, NULL); if (!hWnd) { return FALSE; } // ---------------- Start gdiplus ------------------ GdiplusStartup(&gdiToken,&gdiStartInput,NULL); // ------------------------------------------------- // Init GameMain gGameMain = new CGameMain(); ShowWindow(hWnd, nCmdShow); UpdateWindow(hWnd); return TRUE; } LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) { int wmId, wmEvent; switch (message) { case WM_COMMAND: wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_KEYDOWN: OnKeyDown(hWnd,wParam); break; case WM_KEYUP: OnKeyUp(wParam); break; case WM_CREATE: OnCreate(hWnd); break; case WM_PAINT: OnPaint(hWnd); break; case WM_DESTROY: OnDestroy(); PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0; } // Message handler for about box. INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE; } int APIENTRY _tWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPTSTR lpCmdLine,int nCmdShow) { UNREFERENCED_PARAMETER(hPrevInstance); UNREFERENCED_PARAMETER(lpCmdLine); // TODO: Place code here. MSG msg; HACCEL hAccelTable; // Initialize global strings LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING); LoadString(hInstance, IDC_GDIMARIO, szWindowClass, MAX_LOADSTRING); MyRegisterClass(hInstance); // Perform application initialization: if (!InitInstance (hInstance, nCmdShow)) { return FALSE; } hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_GDIMARIO)); // Main message loop: // GameLoop PeekMessage(&msg,NULL,0,0,PM_NOREMOVE); while (gGameMain->isPlaying) { while (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) { if (msg.message == WM_QUIT) break; TranslateMessage(&msg); DispatchMessage(&msg); } if (gGameMain->enterNextState) { gGameMain->SendMessage(MESSAGE_ENTER); gGameMain->enterNextState = false; } gGameMain->SendMessage(MESSAGE_UPDATE); InvalidateRect(hWnd,NULL,FALSE); /*if (gGameMain->exitCurrentState) { gGameMain->SendMessage(MESSAGE_EXIT); gGameMain->enterNextState = true; gGameMain->exitCurrentState = false; }*/ ::Sleep(gGameMain->timer); // Do your game stuff here } GdiplusShutdown(gdiToken); // Shut down gdiplus token return (int) msg.wParam; } I use InvalidateRect(hWnd,NULL,FALSE); for repaint window, but the problem I met is when I repaint without any changes in Game struct . First it paints my logo well, the second time ( just call InvalidateRect(hWnd,NULL,FALSE); without gGameMain-SendMessage(MESSAGE_ENTER); which is init some variables for painting . Thanks for reading this :)

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  • Grouping with operands question

    - by Filip
    I have a table: mysql> desc kursy_bid; +-----------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+-------+ | datetime | datetime | NO | PRI | NULL | | | currency | varchar(6) | NO | PRI | NULL | | | value | varchar(10) | YES | | NULL | | +-----------+-------------+------+-----+---------+-------+ 3 rows in set (0.01 sec) I would like to select some rows from a table, grouped by some time interval (can be one day) where I will have the first row and the last row of the group, the max(value) and min(value). I tried: select datetime, (select value order by datetime asc limit 1) open, (select value order by datetime desc limit 1) close, max(value), min(value) from kursy_bid_test where datetime > '2009-09-14 00:00:00' and currency = 'eurpln' group by month(datetime), day(datetime), hour(datetime); but the output is: | open | close | datetime | max(value) | min(value) | +--------+--------+---------------------+------------+------------+ | 1.4581 | 1.4581 | 2009-09-14 00:00:05 | 4.1712 | 1.4581 | | 1.4581 | 1.4581 | 2009-09-14 01:00:01 | 1.4581 | 1.4581 | As you see open and close is the same (but they shouldn't be). What should be the query to do what I want?

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  • How to parse a string into a nullable int in C# (.NET 3.5)

    - by Glenn Slaven
    I'm wanting to parse a string into a nullable int in C#. ie. I want to get back either the int value of the string or null if it can't be parsed. I was kind of hoping that this would work int? val = stringVal as int?; But that won't work, so the way I'm doing it now is I've written this extension method public static int? ParseNullableInt(this string value) { if (value == null || value.Trim() == string.Empty) { return null; } else { try { return int.Parse(value); } catch { return null; } } } Is there a better way of doing this? EDIT: Thanks for the TryParse suggestions, I did know about that, but it worked out about the same. I'm more interested in knowing if there is a built-in framework method that will parse directly into a nullable int?

