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Create xml document in java applet.

- by zproxy

If I try to create a new xml document in a java applet by this code: http://java.sun.com/j2se/1.4.2/docs/api/javax/xml/parsers/DocumentBuilderFactory.html#newInstance() DocumentBuilderFactory.newInstance(); I will get this error: Java Plug-in 1.6.0_19 Using JRE version 1.6.0_19-b04 Java HotSpot(TM) Client VM javax.xml.parsers.FactoryConfigurationError: Provider <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> not found at javax.xml.parsers.DocumentBuilderFactory.newInstance(Unknown Source) I do not care about DTD's. Why is it looking for it? How am I supposed to create a xml document in java applets? How can I make it work? The enclosing html document looks like this: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <title>Loading...</title> </head> Can some comment this thread? The problem was with the entity resolver, which points to the w3c.org web site. The access to the reference DTDs on this site has been restricted for application use. The solution was to implement my own entity resolver. Related: http://forums.sun.com/thread.jspa?threadID=515055 http://stackoverflow.com/questions/1016286/org-apache-xerces-jaxp-saxparserfactoryimpl-not-found-when-importing-gears-api-in http://java.itags.org/java-desktop/4839/

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How do I format the contents of a DataGrid cell as a Date? as Currency?

- by Ben McCormack

I have a Silverlight DataGrid that's being populated with different types of data for each column. I'm trying to figure out how to format some of the contents of the DataGrid's cells, specifically for dates and formatting. I have a date column that's currently displaying like: 3/11/2010 12:00:00 AM. I would rather it display like 3/14/2010. I have a number column that's currently displaying like: 51.32. I'd rather it display as currency like $51.32. I'm not sure how I can go about doing this. I'd prefer to do it in XAML instead of C#, but both solutions are fine. For reference, here's my XAML so far: </data:DataGridTextColumn> <data:DataGridTextColumn Header="Payee" Binding="{Binding Payee}"/> <data:DataGridTextColumn Header="Category" Binding="{Binding Category}"/> <data:DataGridTextColumn Header="Memo" Binding="{Binding Memo}"/> <data:DataGridTextColumn Header="Inflow" Binding="{Binding Inflow}"/> <data:DataGridTextColumn Header="Outflow" Binding="{Binding Outflow}"/> </data:DataGrid.Columns>

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use startActivityForResult from non-activity

- by rayman

Hi, I have MainActivity which is an Activity and other class(which is a simple java class), we`ll call it "SimpleClass". now i want to run from that class the command startActivityForResult. now i though that i could pass that class(SimpleClass), only MainActivity's context, problem is that, u cant run context.startActivityForResult(...); so the only way making SimpleClass to use 'startActivityForResult; is to pass the reference of MainActivity as an Activity variable to the SimpleClass something like that: inside the MainActivity class i create the instance of SimpleClass this way: SimpleClass simpleClass=new SimpleClass(MainActivity.this); now this is how SimpleClass looks like: public Class SimpleClass { Activity myMainActivity; public SimpleClass(Activity mainActivity) { super(); this.myMainActivity=mainActivity; } .... } public void someMethod(...) { myMainActivity.startActivityForResult(...); } now its working, but isnt a proper way of doing this? I`am afraid i could have some memory leaks in the future. thanks. ray.

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Super simple CSS tooltip in a table, why is it not displaying and can I make it work?

- by Kyle Sevenoaks

Hi, I have been trying to implement many different tooltips on this page for my client, he's adamant that we have a picture of the product show up when you hover over the product name in the order page. I decided to use the super simple CSS tooltip, it's very easy to implement and does exactly what we want. It works on a dynamic page, the others I tried didn't. I have made an example here: CSS tooltip in table example. This page used to be displayed using divs, I have since changed it to a table, as it's tabular data and easier to work with. It worked fine when it used divs, now it's in a table, it won't display the span on hover. My questions are: Why is it not working? How can I make it work? If not, does anyone know another super easy to implement tooltip that can work properly on a dynamic page? Here's the DIV tooltip for reference: DIV display tooltip. Edit: Just noticed it kinda half works in IE8. Thanks.

