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  • C# Dev Challenge Part 1 of n &ndash; Beginner Edition

    - by mbcrump
    I developed this challenge to test one’s knowledge of C Sharp. I am planning on creating several challenges with different skill sets, so don’t get mad if this challenge doesn’t well challenge you... I noticed that most people like short quizzes so this one only contains 5 questions. All of the challenges are clear and concise of what I am asking you to do. No smoke and mirrors here, meaning that none of the code has syntax errors. The purpose of this exercise is to test several OOP concepts and see how much of the C# language you really know. Question #1 – Lets start off Easy… Will the following code snippet compile successfully? What does this question test? - Can this compile without a namespace? Do you have to have an entry point of “static void Main()”? class Test { static int Main() { System.Console.WriteLine("Developer Challenge"); return 0; } } Answer (select text in box below): Yes, it will compile successfully. Question #2 – What is the value of the Console.WriteLine statements? What does this question test? – Do I understand reference types/value types? If a variable is declared with the @ symbol and its not a reserved keyword does the application compile successfully? using System; internal struct MyStruct { public int Value; } internal class MyClass { public int Value; } class Test { static void Main() { MyStruct @struct1 = new MyStruct(); MyStruct @struct2 = @struct1; @struct2.Value = 100; MyClass @ref1 = new MyClass(); MyClass @ref2 = @ref1; @ref2.Value = 100; Console.WriteLine("Value Type: {0} {1}", @struct1.Value, @struct2.Value); Console.WriteLine("Reference Type: {0} {1}", @ref1.Value, @ref2.Value); } } Answer (select text in box below): Value Type: 0 100 Reference Type: 100 100 Question #3 – What is the value of the Console.WriteLine statements? What does this question test? – Can 2 objects reference the same point in memory? using System; class Test { static void Main() { string s1 = "Testing2"; string t1 = s1; Console.WriteLine(s1 == t1); Console.WriteLine((object)s1 == (object)t1); } } Answer (select text in box below): True True Question #4 – What is the value of the Console.WriteLine statements? What does this question test? – How does the “Stack” work – LIFO or FIFO?   using System; using System.Collections; class Test { static void Main() { Stack a = new Stack(5); a.Push("1"); a.Push("2"); a.Push("3"); a.Push("4"); a.Push("5"); foreach (var o in a) { Console.WriteLine(o); } } } Answer (select text in box below): 5 4 3 2 1 Question #5 – What is the value of the Console.WriteLine statements? What does this question test? – Array and General Looping Knowledge. using System; namespace ConsoleApplication5 { class Program { static void Main(string[] args) { int[] J_LIST = new int[5] { 1, 2, 3, 4, 5 }; int K = 10; int L = 5; foreach (var J in J_LIST) { K = K - J; L = K + 2 * J; Console.WriteLine("J = {0, 5} K = {1, 5} L = {2, 5}", J, K, L); } Console.ReadLine(); } } } Answer (select text in box below): J = 1 K = 9 L = 11 J = 2 K = 7 L = 11 J = 3 K = 4 L = 10 J = 4 K = 0 L = 8 J = 5 K = -5 L = 5 Stay Tuned for more challenges!

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  • InternalsVisibleTo attribute and security vulnerability

    - by Sergey Litvinov
    I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

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  • Combining MVVM Light Toolkit and Unity 2.0

    - by Alan Cordner
    This is more of a commentary than a question, though feedback would be nice. I have been tasked to create the user interface for a new project we are doing. We want to use WPF and I wanted to learn all of the modern UI design techniques available. Since I am fairly new to WPF I have been researching what is available. I think I have pretty much settled on using MVVM Light Toolkit (mainly because of its "Blendability" and the EventToCommand behavior!), but I wanted to incorporate IoC also. So, here is what I have come up with. I have modified the default ViewModelLocator class in a MVVM Light project to use a UnityContainer to handle dependency injections. Considering I didn't know what 90% of these terms meant 3 months ago, I think I'm on the right track. // Example of MVVM Light Toolkit ViewModelLocator class that implements Microsoft // Unity 2.0 Inversion of Control container to resolve ViewModel dependencies. using Microsoft.Practices.Unity; namespace MVVMLightUnityExample { public class ViewModelLocator { public static UnityContainer Container { get; set; } #region Constructors static ViewModelLocator() { if (Container == null) { Container = new UnityContainer(); // register all dependencies required by view models Container .RegisterType<IDialogService, ModalDialogService>(new ContainerControlledLifetimeManager()) .RegisterType<ILoggerService, LogFileService>(new ContainerControlledLifetimeManager()) ; } } /// <summary> /// Initializes a new instance of the ViewModelLocator class. /// </summary> public ViewModelLocator() { ////if (ViewModelBase.IsInDesignModeStatic) ////{ //// // Create design time view models ////} ////else ////{ //// // Create run time view models ////} CreateMain(); } #endregion #region MainViewModel private static MainViewModel _main; /// <summary> /// Gets the Main property. /// </summary> public static MainViewModel MainStatic { get { if (_main == null) { CreateMain(); } return _main; } } /// <summary> /// Gets the Main property. /// </summary> [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification = "This non-static member is needed for data binding purposes.")] public MainViewModel Main { get { return MainStatic; } } /// <summary> /// Provides a deterministic way to delete the Main property. /// </summary> public static void ClearMain() { _main.Cleanup(); _main = null; } /// <summary> /// Provides a deterministic way to create the Main property. /// </summary> public static void CreateMain() { if (_main == null) { // allow Unity to resolve the view model and hold onto reference _main = Container.Resolve<MainViewModel>(); } } #endregion #region OrderViewModel // property to hold the order number (injected into OrderViewModel() constructor when resolved) public static string OrderToView { get; set; } /// <summary> /// Gets the OrderViewModel property. /// </summary> public static OrderViewModel OrderViewModelStatic { get { // allow Unity to resolve the view model // do not keep local reference to the instance resolved because we need a new instance // each time - the corresponding View is a UserControl that can be used multiple times // within a single window/view // pass current value of OrderToView parameter to constructor! return Container.Resolve<OrderViewModel>(new ParameterOverride("orderNumber", OrderToView)); } } /// <summary> /// Gets the OrderViewModel property. /// </summary> [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification = "This non-static member is needed for data binding purposes.")] public OrderViewModel Order { get { return OrderViewModelStatic; } } #endregion /// <summary> /// Cleans up all the resources. /// </summary> public static void Cleanup() { ClearMain(); Container = null; } } } And the MainViewModel class showing dependency injection usage: using GalaSoft.MvvmLight; using Microsoft.Practices.Unity; namespace MVVMLightUnityExample { public class MainViewModel : ViewModelBase { private IDialogService _dialogs; private ILoggerService _logger; /// <summary> /// Initializes a new instance of the MainViewModel class. This default constructor calls the /// non-default constructor resolving the interfaces used by this view model. /// </summary> public MainViewModel() : this(ViewModelLocator.Container.Resolve<IDialogService>(), ViewModelLocator.Container.Resolve<ILoggerService>()) { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { // Code runs "for real" } } /// <summary> /// Initializes a new instance of the MainViewModel class. /// Interfaces are automatically resolved by the IoC container. /// </summary> /// <param name="dialogs">Interface to dialog service</param> /// <param name="logger">Interface to logger service</param> public MainViewModel(IDialogService dialogs, ILoggerService logger) { _dialogs = dialogs; _logger = logger; if (IsInDesignMode) { // Code runs in Blend --> create design time data. _dialogs.ShowMessage("Running in design-time mode!", "Injection Constructor", DialogButton.OK, DialogImage.Information); _logger.WriteLine("Running in design-time mode!"); } else { // Code runs "for real" _dialogs.ShowMessage("Running in run-time mode!", "Injection Constructor", DialogButton.OK, DialogImage.Information); _logger.WriteLine("Running in run-time mode!"); } } public override void Cleanup() { // Clean up if needed _dialogs = null; _logger = null; base.Cleanup(); } } } And the OrderViewModel class: using GalaSoft.MvvmLight; using Microsoft.Practices.Unity; namespace MVVMLightUnityExample { /// <summary> /// This class contains properties that a View can data bind to. /// <para> /// Use the <strong>mvvminpc</strong> snippet to add bindable properties to this ViewModel. /// </para> /// <para> /// You can also use Blend to data bind with the tool's support. /// </para> /// <para> /// See http://www.galasoft.ch/mvvm/getstarted /// </para> /// </summary> public class OrderViewModel : ViewModelBase { private const string testOrderNumber = "123456"; private Order _order; /// <summary> /// Initializes a new instance of the OrderViewModel class. /// </summary> public OrderViewModel() : this(testOrderNumber) { } /// <summary> /// Initializes a new instance of the OrderViewModel class. /// </summary> public OrderViewModel(string orderNumber) { if (IsInDesignMode) { // Code runs in Blend --> create design time data. _order = new Order(orderNumber, "My Company", "Our Address"); } else { _order = GetOrder(orderNumber); } } public override void Cleanup() { // Clean own resources if needed _order = null; base.Cleanup(); } } } And the code that could be used to display an order view for a specific order: public void ShowOrder(string orderNumber) { // pass the order number to show to ViewModelLocator to be injected //into the constructor of the OrderViewModel instance ViewModelLocator.OrderToShow = orderNumber; View.OrderView orderView = new View.OrderView(); } These examples have been stripped down to show only the IoC ideas. It took a lot of trial and error, searching the internet for examples, and finding out that the Unity 2.0 documentation is lacking (at best) to come up with this solution. Let me know if you think it could be improved.

