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  • HowTo check whether Exception Block is available for the main PLSQL block or routine

    - by user1297211
    I am trying to think of a validator that checks for Exception block available in PL/SQL block or any routine for the main body ( Highlighted in Bold). Eg : DECLARE some data Procedure xyx IS BEGIN .... EXCEPTION .. END; BEGIN some data BEGIN .... EXCEPTION .. END; **EXCEPTION** some data BEGIN .... EXCEPTION .. END; END; This is a simple example there can be many other scenarios but my need id to find that Exception block is avaialble for the main block of PL/SQL code. Please let me know if you have any suggestion. Thanks

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  • 2D Platformer Collision Handling

    - by defender-zone
    Hello, everyone! I am trying to create a 2D platformer (Mario-type) game and I am some having some issues with handling collisions properly. I am writing this game in C++, using SDL for input, image loading, font loading, etcetera. I am also using OpenGL via the FreeGLUT library in conjunction with SDL to display graphics. My method of collision detection is AABB (Axis-Aligned Bounding Box), which is really all I need to start with. What I need is an easy way to both detect which side the collision occurred on and handle the collisions properly. So, basically, if the player collides with the top of the platform, reposition him to the top; if there is a collision to the sides, reposition the player back to the side of the object; if there is a collision to the bottom, reposition the player under the platform. I have tried many different ways of doing this, such as trying to find the penetration depth and repositioning the player backwards by the penetration depth. Sadly, nothing I've tried seems to work correctly. Player movement ends up being very glitchy and repositions the player when I don't want it to. Part of the reason is probably because I feel like this is something so simple but I'm over-thinking it. If anyone thinks they can help, please take a look at the code below and help me try to improve on this if you can. I would like to refrain from using a library to handle this (as I want to learn on my own) or the something like the SAT (Separating Axis Theorem) if at all possible. Thank you in advance for your help! void world1Level1CollisionDetection() { for(int i; i < blocks; i++) { if (de2dCheckCollision(ball,block[i],0.0f,0.0f)==true) { int up = 0; int left = 0; int right = 0; int down = 0; if(ball.coords[0] < block[i].coords[0] && block[i].coords[0] < ball.coords[2] && ball.coords[2] < block[i].coords[2]) { left = 1; } if(block[i].coords[0] < ball.coords[0] && ball.coords[0] < block[i].coords[2] && block[i].coords[2] < ball.coords[2]) { right = 1; } if(ball.coords[1] < block[i].coords[1] && block[i].coords[1] < ball.coords[3] && ball.coords[3] < block[i].coords[3]) { up = 1; } if(block[i].coords[1] < ball.coords[1] && ball.coords[1] < block[i].coords[3] && block[i].coords[3] < ball.coords[3]) { down = 1; } cout << left << ", " << right << ", " << up << ", " << down << ", " << endl; if (left == 1) { ball.coords[0] = block[i].coords[0] - 16.0f; ball.coords[2] = block[i].coords[0] - 0.0f; } if (right == 1) { ball.coords[0] = block[i].coords[2] + 0.0f; ball.coords[2] = block[i].coords[2] + 16.0f; } if (down == 1) { ball.coords[1] = block[i].coords[3] + 0.0f; ball.coords[3] = block[i].coords[3] + 16.0f; } if (up == 1) { ball.yspeed = 0.0f; ball.gravity = 0.0f; ball.coords[1] = block[i].coords[1] - 16.0f; ball.coords[3] = block[i].coords[1] - 0.0f; } } if (de2dCheckCollision(ball,block[i],0.0f,0.0f)==false) { ball.gravity = -0.5f; } } } To explain what some of this code means: The blocks variable is basically an integer that is storing the amount of blocks, or platforms. I am checking all of the blocks using a for loop, and the number that the loop is currently on is represented by integer i. The coordinate system might seem a little weird, so that's worth explaining. coords[0] represents the x position (left) of the object (where it starts on the x axis). coords[1] represents the y position (top) of the object (where it starts on the y axis). coords[2] represents the width of the object plus coords[0] (right). coords[3] represents the height of the object plus coords[1] (bottom). de2dCheckCollision performs an AABB collision detection. Up is negative y and down is positive y, as it is in most games. Hopefully I have provided enough information for someone to help me successfully. If there is something I left out that might be crucial, let me know and I'll provide the necessary information. Finally, for anyone who can help, providing code would be very helpful and much appreciated. Thank you again for your help!

