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  • Is there a pattern for initializing objects created wth a DI container

    - by Igor Zevaka
    I am trying to get Unity to manage the creation of my objects and I want to have some initialization parameters that are not known until run-time: At the moment the only way I could think of the way to do it is to have an Init method on the interface. interface IMyIntf { void Initialize(string runTimeParam); string RunTimeParam { get; } } Then to use it (in Unity) I would do this: var IMyIntf = unityContainer.Resolve<IMyIntf>(); IMyIntf.Initialize("somevalue"); In this scenario runTimeParam param is determined at run-time based on user input. The trivial case here simply returns the value of runTimeParam but in reality the parameter will be something like file name and initialize method will do something with the file. This creates a number of issues, namely that the Initialize method is available on the interface and can be called multiple times. Setting a flag in the implementation and throwing exception on repeated call to Initialize seems way clunky. At the point where I resolve my interface I don't want to know anything about the implementation of IMyIntf. What I do want, though, is the knowledge that this interface needs certain one time initialization parameters. Is there a way to somehow annotate(attributes?) the interface with this information and pass those to framework when the object is created? Edit: Described the interface a bit more.

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  • Why I get this error in CXF

    - by Milan
    I want to make dynamic web service invoker in JSF with CXF. But when I load this simple code I get error. The code: JaxWsDynamicClientFactory dcf = JaxWsDynamicClientFactory.newInstance(); Client client = dcf.createClient("http://ws.strikeiron.com/IPLookup2?wsdl"); The error: No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions! If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml. A typical config looks like this; org.apache.myfaces.webapp.StartupServletContextListener Caused by: java.lang.IllegalStateException - No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions! If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml. A typical config looks like this; org.apache.myfaces.webapp.StartupServletContextListener Any Idea how to solve the problem?

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  • A trivial Python SWIG error question

    - by Alex
    I am trying to get Python running with swig to do C/C++. I am running the tutorial here, 'building a python module'. When I do the call gcc -c example.c example_wrap.c -I /my_correct_path/python2.5 I get an error: my_correct_path/python2.5/pyport.h:761:2: error: #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)." example_wrap.c: In function 'SWIG_Python_ConvertFunctionPtr': example_wrap.c:2034: warning: initialization discards qualifiers from pointer target type example_wrap.c: In function 'SWIG_Python_FixMethods': example_wrap.c:3232: warning: initialization discards qualifiers from pointer target type It actually does create an example.o file, but it doesn't work. I am using python2.5 not 2.1 as in the example, is this a problem? The error (everything else is just a 'warning') says something about wrong platform. This is a 64bit machine; is this a problem? Is my gcc configured wrong for my machine? How do I get past this? UPDATE: I am still having problems. How do I actually implement this "fix"?

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  • Converting "A* Search" code from C++ to Java [on hold]