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  • CLR 4.0 inlining policy? (maybe bug with MethodImplOptions.NoInlining)

    - by ControlFlow
    I've testing some new CLR 4.0 behavior in method inlining (cross-assembly inlining) and found some strage results: Assembly ClassLib.dll: using System.Diagnostics; using System; using System.Reflection; using System.Security; using System.Runtime.CompilerServices; namespace ClassLib { public static class A { static readonly MethodInfo GetExecuting = typeof(Assembly).GetMethod("GetExecutingAssembly"); public static Assembly Foo(out StackTrace stack) // 13 bytes { // explicit call to GetExecutingAssembly() stack = new StackTrace(); return Assembly.GetExecutingAssembly(); } public static Assembly Bar(out StackTrace stack) // 25 bytes { // reflection call to GetExecutingAssembly() stack = new StackTrace(); return (Assembly) GetExecuting.Invoke(null, null); } public static Assembly Baz(out StackTrace stack) // 9 bytes { stack = new StackTrace(); return null; } public static Assembly Bob(out StackTrace stack) // 13 bytes { // call of non-inlinable method! return SomeSecurityCriticalMethod(out stack); } [SecurityCritical, MethodImpl(MethodImplOptions.NoInlining)] static Assembly SomeSecurityCriticalMethod(out StackTrace stack) { stack = new StackTrace(); return Assembly.GetExecutingAssembly(); } } } Assembly ConsoleApp.exe using System; using ClassLib; using System.Diagnostics; class Program { static void Main() { Console.WriteLine("runtime: {0}", Environment.Version); StackTrace stack; Console.WriteLine("Foo: {0}\n{1}", A.Foo(out stack), stack); Console.WriteLine("Bar: {0}\n{1}", A.Bar(out stack), stack); Console.WriteLine("Baz: {0}\n{1}", A.Baz(out stack), stack); Console.WriteLine("Bob: {0}\n{1}", A.Bob(out stack), stack); } } Results: runtime: 4.0.30128.1 Foo: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at ClassLib.A.Foo(StackTrace& stack) at Program.Main() Bar: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at ClassLib.A.Bar(StackTrace& stack) at Program.Main() Baz: at Program.Main() Bob: ClassLib, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null at Program.Main() So questions are: Why JIT does not inlined Foo and Bar calls as Baz does? They are lower than 32 bytes of IL and are good candidates for inlining. Why JIT inlined call of Bob and inner call of SomeSecurityCriticalMethod that is marked with the [MethodImpl(MethodImplOptions.NoInlining)] attribute? Why GetExecutingAssembly returns a valid assembly when is called by inlined Baz and SomeSecurityCriticalMethod methods? I've expect that it performs the stack walk to detect the executing assembly, but stack will contains only Program.Main() call and no methods of ClassLib assenbly, to ConsoleApp should be returned.

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  • Not able to get IME Input Context through C++ (ImmGetContext)

    - by Prakash
    Hi I am trying to disable the IME on notepad using the following psuedo code: MakeNotepadActiveWindow();//Notepad is already open and set to Japanese IME HWND hwnd = GetTheHWNDForNotepad(); HIMC context = ImmGetContext(hwnd); if(context == NULL) printf("context is null %d ",GetLastError()); and the above code is always giving me the null context. GetLastError() gives 0; Could somebody tell me how to get the InputContext

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  • Optimize date query for large child tables: GiST or GIN?