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How do I add and remove an event listener using a function with parameters?

- by Bungle

Sorry if this is a common question, but I couldn't find any answers that seemed pertinent through searching. If I attach an event listener like this: window.addEventListener('scroll', function() { check_pos(box); }, false); it doesn't seem to work to try to remove it later, like this: window.removeEventListener('scroll', function() { check_pos(box); }, false); I assume this is because the addEventListener and removeEventListener methods want a reference to the same function, while I've provided them with anonymous functions, which, while identical in code, are not literally the same. How can I change my code to get the call to removeEventListener to work? The "box" argument refers to the name of an <iframe> that I'm tracking on the screen; that is, I want to be able to subscribe to the scroll event once for each <iframe> that I have (the quantity varies), and once the check_pos() function measures a certain position, it will call another function and also remove the event listener to free up system resources. My hunch is that the solution will involve a closure and/or naming the anonymous function, but I'm not sure exactly what that looks like, and would appreciate a concrete example. Hope that makes sense. Thanks for any help!

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Index Tuning for SSIS tasks

- by Raj More

I am loading tables in my warehouse using SSIS. Since my SSIS is slow, it seemed like a great idea to build indexes on the tables. There are no primary keys (and therefore, foreign keys), indexes (clustered or otherwise), constraints, on this warehouse. In other words, it is 100% efficiency free. We are going to put indexes based on usage - by analyzing new queries and current query performance. So, instead of doing it our old fashioned sweat and grunt way of actually reading the SQL statements and execution plans, I thought I'd put the shiny new Database Engine Tuning Advisor to use. I turned SQL logging off in my SSIS package and ran a "Tuning" trace, saved it to a table and analyzed the output in the Tuning Advisor. Most of the lookups are done as: exec sp_executesql N'SELECT [Active], [CompanyID], [CompanyName], [CompanyShortName], [CompanyTypeID], [HierarchyNodeID] FROM [dbo].[Company] WHERE ([CompanyID]=@P1) AND ([StartDateTime] IS NOT NULL AND [EndDateTime] IS NULL)',N'@P1 int',1 exec sp_executesql N'SELECT [Active], [CompanyID], [CompanyName], [CompanyShortName], [CompanyTypeID], [HierarchyNodeID] FROM [dbo].[Company] WHERE ([CompanyID]=@P1) AND ([StartDateTime] IS NOT NULL AND [EndDateTime] IS NULL)',N'@P1 int',2 exec sp_executesql N'SELECT [Active], [CompanyID], [CompanyName], [CompanyShortName], [CompanyTypeID], [HierarchyNodeID] FROM [dbo].[Company] WHERE ([CompanyID]=@P1) AND ([StartDateTime] IS NOT NULL AND [EndDateTime] IS NULL)',N'@P1 int',3 exec sp_executesql N'SELECT [Active], [CompanyID], [CompanyName], [CompanyShortName], [CompanyTypeID], [HierarchyNodeID] FROM [dbo].[Company] WHERE ([CompanyID]=@P1) AND ([StartDateTime] IS NOT NULL AND [EndDateTime] IS NULL)',N'@P1 int',4 and when analyzed, these statements have the reason "Event does not reference any tables". Huh? Does it not see the FROM dbo.Company??!! What is going on here? So, I have multiple questions: How do I get it to capture the actual statement executing in my trace, not what was submitted in a batch? Are there any best practices to follow for tuning performance related to SSIS packages running against SQL Server 2008?

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Backreferences syntax in replacement strings (why dollar sign?)