    - by mr5
    Updated! I get this code from this site It's A* Search Algorithm(finding shortest path with heuristics) I modify most of variable names and some if conditions from the original version to satisfy my syntactic taste. It works in C++ (as I can't see any trouble with it) but fails in Java version. Java Code: String findPath(int startX, int startY, int finishX, int finishY) { @SuppressWarnings("unchecked") LinkedList<Node>[] nodeList = (LinkedList<Node>[]) new LinkedList<?>[2]; nodeList[0] = new LinkedList<Node>(); nodeList[1] = new LinkedList<Node>(); Node n0; Node m0; int nlIndex = 0; // queueList index // reset the node maps for(int y = 0;y < ROW_COUNT; ++y) { for(int x = 0;x < COL_COUNT; ++x) { close_nodes_map[y][x] = 0; open_nodes_map[y][x] = 0; } } // create the start node and push into list of open nodes n0 = new Node( startX, startY, 0, 0 ); n0.updatePriority( finishX, finishY ); nodeList[nlIndex].push( n0 ); open_nodes_map[startY][startX] = n0.getPriority(); // mark it on the open nodes map // A* search while( !nodeList[nlIndex].isEmpty() ) { LinkedList<Node> pq = nodeList[nlIndex]; // get the current node w/ the highest priority // from the list of open nodes n0 = new Node( pq.peek().getX(), pq.peek().getY(), pq.peek().getIterCount(), pq.peek().getPriority()); int x = n0.getX(); int y = n0.getY(); nodeList[nlIndex].pop(); // remove the node from the open list open_nodes_map[y][x] = 0; // mark it on the closed nodes map close_nodes_map[y][x] = 1; // quit searching when the goal state is reached //if((*n0).estimate(finishX, finishY) == 0) if( x == finishX && y == finishY ) { // generate the path from finish to start // by following the directions String path = ""; while( !( x == startX && y == startY) ) { int j = dir_map[y][x]; int c = '0' + ( j + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; path = (char)c + path; x += DIR_X[j]; y += DIR_Y[j]; } return path; } // generate moves (child nodes) in all possible directions for(int i = 0; i < Node.DIRECTION_COUNT; ++i) { int xdx = x + DIR_X[i]; int ydy = y + DIR_Y[i]; // boundary check if (!(xdx >= 0 && xdx < COL_COUNT && ydy >= 0 && ydy < ROW_COUNT)) continue; if ( ( gridMap.getData( ydy, xdx ) == GridMap.WALKABLE || gridMap.getData( ydy, xdx ) == GridMap.FINISH) && close_nodes_map[ydy][xdx] != 1 ) { // generate a child node m0 = new Node( xdx, ydy, n0.getIterCount(), n0.getPriority() ); m0.nextLevel( i ); m0.updatePriority( finishX, finishY ); // if it is not in the open list then add into that if( open_nodes_map[ydy][xdx] == 0 ) { open_nodes_map[ydy][xdx] = m0.getPriority(); nodeList[nlIndex].push( m0 ); // mark its parent node direction dir_map[ydy][xdx] = ( i + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; } else if( open_nodes_map[ydy][xdx] > m0.getPriority() ) { // update the priority info open_nodes_map[ydy][xdx] = m0.getPriority(); // update the parent direction info dir_map[ydy][xdx] = ( i + Node.DIRECTION_COUNT / 2 ) % Node.DIRECTION_COUNT; // replace the node // by emptying one queueList to the other one // except the node to be replaced will be ignored // and the new node will be pushed in instead while( !(nodeList[nlIndex].peek().getX() == xdx && nodeList[nlIndex].peek().getY() == ydy ) ) { nodeList[1 - nlIndex].push( nodeList[nlIndex].pop() ); } nodeList[nlIndex].pop(); // remove the wanted node // empty the larger size queueList to the smaller one if( nodeList[nlIndex].size() > nodeList[ 1 - nlIndex ].size() ) nlIndex = 1 - nlIndex; while( !nodeList[nlIndex].isEmpty() ) { nodeList[1 - nlIndex].push( nodeList[nlIndex].pop() ); } nlIndex = 1 - nlIndex; nodeList[nlIndex].push( m0 ); // add the better node instead } } } } return ""; // no route found } Output1: Legends . = PATH ? = START X = FINISH 3,2,1 = OBSTACLES (Misleading path) Output2: Changing these lines: n0 = new Node( a, b, c, d ); m0 = new Node( e, f, g, h ); to n0.set( a, b, c, d ); m0.set( e, f, g, h ); I get (I'm really confused) C++ Code: std::string A_Star::findPath(int startX, int startY, int finishX, int finishY) { typedef std::queue<Node> List_Container; List_Container nodeList[2]; // list of open (not-yet-tried) nodes Node n0; Node m0; int pqIndex = 0; // nodeList index // reset the node maps for(int y = 0;y < ROW_COUNT; ++y) { for(int x = 0;x < COL_COUNT; ++x) { close_nodes_map[y][x] = 0; open_nodes_map[y][x] = 0; } } // create the start node and push into list of open nodes n0 = Node( startX, startY, 0, 0 ); n0.updatePriority( finishX, finishY ); nodeList[pqIndex].push( n0 ); open_nodes_map[startY][startX] = n0.getPriority(); // mark it on the open nodes map // A* search while( !nodeList[pqIndex].empty() ) { List_Container &pq = nodeList[pqIndex]; // get the current node w/ the highest priority // from the list of open nodes n0 = Node( pq.front().getX(), pq.front().getY(), pq.front().getIterCount(), pq.front().getPriority()); int x = n0.getX(); int y = n0.getY(); nodeList[pqIndex].pop(); // remove the node from the open list open_nodes_map[y][x] = 0; // mark it on the closed nodes map close_nodes_map[y][x] = 1; // quit searching when the goal state is reached //if((*n0).estimate(finishX, finishY) == 0) if( x == finishX && y == finishY ) { // generate the path from finish to start // by following the directions std::string path = ""; while( !( x == startX && y == startY) ) { int j = dir_map[y][x]; char c = '0' + ( j + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; path = c + path; x += DIR_X[j]; y += DIR_Y[j]; } return path; } // generate moves (child nodes) in all possible directions for(int i = 0; i < DIRECTION_COUNT; ++i) { int xdx = x + DIR_X[i]; int ydy = y + DIR_Y[i]; // boundary check if (!( xdx >= 0 && xdx < COL_COUNT && ydy >= 0 && ydy < ROW_COUNT)) continue; if ( ( pGrid->getData(ydy,xdx) == WALKABLE || pGrid->getData(ydy, xdx) == FINISH) && close_nodes_map[ydy][xdx] != 1 ) { // generate a child node m0 = Node( xdx, ydy, n0.getIterCount(), n0.getPriority() ); m0.nextLevel( i ); m0.updatePriority( finishX, finishY ); // if it is not in the open list then add into that if( open_nodes_map[ydy][xdx] == 0 ) { open_nodes_map[ydy][xdx] = m0.getPriority(); nodeList[pqIndex].push( m0 ); // mark its parent node direction dir_map[ydy][xdx] = ( i + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; } else if( open_nodes_map[ydy][xdx] > m0.getPriority() ) { // update the priority info open_nodes_map[ydy][xdx] = m0.getPriority(); // update the parent direction info dir_map[ydy][xdx] = ( i + DIRECTION_COUNT / 2 ) % DIRECTION_COUNT; // replace the node // by emptying one nodeList to the other one // except the node to be replaced will be ignored // and the new node will be pushed in instead while ( !( nodeList[pqIndex].front().getX() == xdx && nodeList[pqIndex].front().getY() == ydy ) ) { nodeList[1 - pqIndex].push( nodeList[pqIndex].front() ); nodeList[pqIndex].pop(); } nodeList[pqIndex].pop(); // remove the wanted node // empty the larger size nodeList to the smaller one if( nodeList[pqIndex].size() > nodeList[ 1 - pqIndex ].size() ) pqIndex = 1 - pqIndex; while( !nodeList[pqIndex].empty() ) { nodeList[1-pqIndex].push(nodeList[pqIndex].front()); nodeList[pqIndex].pop(); } pqIndex = 1 - pqIndex; nodeList[pqIndex].push( m0 ); // add the better node instead } } } } return ""; // no route found } Output: Legends . = PATH ? = START X = FINISH 3,2,1 = OBSTACLES (Just right) From what I read about Java's documentation, I came up with the conclusion: C++'s std::queue<T>::front() == Java's LinkedList<T>.peek() Java's LinkedList<T>.pop() == C++'s std::queue<T>::front() + std::queue<T>::pop() What might I be missing in my Java version? In what way does it became different algorithmically from the C++ version?

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  • Dynamically loading external HTML in a div using Java Script

    - by user354051
    I have prepared some demo examples for the topic. There is page name "changelog.html" here: http://pantheon-studios.in/test/jquery/changelog.html This is working fine if loaded directly. I am trying to load this page dynamically into: http://pantheon-studios.in/test/jquery/index.html Here changelog.html doesn't behaving as expected. I think the init script on changelog.html is not getting executed or something else is happening when loading it dynamically. Like wise I do have couple of other pages using various jQuery and other java scripts plugins. Some of those needs initialization like animatedcollapse.js in the above example, and couple of them doesn't need initialization, you can directly call the script and go. I also gave a try using: jQuery.getScript("anim.js") after dynamically loading "changelog.html" but doesn't work. The "anim.js" contains animatedcollapse.addDiv('cat', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.addDiv('dog', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.addDiv('rabbit', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.init(); I would really appreciate is some one point me out the right direction. I am completely new to web programming so please have some patience with me. Thanks

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  • Not getting key value from Identity column back after inserting new row with SubSonic ActiveRecord

    - by mikedevenney
    I'm sure I'm missing the obvious answer here, but could use a hand. I'm new to SubSonic and using version 3. I've got myself to the point of being able to query and insert, but I'm stuck with how I would get the value of the identity column back after my insert. I saw another post that mentioned Linq Templates. I'm not using those (at least I don't think I am...?) TIA ... UPDATE ... So I've been debugging through my code watching how the SubSonic code works and I found where the indentity column is being ignored. I use int as the datatype for my ID columns in the database and set them as identity. Since int is a non-nullable data type in c# the logical test in the Add method (public void Add(IDataProvider provider)) that checks if there is a value in the key column by doing a (key==null) could be the issue. The code that gets the new value for the identity field is in the 'true path', since an int can't be null and I use ints as my identity column data types this test will never pass. The ID field for my object has a 0 in it that I didn't put there. I assume it's set during the initialization of the object. Am I off base here? Is the answer to change my data types in the database? Another question (more a curiosity). I noticed that some of the properties in the generated classes are declared with a ? after the datatype. I'm not familiar with this declaration construct... what gives? There are some declared as an int (non key fields) and others that are declared as int? (key fields). Does this have something to do with how they're treated at initialization? Any help is appreciated! --BUMP--

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  • GWT Deserialisation of Persistent Entities (JPA)