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  • how do you make a "concurrent queue safe" lazy loader (singleton manager) in objective-c

    - by Rich
    Hi, I made this class that turns any object into a singleton, but I know that it's not "concurrent queue safe." Could someone please explain to me how to do this, or better yet, show me the code. To be clear I want to know how to use this with operation queues and dispatch queues (NSOperationQueue and Grand Central Dispatch) on iOS. Thanks in advance, Rich EDIT: I had an idea for how to do it. If someone could confirm it for me I'll do it and post the code. The idea is that proxies make queues all on their own. So if I make a mutable proxy (like Apple does in key-value coding/observing) for any object that it's supposed to return, and always return the same proxy for the same object/identifier pair (using the same kind of lazy loading technique as I used to create the singletons), the proxies would automatically queue up the any messages to the singletons, and make it totally thread safe. IMHO this seems like a lot of work to do, so I don't want to do it if it's not gonna work, or if it's gonna slow my apps down to a crawl. Here's my non-thread safe code: RMSingletonCollector.h // // RMSingletonCollector.h // RMSingletonCollector // // Created by Rich Meade-Miller on 2/11/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import <Foundation/Foundation.h> #import "RMWeakObjectRef.h" struct RMInitializerData { // The method may take one argument. // required SEL designatedInitializer; // data to pass to the initializer or nil. id data; }; typedef struct RMInitializerData RMInitializerData; RMInitializerData RMInitializerDataMake(SEL initializer, id data); @interface NSObject (SingletonCollector) // Returns the selector and data to pass to it (if the selector takes an argument) for use when initializing the singleton. // If you override this DO NOT call super. + (RMInitializerData)designatedInitializerForIdentifier:(NSString *)identifier; @end @interface RMSingletonCollector : NSObject { } + (id)collectionObjectForType:(NSString *)className identifier:(NSString *)identifier; + (id<RMWeakObjectReference>)referenceForObjectOfType:(NSString *)className identifier:(NSString *)identifier; + (void)destroyCollection; + (void)destroyCollectionObjectForType:(NSString *)className identifier:(NSString *)identifier; @end // ==--==--==--==--==Notifications==--==--==--==--== extern NSString *const willDestroySingletonCollection; extern NSString *const willDestroySingletonCollectionObject; RMSingletonCollector.m // // RMSingletonCollector.m // RMSingletonCollector // // Created by Rich Meade-Miller on 2/11/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import "RMSingletonCollector.h" #import <objc/objc-runtime.h> NSString *const willDestroySingletonCollection = @"willDestroySingletonCollection"; NSString *const willDestroySingletonCollectionObject = @"willDestroySingletonCollectionObject"; RMInitializerData RMInitializerDataMake(SEL initializer, id data) { RMInitializerData newData; newData.designatedInitializer = initializer; newData.data = data; return newData; } @implementation NSObject (SingletonCollector) + (RMInitializerData)designatedInitializerForIdentifier:(NSString *)identifier { return RMInitializerDataMake(@selector(init), nil); } @end @interface RMSingletonCollector () + (NSMutableDictionary *)singletonCollection; + (void)setSingletonCollection:(NSMutableDictionary *)newSingletonCollection; @end @implementation RMSingletonCollector static NSMutableDictionary *singletonCollection = nil; + (NSMutableDictionary *)singletonCollection { if (singletonCollection != nil) { return singletonCollection; } NSMutableDictionary *collection = [[NSMutableDictionary alloc] initWithCapacity:1]; [self setSingletonCollection:collection]; [collection release]; return singletonCollection; } + (void)setSingletonCollection:(NSMutableDictionary *)newSingletonCollection { if (newSingletonCollection != singletonCollection) { [singletonCollection release]; singletonCollection = [newSingletonCollection retain]; } } + (id)collectionObjectForType:(NSString *)className identifier:(NSString *)identifier { id obj; NSString *key; if (identifier) { key = [className stringByAppendingFormat:@".%@", identifier]; } else { key = className; } if (obj = [[self singletonCollection] objectForKey:key]) { return obj; } // dynamic creation. // get a class for Class classForName = NSClassFromString(className); if (classForName) { obj = objc_msgSend(classForName, @selector(alloc)); // if the initializer takes an argument... RMInitializerData initializerData = [classForName designatedInitializerForIdentifier:identifier]; if (initializerData.data) { // pass it. obj = objc_msgSend(obj, initializerData.designatedInitializer, initializerData.data); } else { obj = objc_msgSend(obj, initializerData.designatedInitializer); } [singletonCollection setObject:obj forKey:key]; [obj release]; } else { // raise an exception if there is no class for the specified name. NSException *exception = [NSException exceptionWithName:@"com.RMDev.RMSingletonCollector.failed_to_find_class" reason:[NSString stringWithFormat:@"SingletonCollector couldn't find class for name: %@", [className description]] userInfo:nil]; [exception raise]; [exception release]; } return obj; } + (id<RMWeakObjectReference>)referenceForObjectOfType:(NSString *)className identifier:(NSString *)identifier { id obj = [self collectionObjectForType:className identifier:identifier]; RMWeakObjectRef *objectRef = [[RMWeakObjectRef alloc] initWithObject:obj identifier:identifier]; return [objectRef autorelease]; } + (void)destroyCollection { NSDictionary *userInfo = [singletonCollection copy]; [[NSNotificationCenter defaultCenter] postNotificationName:willDestroySingletonCollection object:self userInfo:userInfo]; [userInfo release]; // release the collection and set it to nil. [self setSingletonCollection:nil]; } + (void)destroyCollectionObjectForType:(NSString *)className identifier:(NSString *)identifier { NSString *key; if (identifier) { key = [className stringByAppendingFormat:@".%@", identifier]; } else { key = className; } [[NSNotificationCenter defaultCenter] postNotificationName:willDestroySingletonCollectionObject object:[singletonCollection objectForKey:key] userInfo:nil]; [singletonCollection removeObjectForKey:key]; } @end RMWeakObjectRef.h // // RMWeakObjectRef.h // RMSingletonCollector // // Created by Rich Meade-Miller on 2/12/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // // In order to offset the performance loss from always having to search the dictionary, I made a retainable, weak object reference class. #import <Foundation/Foundation.h> @protocol RMWeakObjectReference <NSObject> @property (nonatomic, assign, readonly) id objectRef; @property (nonatomic, retain, readonly) NSString *className; @property (nonatomic, retain, readonly) NSString *objectIdentifier; @end @interface RMWeakObjectRef : NSObject <RMWeakObjectReference> { id objectRef; NSString *className; NSString *objectIdentifier; } - (RMWeakObjectRef *)initWithObject:(id)object identifier:(NSString *)identifier; - (void)objectWillBeDestroyed:(NSNotification *)notification; @end RMWeakObjectRef.m // // RMWeakObjectRef.m // RMSingletonCollector // // Created by Rich Meade-Miller on 2/12/11. // Copyright 2011 Rich Meade-Miller. All rights reserved. // #import "RMWeakObjectRef.h" #import "RMSingletonCollector.h" @implementation RMWeakObjectRef @dynamic objectRef; @synthesize className, objectIdentifier; - (RMWeakObjectRef *)initWithObject:(id)object identifier:(NSString *)identifier { if (self = [super init]) { NSString *classNameForObject = NSStringFromClass([object class]); className = classNameForObject; objectIdentifier = identifier; objectRef = object; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(objectWillBeDestroyed:) name:willDestroySingletonCollectionObject object:object]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(objectWillBeDestroyed:) name:willDestroySingletonCollection object:[RMSingletonCollector class]]; } return self; } - (id)objectRef { if (objectRef) { return objectRef; } objectRef = [RMSingletonCollector collectionObjectForType:className identifier:objectIdentifier]; return objectRef; } - (void)objectWillBeDestroyed:(NSNotification *)notification { objectRef = nil; } - (void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; [className release]; [super dealloc]; } @end