    - by Dave Jarvis
    Problem 72 child tables, each having a year index and a station index, are defined as follows: CREATE TABLE climate.measurement_12_013 ( -- Inherited from table climate.measurement_12_013: id bigint NOT NULL DEFAULT nextval('climate.measurement_id_seq'::regclass), -- Inherited from table climate.measurement_12_013: station_id integer NOT NULL, -- Inherited from table climate.measurement_12_013: taken date NOT NULL, -- Inherited from table climate.measurement_12_013: amount numeric(8,2) NOT NULL, -- Inherited from table climate.measurement_12_013: category_id smallint NOT NULL, -- Inherited from table climate.measurement_12_013: flag character varying(1) NOT NULL DEFAULT ' '::character varying, CONSTRAINT measurement_12_013_category_id_check CHECK (category_id = 7), CONSTRAINT measurement_12_013_taken_check CHECK (date_part('month'::text, taken)::integer = 12) ) INHERITS (climate.measurement) CREATE INDEX measurement_12_013_s_idx ON climate.measurement_12_013 USING btree (station_id); CREATE INDEX measurement_12_013_y_idx ON climate.measurement_12_013 USING btree (date_part('year'::text, taken)); (Foreign key constraints to be added later.) The following query runs abysmally slow due to a full table scan: SELECT count(1) AS measurements, avg(m.amount) AS amount FROM climate.measurement m WHERE m.station_id IN ( SELECT s.id FROM climate.station s, climate.city c WHERE -- For one city ... -- c.id = 5182 AND -- Where stations are within an elevation range ... -- s.elevation BETWEEN 0 AND 3000 AND 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 ) AND -- -- Begin extracting the data from the database. -- -- The data before 1900 is shaky; insufficient after 2009. -- extract( YEAR FROM m.taken ) BETWEEN 1900 AND 2009 AND -- Whittled down by category ... -- m.category_id = 1 AND m.taken BETWEEN -- Start date. (extract( YEAR FROM m.taken )||'-01-01')::date AND -- End date. Calculated by checking to see if the end date wraps -- into the next year. If it does, then add 1 to the current year. -- (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date GROUP BY extract( YEAR FROM m.taken ) The sluggishness comes from this part of the query: m.taken BETWEEN /* Start date. */ (extract( YEAR FROM m.taken )||'-01-01')::date AND /* End date. Calculated by checking to see if the end date wraps into the next year. If it does, then add 1 to the current year. */ (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date The HashAggregate from the plan shows a cost of 10006220141.11, which is, I suspect, on the astronomically huge side. There is a full table scan on the measurement table (itself having neither data nor indexes) being performed. The table aggregates 237 million rows from its child tables. Question What is the proper way to index the dates to avoid full table scans? Options I have considered: GIN GiST Rewrite the WHERE clause Separate year_taken, month_taken, and day_taken columns to the tables What are your thoughts? Thank you!

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  • FluentNHibernate Many-To-One References where Foreign Key is not to Primary Key and column names are

    - by Todd Langdon
    I've been sitting here for an hour trying to figure this out... I've got 2 tables (abbreviated): CREATE TABLE TRUST ( TRUSTID NUMBER NOT NULL, ACCTNBR VARCHAR(25) NOT NULL ) CONSTRAINT TRUST_PK PRIMARY KEY (TRUSTID) CREATE TABLE ACCOUNTHISTORY ( ID NUMBER NOT NULL, ACCOUNTNUMBER VARCHAR(25) NOT NULL, TRANSAMT NUMBER(38,2) NOT NULL POSTINGDATE DATE NOT NULL ) CONSTRAINT ACCOUNTHISTORY_PK PRIMARY KEY (ID) I have 2 classes that essentially mirror these: public class Trust { public virtual int Id {get; set;} public virtual string AccountNumber { get; set; } } public class AccountHistory { public virtual int Id { get; set; } public virtual Trust Trust {get; set;} public virtual DateTime PostingDate { get; set; } public virtual decimal IncomeAmount { get; set; } } How do I do the many-to-one mapping in FluentNHibernate to get the AccountHistory to have a Trust? Specifically, since it is related on a different column than the Trust primary key of TRUSTID and the column it is referencing is also named differently (ACCTNBR vs. ACCOUNTNUMBER)???? Here's what I have so far - how do I do the References on the AccountHistoryMap to Trust??? public class TrustMap : ClassMap<Trust> { public TrustMap() { Table("TRUST"); Id(x => x.Id).Column("TRUSTID"); Map(x => x.AccountNumber).Column("ACCTNBR"); } } public class AccountHistoryMap : ClassMap<AccountHistory> { public AccountHistoryMap() { Table("TRUSTACCTGHISTORY"); Id (x=>x.Id).Column("ID"); References<Trust>(x => x.Trust).Column("ACCOUNTNUMBER").ForeignKey("ACCTNBR").Fetch.Join(); Map(x => x.PostingDate).Column("POSTINGDATE"); ); I've tried a few different variations of the above line but can't get anything to work - it pulls back AccountHistory data and a proxy for the Trust; however it says no Trust row with given identifier. This has to be something simple. Anyone? Thanks in advance.