    - by slartidan
    Hi everyone, I am currently developing Java/GWT-application which is hosted on a weblogic application server. I am using EJB3.0 with EclipseLink as persistence layer. Sadly my GWT has problems to deserialize persistent entities. It might be helpful for you to know, that I have the EclipseLink-Library in my classpath (including javax.persistence.Entity) am not recieving the persistence objects from a database or persistence-manager - I am creating the objects with standard java code use Eclipse IDE for Java EE Developers for development and deploying and I am compiling my GWT code with the GWT-Plugin (GWT 2.1.0) - my source code is split up in several projects am pretty sure, that the problems occures on client side, since the HTTP response of my server is the same in my working and in my not working example tried to patch javax.persistence.Entity and tried to include several libraries which included javax.persistence.Entity but nothing was helping In my server provides a list of instances of class SerialClass; the interface looks like this: public interface GreetingService extends RemoteService { List<SerialClass> greetServer(); } My onModuleLoad()-Method gets those instances and creates a browser-popup with the information: public void onModuleLoad() { GreetingServiceAsync server = (GreetingServiceAsync) GWT.create(GreetingService.class); server.greetServer(new AsyncCallback<List<SerialClass>>() { public void onFailure(Throwable caught) { } public void onSuccess(List<SerialClass> result) { String resultString = ""; try { for (SerialClass serial : result) { if (serial == null) { resultString += "null "; } else { resultString += ">" + serial.id + "< "; } } } catch (Throwable t) { Window.alert("failed to process"); } Window.alert("success:" + resultString); } }); } My server is looking like this: public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService { public List<SerialClass> greetServer() throws IllegalArgumentException { List<SerialClass> list = new ArrayList<SerialClass>(); for (int i = 0; i < 100; i++) { list.add(new SerialClass()); } return list; } } Case 1 = everything works fine I am using this SerialClass (either without any annotation, or with any annotation other than Entity - for example javax.persistence.PersistenceContext works fine): //@Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } The popup contains (as expected): success:>4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< The data sent over HTTP looks like this: //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] Case 2 = its not working at all I am using this SerialClass: @Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } My popup contains (THIS IS MY PROBLEM): success:>2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null The data sent over HTTP looks like this (exactly the same!): //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] There is no suspicious logging output - neither on server, nor on client. All HTTP-responses have return code 200. My current workaround I am going to try to create transfer objects as a copy of my SerialClass - those transfer objects will look exactly the same, but will not have the @Entity annotation. Alternatively I could try to use the RequestFactory (thanks to @Hilbrand for the hint). I really don't know how to solve that problem and I'm really thankful about any suggestions, hints, tips, links, etc.

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  • How to manage lifecycle in a ViewGroup-derived class?

    - by Scott Smith
    I had a bunch of code in an activity that displays a running graph of some external data. As the activity code was getting kind of cluttered, I decided to extract this code and create a GraphView class: public class GraphView extends LinearLayout { public GraphView(Context context, AttributeSet attrs) { super(context, attrs); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.graph_view, this, true); } public void start() { // Perform initialization (bindings, timers, etc) here } public void stop() { // Unbind, destroy timers, yadda yadda } . . . } Moving stuff into this new LinearLayout-derived class was simple. But there was some lifecycle management code associated with creating and destroying timers and event listeners used by this graph (I didn't want this thing polling in the background if the activity was paused, for example). Coming from a MS Windows background, I kind of expected to find overridable onCreate() and onDestroy() methods or something similar, but I haven't found anything of the sort in LinearLayout (or any of its inherited members). Having to leave all of this initialization code in the Activity, and then having to pass it into the view seemed like it defeated the original purpose of encapsulating all of this code into a reusable view. I ended up adding two additional public methods to my view: start() and stop(). I make these calls from the activity's onResume() and onPause() methods respectively. This seems to work, but it feels like I'm using duct tape here. Does anyone know how this is typically done? I feel like I'm missing something...

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  • clang does not compile but g++ does

    - by user1095108
    Can someone help me with this code: #include <type_traits> #include <vector> struct nonsense { }; template <struct nonsense const* ptr, typename R> typename std::enable_if<!std::is_void<R>::value, int>::type fo(void* const) { return 0; } template <struct nonsense const* ptr, typename R> typename std::enable_if<std::is_void<R>::value, int>::type fo(void* const) { return 1; } typedef int (*func_type)(void*); template <std::size_t O> void run_me() { static struct nonsense data; typedef std::pair<char const* const, func_type> pair_type; std::vector<pair_type> v; v.push_back(pair_type{ "a", fo<&data, int> }); v.push_back(pair_type{ "b", fo<&data, void> }); } int main(int, char*[]) { run_me<2>(); return 0; } clang-3.3 does not compile this code, but g++-4.8.1 does, which of the two compiler is right? Is something wrong with the code, as I suspect? The error reads: a.cpp:32:15: error: no matching constructor for initialization of 'pair_type' (aka 'pair<const char *const, func_type>') v.push_back(pair_type{ "a", fo<&data, int> }); ^ ~~~~~~~~~~~~~~~~~~~~~~~ a.cpp:33:15: error: no matching constructor for initialization of 'pair_type' (aka 'pair<const char *const, func_type>') v.push_back(pair_type{ "b", fo<&data, void> }); ^ ~~~~~~~~~~~~~~~~~~~~~~~~

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  • SQL Compact performance on device

    - by Ben M
    My SQL Compact database is very simple, with just three tables and a single index on one of the tables (the table with 200k rows; the other two have less than a hundred each). The first time the .sdf file is used by my Compact Framework application on the target Windows Mobile device, the system hangs for well over a minute while "something" is done to the database: when deployed, the DB is 17 megabytes, and after this first usage, it balloons to 24 megs. All subsequent usage is pretty fast, so I'm assuming there's some sort of initialization / index building going on during this first usage. I'd rather not subject the user to this delay, so I'm wondering what this initialization process is and whether it can be performed before deployment. For now, I've copied the "initialized" database back to my desktop for use in the setup project, but I'd really like to have a better answer / solution. I've tried "full compact / repair" in the VS Database Properties dialog, but this made no difference. Any ideas? For the record, I should add that the database is only read from by the device application -- no modifications are made by that code.

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  • std::vector elements initializing

    - by Chameleon
    std::vector<int> v1(1000); std::vector<std::vector<int>> v2(1000); std::vector<std::vector<int>::const_iterator> v3(1000); How elements of these 3 vectors initialized? About int, I test it and I saw that all elements become 0. Is this standard? I believed that primitives remain undefined. I create a vector with 300000000 elements, give non-zero values, delete it and recreate it, to avoid OS memory clear for data safety. Elements of recreated vector were 0 too. What about iterator? Is there a initial value (0) for default constructor or initial value remains undefined? When I check this, iterators point to 0, but this can be OS When I create a special object to track constructors, I saw that for first object, vector run the default constructor and for all others it run the copy constructor. Is this standard? Is there a way to completely avoid initialization of elements? Or I must create my own vector? (Oh my God, I always say NOT ANOTHER VECTOR IMPLEMENTATION) I ask because I use ultra huge sparse matrices with parallel processing, so I cannot use push_back() and of course I don't want useless initialization, when later I will change the value.

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  • How can one enforce calling a base class function after derived class constructor?