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  • Error with my Android Application httpGet

    - by Coombes
    Basically I'm getting a strange issue with my Android application, it's supposed to grab a JSON Array and print out some values, the class looks like this: ShowComedianActivity.class package com.example.connecttest; public class ShowComedianActivity extends Activity{ TextView name; TextView add; TextView email; TextView tel; String id; // Progress Dialog private ProgressDialog pDialog; //JSON Parser class JSONParser jsonParser = new JSONParser(); // Single Comedian url private static final String url_comedian_details = "http://86.9.71.17/connect/get_comedian_details.php"; // JSON Node names private static final String TAG_SUCCESS = "success"; private static final String TAG_COMEDIAN = "comedian"; private static final String TAG_ID = "id"; private static final String TAG_NAME = "name"; private static final String TAG_ADDRESS = "address"; private static final String TAG_EMAIL = "email"; private static final String TAG_TEL = "tel"; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.show_comedian); // Getting Comedian Details from intent Intent i = getIntent(); // Getting id from intent id = i.getStringExtra(TAG_ID); new GetComedianDetails().execute(); } class GetComedianDetails extends AsyncTask<String, String, String>{ protected void onPreExecute(){ super.onPreExecute(); pDialog = new ProgressDialog(ShowComedianActivity.this); pDialog.setMessage("Fetching Comedian details. Please wait..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected String doInBackground(String... params) { runOnUiThread(new Runnable(){ public void run(){ int success; try{ //Building parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("id",id)); // Getting comedian details via HTTP request // Uses a GET request JSONObject json = jsonParser.makeHttpRequest(url_comedian_details, "GET", params); // Check Log for json response Log.d("Single Comedian details", json.toString()); //JSON Success tag success = json.getInt(TAG_SUCCESS); if(success == 1){ // Succesfully received product details JSONArray comedianObj = json.getJSONArray(TAG_COMEDIAN); //JSON Array // get first comedian object from JSON Array JSONObject comedian = comedianObj.getJSONObject(0); // comedian with id found name = (TextView) findViewById(R.id.name); add = (TextView) findViewById(R.id.add); email = (TextView) findViewById(R.id.email); tel = (TextView) findViewById(R.id.tel); // Set text to details name.setText(comedian.getString(TAG_NAME)); add.setText(comedian.getString(TAG_ADDRESS)); email.setText(comedian.getString(TAG_EMAIL)); tel.setText(comedian.getString(TAG_TEL)); } } catch (JSONException e){ e.printStackTrace(); } } }); return null; } } } And my JSON Parser class looks like: package com.example.connecttest; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } // function get json from url // by making HTTP POST or GET method public JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } Now when I run a debug it's querying the correct address with ?id=1 on the end of the URL, and when I navigate to that url I get the following JSON Array: {"success":1,"comedian":[{"id":"1","name":"Michael Coombes","address":"5 Trevethenick Road","email":"[email protected]","tel":"xxxxxxxxxxxx"}]} However my app just crashes, the log-cat report looks like this: 03-22 02:05:02.140: E/Trace(3776): error opening trace file: No such file or directory (2) 03-22 02:05:04.590: E/AndroidRuntime(3776): FATAL EXCEPTION: main 03-22 02:05:04.590: E/AndroidRuntime(3776): android.os.NetworkOnMainThreadException 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connect(IoBridge.java:112) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.Socket.connect(Socket.java:842) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.JSONParser.makeHttpRequest(JSONParser.java:62) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.ShowComedianActivity$GetComedianDetails$1.run(ShowComedianActivity.java:89) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.handleCallback(Handler.java:615) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.dispatchMessage(Handler.java:92) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Looper.loop(Looper.java:137) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.app.ActivityThread.main(ActivityThread.java:4745) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invokeNative(Native Method) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invoke(Method.java:511) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-22 02:05:04.590: E/AndroidRuntime(3776): at dalvik.system.NativeStart.main(Native Method) From this I'm guessing the error is in the jsonParser.makeHttpRequest however I can't for the life of me figure out what's going wrong and was hoping someone brighter than I could illuminate me.

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  • C# performance analysis- how to count CPU cycles?

    - by Lirik
    Is this a valid way to do performance analysis? I want to get nanosecond accuracy and determine the performance of typecasting: class PerformanceTest { static double last = 0.0; static List<object> numericGenericData = new List<object>(); static List<double> numericTypedData = new List<double>(); static void Main(string[] args) { double totalWithCasting = 0.0; double totalWithoutCasting = 0.0; for (double d = 0.0; d < 1000000.0; ++d) { numericGenericData.Add(d); numericTypedData.Add(d); } Stopwatch stopwatch = new Stopwatch(); for (int i = 0; i < 10; ++i) { stopwatch.Start(); testWithTypecasting(); stopwatch.Stop(); totalWithCasting += stopwatch.ElapsedTicks; stopwatch.Start(); testWithoutTypeCasting(); stopwatch.Stop(); totalWithoutCasting += stopwatch.ElapsedTicks; } Console.WriteLine("Avg with typecasting = {0}", (totalWithCasting/10)); Console.WriteLine("Avg without typecasting = {0}", (totalWithoutCasting/10)); Console.ReadKey(); } static void testWithTypecasting() { foreach (object o in numericGenericData) { last = ((double)o*(double)o)/200; } } static void testWithoutTypeCasting() { foreach (double d in numericTypedData) { last = (d * d)/200; } } } The output is: Avg with typecasting = 468872.3 Avg without typecasting = 501157.9 I'm a little suspicious... it looks like there is nearly no impact on the performance. Is casting really that cheap?