- by polygenelubricants

In Java, and it seems in a few other languages, backreferences in the pattern is preceded by a slash (e.g. \1, \2, \3, etc), but in a replacement string it's preceded by a dollar sign (e.g. $1, $2, $3, and also $0). Here's a snippet to illustrate: System.out.println( "left-right".replaceAll("(.*)-(.*)", "\\2-\\1") // WRONG!!! ); // prints "2-1" System.out.println( "left-right".replaceAll("(.*)-(.*)", "$2-$1") // CORRECT! ); // prints "right-left" System.out.println( "You want million dollar?!?".replaceAll("(\\w*) dollar", "US\\$ $1") ); // prints "You want US$ million?!?" System.out.println( "You want million dollar?!?".replaceAll("(\\w*) dollar", "US$ \\1") ); // throws IllegalArgumentException: Illegal group reference Questions: Is the use of $ for backreferences in replacement strings unique to Java? If not, what language started it? What flavors use it and what don't? Why is this a good idea? Why not stick to the same pattern syntax? Wouldn't that lead to a more cohesive and an easier to learn language? Wouldn't the syntax be more streamlined if statements 1 and 4 in the above were the "correct" ones instead of 2 and 3?

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C# System.Xml.Serialization Self-nested elements

- by Jake

Hi, I am trying to deserialize <graph> <node> <node> <node></node> </node> </node> <node> <node> <node></node> </node> </node> </graph> with [XmlRoot("graph")] class graph { List<node> _children = new List<node>(); [XmlElement("node")] public Node[] node { get { return _children.ToArray(); } set { foreach(node n in value) children.add(n) } }; } class node { List<node> _children = new List<node>(); [XmlElement("node")] public Node[] node { get { return _children.ToArray(); } set { foreach(node n in value) children.add(n) } }; } but it keeps saying object not created, null reference encountered when trying to set children nodes. What is wrong above? Thanks in advance~

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Can the Singleton be replaced by Factory?

- by lostiniceland

Hello Everyone There are already quite some posts about the Singleton-Pattern around, but I would like to start another one on this topic since I would like to know if the Factory-Pattern would be the right approach to remove this "anti-pattern". In the past I used the singleton quite a lot, also did my fellow collegues since it is so easy to use. For example, the Eclipse IDE or better its workbench-model makes heavy usage of singletons as well. It was due to some posts about E4 (the next big Eclipse version) that made me start to rethink the singleton. The bottom line was that due to this singletons the dependecies in Eclipse 3.x are tightly coupled. Lets assume I want to get rid of all singletons completely and instead use factories. My thoughts were as follows: hide complexity less coupling I have control over how many instances are created (just store the reference I a private field of the factory) mock the factory for testing (with Dependency Injection) when it is behind an interface In some cases the factories can make more than one singleton obsolete (depending on business logic/component composition) Does this make sense? If not, please give good reasons for why you think so. An alternative solution is also appreciated. Thanks Marc

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Can't connect to MySql database from server using Devart

- by annelie

Hello, I'm having trouble connecting to a MySql database from a server. I'm using Devart to connect, and I'm not sure if I need to do something more than to simply reference the dlls. When I started working on this project it was referencing the CoreLabs dlls, which if I've understood is the previous name for Devart. That didn't work, so I downloaded the new Devart dlls instead. It works on my local machine, but when uploading to the server it crashes. I made a tiny console app to test the connection, and it fails when initialising, before I've even assigned a host etc. Do I need to do anything more than just upload my .exe file to the server? using System; using System.Collections.Generic; using System.Linq; using System.Text; using Devart.Data; using Devart.Data.MySql; namespace TestDatabaseConnection { public class Program { public static void Main(string[] args) { Console.WriteLine("about to connect"); ConnectToDatabase(); Console.ReadLine(); } public static void ConnectToDatabase() { MySqlConnection connection = new MySqlConnection(); } } } UPDATE: I can't see what the error is, I had a try catch around MySqlConnection connection = new MySqlConnection(); but no exception is thrown, it just crashes. Thanks, Annelie

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Java (or possibly other languages) learning path

- by bgo

I am familiar (as a self-learner) with C, python and php such that i can solve some problems involving simple steps (for example, i easily do calculations for physics lab reports with python which normally would take 4x-5x times longer with a calculator). The point here is, as doing such things, i learnt the idea / concepts of programming language and problem solving along with oop or fuctional programming etc. Recently i have started Java and, with the familiarity of other languages, i am doing well for starters but i need guidence. -I am thinking of learning syntax from sun java tutorials and then practicing with codingbat.com or similar sites. I need a reference book that i can study deeper aspects of the topics i am learning. What do you suggest about these? -The problem is (and always have been) the lack of practice. I need coding and problem-solving practices sources. I stuck at the point where i can't figure out what to do next. Can you suggest any source (possibly like codingbat)? If i could plan a learning trail, i can progress faster and efficiently. So i need ideas, comments, suggestions. Thanks in advance.