    - by Mike Elkins
    I'm looking for a clean C++ idiom for the following situation: class SomeLibraryClass { public: SomeLibraryClass() { /* start initialization */ } void addFoo() { /* we are a collection of foos */ } void funcToCallAfterAllAddFoos() { /* Making sure this is called is the issue */ } }; class SomeUserClass : public SomeLibraryClass { public: SomeUserClass() { addFoo(); addFoo(); addFoo(); // SomeUserClass has three foos. } }; class SomeUserDerrivedClass : public SomeUserClass { public: SomeUserDerrivedClass() { addFoo(); // This one has four foos. } }; So, what I really want is for SomeLibraryClass to enforce the calling of funcToCallAfterAllAddFoos at the end of the construction process. The user can't put it at the end of SomeUserClass::SomeUserClass(), that would mess up SomeUserDerrivedClass. If he puts it at the end of SomeUserDerrivedClass, then it never gets called for SomeUserClass. To further clarify what I need, imagine that /* start initialization */ acquires a lock, and funcToCallAfterAllAddFoos() releases a lock. The compiler knows when all the initializations for an object are done, but can I get at that information by some nice trick?

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  • How can this Ambient Context become null?

    - by Mark Seemann
    Can anyone help me explain how TimeProvider.Current can become null in the following class? public abstract class TimeProvider { private static TimeProvider current = DefaultTimeProvider.Instance; public static TimeProvider Current { get { return TimeProvider.current; } set { if (value == null) { throw new ArgumentNullException("value"); } TimeProvider.current = value; } } public abstract DateTime UtcNow { get; } public static void ResetToDefault() { TimeProvider.current = DefaultTimeProvider.Instance; } } Observations All unit tests that directly reference TimeProvider also invokes ResetToDefault() in their Fixture Teardown. There is no multithreaded code involved. Once in a while, one of the unit tests fail because TimeProvider.Current is null (NullReferenceException is thrown). This only happens when I run the entire suite, but not when I just run a single unit test, suggesting to me that there is some subtle test interdependence going on. It happens approximately once every five or six test runs. When a failure occurs, it seems to be occuring in the first executed tests that involves TimeProvider.Current. More than one test can fail, but only one fails in a given test run. FWIW, here's the DefaultTimeProvider class as well: public class DefaultTimeProvider : TimeProvider { private readonly static DefaultTimeProvider instance = new DefaultTimeProvider(); private DefaultTimeProvider() { } public override DateTime UtcNow { get { return DateTime.UtcNow; } } public static DefaultTimeProvider Instance { get { return DefaultTimeProvider.instance; } } } I suspect that there's some subtle interplay going on with static initialization where the runtime is actually allowed to access TimeProvider.Current before all static initialization has finished, but I can't quite put my finger on it. Any help is appreciated.

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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  • Strange compilation error on reference passing argument to function

    - by Grewdrewgoo Goobergabbsoen
    Here's the code: #include <iostream> using namespace std; void mysize(int &size, int size2); int main() { int *p; int val; p = &val; cout << p; mysize(&val, 20); // Error is pointed here! } void mysize(int &size, int size2) { cout << sizeof(size); size2 = size2 + 6000; cout << size2; } Here's the error output from GCC: In function 'int main()': Line 10: error: invalid initialization of non-const reference of type 'int&' from a temporary of type 'int*' compilation terminated due to -Wfatal-errors. What does that imply? I do not understand the error message ... invalid initialization of a non-constant? I declared the prototype function above with two parameters to take, one a reference of an integer and one just an integer value itself. I passed the reference of the int (see line 10), yet this error keeps being thrown at me. What is the issue?

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  • How to implement the disposable pattern in a class that inherits from another disposable class?

    - by TheRHCP
    Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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  • Strange code behaviour?

    - by goldenmean
    Hi, I have a C code in which i have a structure declaration which has an array of int[576] declared in it. For some reason, i had to remove this array from the structure, So i replaced this array with a pointer as int *ptr; declared some global array of same type, somewhere else in the code, and initialized this pointer by assigning the global array to this pointer. So i did not have to change the way i was accessing this array, from other parts of my code. But it works fine/gives desired output when i have the array declared in the structure, but it gives junk output when i declare it as a pointer in the structure and assign a global array to this pointer, as a part of the pointer initialization. All this code is being run on MS-VC 6.0/Windows setup/Intel-x86. I tried below things: 1)Suspected structure padding/alignment but could not get any leads? If at all structure alignment could be a culprit how can i proceed to narrow it down and confirm it? 2) I have made sure that in both cases the array is initialized to some default values, say 0 before its first use, and its not being used before initialization. 3)I tried using global array as well as malloc based memory for this newly declared array. Same result, junk output. Am i missing something? How can i zero down the problem. Any pointers would be helpful. Thanks, -AD.

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  • Initializing an object to all zeroes

    - by dash-tom-bang
    Oftentimes data structures' valid initialization is to set all members to zero. Even when programming in C++, one may need to interface with an external API for which this is the case. Is there any practical difference between: some_struct s; memset(s, 0, sizeof(s)); and simply some_struct s = { 0 }; Do folks find themselves using both, with a method for choosing which is more appropriate for a given application? For myself, as mostly a C++ programmer who doesn't use memset much, I'm never certain of the function signature so I find the second example is just easier to use in addition to being less typing, more compact, and maybe even more obvious since it says "this object is initialized to zero" right in the declaration rather than waiting for the next line of code and seeing, "oh, this object is zero initialized." When creating classes and structs in C++ I tend to use initialization lists; I'm curious about folks thoughts on the two "C style" initializations above rather than a comparison against what is available in C++ since I suspect many of us interface with C libraries even if we code mostly in C++ ourselves.

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  • Java: immutability, overuse of stack -- better data structure?