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  • Singletons, thread safety and structuremap

    - by Ben
    Hi, Currently I have the following class: public class PluginManager { private static bool s_initialized; private static object s_lock = new object(); public static void Initialize() { if (!s_initialized) { lock (s_lock) { if (!s_initialized) { // initialize s_initialized = true; } } } } } The important thing here is that Initialize() should only be executed once whilst the application is running. I thought that I would refactor this into a singleton class since this would be more thread safe?: public sealed class PluginService { static PluginService() { } private static PluginService _instance = new PluginService(); public static PluginService Instance { get { return _instance; } } private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } Question one, is it still necessary to have the lock here (I have removed it) since we will only ever be working on the same instance? Finally, I want to use DI and structure map to initialize my servcices so I have refactored as below: public interface IPluginService { void Initialize(); } public class NewPluginService : IPluginService { private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } And in my registry: ForRequestedType<IPluginService>() .TheDefaultIsConcreteType<NewPluginService>().AsSingletons(); This works as expected (singleton returning true in the following code): var instance1 = ObjectFactory.GetInstance<IPluginService>(); var instance2 = ObjectFactory.GetInstance<IPluginService>(); bool singleton = (instance1 == instance2); So my next question, is the structure map solution as thread safe as the singleton class (second example). The only downside is that this would still allow NewPluginService to be instantiated directly (if not using structure map). Many thanks, Ben

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  • NAudio Mp3 Playback in Console

    - by Kurru
    Hi I'm trying to make a helper dll that will simplify the NAudio framework into a subset of functions I'm likely to need but I've hit a stumbling block right off the bat. I'm trying to use the following code to play an mp3 but I'm not hearing anything at all. Any help would be appreciated! static WaveOut waveout; static WaveStream playback; static System.Threading.ManualResetEvent wait = new System.Threading.ManualResetEvent(false); static void Main(string[] args) { System.Threading.Thread t = new System.Threading.Thread(new System.Threading.ThreadStart(PlaySong)); t.Start(); wait.WaitOne(); System.Threading.Thread.Sleep(2 * 1000); waveout.Stop(); waveout.Dispose(); playback.Dispose(); } static void PlaySong() { waveout = new WaveOut(); playback = OpenMp3Stream(@"songname.mp3"); waveout.Init(playback); waveout.Play(); Console.WriteLine("Started"); wait.Set(); } private static WaveChannel32 OpenMp3Stream(string fileName) { WaveChannel32 inputStream; WaveStream mp3Reader = new Mp3FileReader(fileName); WaveStream pcmStream = WaveFormatConversionStream.CreatePcmStream(mp3Reader); WaveStream blockAlignedStream = new BlockAlignReductionStream(pcmStream); inputStream = new WaveChannel32(blockAlignedStream); return inputStream; }

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  • How to Implement the ImageAdapter for this listView Code?

    - by iDroid Explorer
    Code of Lost View is like: public final static String ITEM_TITLE = "title"; public final static String ITEM_CAPTION = "caption"; public Resources resources; public static Uri path; public static File file; public static ProgressDialog m_progressDialog; public static ListView list; @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(R.layout.main); // create our list and custom adapter SeparatedListAdapter adapter = new SeparatedListAdapter(this); adapter.addSection("Local documents:", new ArrayAdapter<String>(this, R.layout.list_item, new String[] { "WindowsONE Mobile PK", "WindowsorONE Moldings","Filet for a burger video" })); adapter.addSection("Non-local resources:", new ArrayAdapter<String>(this, R.layout.list_item, new String[] { "Launch Photo slideshow link", "Dealer locator link" })); adapter.addSection("Send emails:", new ArrayAdapter<String>(this, R.layout.list_item, new String[] { "Send Dealer Locator email", "Send Catalog email","Send install instrucation link" })); //For extra Information in Listview //adapter.addSection("Non-local resources:", new SimpleAdapter(this, security, R.layout.list_complex, //new String[] { ITEM_TITLE, ITEM_CAPTION }, new int[] { R.id.list_complex_title, R.id.list_complex_caption })); list = getListView(); list.setAdapter(adapter); list.setTextFilterEnabled(true); list.setOnItemClickListener(this); } }

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  • Is Structuremap singleton thread safe?

    - by Ben
    Hi, Currently I have the following class: public class PluginManager { private static bool s_initialized; private static object s_lock = new object(); public static void Initialize() { if (!s_initialized) { lock (s_lock) { if (!s_initialized) { // initialize s_initialized = true; } } } } } The important thing here is that Initialize() should only be executed once whilst the application is running. I thought that I would refactor this into a singleton class since this would be more thread safe?: public sealed class PluginService { static PluginService() { } private static PluginService _instance = new PluginService(); public static PluginService Instance { get { return _instance; } } private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } Question one, is it still necessary to have the lock here (I have removed it) since we will only ever be working on the same instance? Finally, I want to use DI and structure map to initialize my servcices so I have refactored as below: public interface IPluginService { void Initialize(); } public class NewPluginService : IPluginService { private bool s_initialized; public void Initialize() { if (!s_initialized) { // initialize s_initialized = true; } } } And in my registry: ForRequestedType<IPluginService>() .TheDefaultIsConcreteType<NewPluginService>().AsSingletons(); This works as expected (singleton returning true in the following code): var instance1 = ObjectFactory.GetInstance<IPluginService>(); var instance2 = ObjectFactory.GetInstance<IPluginService>(); bool singleton = (instance1 == instance2); So my next question, is the structure map solution as thread safe as the singleton class (second example). The only downside is that this would still allow NewPluginService to be instantiated directly (if not using structure map). Many thanks, Ben

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  • Knight's tour / recursion

    - by Layne
    Hey, I'm trying to learn a little bit more about recursion but somehow I can't solve the knight's tour and I'm hoping someone can point out my logic error. public class main { static int fsize = 5; static int board[][] = new int[fsize][fsize]; static int[] sprung_x = {1,2,2,1,-1,-2,-2,-1}; static int[] sprung_y = {-2,-1,1,2,2,1,-1,-2}; static void SucheWeg(int schrittnummer, int x, int y) { board[x][y] = schrittnummer; if( schrittnummer == ((fsize*fsize)-1)) { for(int i = 0; i<fsize; i++) { for(int c=0; c<fsize; c++) { System.out.printf("%3d", board[i][c]); } System.out.println("\n"); } } else { for(int i = 0; i<8; i++) { for(int c = 0; c<8; c++) { if( (x+sprung_x[i]) >= 0 && (x+sprung_x[i]) < fsize && (y+sprung_y[c]) >= 0 && (y+sprung_y[c]) < fsize ) { if(board[x+sprung_x[i]][y+sprung_y[c]] == -1) { System.out.println("Move: "+schrittnummer + "\n"); SucheWeg(schrittnummer+1, (x+sprung_x[i]), (y+sprung_y[c])); } } } } board[x][y] = -1; } } public static void main(String[] args) { System.out.println("Begin: \n"); for(int i = 0; i<fsize; i++) { for(int c = 0; c<fsize; c++) { board[i][c] = -1; } } SucheWeg(0, 0, 0); System.out.println("\nEnd"); } }

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  • MVVM- How can I bind to a property, which is not a DependancyProperty?

    - by highone
    I have found this question http://stackoverflow.com/questions/2245928/mvvm-and-the-textboxs-selectedtext-property. However, I am having trouble getting the solution given to work. This is my non-working code: View: SelectedText and Text are just string properties from my ViewModel. <TextBox Text="{Binding Path=Text, UpdateSourceTrigger=PropertyChanged}" Height="155" HorizontalAlignment="Left" Margin="68,31,0,0" Name="textBox1" VerticalAlignment="Top" Width="264" AcceptsReturn="True" AcceptsTab="True" local:TextBoxHelper.SelectedText="{Binding SelectedText, UpdateSourceTrigger=PropertyChanged}" /> <TextBox Text="{Binding SelectedText, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" Height="154" HorizontalAlignment="Left" Margin="82,287,0,0" Name="textBox2" VerticalAlignment="Top" Width="239" /> TextBoxHelper public static class TextBoxHelper { #region "Selected Text" public static string GetSelectedText(DependencyObject obj) { return (string)obj.GetValue(SelectedTextProperty); } public static void SetSelectedText(DependencyObject obj, string value) { obj.SetValue(SelectedTextProperty, value); } // Using a DependencyProperty as the backing store for SelectedText. This enables animation, styling, binding, etc... public static readonly DependencyProperty SelectedTextProperty = DependencyProperty.RegisterAttached( "SelectedText", typeof(string), typeof(TextBoxHelper), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, SelectedTextChanged)); private static void SelectedTextChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) { TextBox tb = obj as TextBox; if (tb != null) { if (e.OldValue == null && e.NewValue != null) { tb.SelectionChanged += tb_SelectionChanged; } else if (e.OldValue != null && e.NewValue == null) { tb.SelectionChanged -= tb_SelectionChanged; } string newValue = e.NewValue as string; if (newValue != null && newValue != tb.SelectedText) { tb.SelectedText = newValue as string; } } } static void tb_SelectionChanged(object sender, RoutedEventArgs e) { TextBox tb = sender as TextBox; if (tb != null) { SetSelectedText(tb, tb.SelectedText); } } #endregion } What am I doing wrong?