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self referencing object in JPA

- by geoaxis

Hello, I am trying to save a SystemUser entity in JPA. I also want to save certain things like who created the SystemUser and who last modified the system User as well. @ManyToOne(targetEntity = SystemUser.class) @JoinColumn private SystemUser userWhoCreated; @Temporal(TemporalType.TIMESTAMP) @DateTimeFormat(iso=ISO.DATE_TIME) private Date timeCreated; @ManyToOne(targetEntity = SystemUser.class) @JoinColumn private SystemUser userWhoLastModified; @Temporal(TemporalType.TIMESTAMP) @DateTimeFormat(iso=ISO.DATE_TIME) private Date timeLastModified; I also want to ensure that these values are not null when persisted. So If I use the NotNull JPA annotation, that is easily solved (along with reference to another entity) The problem description is simple, I cannot save rootuser without having rootuser in the system if I am to use a DataLoader class to persist JPA entity. Every other later user can be easily persisted with userWhoModified as the "systemuser" , but systemuser it's self cannot be added in this scheme. Is there a way so persist this first system user (I am thinking with SQL). This is a typical bootstrap (chicken or the egg) problem i suppose.

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binding nested json object value to a form field

- by Jack

I am building a dynamic form to edit data in a json object. First, if something like this exists let me know. I would rather not build it but I have searched many times for a tool and have found only tree like structures that require entering quotes. I would be happy to treat all values as strings. This edit functionality is for end users so it needs to be easy an not intimidating. So far I have code that generates nested tables to represent a json object. For each value I display a form field. I would like to bind the form field to the associated nested json value. If I could store a reference to the json value I would build an array of references to each value in a json object tree. I have not found a way to do that with javascript. My last resort approach will be to traverse the table after edits are made. I would rather have dynamic updates but a single submit would be better than nothing. Any ideas? // the json in files nests only a few levels. Here is the format of a simple case, { "researcherid_id":{ "id_key":"researcherid_id", "description":"Use to retrieve bibliometric data", "url_template" :[ { "name": "Author Detail", "url": "http://www.researcherid.com/rid/${key}" } ] } } $.get('file.json',make_json_form); function make_json_form(response) { dataset = $.secureEvalJSON(response); // iterate through the object and generate form field for string values. } // Then after the form is edited I want to display the raw updated json (then I want to save it but that is for another thread) // now I iterate through the form and construct the json object // I would rather have the dataset object var updated on focus out after each edit. function show_json(form_id){ var r = {}; var el = document.getElementById(form_id); table_to_json(r,el,null); $('body').html(formattedJSON(r)); }

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Template operator linker error

- by Dani

I have a linker error I've reduced to a simple example. The build output is: debug/main.o: In function main': C:\Users\Dani\Documents\Projects\Test1/main.cpp:5: undefined reference tolog& log::operator<< (char const (&) [6])' collect2: ld returned 1 exit status It looks like the linker ignores the definition in log.cpp. I also cant put the definition in log.h because I include the file alot of times and it complains about redefinitions. main.cpp: #include "log.h" int main() { log() << "hello"; return 0; } log.h: #ifndef LOG_H #define LOG_H class log { public: log(); template<typename T> log &operator <<(T &t); }; #endif // LOG_H log.cpp: #include "log.h" #include <iostream> log::log() { } template<typename T> log &log::operator <<(T &t) { std::cout << t << std::endl; return *this; }

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IE event callback object JavaScript