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  • NHibernate HQL logic problem

    - by Jon
    Hi I'm trying to write an NHibernate HQL query that makes use of parenthesis in the where clause. However, the HQL parser seems to be ignoring my parenthesis, thus changing the meaning of my statement. Can anyone shed any light on the matter? The following HQL query: from WebUser u left join fetch u.WebUserProfile left join fetch u.CommunicationPreferences where (u.CommunicationPreferences.Email = 0 and u.SyncDate is not null) or u.DateDeleted is not null translates to: from WebUser webuser0_ left outer join WebUserProfile webuserpro1_ on webuser0_.UserId = webuserpro1_.WebUserId left outer join WebUserCommunicationPreferences communicat2_ on webuser0_.UserId = communicat2_.UserId where communicat2_.Email = 0 and (webuser0_.SyncDate is not null) or webuser0_.DateDeleted is not null Thanks Jon

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  • Refresh page isnt working in asp.net using treeview

    - by Greg
    Hi, I am trying to refresh an asp.net page using this command: <meta http-equiv="Refresh" content="10"/> On that page I have 2 treeviews. The refresh works ok when I just open the page, but when I click on one of the treeviews and expand it, the refresh stopps working and the page isnt being refreshed. Any ideas why this can happen? Is there any connection to the treeview being expanded? Here is the full code of the page: public partial class Results : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } // Function that moves reviewed yellow card to reviewed tree protected void ycActiveTree_SelectedNodeChanged(object sender, EventArgs e) { ycActiveTree.SelectedNode.Text = "Move To Active"; ycReviewedTree.PopulateNodesFromClient = false; ycReviewedTree.Nodes[ycReviewedTree.Nodes.Count - 1].ChildNodes.Add(ycActiveTree.SelectedNode.Parent); Application["reviewedTree"] = new ArrayList(); int count = ((ArrayList)Application["activeTree"]).Count; // Move all the nodes from activeTree application to reviewedTree application for (int i = 0; Application["activeTree"] != null && i < count; i++) { ((ArrayList)Application["reviewedTree"]).Add(((ArrayList)Application["activeTree"])[i]); ((ArrayList)Application["activeTree"]).RemoveAt(0); } } protected void ycActiveTree_TreeNodePopulate(object sender, TreeNodeEventArgs e) { if (Application["idList"] != null && e.Node.Depth == 0) { string[] words = ((String)Application["idList"]).Split(' '); // Yellow Card details TreeNode child = new TreeNode(""); // Go over all the yellow card details and populate the treeview for (int i = 1; i < words.Length; i++) { child.SelectAction = TreeNodeSelectAction.None; // Same yellow card if (words[i] != "*") { // End of details and start of point ip's if (words[i] == "$") { // Add the yellow card node TreeNode yellowCardNode = new TreeNode(child.Text); yellowCardNode.SelectAction = TreeNodeSelectAction.Expand; e.Node.ChildNodes.Add(yellowCardNode); child.Text = ""; } // yellow card details else { child.Text = child.Text + words[i] + " "; } } // End of yellow card else { child.PopulateOnDemand = false; child.SelectAction = TreeNodeSelectAction.None; // Populate the yellow card node e.Node.ChildNodes[e.Node.ChildNodes.Count - 1].ChildNodes.Add(child); TreeNode moveChild = new TreeNode("Move To Reviewed"); moveChild.PopulateOnDemand = false; moveChild.SelectAction = TreeNodeSelectAction.Select; e.Node.ChildNodes[e.Node.ChildNodes.Count - 1].ChildNodes.Add(moveChild); child = new TreeNode(""); Application["activeTree"] = new ArrayList(); ((ArrayList)Application["activeTree"]).Add(e.Node.ChildNodes[e.Node.ChildNodes.Count - 1]); } } } // If there arent new yellow cards else if (Application["activeTree"] != null) { // Populate the active tree for (int i = 0; i < ((ArrayList)Application["activeTree"]).Count; i++) { e.Node.ChildNodes.Add((TreeNode)((ArrayList)Application["activeTree"])[i]); } } // If there were new yellow cards and nodes that moved from reviewed tree to active tree if (Application["idList"] != null && Application["activeTree"] != null && e.Node.ChildNodes.Count != ((ArrayList)Application["activeTree"]).Count) { for (int i = e.Node.ChildNodes.Count; i < ((ArrayList)Application["activeTree"]).Count; i++) { e.Node.ChildNodes.Add((TreeNode)((ArrayList)Application["activeTree"])[i]); } } // Nullify the yellow card id's Application["idList"] = null; } protected void ycReviewedTree_SelectedNodeChanged(object sender, EventArgs e) { ycActiveTree.PopulateNodesFromClient = false; ycReviewedTree.SelectedNode.Text = "Move To Reviewed"; ycActiveTree.Nodes[ycActiveTree.Nodes.Count - 1].ChildNodes.Add(ycReviewedTree.SelectedNode.Parent); int count = ((ArrayList)Application["reviewedTree"]).Count; // Move all the nodes from reviewedTree application to activeTree application for (int i = 0; Application["reviewedTree"] != null && i < count; i++) { ((ArrayList)Application["activeTree"]).Add(((ArrayList)Application["reviewedTree"])[i]); ((ArrayList)Application["reviewedTree"]).RemoveAt(0); } } protected void ycReviewedTree_TreeNodePopulate(object sender, TreeNodeEventArgs e) { if (Application["reviewedTree"] != null) { // Populate the reviewed tree for (int i = 0; i < ((ArrayList)Application["reviewedTree"]).Count; i++) { e.Node.ChildNodes.Add((TreeNode)((ArrayList)Application["reviewedTree"])[i]); } } } } Thanks, Greg