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  • HSQLDB connection error

    - by user1478527
    I created a java program for connect the HSQLDB , the first one works well, public final static String DRIVER = "org.hsqldb.jdbcDriver"; public final static String URL = "jdbc:hsqldb:file:F:/hsqlTest/data/db"; public final static String DBNAME = "SA"; but these are not public final static String DRIVER = "org.hsqldb.jdbcDriver"; public final static String URL = "jdbc:hsqldb:file:C:/Program Files/tich Tools/mos tech/app/data/db/t1/t2/01/db"; public final static String DBNAME = "SA"; the error shows like this: java.sql.SQLException: error in script file line: 1 unexpected token: ? at org.hsqldb.jdbc.Util.sqlException(Unknown Source) at org.hsqldb.jdbc.Util.sqlException(Unknown Source) at org.hsqldb.jdbc.JDBCConnection.<init>(Unknown Source) at org.hsqldb.jdbc.JDBCDriver.getConnection(Unknown Source) at org.hsqldb.jdbc.JDBCDriver.connect(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at HSQLDBManagerImp.getconn(HSQLDBManagerImp.java:48) at TESTHSQLDB.main(TESTHSQLDB.java:15) Caused by: org.hsqldb.HsqlException: error in script file line: 1 unexpected token: ? at org.hsqldb.error.Error.error(Unknown Source) at org.hsqldb.scriptio.ScriptReaderText.readDDL(Unknown Source) at org.hsqldb.scriptio.ScriptReaderBase.readAll(Unknown Source) at org.hsqldb.persist.Log.processScript(Unknown Source) at org.hsqldb.persist.Log.open(Unknown Source) at org.hsqldb.persist.Logger.openPersistence(Unknown Source) at org.hsqldb.Database.reopen(Unknown Source) at org.hsqldb.Database.open(Unknown Source) at org.hsqldb.DatabaseManager.getDatabase(Unknown Source) at org.hsqldb.DatabaseManager.newSession(Unknown Source) ... 7 more Caused by: org.hsqldb.HsqlException: unexpected token: ? at org.hsqldb.error.Error.parseError(Unknown Source) at org.hsqldb.ParserBase.unexpectedToken(Unknown Source) at org.hsqldb.ParserCommand.compilePart(Unknown Source) at org.hsqldb.ParserCommand.compileStatement(Unknown Source) at org.hsqldb.Session.compileStatement(Unknown Source) ... 16 more I googled this connection question , but most of them not help much, someone says that may be the HSQLDB version problem. The dbase shut down in "SHUT COMPRESS" model. Anyone give some advice?

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  • Generic Singleton Façade design pattern

    - by Paul
    Hi I try write singleton façade pattern with generics. I have one problem, how can I call method from generic variable. Something like this: T1 t1 = new T1(); //call method from t1 t1.Method(); In method SingletonFasadeMethod I have compile error: Error 1 'T1' does not contain a definition for 'Method' and no extension method 'Method' accepting a first argument of type 'T1' could be found (are you missing a using directive or an assembly reference?) Any advace? Thank, I am beginner in C#. All code is here: namespace GenericSingletonFasade { public interface IMyInterface { string Method(); } internal class ClassA : IMyInterface { public string Method() { return " Calling MethodA "; } } internal class ClassB : IMyInterface { public string Method() { return " Calling MethodB "; } } internal class ClassC : IMyInterface { public string Method() { return "Calling MethodC"; } } internal class ClassD : IMyInterface { public string Method() { return "Calling MethodD"; } } public class SingletonFasade<T1,T2,T3> where T1 : class,new() where T2 : class,new() where T3 : class,new() { private static T1 t1; private static T2 t2; private static T3 t3; private SingletonFasade() { t1 = new T1(); t2 = new T2(); t3 = new T3(); } class SingletonCreator { static SingletonCreator() { } internal static readonly SingletonFasade<T1,T2,T3> uniqueInstace = new SingletonFasade<T1,T2,T3>(); } public static SingletonFasade<T1,T2,T3> UniqueInstace { get { return SingletonCreator.uniqueInstace; } } public string SingletonFasadeMethod() { //Problem is here return t1.Method() + t2.Method() + t3.Method(); } } } I use this for my problem. public class SingletonFasade<T1, T2, T3> where T1 : class, IMyInterface, new() where T2 : class, IMyInterface, new() where T3 : class, IMyInterface, new() {//...} Is any solution without Interfaces ??

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  • How do I get a window caption?

    - by P.Brian.Mackey
    I would like to get a Window Caption as given by spy++ (highlighted in red) I have code to do this (or so I thought)...but it seems to work pretty awful....in some cases 1% of the time... public delegate bool EnumDelegate(IntPtr hWnd, int lParam); [DllImport("user32.dll")] [return: MarshalAs(UnmanagedType.Bool)] static extern bool IsWindowVisible(IntPtr hWnd); [DllImport("user32.dll", EntryPoint = "GetWindowText", ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)] static extern int GetWindowText(IntPtr hWnd, StringBuilder lpWindowText, int nMaxCount); [DllImport("user32.dll", EntryPoint = "EnumDesktopWindows", ExactSpelling = false, CharSet = CharSet.Auto, SetLastError = true)] static extern bool EnumDesktopWindows(IntPtr hDesktop, EnumDelegate lpEnumCallbackFunction, IntPtr lParam); static List<NativeWindow> collection = new List<NativeWindow>(); public static NativeWindow GetAppNativeMainWindow() { GetNativeWindowHelper.EnumDelegate filter = delegate(IntPtr hWnd, int lParam) { StringBuilder strbTitle = new StringBuilder(255); int nLength = GetNativeWindowHelper.GetWindowText(hWnd, strbTitle, strbTitle.Capacity + 1); string strTitle = strbTitle.ToString(); if (!string.IsNullOrEmpty(strTitle)) { if (strTitle.ToLower().StartsWith("window title | my application")) { NativeWindow window = new NativeWindow(); window.AssignHandle(hWnd); collection.Add(window); return false;//stop enumerating } } return true;//continue enumerating }; GetNativeWindowHelper.EnumDesktopWindows(IntPtr.Zero, filter, IntPtr.Zero); if (collection.Count != 1) { //log error ReleaseWindow(); return null; } else return collection[0]; } public static void ReleaseWindow() { foreach (var item in collection) { item.ReleaseHandle(); } }

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  • Thread safe lazy contruction of a singleton in C++

    - by pauldoo
    Is there a way to implement a singleton object in C++ that is: Lazily constructed in a thread safe manner (two threads might simultaneously be the first user of the singleton - it should still only be constructed once). Doesn't rely on static variables being constructed beforehand (so the singleton object is itself safe to use during the construction of static variables). (I don't know my C++ well enough, but is it the case that integral and constant static variables are initialized before any code is executed (ie, even before static constructors are executed - their values may already be "initialized" in the program image)? If so - perhaps this can be exploited to implement a singleton mutex - which can in turn be used to guard the creation of the real singleton..) Excellent, it seems that I have a couple of good answers now (shame I can't mark 2 or 3 as being the answer). There appears to be two broad solutions: Use static initialisation (as opposed to dynamic initialisation) of a POD static varible, and implementing my own mutex with that using the builtin atomic instructions. This was the type of solution I was hinting at in my question, and I believe I knew already. Use some other library function like pthread_once or boost::call_once. These I certainly didn't know about - and am very grateful for the answers posted.