- by Randy Hall

I may be WAY off on my terminology, so please feel free to correct me. Perhaps this is why I cannot seem to find anything relevant. No libraries, please. I have an event handler, which invokes a callback function. Fancy, right? In IE<9 the this object in the handler is the window. I don't know why, or how to access the correct object. if (document.addEventListener){ element.addEventListener(event, callback, false); } else { element.attachEvent('on' +event, callback); } This part DOES WORK. This part doesn't: function callback(event){ console.log(this); } this in IE is returning [object Window], whereas it returns the element that called the callback function in every other browser. This is cut down significantly from my full script, but this should be everything that's relevant. EDIT This link provided by @metadings How to reference the caller object ("this") using attachEvent is very close. However, there are still two issues. 1) I need to get both the event object and the DOM element calling this function. 2) This event is handled delegation style: there may be child DOM elements firing the event, meaning event.target is not necessarily (and in my case, not typically) the element with the listener.

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Perl - Read XML

- by chinna_82

XML <?xml version='1.0'?> <employee> <name>Smith</name> <age>43</age> <sex>M</sex> <department role='manager'>Operations</department> </employee> Perl use XML::Simple; use Data::Dumper; $xml = new XML::Simple; foreach my $data1 ($data = $xml->XMLin("test.xml")) { print Dumper($data1); } Above code managed to all the xml value like this. Output $VAR1 = { 'department' => { 'content' => 'Operations', 'role' => 'manager' }, 'name' => 'John Doe', 'sex' => 'M', 'age' => '43' }; How do I do, if I only want to get the role value. For this example I need to get Role = manager. Any advice or reference link is highly appreciated.

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Facebook SDK Comment Deleting

- by mwoodworth

Working with the Facebook php SDK's, I am having a lot of trouble figuring out how to delete comments, given its id and xid. At first I was using the REST API, where you can call 'comments_remove($xid, $id);' to delete a comment. The problem with this method came when the xid parameter only accepts alphanumeric characters and underscores. Based on the documentation (http://developers.facebook.com/docs/reference/fbml/comments ) a valid XID can be the result of any url_encode. Now I am testing my luck with the new GRAPH api. Looking at http://developers.facebook.com/docs/api under 'Deleting Objects', It seems that comment deleting is definitely supported. However, I have tried sending a DELETE request, and I have also tried sending POST and GET to the object url with the argument 'method=delete'. No matter how I try it, I always get the same error: {"error":{"type":"GraphMethodException","message":"Unsupported delete request."}} I am sending the access token as a parameter as well. The access token that I am sending is the access token saved in the facebook cookie from the single sign on javascript cookie. These are all comments made on my application. Does this happen to anyone else, or am I simply not doing this right? Any help or guidance is GREATLY appreciated.

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How do I draw the points in an ESRI Polyline, given the bounding box as lat/long and the "points" as

- by Aaron

I'm using OpenMap and I'm reading a ShapeFile using com.bbn.openmap.layer.shape.ShapeFile. The bounding box is read in as lat/long points, for example 39.583642,-104.895486. The bounding box is a lower-left point and an upper-right point which represents where the points are contained. The "points," which are named "radians" in OpenMap, are in a different format, which looks like this: [0.69086486, -1.8307719, 0.6908546, -1.8307716, 0.6908518, -1.8307717, 0.69085056, -1.8307722, 0.69084936, -1.8307728, 0.6908477, -1.8307738, 0.69084626, -1.8307749, 0.69084185, -1.8307792]. How do I convert the points like "0.69086486, -1.8307719" into x,y coordinates that are usable in normal graphics? I believe all that's needed here is some kind of conversion, because bringing the points into Excel and graphing them creates a line whose curve matches the curve of the road at the given location (lat/long). However, the axises need to be adjusted manually and I have no reference as how to adjust the axises, since the given bounding box appears to be in a different format than the given points. The ESRI Shapefile technical description doesn't seem to mention this (http://www.esri.com/library/whitepapers/pdfs/shapefile.pdf).