    - by HH
    I overused hashSets but it was slow, then changed to Stacks, speed boost-up. Poly's reply uses Collections.emptyList() as immutable list, cutting out excess null-checkers. No Collections.emptyStack(). Combining the words stack and immutability, from the last experiences, gets "immutable stack" (probably not related to functional prog). Java Api 5 for list interface shows that Stack is an implementing class for list and arraylist, here. The java.coccurrent pkg does not have any immutable Stack data structure. The first hinted of misusing stack. The lack of immutabily in the last and poly's book recommendation leads way to list. Something very primitive, fast, no extra layers, with methods like emptyThing(). Overuse of stack and where I use it DataFile.java: public Stack<DataFile> files; FileObject.java: public Stack<String> printViews = new Stack<String>(); FileObject.java:// private static Stack<Object> getFormat(File f){return (new Format(f)).getFormat();} Format.java: private Stack<Object> getLine(File[] fs,String s){return wF;} Format.java: private Stack<Object> getFormat(){return format;} Positions.java: public static Stack<Integer[]> getPrintPoss(String s,File f,Integer maxViewPerF) Positions.java: Stack<File> possPrint = new Stack<File>(); Positions.java: Stack<Integer> positions=new Stack<Integer>(); Record.java: private String getFormatLine(Stack<Object> st) Record.java: Stack<String> lines=new Stack<String>(); SearchToUser.java: public static final Stack<File> allFiles = findf.getFs(); SearchToUser.java: public static final Stack<File> allDirs = findf.getDs(); SearchToUser.java: private Stack<Integer[]> positionsPrint=new Stack<Integer[]>(); SearchToUser.java: public Stack<String> getSearchResults(String s, Integer countPerFile, Integer resCount) SearchToUser.java: Stack<File> filesToS=Fs2Word.getFs2W(s,50); SearchToUser.java: Stack<String> rs=new Stack<String>(); View.java: public Stack<Integer[]> poss = new Stack<Integer[4]>(); View.java: public static Stack<String> getPrintViewsFileWise(String s,Object[] df,Integer maxViewsPerF) View.java: Stack<String> substrings = new Stack<String>(); View.java: private Stack<String> printViews=new Stack<String>(); View.java: MatchView(Stack<Integer> pss,File f,Integer maxViews) View.java: Stack<String> formatFile; View.java: private Stack<Search> files; View.java: private Stack<File> matchingFiles; View.java: private Stack<String> matchViews; View.java: private Stack<String> searchMatches; View.java: private Stack<String> getSearchResults(Integer numbResults) Easier with List: AllDirs and AllFs, now looping with push, but list has more pow. methods such as addAll [OLD] From Stack to some immutable data structure How to get immutable Stack data structure? Can I box it with list? Should I switch my current implementatios from stacks to Lists to get immutable? Which immutable data structure is Very fast with about similar exec time as Stack? No immutability to Stack with Final import java.io.*; import java.util.*; public class TestStack{ public static void main(String[] args) { final Stack<Integer> test = new Stack<Integer>(); Stack<Integer> test2 = new Stack<Integer>(); test.push(37707); test2.push(80437707); //WHY is there not an error to remove an elment // from FINAL stack? System.out.println(test.pop()); System.out.println(test2.pop()); } }

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  • JPA : optimize EJB-QL query involving large many-to-many join table

    - by Fabien
    Hi all. I'm using Hibernate Entity Manager 3.4.0.GA with Spring 2.5.6 and MySql 5.1. I have a use case where an entity called Artifact has a reflexive many-to-many relation with itself, and the join table is quite large (1 million lines). As a result, the HQL query performed by one of the methods in my DAO takes a long time. Any advice on how to optimize this and still use HQL ? Or do I have no choice but to switch to a native SQL query that would perform a join between the table ARTIFACT and the join table ARTIFACT_DEPENDENCIES ? Here is the problematic query performed in the DAO : @SuppressWarnings("unchecked") public List<Artifact> findDependentArtifacts(Artifact artifact) { Query query = em.createQuery("select a from Artifact a where :artifact in elements(a.dependencies)"); query.setParameter("artifact", artifact); List<Artifact> list = query.getResultList(); return list; } And the code for the Artifact entity : package com.acme.dependencytool.persistence.model; import java.util.ArrayList; import java.util.List; import javax.persistence.CascadeType; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.FetchType; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.JoinTable; import javax.persistence.ManyToMany; import javax.persistence.Table; import javax.persistence.UniqueConstraint; @Entity @Table(name = "ARTIFACT", uniqueConstraints={@UniqueConstraint(columnNames={"GROUP_ID", "ARTIFACT_ID", "VERSION"})}) public class Artifact { @Id @GeneratedValue @Column(name = "ID") private Long id = null; @Column(name = "GROUP_ID", length = 255, nullable = false) private String groupId; @Column(name = "ARTIFACT_ID", length = 255, nullable = false) private String artifactId; @Column(name = "VERSION", length = 255, nullable = false) private String version; @ManyToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER) @JoinTable( name="ARTIFACT_DEPENDENCIES", joinColumns = @JoinColumn(name="ARTIFACT_ID", referencedColumnName="ID"), inverseJoinColumns = @JoinColumn(name="DEPENDENCY_ID", referencedColumnName="ID") ) private List<Artifact> dependencies = new ArrayList<Artifact>(); public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getGroupId() { return groupId; } public void setGroupId(String groupId) { this.groupId = groupId; } public String getArtifactId() { return artifactId; } public void setArtifactId(String artifactId) { this.artifactId = artifactId; } public String getVersion() { return version; } public void setVersion(String version) { this.version = version; } public List<Artifact> getDependencies() { return dependencies; } public void setDependencies(List<Artifact> dependencies) { this.dependencies = dependencies; } } Thanks in advance. EDIT 1 : The DDLs are generated automatically by Hibernate EntityMananger based on the JPA annotations in the Artifact entity. I have no explicit control on the automaticaly-generated join table, and the JPA annotations don't let me explicitly set an index on a column of a table that does not correspond to an actual Entity (in the JPA sense). So I guess the indexing of table ARTIFACT_DEPENDENCIES is left to the DB, MySQL in my case, which apparently uses a composite index based on both clumns but doesn't index the column that is most relevant in my query (DEPENDENCY_ID). mysql describe ARTIFACT_DEPENDENCIES; +---------------+------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------------+------------+------+-----+---------+-------+ | ARTIFACT_ID | bigint(20) | NO | MUL | NULL | | | DEPENDENCY_ID | bigint(20) | NO | MUL | NULL | | +---------------+------------+------+-----+---------+-------+ EDIT 2 : When turning on showSql in the Hibernate session, I see many occurences of the same type of SQL query, as below : select dependenci0_.ARTIFACT_ID as ARTIFACT1_1_, dependenci0_.DEPENDENCY_ID as DEPENDENCY2_1_, artifact1_.ID as ID1_0_, artifact1_.ARTIFACT_ID as ARTIFACT2_1_0_, artifact1_.GROUP_ID as GROUP3_1_0_, artifact1_.VERSION as VERSION1_0_ from ARTIFACT_DEPENDENCIES dependenci0_ left outer join ARTIFACT artifact1_ on dependenci0_.DEPENDENCY_ID=artifact1_.ID where dependenci0_.ARTIFACT_ID=? Here's what EXPLAIN in MySql says about this type of query : mysql explain select dependenci0_.ARTIFACT_ID as ARTIFACT1_1_, dependenci0_.DEPENDENCY_ID as DEPENDENCY2_1_, artifact1_.ID as ID1_0_, artifact1_.ARTIFACT_ID as ARTIFACT2_1_0_, artifact1_.GROUP_ID as GROUP3_1_0_, artifact1_.VERSION as VERSION1_0_ from ARTIFACT_DEPENDENCIES dependenci0_ left outer join ARTIFACT artifact1_ on dependenci0_.DEPENDENCY_ID=artifact1_.ID where dependenci0_.ARTIFACT_ID=1; +----+-------------+--------------+--------+-------------------+-------------------+---------+---------------------------------------------+------+-------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------+--------+-------------------+-------------------+---------+---------------------------------------------+------+-------+ | 1 | SIMPLE | dependenci0_ | ref | FKEA2DE763364D466 | FKEA2DE763364D466 | 8 | const | 159 | | | 1 | SIMPLE | artifact1_ | eq_ref | PRIMARY | PRIMARY | 8 | dependencytooldb.dependenci0_.DEPENDENCY_ID | 1 | | +----+-------------+--------------+--------+-------------------+-------------------+---------+---------------------------------------------+------+-------+ EDIT 3 : I tried setting the FetchType to LAZY in the JoinTable annotation, but I then get the following exception : Hibernate: select artifact0_.ID as ID1_, artifact0_.ARTIFACT_ID as ARTIFACT2_1_, artifact0_.GROUP_ID as GROUP3_1_, artifact0_.VERSION as VERSION1_ from ARTIFACT artifact0_ where artifact0_.GROUP_ID=? and artifact0_.ARTIFACT_ID=? 51545 [btpool0-2] ERROR org.hibernate.LazyInitializationException - failed to lazily initialize a collection of role: com.acme.dependencytool.persistence.model.Artifact.dependencies, no session or session was closed org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.acme.dependencytool.persistence.model.Artifact.dependencies, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) at org.hibernate.collection.AbstractPersistentCollection.readSize(AbstractPersistentCollection.java:119) at org.hibernate.collection.PersistentBag.size(PersistentBag.java:248) at com.acme.dependencytool.server.DependencyToolServiceImpl.createArtifactViewBean(DependencyToolServiceImpl.java:93) at com.acme.dependencytool.server.DependencyToolServiceImpl.createArtifactViewBean(DependencyToolServiceImpl.java:109) at com.acme.dependencytool.server.DependencyToolServiceImpl.search(DependencyToolServiceImpl.java:48) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:527) at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:166) at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost(RemoteServiceServlet.java:86) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