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  • how to call any method of Project from classlibrary?

    - by Pankaj Mishra
    Hello I have Class Library Where a class of multithreading Of Producer and consumer based. private void WorkDeQueue() { while (true) { string Url = null; lock (locker) { if (queueList.Count > 0) { Url = queueList.Dequeue(); /* return if a null is found in the queue */ if (Url == null) return; } } if (Url != null) { /* if a job was found then process it */ GetData(Url); //This Is a Method } else { /* if a job was not found (meaning list is empty) then * wait till something is added to it*/ wh.WaitOne(); } } } this GetData method has no body on that class. How can i call any method of my project in palace of getdata. I tried with factory Pattern and also with reflection. but both didn't worked for me. So plz tell me how can i call any method of my project from here.

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  • javascript string exec strange behavior

    - by Michael
    have funciton in my object which is called regularly. parse : function(html) { var regexp = /...some pattern.../ var match = regexp.exec(html); while (match != null) { ... match = regexp.exec(html); } ... var r = /...pattern.../g; var m = r.exec(html); } with unchanged html the m returns null each other call. let's say parse(html);// ok parse(html);// m is null!!! parse(html);// ok parse(html);// m is null!!! // ...and so on... is there any index or somrthing that has to be reset on html ... I'm really confused. Why match always returns proper result?

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  • help on ejb stateless datagram and message driven beans

    - by Kemmal
    i have a client thats sending a message to the ejbserver using UDP, i want the server(stateless bean) to echo back this message to the client but i cant seem to do this. or can i implement the same logic by using JMS? please help and enlighten. this is just a test, in the end i want a midp to be sending the message to the ejb using datagrams. here is my code. @Stateless public class SessionFacadeBean implements SessionFacadeRemote { public SessionFacadeBean() { } public static void main(String[] args) { DatagramSocket aSocket = null; byte[] buffer = null; try { while(true) { DatagramPacket request = new DatagramPacket(buffer, buffer.length); aSocket.receive(request); DatagramPacket reply = new DatagramPacket(request.getData(), request.getLength(), request.getAddress(), request.getPort()); aSocket.send(reply); } } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } } and the client: public static void main(String[] args) { DatagramSocket aSocket = null; try { aSocket = new DatagramSocket(); byte [] m = "Test message!".getBytes(); InetAddress aHost = InetAddress.getByName("localhost"); int serverPort = 6789; DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort); aSocket.send(request); byte[] buffer = new byte[1000]; DatagramPacket reply = new DatagramPacket(buffer, buffer.length); aSocket.receive(reply); System.out.println("Reply: " + new String(reply.getData())); } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } please help.