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Weird .net 4.0 exception when running unit tests

- by vdh_ant

Hi guys I am receiving the following exception when trying to run my unit tests using .net 4.0 under VS2010 with moq 3.1. Attempt by security transparent method 'SPPD.Backend.DataAccess.Test.Specs_for_Core.When_using_base.Can_create_mapper()' to access security critical method 'Microsoft.VisualStudio.TestTools.UnitTesting.Assert.IsNotNull(System.Object)' failed. Assembly 'SPPD.Backend.DataAccess.Test, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' is marked with the AllowPartiallyTrustedCallersAttribute, and uses the level 2 security transparency model. Level 2 transparency causes all methods in AllowPartiallyTrustedCallers assemblies to become security transparent by default, which may be the cause of this exception. The test I am running is really straight forward and looks something like the following: [TestMethod] public void Can_create_mapper() { this.SetupTest(); var mockMapper = new Moq.Mock<IMapper>().Object; this._Resolver.Setup(x => x.Resolve<IMapper>()).Returns(mockMapper).Verifiable(); var testBaseDa = new TestBaseDa(); var result = testBaseDa.TestCreateMapper<IMapper>(); Assert.IsNotNull(result); //<<< THROWS EXCEPTION HERE Assert.AreSame(mockMapper, result); this._Resolver.Verify(); } I have no idea what this means and I have been looking around and have found very little on the topic. The closest reference I have found is this http://dotnetzip.codeplex.com/Thread/View.aspx?ThreadId=80274 but its not very clear on what they did to fix it... Anyone got any ideas?

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Value objects in DDD - Why immutable?

- by Hobbes

I don't get why value objects in DDD should be immutable, nor do I see how this is easily done. (I'm focusing on C# and Entity Framework, if that matters.) For example, let's consider the classic Address value object. If you needed to change "123 Main St" to "123 Main Street", why should I need to construct a whole new object instead of saying myCustomer.Address.AddressLine1 = "123 Main Street"? (Even if Entity Framework supported structs, this would still be a problem, wouldn't it?) I understand (I think) the idea that value objects don't have an identity and are part of a domain object, but can someone explain why immutability is a Good Thing? EDIT: My final question here really should be "Can someone explain why immutability is a Good Thing as applied to Value Objects?" Sorry for the confusion! EDIT: To clairfy, I am not asking about CLR value types (vs reference types). I'm asking about the higher level DDD concept of Value Objects. For example, here is a hack-ish way to implement immutable value types for Entity Framework: http://rogeralsing.com/2009/05/21/entity-framework-4-immutable-value-objects. Basically, he just makes all setters private. Why go through the trouble of doing this?

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Problem with using malloc in link lists (urgent ! help please)

- by Abhinav

I've been working on this program for five months now. Its a real time application of a sensor network. I create several link lists during the life of the program and Im using malloc for creating a new node in the link. What happens is that the program suddenly stops or goes crazy and restarts. Im using AVR and the microcontroller is ATMEGA 1281. After a lot of debugging I figured out that that the malloc is causing the problem. I do not free the memory after exiting the function that creates a new link so Im guessing that this is eventually causing the heap memory to overflow or something like that. Now if I use the free() function to deallocate the memory at the end of the function using malloc, the program just gets stuck when the control reaches free(). Is this because the memory becomes too clustered after calling free() ? I also create reference tables for example if 'head' is a new link list and I create another list called current and make it equal to head. table *head; table *current = head; After the end of the function if I use free free(current); current = NULL: Then the program gets stuck here. I dont know what to do. What am I doing wrong? Is there a way to increase the size of the heap memory Please help...