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  • using the ASP.NET Caching API via method annotations in C#

    - by craigmoliver
    In C#, is it possible to decorate a method with an annotation to populate the cache object with the return value of the method? Currently I'm using the following class to cache data objects: public class SiteCache { // 7 days + 6 hours (offset to avoid repeats peak time) private const int KeepForHours = 174; public static void Set(string cacheKey, Object o) { if (o != null) HttpContext.Current.Cache.Insert(cacheKey, o, null, DateTime.Now.AddHours(KeepForHours), TimeSpan.Zero); } public static object Get(string cacheKey) { return HttpContext.Current.Cache[cacheKey]; } public static void Clear(string sKey) { HttpContext.Current.Cache.Remove(sKey); } public static void Clear() { foreach (DictionaryEntry item in HttpContext.Current.Cache) { Clear(item.Key.ToString()); } } } In methods I want to cache I do this: [DataObjectMethod(DataObjectMethodType.Select)] public static SiteSettingsInfo SiteSettings_SelectOne_Name(string Name) { var ck = string.Format("SiteSettings_SelectOne_Name-Name_{0}-", Name.ToLower()); var dt = (DataTable)SiteCache.Get(ck); if (dt == null) { dt = new DataTable(); dt.Load(ModelProvider.SiteSettings_SelectOne_Name(Name)); SiteCache.Set(ck, dt); } var info = new SiteSettingsInfo(); foreach (DataRowView dr in dt.DefaultView) info = SiteSettingsInfo_Load(dr); return info; } Is it possible to separate those concerns like so: (notice the new annotation) [CacheReturnValue] [DataObjectMethod(DataObjectMethodType.Select)] public static SiteSettingsInfo SiteSettings_SelectOne_Name(string Name) { var dt = new DataTable(); dt.Load(ModelProvider.SiteSettings_SelectOne_Name(Name)); var info = new SiteSettingsInfo(); foreach (DataRowView dr in dt.DefaultView) info = SiteSettingsInfo_Load(dr); return info; }

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  • DeSerialization doesn't work though i Implement GetObjectData method and Constructor

    - by Punit Singhi
    Hi, I have a static generic dictionary in a class. As static memeber cannot serialized so i have implented ISerializable interface and method GetObjectData to serialize. I have a constructor which will also accept SerializationInfo and StreamingContext to deserliaze the dictionay. Now when i try to serialize and deserialize , it always return 1(thoug i added 2 entries). please find the pseduo code- [Serializable] public class MyClass : ISerializable { internal static Dictionary<long, string> dict = new Dictionary<long,string>(); public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("static.dic", MyClass1.dict, typeof(Dictionary<long, string>)); } public MyClass(SerializationInfo info, StreamingContext context) { MyClass.dict= (Dictionary<long, string>)info.GetValue("static.dic", typeof(Dictionary<long, string>)); } public void Add() { dict.Add(21, "11"); } public MyClass() { dict.Add(21, "11"); } } public class MyClass { MyClass myClass = new MyClass(); public static void Main() { myClass.Add(); FileStream fileStream = new FileStream("test.binary", FileMode.Create); IFormatter bf = new BinaryFormatter(); bf.Serialize(fileStream, myClass); fileStream.Dispose(); fileStream.Close(); fileStream = new FileStream("test.binary", FileMode.Open); bf = new BinaryFormatter(); myClass = (MyClass1)bf.Deserialize(fileStream); } }

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  • User entered value validation and level of error catching

    - by Terry
    May I ask should the error catching code be placed at the lowest level or at the top as I am not sure what is the best practice? I prefer placing at the bottom, example a, as Example a public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { if (month < 1 || month > 12) { throw new Exception(""); } } public static void DoDate(int date) { if (date < 1 || date > 31) { throw new Exception(""); } } or example b public static void Main(string[] args) { string operation = args[0]; int value = Convert.ToInt32(args[1]); if (operation == "date" && (date < 1 || date > 12)) { throw new Exception(""); } else if (operation == "month" && (month < 1 || month > 31)) { throw new Exception(""); } if (operation == "date") { DoDate(value); } else if (operation == "month") { DoMonth(value); } } public static void DoMonth(int month) { } public static void DoDate(int date) { }

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  • Closing a hook that captures global input events

    - by Margus
    Intro Here is an example to illustrate the problem. Consider I am tracking and displaying mouse global current position and last click button and position to the user. Here is an image: To archive capturing click events on windows box, that would and will be sent to the other programs event messaging queue, I create a hook using winapi namely user32.dll library. This is outside JDK sandbox, so I use JNA to call the native library. This all works perfectly, but it does not close as I expect it to. My question is - How do I properly close following example program? Example source Code below is not fully written by Me, but taken from this question in Oracle forum and partly fixed. import java.awt.AWTException; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.GridLayout; import java.awt.MouseInfo; import java.awt.Point; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.JFrame; import javax.swing.JLabel; import com.sun.jna.Native; import com.sun.jna.NativeLong; import com.sun.jna.Platform; import com.sun.jna.Structure; import com.sun.jna.platform.win32.BaseTSD.ULONG_PTR; import com.sun.jna.platform.win32.Kernel32; import com.sun.jna.platform.win32.User32; import com.sun.jna.platform.win32.WinDef.HWND; import com.sun.jna.platform.win32.WinDef.LRESULT; import com.sun.jna.platform.win32.WinDef.WPARAM; import com.sun.jna.platform.win32.WinUser.HHOOK; import com.sun.jna.platform.win32.WinUser.HOOKPROC; import com.sun.jna.platform.win32.WinUser.MSG; import com.sun.jna.platform.win32.WinUser.POINT; public class MouseExample { final JFrame jf; final JLabel jl1, jl2; final CWMouseHook mh; final Ticker jt; public class Ticker extends Thread { public boolean update = true; public void done() { update = false; } public void run() { try { Point p, l = MouseInfo.getPointerInfo().getLocation(); int i = 0; while (update == true) { try { p = MouseInfo.getPointerInfo().getLocation(); if (!p.equals(l)) { l = p; jl1.setText(new GlobalMouseClick(p.x, p.y) .toString()); } Thread.sleep(35); } catch (InterruptedException e) { e.printStackTrace(); return; } } } catch (Exception e) { update = false; } } } public MouseExample() throws AWTException, UnsupportedOperationException { this.jl1 = new JLabel("{}"); this.jl2 = new JLabel("{}"); this.jf = new JFrame(); this.jt = new Ticker(); this.jt.start(); this.mh = new CWMouseHook() { @Override public void globalClickEvent(GlobalMouseClick m) { jl2.setText(m.toString()); } }; mh.setMouseHook(); jf.setLayout(new GridLayout(2, 2)); jf.add(new JLabel("Position")); jf.add(jl1); jf.add(new JLabel("Last click")); jf.add(jl2); jf.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent we) { mh.dispose(); jt.done(); jf.dispose(); } }); jf.setLocation(new Point(0, 0)); jf.setPreferredSize(new Dimension(200, 90)); jf.pack(); jf.setVisible(true); } public static class GlobalMouseClick { private char c; private int x, y; public GlobalMouseClick(char c, int x, int y) { super(); this.c = c; this.x = x; this.y = y; } public GlobalMouseClick(int x, int y) { super(); this.x = x; this.y = y; } public char getC() { return c; } public void setC(char c) { this.c = c; } public int getX() { return x; } public void setX(int x) { this.x = x; } public int getY() { return y; } public void setY(int y) { this.y = y; } @Override public String toString() { return (c != 0 ? c : "") + " [" + x + "," + y + "]"; } } public static class CWMouseHook { public User32 USER32INST; public CWMouseHook() throws UnsupportedOperationException { if (!Platform.isWindows()) { throw new UnsupportedOperationException( "Not supported on this platform."); } USER32INST = User32.INSTANCE; mouseHook = hookTheMouse(); Native.setProtected(true); } private static LowLevelMouseProc mouseHook; private HHOOK hhk; private boolean isHooked = false; public static final int WM_LBUTTONDOWN = 513; public static final int WM_LBUTTONUP = 514; public static final int WM_RBUTTONDOWN = 516; public static final int WM_RBUTTONUP = 517; public static final int WM_MBUTTONDOWN = 519; public static final int WM_MBUTTONUP = 520; public void dispose() { unsetMouseHook(); mousehook_thread = null; mouseHook = null; hhk = null; USER32INST = null; } public void unsetMouseHook() { isHooked = false; USER32INST.UnhookWindowsHookEx(hhk); System.out.println("Mouse hook is unset."); } public boolean isIsHooked() { return isHooked; } public void globalClickEvent(GlobalMouseClick m) { System.out.println(m); } private Thread mousehook_thread; public void setMouseHook() { mousehook_thread = new Thread(new Runnable() { @Override public void run() { try { if (!isHooked) { hhk = USER32INST.SetWindowsHookEx(14, mouseHook, Kernel32.INSTANCE.GetModuleHandle(null), 0); isHooked = true; System.out .println("Mouse hook is set. Click anywhere."); // message dispatch loop (message pump) MSG msg = new MSG(); while ((USER32INST.GetMessage(msg, null, 0, 0)) != 0) { USER32INST.TranslateMessage(msg); USER32INST.DispatchMessage(msg); if (!isHooked) break; } } else System.out .println("The Hook is already installed."); } catch (Exception e) { System.err.println("Caught exception in MouseHook!"); } } }); mousehook_thread.start(); } private interface LowLevelMouseProc extends HOOKPROC { LRESULT callback(int nCode, WPARAM wParam, MOUSEHOOKSTRUCT lParam); } private LowLevelMouseProc hookTheMouse() { return new LowLevelMouseProc() { @Override public LRESULT callback(int nCode, WPARAM wParam, MOUSEHOOKSTRUCT info) { if (nCode >= 0) { switch (wParam.intValue()) { case CWMouseHook.WM_LBUTTONDOWN: globalClickEvent(new GlobalMouseClick('L', info.pt.x, info.pt.y)); break; case CWMouseHook.WM_RBUTTONDOWN: globalClickEvent(new GlobalMouseClick('R', info.pt.x, info.pt.y)); break; case CWMouseHook.WM_MBUTTONDOWN: globalClickEvent(new GlobalMouseClick('M', info.pt.x, info.pt.y)); break; default: break; } } return USER32INST.CallNextHookEx(hhk, nCode, wParam, info.getPointer()); } }; } public class Point extends Structure { public class ByReference extends Point implements Structure.ByReference { }; public NativeLong x; public NativeLong y; } public static class MOUSEHOOKSTRUCT extends Structure { public static class ByReference extends MOUSEHOOKSTRUCT implements Structure.ByReference { }; public POINT pt; public HWND hwnd; public int wHitTestCode; public ULONG_PTR dwExtraInfo; } } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { new MouseExample(); } catch (AWTException e) { e.printStackTrace(); } } }); } }