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  • Nested property binding

    - by EtherealMonkey
    Recently, I have been trying to wrap my mind around the BindingList<T> and INotifyPropertChanged. More specifically - How do I make a collection of objects (having objects as properties) which will allow me to subscribe to events throughout the tree? To that end, I have examined the code offered as examples by others. One such project that I downloaded was Nested Property Binding - CodeProject by "seesharper". Now, the article explains the implementation, but there was a question by "Someone@AnotherWorld" about "INotifyPropertyChanged in nested objects". His question was: Hi, nice stuff! But after a couple of time using your solution I realize the ObjectBindingSource ignores the PropertyChanged event of nested objects. E.g. I've got a class 'Foo' with two properties named 'Name' and 'Bar'. 'Name' is a string an 'Bar' reference an instance of class 'Bar', which has a 'Name' property of type string too and both classes implements INotifyPropertyChanged. With your binding source reading and writing with both properties ('Name' and 'Bar_Name') works fine but the PropertyChanged event works only for the 'Name' property, because the binding source listen only for events of 'Foo'. One workaround is to retrigger the PropertyChanged event in the appropriate class (here 'Foo'). What's very unclean! The other approach would be to extend ObjectBindingSource so that all owner of nested property which implements INotifyPropertyChanged get used for receive changes, but how? Thanks! I had asked about BindingList<T> yesterday and received a good answer from Aaronaught. In my question, I had a similar point as "Someone@AnotherWorld": if Keywords were to implement INotifyPropertyChanged, would changes be accessible to the BindingList through the ScannedImage object? To which Aaronaught's response was: No, they will not. BindingList only looks at the specific object in the list, it has no ability to scan all dependencies and monitor everything in the graph (nor would that always be a good idea, if it were possible). I understand Aaronaught's comment regarding this behavior not necessarily being a good idea. Additionally, his suggestion to have my bound object "relay" events on behalf of it's member objects works fine and is perfectly acceptable. For me, "re-triggering" the PropertyChanged event does not seem so unclean as "Someone@AnotherWorld" laments. I do understand why he protests - in the interest of loosely coupled objects. However, I believe that coupling between objects that are part of a composition is logical and not so undesirable as this may be in other scenarios. (I am a newb, so I could be waaayyy off base.) Anyway, in the interest of exploring an answer to the question by "Someone@AnotherWorld", I altered the MainForm.cs file of the example project from Nested Property Binding - CodeProject by "seesharper" to the following: using System; using System.Collections.Generic; using System.ComponentModel; using System.Core.ComponentModel; using System.Windows.Forms; namespace ObjectBindingSourceDemo { public partial class MainForm : Form { private readonly List<Customer> _customers = new List<Customer>(); private readonly List<Product> _products = new List<Product>(); private List<Order> orders; public MainForm() { InitializeComponent(); dataGridView1.AutoGenerateColumns = false; dataGridView2.AutoGenerateColumns = false; CreateData(); } private void CreateData() { _customers.Add( new Customer(1, "Jane Wilson", new Address("98104", "6657 Sand Pointe Lane", "Seattle", "USA"))); _customers.Add( new Customer(1, "Bill Smith", new Address("94109", "5725 Glaze Drive", "San Francisco", "USA"))); _customers.Add( new Customer(1, "Samantha Brown", null)); _products.Add(new Product(1, "Keyboard", 49.99)); _products.Add(new Product(2, "Mouse", 10.99)); _products.Add(new Product(3, "PC", 599.99)); _products.Add(new Product(4, "Monitor", 299.99)); _products.Add(new Product(5, "LapTop", 799.99)); _products.Add(new Product(6, "Harddisc", 89.99)); customerBindingSource.DataSource = _customers; productBindingSource.DataSource = _products; orders = new List<Order>(); orders.Add(new Order(1, DateTime.Now, _customers[0])); orders.Add(new Order(2, DateTime.Now, _customers[1])); orders.Add(new Order(3, DateTime.Now, _customers[2])); #region Added by me OrderLine orderLine1 = new OrderLine(_products[0], 1); OrderLine orderLine2 = new OrderLine(_products[1], 3); orderLine1.PropertyChanged += new PropertyChangedEventHandler(OrderLineChanged); orderLine2.PropertyChanged += new PropertyChangedEventHandler(OrderLineChanged); orders[0].OrderLines.Add(orderLine1); orders[0].OrderLines.Add(orderLine2); #endregion // Removed by me in lieu of region above. //orders[0].OrderLines.Add(new OrderLine(_products[0], 1)); //orders[0].OrderLines.Add(new OrderLine(_products[1], 3)); ordersBindingSource.DataSource = orders; } #region Added by me // Have to wait until the form is Shown to wire up the events // for orderDetailsBindingSource. Otherwise, they are triggered // during MainForm().InitializeComponent(). private void MainForm_Shown(object sender, EventArgs e) { orderDetailsBindingSource.AddingNew += new AddingNewEventHandler(orderDetailsBindSrc_AddingNew); orderDetailsBindingSource.CurrentItemChanged += new EventHandler(orderDetailsBindSrc_CurrentItemChanged); orderDetailsBindingSource.ListChanged += new ListChangedEventHandler(orderDetailsBindSrc_ListChanged); } private void orderDetailsBindSrc_AddingNew( object sender, AddingNewEventArgs e) { } private void orderDetailsBindSrc_CurrentItemChanged( object sender, EventArgs e) { } private void orderDetailsBindSrc_ListChanged( object sender, ListChangedEventArgs e) { ObjectBindingSource bindingSource = (ObjectBindingSource)sender; if (!(bindingSource.Current == null)) { // Unsure if GetType().ToString() is required b/c ToString() // *seems* // to return the same value. if (bindingSource.Current.GetType().ToString() == "ObjectBindingSourceDemo.OrderLine") { if (e.ListChangedType == ListChangedType.ItemAdded) { // I wish that I knew of a way to determine // if the 'PropertyChanged' delegate assignment is null. // I don't like the current test, but it seems to work. if (orders[ ordersBindingSource.Position].OrderLines[ e.NewIndex].Product == null) { orders[ ordersBindingSource.Position].OrderLines[ e.NewIndex].PropertyChanged += new PropertyChangedEventHandler( OrderLineChanged); } } if (e.ListChangedType == ListChangedType.ItemDeleted) { // Will throw exception when leaving // an OrderLine row with unitialized properties. // // I presume this is because the item // has already been 'disposed' of at this point. // *but* // Will it be actually be released from memory // if the delegate assignment for PropertyChanged // was never removed??? if (orders[ ordersBindingSource.Position].OrderLines[ e.NewIndex].Product != null) { orders[ ordersBindingSource.Position].OrderLines[ e.NewIndex].PropertyChanged -= new PropertyChangedEventHandler( OrderLineChanged); } } } } } private void OrderLineChanged(object sender, PropertyChangedEventArgs e) { MessageBox.Show(e.PropertyName, "Property Changed:"); } #endregion } } In the method private void orderDetailsBindSrc_ListChanged(object sender, ListChangedEventArgs e) I am able to hook up the PropertyChangedEventHandler to the OrderLine object as it is being created. However, I cannot seem to find a way to unhook the PropertyChangedEventHandler from the OrderLine object before it is being removed from the orders[i].OrderLines list. So, my questions are: Am I simply trying to do something that is very, very wrong here? Will the OrderLines object that I add the delegate assignments to ever be released from memory if the assignment is not removed? Is there a "sane" method of achieving this scenario? Also, note that this question is not specifically related to my prior. I have actually solved the issue which had prompted me to inquire before. However, I have reached a point with this particular topic of discovery where my curiosity has exceeded my patience - hopefully someone here can shed some light on this?