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Updating MS Access Database from Datagridview

- by Peter Roche

I am trying to update an ms access database from a datagridview. The datagridview is populated on a button click and the database is updated when any cell is modified. The code example I have been using populates on form load and uses the cellendedit event. private OleDbConnection connection = null; private OleDbDataAdapter dataadapter = null; private DataSet ds = null; private void Form2_Load(object sender, EventArgs e) { string connetionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='C:\\Users\\Peter\\Documents\\Visual Studio 2010\\Projects\\StockIT\\StockIT\\bin\\Debug\\StockManagement.accdb';Persist Security Info=True;Jet OLEDB:Database Password="; string sql = "SELECT * FROM StockCount"; connection = new OleDbConnection(connetionString); dataadapter = new OleDbDataAdapter(sql, connection); ds = new DataSet(); connection.Open(); dataadapter.Fill(ds, "Stock"); connection.Close(); dataGridView1.DataSource = ds; dataGridView1.DataMember = "Stock"; } private void addUpadateButton_Click(object sender, EventArgs e) { } private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e) { try { dataadapter.Update(ds,"Stock"); } catch (Exception exceptionObj) { MessageBox.Show(exceptionObj.Message.ToString()); } } The error I receive is Update requires a valid UpdateCommand when passed DataRow collection with modified rows. I'm not sure where this command needs to go and how to reference the cell to update the value in the database.

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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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JDO difficulties in retrieving persistent vector

- by Michael Omer

I know there are already some posts regarding this subject, but although I tried using them as a reference, I am still stuck. I have a persistent class as follows: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class GameObject implements IMySerializable{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) protected Key m_databaseKey; @NotPersistent private final static int END_GAME_VAR = -1000; @Persistent(defaultFetchGroup = "true") protected GameObjectSet m_set; @Persistent protected int m_databaseType = IDatabaseAccess.TYPE_NONE; where GameObjectSet is: @PersistenceCapable(identityType = IdentityType.APPLICATION) @FetchGroup(name = "mySet", members = {@Persistent(name = "m_set")}) public class GameObjectSet { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key id; @Persistent private Vector<GameObjectSetPair> m_set; and GameObjectSetPair is: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class GameObjectSetPair { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key id; @Persistent private String key; @Persistent(defaultFetchGroup = "true") private GameObjectVar value; When I try to fetch the entire structure by fetching the GameObject, the set doesn't have any elements (they are all null) I tried adding the fetching group to the PM, but to no avail. This is my fetching code Vector<GameObject> ret = new Vector<GameObject>(); PersistenceManager pm = PMF.get().getPersistenceManager(); pm.getFetchPlan().setMaxFetchDepth(-1); pm.getFetchPlan().addGroup("mySet"); Query myQuery = pm.newQuery(GameObject.class); myQuery.setFilter("m_databaseType == objectType"); myQuery.declareParameters("int objectType"); try { List<GameObject> res = (List<GameObject>)myQuery.execute(objectType); ret = new Vector<GameObject>(res); for (int i = 0; i < ret.size(); i++) { ret.elementAt(i).getSet(); ret.elementAt(i).getSet().touchSet(); } } catch (Exception e) { } finally { pm.close(); } Does anyone have any idea? Thanks Mike

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Return an empty collection when Linq where returns nothing

- by ahsteele

I am using the below statement with the intent of getting all of the machine objects from the MachineList collection (type IEnumerable) that have a MachineStatus of i. The MachineList collection will not always contain machines with a status of i. At times when no machines have a MachineStatus of i I'd like to return an empty collection. My call to ActiveMachines (which is used first) works but InactiveMachines does not. public IEnumerable<Machine> ActiveMachines { get { return Customer.MachineList .Where(m => m.MachineStatus == "a"); } } public IEnumerable<Machine> InactiveMachines { get { return Customer.MachineList .Where(m => m.MachineStatus == "i"); } } Edit Upon further examination it appears that any enumeration of MachineList will cause subsequent enumerations of MachineList to throw an exeception: Object reference not set to an instance of an object. Therefore, it doesn't matter if a call is made to ActiveMachines or InactiveMachines as its an issue with the MachineList collection. This is especially troubling because I can break calls to MachineList simply by enumerating it in a Watch before it is called in code. At its lowest level MachineList implements NHibernate.IQuery being returned as an IEnumerable. What's causing MachineList to lose its contents after an initial enumeration?

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