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  • How to make a thread that runs at x:00 x:15 x:30 and x:45 do something different at 2:00.

    - by rmarimon
    I have a timer thread that needs to run at a particular moments of the day to do an incremental replication with a database. Right now it runs at the hour, 15 minutes past the hour, 30 minutes past the hour and 45 minutes past the hour. This is the code I have which is working ok: public class TimerRunner implements Runnable { private static final Semaphore lock = new Semaphore(1); private static final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor(); public static void initialize() { long delay = getDelay(); executor.schedule(new TimerRunner(), delay, TimeUnit.SECONDS); } public static void destroy() { executor.shutdownNow(); } private static long getDelay() { Calendar now = Calendar.getInstance(); long p = 15 * 60; // run at 00, 15, 30 and 45 minutes past the hour long second = now.get(Calendar.MINUTE) * 60 + now.get(Calendar.SECOND); return p - (second % p); } public static void replicate() { if (lock.tryAcquire()) { try { Thread t = new Thread(new Runnable() { public void run() { try { // here is where the magic happens } finally { lock.release(); } } }); t.start(); } catch (Exception e) { lock.release(); } } else { throw new IllegalStateException("already running a replicator"); } } public void run() { try { TimerRunner.replicate(); } finally { long delay = getDelay(); executor.schedule(new TimerRunner(), delay, TimeUnit.SECONDS); } } } This process is started by calling TimerRunner.initialize() when a server starts and calling TimerRunner.destroy(). I have created a full replication process (as opposed to incremental) that I would like to run at a certain moment of the day, say 2:00am. How would change the above code to do this? I think that it should be very simple something like if it is now around 2:00am and it's been a long time since I did the full replication then do it now, but I can't get the if right. Beware that sometimes the replicate process takes way longer to complete. Sometimes beyond the 15 minutes, posing a problem in running at around 2:00am.

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  • About AMR audio file playing issue on different devices

    - by user352537
    I have got a quite strange problem here. I am developing an IM software and need to play audio files recorded by another client on Android. The same audio file I've got can be played with AVAudioPlayer on 3GS(IOS 4.2.1) device and simulator 4.2. But when I tried by play it on iPhone4(iOS 4.3.3), the function "play" always return NO. I also tried with two iPhone devices, the audio files recorded by iPhone client can be played on both 3GS and iPhone4. So I asked the Android developers about the record parameters they've used. They said that the "AudioEncoder" used by them was "DEFAULT". There are also some other parameters as following: **private AudioEncoder() {} public static final int DEFAULT = 0; /** AMR (Narrowband) audio codec */ public static final int AMR_NB = 1; /** @hide AMR (Wideband) audio codec */ public static final int AMR_WB = 2; /** @hide AAC audio codec */ public static final int AAC = 3; /** @hide enhanced AAC audio codec */ public static final int AAC_PLUS = 4; /** @hide enhanced AAC plus audio codec */ public static final int EAAC_PLUS = 5;** Does anybody know what's the matter?

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  • org.apache.http.conn.HttpHostConnectException:Connection to http://172.20.38.143 refused