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  • How to find nth element from the end of a singly linked list?

    - by Codenotguru
    The following function is trying to find the nth to last element of a singly linked list. For example: If the elements are 8->10->5->7->2->1->5->4->10->10 then the result is 7th to last node is 7. Can anybody help me on how this code is working or is there a better and simpler approach? LinkedListNode nthToLast(LinkedListNode head, int n) { if (head == null || n < 1) { return null; } LinkedListNode p1 = head; LinkedListNode p2 = head; for (int j = 0; j < n - 1; ++j) { // skip n-1 steps ahead if (p2 == null) { return null; // not found since list size < n } p2 = p2.next; } while (p2.next != null) { p1 = p1.next; p2 = p2.next; } return p1; }

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  • SQL Server IS_NULLABLE

    - by J Harley
    Good Morning, Just a quick question what this field actually means? I am trying to create an export script which follows this standard: lname varchar(30) **NOT NULL**, So if last name is_nullable=yes then would I put NULL rather than NOT NULL at the *'d code. Many Thanks, Joel

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  • multipart file-upload post request from java

    - by Martin
    I'm trying to make a program that uploads a image to a webserver that accepts multipart file-uploads. More specificly i want to make a http POST request to http://iqs.me that sends a file in the variable "pic". I've made a lot of tries but i don't know if i've even been close. The hardest part seems to be to get a HttpURLConnection to make a request of the type POST. The response i get looks like it makes a GET. (And i want to do this without any third party libs) UPDATE: non-working code goes here (no errors but doesn't seem to do a POST): HttpURLConnection conn = null; BufferedReader br = null; DataOutputStream dos = null; DataInputStream inStream = null; InputStream is = null; OutputStream os = null; boolean ret = false; String StrMessage = ""; String exsistingFileName = "myScreenShot.png"; String lineEnd = "\r\n"; String twoHyphens = "--"; String boundary = "*****"; int bytesRead, bytesAvailable, bufferSize; byte[] buffer; int maxBufferSize = 1*1024*1024; String responseFromServer = ""; String urlString = "http://iqs.local.com/index.php"; try{ FileInputStream fileInputStream = new FileInputStream( new File(exsistingFileName) ); URL url = new URL(urlString); conn = (HttpURLConnection) url.openConnection(); conn.setDoInput(true); conn.setDoOutput(true); conn.setRequestMethod("POST"); conn.setUseCaches(false); conn.setRequestProperty("Connection", "Keep-Alive"); conn.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary); dos = new DataOutputStream( conn.getOutputStream() ); dos.writeBytes(twoHyphens + boundary + lineEnd); dos.writeBytes("Content-Disposition: form-data; name=\"pic\";" + " filename=\"" + exsistingFileName +"\"" + lineEnd); dos.writeBytes(lineEnd); bytesAvailable = fileInputStream.available(); bufferSize = Math.min(bytesAvailable, maxBufferSize); buffer = new byte[bufferSize]; bytesRead = fileInputStream.read(buffer, 0, bufferSize); while (bytesRead > 0){ dos.write(buffer, 0, bufferSize); bytesAvailable = fileInputStream.available(); bufferSize = Math.min(bytesAvailable, maxBufferSize); bytesRead = fileInputStream.read(buffer, 0, bufferSize); } dos.writeBytes(lineEnd); dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd); fileInputStream.close(); dos.flush(); dos.close(); }catch (MalformedURLException ex){ System.out.println("Error:"+ex); }catch (IOException ioe){ System.out.println("Error:"+ioe); } try{ inStream = new DataInputStream ( conn.getInputStream() ); String str; while (( str = inStream.readLine()) != null){ System.out.println(str); } inStream.close(); }catch (IOException ioex){ System.out.println("Error: "+ioex); }

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  • Please help optimizing a long running query (left outer join, with 2 subqueries)

    - by 46and2
    Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

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