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  • Elusive race condition in Java

    - by nasufara
    I am creating a graphing calculator. In an attempt to squeeze some more performance out of it, I added some multithreaded to the line calculator. Essentially what my current implementation does is construct a thread-safe Queue of X values, then start however many threads it needs, each one calculating a point on the line using the queue to get its values, and then ordering the points using a HashMap when the calculations are done. This implementation works great, and that's not where my race condition is (merely some background info). In examining the performance results from this, I found that the HashMap is a performance bottleneck, since I do that synchronously on one thread. So I figured that ordering each point as its calculated would work best. I tried a PriorityQueue, but that was slower than the HashMap. I ended up creating an algorithm that essentially works like this: I construct a list of X values to calculate, like in my current algorithm. I then copy that list of values into another class, unimaginatively and temporarily named BlockingList, which is responsible for ordering the points as they are calculated. BlockingList contains a put() method, which takes in two BigDecimals as parameters, the first the X value, the second the calculated Y value. put() will only accept a value if the X value is the next one on the list to be accepted in the list of X values, and will block until another thread gives it the next excepted value. For example, since that can be confusing, say I have two threads, Thread-1 and Thread-2. Thread-2 gets the X value 10.0 from the values queue, and Thread-1 gets 9.0. However, Thread-1 completes its calculations first, and calls put() before Thread-2 does. Because BlockingList is expecting to get 10.0 first, and not 9.0, it will block on Thread-1 until Thread-2 finishes and calls put(). Once Thread-2 gives BlockingList 10.0, it notify()s all waiting threads, and expects 9.0 next. This continues until BlockingList gets all of its expected values. (I apologise if that was hard to follow, if you need more clarification, just ask.) As expected by the question title, there is a race condition in here. If I run it without any System.out.printlns, it will sometimes lock because of conflicting wait() and notifyAll()s, but if I put a println in, it will run great. A small implementation of this is included below, and exhibits the same behavior: import java.math.BigDecimal; import java.util.concurrent.ConcurrentLinkedQueue; public class Example { public static void main(String[] args) throws InterruptedException { // Various scaling values, determined based on the graph size // in the real implementation BigDecimal xMax = new BigDecimal(10); BigDecimal xStep = new BigDecimal(0.05); // Construct the values list, from -10 to 10 final ConcurrentLinkedQueue<BigDecimal> values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal i = new BigDecimal(-10); i.compareTo(xMax) <= 0; i = i.add(xStep)) { values.add(i); } // Contains the calculated values final BlockingList list = new BlockingList(values); for (int i = 0; i < 4; i++) { new Thread() { public void run() { BigDecimal x; // Keep looping until there are no more values while ((x = values.poll()) != null) { PointPair pair = new PointPair(); pair.realX = x; try { list.put(pair); } catch (Exception ex) { ex.printStackTrace(); } } } }.start(); } } private static class PointPair { public BigDecimal realX; } private static class BlockingList { private final ConcurrentLinkedQueue<BigDecimal> _values; private final ConcurrentLinkedQueue<PointPair> _list = new ConcurrentLinkedQueue<PointPair>(); public BlockingList(ConcurrentLinkedQueue<BigDecimal> expectedValues) throws InterruptedException { // Copy the values into a new queue BigDecimal[] arr = expectedValues.toArray(new BigDecimal[0]); _values = new ConcurrentLinkedQueue<BigDecimal>(); for (BigDecimal dec : arr) { _values.add(dec); } } public void put(PointPair item) throws InterruptedException { while (item.realX.compareTo(_values.peek()) != 0) { synchronized (this) { // Block until someone enters the next desired value wait(); } } _list.add(item); _values.poll(); synchronized (this) { notifyAll(); } } } } My question is can anybody help me find the threading error? Thanks!

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  • java - register problem

    - by Jake
    Hi! When i try to register a person with the name Eric for example, and then again registrating Eric it works. This should not happen with the code i have. Eric should not be registrated if theres already an Eric in the list. Here is my full code: import java.util.*; import se.lth.cs.pt.io.*; class Person { private String name; private String nbr; public Person (String name, String nbr) { this.name = name; this.nbr = nbr; } public String getName() { return name; } public String getNumber() { return nbr; } public String toString() { return name + " : " + nbr; } } class Register { private List<Person> personer; public Register() { personer = new ArrayList<Person>(); } // boolean remove(String name) { // } private Person findName(String name) { for (Person person : personer) { if (person.getName() == name) { return person; } } return null; } private boolean containsName(String name) { return findName(name) != null; } public boolean insert(String name, String nbr) { if (containsName(name)) { return false; } Person person = new Person(name, nbr); personer.add(person); Collections.sort(personer, new A()); return true; } //List<Person> findByPartOfName(String partOfName) { //} //List<Person> findByNumber(String nbr) { //} public List<Person> findAll() { List<Person> copy = new ArrayList<Person>(); for (Person person : personer) { copy.add(person); } return copy; } public void printList(List<Person> personer) { for (Person person : personer) { System.out.println(person.toString()); } } } class A implements Comparator < Person > { @Override public int compare(Person o1, Person o2) { if(o1.getName() != null && o2.getName() != null){ return o1.getName().compareTo(o2.getName()); } return 0; } } class TestScript { public static void main(String[] args) { new TestScript().run(); } void test(String msg, boolean status) { if (status) { System.out.println(msg + " -- ok"); } else { System.out.printf("==== FEL: %s ====\n", msg); } } void run() { Register register = new Register(); System.out.println("Vad vill du göra:"); System.out.println("1. Lägg in ny person."); System.out.println("2. Tag bort person."); System.out.println("3. Sök på del av namn."); System.out.println("4. Se vem som har givet nummer."); System.out.println("5. Skriv ut alla personer."); System.out.println("0. Avsluta."); int cmd = Keyboard.nextInt("Ange kommando (0-5): "); if (cmd == 0 ) { } else if (cmd == 1) { String name = Keyboard.nextLine("Namn: "); String nbr = Keyboard.nextLine("Nummer: "); System.out.println("\n"); String inlagd = "OK - " + name + " är nu inlagd."; String ejinlagd = name + " är redan inlagd."; test("Skapar nytt konto", register.insert(name, nbr) == true); System.out.println("\n"); } else if (cmd == 2) { } else if (cmd == 3) { } else if (cmd == 4) { } else if (cmd == 5) { System.out.println("\n"); register.printList(register.findAll()); System.out.println("\n"); } else { System.out.println("Inget giltigt kommando!"); System.out.println("\n"); } } }