    - by Passion
    I have developed client server Application .I am accessing mysql with php running on my machine and client running on my cell which is connected to machine.WI-FI is also switched ON. Internet Permission are also added in Manifest file but then also the i encounter error 172.20.38.143 is IP OF MY MACHINE 06-01 13:20:10.391: W/System.err(11157): org.apache.http.conn.HttpHostConnectException: Connection to http://172.20.38.143 refused 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:183) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:674) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:511) 06-01 13:20:10.401: W/System.err(11157): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:489) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.library.JSONParser.getJSONFromUrl(JSONParser.java:42) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.library.UserFunctions.registerUser(UserFunctions.java:59) 06-01 13:20:10.401: W/System.err(11157): at nineandroid.net.example.RegisterActivity$1.onClick(RegisterActivity.java:52) 06-01 13:20:10.411: W/System.err(11157): at android.view.View.performClick(View.java:3567) 06-01 13:20:10.411: W/System.err(11157): at android.view.View$PerformClick.run(View.java:14224) 06-01 13:20:10.411: W/System.err(11157): at android.os.Handler.handleCallback(Handler.java:605) 06-01 13:20:10.411: W/System.err(11157): at android.os.Handler.dispatchMessage(Handler.java:92) 06-01 13:20:10.411: W/System.err(11157): at android.os.Looper.loop(Looper.java:137) 06-01 13:20:10.411: W/System.err(11157): at android.app.ActivityThread.main(ActivityThread.java:4517) 06-01 13:20:10.411: W/System.err(11157): at java.lang.reflect.Method.invokeNative(Native Method) 06-01 13:20:10.411: W/System.err(11157): at java.lang.reflect.Method.invoke(Method.java:511) 06-01 13:20:10.411: W/System.err(11157): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993) 06-01 13:20:10.421: W/System.err(11157): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760) 06-01 13:20:10.421: W/System.err(11157): at dalvik.system.NativeStart.main(Native Method) 06-01 13:20:10.421: W/System.err(11157): Caused by: java.net.ConnectException: failed to connect to /172.20.38.143 (port 80): connect failed: ENETUNREACH (Network is unreachable) 06-01 13:20:10.431: W/System.err(11157): at libcore.io.IoBridge.connect(IoBridge.java:114) 06-01 13:20:10.431: W/System.err(11157): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 06-01 13:20:10.431: W/System.err(11157): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 06-01 13:20:10.431: W/System.err(11157): at java.net.Socket.connect(Socket.java:848) 06-01 13:20:10.431: W/System.err(11157): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 06-01 13:20:10.431: W/System.err(11157): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 06-01 13:20:10.431: W/System.err(11157): ... 20 more 06-01 13:20:10.431: W/System.err(11157): Caused by: libcore.io.ErrnoException: connect failed: ENETUNREACH (Network is unreachable) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.Posix.connect(Native Method) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:85) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 06-01 13:20:10.441: W/System.err(11157): at libcore.io.IoBridge.connect(IoBridge.java:112) 06-01 13:20:10.441: W/System.err(11157): ... 25 more 06-01 13:20:10.441: E/Buffer Error(11157): Error converting result java.lang.NullPointerException 06-01 13:20:10.451: E/JSON Parser(11157): Error parsing data org.json.JSONException: End of input at character 0 of 06-01 13:20:10.451: D/AndroidRuntime(11157): Shutting down VM 06-01 13:20:10.451: W/dalvikvm(11157): threadid=1: thread exiting with uncaught exception (group=0x40c0aa68) 06-01 13:20:10.451: E/AndroidRuntime(11157): FATAL EXCEPTION: main 06-01 13:20:10.451: E/AndroidRuntime(11157): java.lang.NullPointerException 06-01 13:20:10.451: E/AndroidRuntime(11157): at nineandroid.net.example.RegisterActivity$1.onClick(RegisterActivity.java:56) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.view.View.performClick(View.java:3567) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.view.View$PerformClick.run(View.java:14224) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Handler.handleCallback(Handler.java:605) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Handler.dispatchMessage(Handler.java:92) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.os.Looper.loop(Looper.java:137) 06-01 13:20:10.451: E/AndroidRuntime(11157): at android.app.ActivityThread.main(ActivityThread.java:4517) 06-01 13:20:10.451: E/AndroidRuntime(11157): at java.lang.reflect.Method.invokeNative(Native Method) 06-01 13:20:10.451: E/AndroidRuntime(11157): at java.lang.reflect.Method.invoke(Method.java:511) 06-01 13:20:10.451: E/AndroidRuntime(11157): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993) 06-01 13:20:10.451: E/AndroidRuntime(11157): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760) 06-01 13:20:10.451: E/AndroidRuntime(11157): at dalvik.system.NativeStart.main(Native Method) UserFunctions.java to call jsonParser public class UserFunctions { private JSONParser jsonParser; private static String loginURL = "http://172.20.38.143/ah_login_api/"; private static String registerURL = "http://172.20.38.143/ah_login_api/"; private static String login_tag = "login"; private static String register_tag = "register"; // constructor public UserFunctions(){ jsonParser = new JSONParser(); } /** * function make Login Request * @param email * @param password * */ public JSONObject loginUser(String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", login_tag)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); JSONObject json = jsonParser.getJSONFromUrl(loginURL, params); // return json // Log.e("JSON", json.toString()); return json; } /** * function make Login Request * @param name * @param email * @param password * */ public JSONObject registerUser(String name, String email, String password){ // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", register_tag)); params.add(new BasicNameValuePair("name", name)); params.add(new BasicNameValuePair("email", email)); params.add(new BasicNameValuePair("password", password)); // getting JSON Object JSONObject json = jsonParser.getJSONFromUrl(registerURL, params); // return json return json; } /** * Function get Login status * */ public boolean isUserLoggedIn(Context context){ DatabaseHandler db = new DatabaseHandler(context); int count = db.getRowCount(); if(count > 0){ // user logged in return true; } return false; } /** * Function to logout user * Reset Database * */ public boolean logoutUser(Context context){ DatabaseHandler db = new DatabaseHandler(context); db.resetTables(); return true; } } jsonParser.java public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(String url, List<NameValuePair> params) { // Making HTTP request try { // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); Log.e("JSON", json); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } RegisterActivity.java public class RegisterActivity extends Activity { Button btnRegister; Button btnLinkToLogin; EditText inputFullName; EditText inputEmail; EditText inputPassword; TextView registerErrorMsg; // JSON Response node names private static String KEY_SUCCESS = "success"; private static String KEY_UID = "uid"; private static String KEY_NAME = "name"; private static String KEY_EMAIL = "email"; private static String KEY_CREATED_AT = "created_at"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.register); // Importing all assets like buttons, text fields inputFullName = (EditText) findViewById(R.id.registerName); inputEmail = (EditText) findViewById(R.id.registerEmail); inputPassword = (EditText) findViewById(R.id.registerPassword); btnRegister = (Button) findViewById(R.id.btnRegister); btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen); registerErrorMsg = (TextView) findViewById(R.id.register_error); // Register Button Click event btnRegister.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { String name = inputFullName.getText().toString(); String email = inputEmail.getText().toString(); String password = inputPassword.getText().toString(); UserFunctions userFunction = new UserFunctions(); JSONObject json = userFunction.registerUser(name, email, password); // check for login response try { if (json.getString(KEY_SUCCESS) != null) { registerErrorMsg.setText(""); String res = json.getString(KEY_SUCCESS); if(Integer.parseInt(res) == 1){ // user successfully registred // Store user details in SQLite Database DatabaseHandler db = new DatabaseHandler(getApplicationContext()); JSONObject json_user = json.getJSONObject("user"); // Clear all previous data in database userFunction.logoutUser(getApplicationContext()); db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT)); // Launch Dashboard Screen Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class); // Close all views before launching Dashboard dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(dashboard); // Close Registration Screen finish(); }else{ // Error in registration registerErrorMsg.setText("Error occured in registration"); } } } catch (JSONException e) { e.printStackTrace(); } } }); // Link to Login Screen btnLinkToLogin.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { Intent i = new Intent(getApplicationContext(), LoginActivity.class); startActivity(i); // Close Registration View finish(); } }); } }

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  • .NET multithreading, volatile and memory model

    - by fedor-serdukov
    Assume that we have the following code: class Program { static volatile bool flag1; static volatile bool flag2; static volatile int val; static void Main(string[] args) { for (int i = 0; i < 10000 * 10000; i++) { if (i % 500000 == 0) { Console.WriteLine("{0:#,0}",i); } flag1 = false; flag2 = false; val = 0; Parallel.Invoke(A1, A2); if (val == 0) throw new Exception(string.Format("{0:#,0}: {1}, {2}", i, flag1, flag2)); } } static void A1() { flag2 = true; if (flag1) val = 1; } static void A2() { flag1 = true; if (flag2) val = 2; } } } It's fault! The main quastion is Why... I suppose that CPU reorder operations with flag1 = true; and if(flag2) statement, but variables flag1 and flag2 marked as volatile fields...

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  • How can I make a family of singletons?

    - by Jay
    I want to create a set of classes that share a lot of common behavior. Of course in OOP when you think that you automatically think "abstract class with subclasses". But among the things I want these classes to do is to each have a static list of instances of the class. The list should function as sort of a singleton within the class. I mean each of the sub-classes has a singleton, not that they share one. "Singleton" to that subclass, not a true singleton. But if it's a static, how can I inherit it? Of course code like this won't work: public abstract A { static List<A> myList; public static List getList() { if (myList==null) myList=new ArrayList<A>(10); return myList; } public static A getSomethingFromList() { List listInstance=getList(); ... do stuff with list ... } public int getSomethingFromA() { ... regular code acting against current instance ... } } public class A1 extends A { ... } public class A2 extends A { ... } A1 somethingfromA1List=(A1) A1.getSomethingFromList(); A2 somethingfromA2List=(A2) A2.getSomethingFromList(); The contents of the list for each subclass would be different, but all the code to work on the lists would be the same. The problem with the above code is that I'd only have one list for all the subclasses, and I want one for each. Yes, I could replicate the code to declare the static list in each of the subclasses, but then I'd also have to replicate all the code that adds to the lists and searches the list, etc, which rather defeats the purpose of subclassing. Any ideas on how to do this without replicating code?

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