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  • Overly accessible and incredibly resource hungry relationships between business objects. How can I f

    - by Mike
    Hi, Firstly, This might seem like a long question. I don't think it is... The code is just an overview of what im currently doing. It doesn't feel right, so I am looking for constructive criticism and warnings for pitfalls and suggestions of what I can do. I have a database with business objects. I need to access properties of parent objects. I need to maintain some sort of state through business objects. If you look at the classes, I don't think that the access modifiers are right. I don't think its structured very well. Most of the relationships are modelled with public properties. SubAccount.Account.User.ID <-- all of those are public.. Is there a better way to model a relationship between classes than this so its not so "public"? The other part of this question is about resources: If I was to make a User.GetUserList() function that returns a List, and I had 9000 users, when I call the GetUsers method, it will make 9000 User objects and inside that it will make 9000 new AccountCollection objects. What can I do to make this project not so resource hungry? Please find the code below and rip it to shreds. public class User { public string ID {get;set;} public string FirstName {get; set;} public string LastName {get; set;} public string PhoneNo {get; set;} public AccountCollection accounts {get; set;} public User { accounts = new AccountCollection(this); } public static List<Users> GetUsers() { return Data.GetUsers(); } } public AccountCollection : IEnumerable<Account> { private User user; public AccountCollection(User user) { this.user = user; } public IEnumerable<Account> GetEnumerator() { return Data.GetAccounts(user); } } public class Account { public User User {get; set;} //This is public so that the subaccount can access its Account's User's ID public int ID; public string Name; public Account(User user) { this.user = user; } } public SubAccountCollection : IEnumerable<SubAccount> { public Account account {get; set;} public SubAccountCollection(Account account) { this.account = account; } public IEnumerable<SubAccount> GetEnumerator() { return Data.GetSubAccounts(account); } } public class SubAccount { public Account account {get; set;} //this is public so that my Data class can access the account, to get the account's user's ID. public SubAccount(Account account) { this.account = account; } public Report GenerateReport() { Data.GetReport(this); } } public static class Data { public static List<Account> GetSubAccounts(Account account) { using (var dc = new databaseDataContext()) { List<SubAccount> query = (from a in dc.Accounts where a.UserID == account.User.ID //this is getting the account's user's ID select new SubAccount(account) { ID = a.ID, Name = a.Name, }).ToList(); } } public static List<Account> GetAccounts(User user) { using (var dc = new databaseDataContext()) { List<Account> query = (from a in dc.Accounts where a.UserID == User.ID //this is getting the user's ID select new Account(user) { ID = a.ID, Name = a.Name, }).ToList(); } } public static Report GetReport(SubAccount subAccount) { Report report = new Report(); //database access code here //need to get the user id of the subaccount's account for data querying. //i've got the subaccount, but how should i get the user id. //i would imagine something like this: int accountID = subAccount.Account.User.ID; //but this would require the subaccount's Account property to be public. //i do not want this to be accessible from my other project (UI). //reading up on internal seems to do the trick, but within my code it still feels //public. I could restrict the property to read, and only private set. return report; } public static List<User> GetUsers() { using (var dc = new databaseDataContext()) { var query = (from u in dc.Users select new User { ID = u.ID, FirstName = u.FirstName, LastName = u.LastName, PhoneNo = u.PhoneNo }).ToList(); return query; } } }

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  • wcf rest service 400 error : There might be a typing error in the address

    - by Lokesh Kondapalli
    I am trying to invoke wcf rest service from url but its showing error like this Error : Most likely causes: •There might be a typing error in the address. •If you clicked on a link, it may be out of date. ** I need JSON responce Here my code : Iservice.cs using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using System.ServiceModel; using System.ServiceModel.Web; using System.Text; namespace SampleRestSample { interface name "IService1" in both code and config file together. [ServiceContract] public interface IService1 { [OperationContract] [WebInvoke(Method = "GET", UriTemplate = "Book/{id}", BodyStyle = WebMessageBodyStyle.Wrapped, ResponseFormat = WebMessageFormat.Json)] List<Prasad> GetBookById(string id); } [DataContract] public class Prasad { [DataMember] public string Name { get; set; } [DataMember] public string Age { get; set; } } } Service1.svc.cs using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using System.ServiceModel; using System.ServiceModel.Web; using System.Text; namespace LoginRestSample { // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Service1" in code, svc and config file together. public class Service1 : SampleRestSample { List<Prasad> list = new List<Prasad>(); public List<Prasad> GetBookById(string id) { try { Prasad cls = new Prasad(); cls.Age = "24"; cls.Name = "prasad"; list.Add(cls); //int bookId = Convert.ToInt32(id); //using (SampleDbEntities entities = new SampleDbEntities()) //{ // return entities.Books.SingleOrDefault(book => book.ID == bookId); //} } catch { throw new FaultException("Something went wrong"); } return list; } } } web.config <?xml version="1.0" encoding="utf-8"?> <configuration> <system.web> <compilation debug="true" targetFramework="4.0"> <assemblies> <add assembly="System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" /> </assemblies> </compilation> </system.web> <system.serviceModel> <services> <service name="WcfRestSample.SampleRestSample"> <endpoint address="" behaviorConfiguration="restfulBehavior" binding="webHttpBinding" bindingConfiguration="" contract="WcfRestSample.ISampleRestSample" /> <host> <baseAddresses> <add baseAddress="http://localhost/SampleRestSample" /> </baseAddresses> </host> </service> </services> <behaviors> <endpointBehaviors> <behavior name="restfulBehavior"> <webHttp automaticFormatSelectionEnabled="true" /> </behavior> </endpointBehaviors> <serviceBehaviors> <behavior name=""> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> </system.serviceModel> <system.webServer> <modules runAllManagedModulesForAllRequests="true" /> </system.webServer> </configuration> Any solutions? Thank you in advance.

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