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  • Handling WCF Service Paths in Silverlight 4 – Relative Path Support

    - by dwahlin
    If you’re building Silverlight applications that consume data then you’re probably making calls to Web Services. We’ve been successfully using WCF along with Silverlight for several client Line of Business (LOB) applications and passing a lot of data back and forth. Due to the pain involved with updating the ServiceReferences.ClientConfig file generated by a Silverlight service proxy (see Tim Heuer’s post on that subject to see different ways to deal with it) we’ve been using our own technique to figure out the service URL. Going that route makes it a peace of cake to switch between development, staging and production environments. To start, we have a ServiceProxyBase class that handles identifying the URL to use based on the XAP file’s location (this assumes that the service is in the same Web project that serves up the XAP file). The GetServiceUrlBase() method handles this work: public class ServiceProxyBase { public ServiceProxyBase() { if (!IsDesignTime) { ServiceUrlBase = GetServiceUrlBase(); } } public string ServiceUrlBase { get; set; } public static bool IsDesignTime { get { return (Application.Current == null) || (Application.Current.GetType() == typeof (Application)); } } public static string GetServiceUrlBase() { if (!IsDesignTime) { string url = Application.Current.Host.Source.OriginalString; return url.Substring(0, url.IndexOf("/ClientBin", StringComparison.InvariantCultureIgnoreCase)); } return null; } } Silverlight 4 now supports relative paths to services which greatly simplifies things.  We changed the code above to the following: public class ServiceProxyBase { private const string ServiceUrlPath = "../Services/JobPlanService.svc"; public ServiceProxyBase() { if (!IsDesignTime) { ServiceUrl = ServiceUrlPath; } } public string ServiceUrl { get; set; } public static bool IsDesignTime { get { return (Application.Current == null) || (Application.Current.GetType() == typeof (Application)); } } public static string GetServiceUrl() { if (!IsDesignTime) { return ServiceUrlPath; } return null; } } Our ServiceProxy class derives from ServiceProxyBase and handles creating the ABC’s (Address, Binding, Contract) needed for a WCF service call. Looking through the code (mainly the constructor) you’ll notice that the service URI is created by supplying the base path to the XAP file along with the relative path defined in ServiceProxyBase:   public class ServiceProxy : ServiceProxyBase, IServiceProxy { private const string CompletedEventargs = "CompletedEventArgs"; private const string Completed = "Completed"; private const string Async = "Async"; private readonly CustomBinding _Binding; private readonly EndpointAddress _EndPointAddress; private readonly Uri _ServiceUri; private readonly Type _ProxyType = typeof(JobPlanServiceClient); public ServiceProxy() { _ServiceUri = new Uri(Application.Current.Host.Source, ServiceUrl); var elements = new BindingElementCollection { new BinaryMessageEncodingBindingElement(), new HttpTransportBindingElement { MaxBufferSize = 2147483647, MaxReceivedMessageSize = 2147483647 } }; // order of entries in collection is significant: dumb _Binding = new CustomBinding(elements); _EndPointAddress = new EndpointAddress(_ServiceUri); } #region IServiceProxy Members /// <summary> /// Used to call a WCF service operation. /// </summary> /// <typeparam name="T">The type of EventArgs that will be returned by the service operation.</typeparam> /// <param name="callback">The method to call once the WCF call returns (the callback).</param> /// <param name="parameters">Any parameters that the service operation expects.</param> public void CallService<T>(EventHandler<T> callback, params object[] parameters) where T : EventArgs { try { var proxy = new JobPlanServiceClient(_Binding, _EndPointAddress); string action = typeof (T).Name.Replace(CompletedEventargs, String.Empty); _ProxyType.GetEvent(action + Completed).AddEventHandler(proxy, callback); _ProxyType.InvokeMember(action + Async, BindingFlags.InvokeMethod, null, proxy, parameters); } catch (Exception exp) { MessageBox.Show("Unable to use ServiceProxy.CallService to retrieve data: " + exp.Message); } } #endregion } The relative path support for calling services in Silverlight 4 definitely simplifies code and is yet another good reason to move from Silverlight 3 to Silverlight 4.   For more information about onsite, online and video training, mentoring and consulting solutions for .NET, SharePoint or Silverlight please visit http://www.thewahlingroup.com.

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  • The hidden cost of interrupting knowledge workers

    - by Piet
    The November issue of pragpub has an interesting article on interruptions. The article is written by Brian Tarbox, who also mentions the article on his blog. I like the subtitle: ‘Simple Strategies for Avoiding Dumping Your Mental Stack’. Brian talks about the effective cost of interrupting a ‘knowledge worker’, often with trivial questions or distractions. In the eyes of the interruptor, the interruption only costs the time the interrupted had to listen to the question and give an answer. However, depending on what the interrupted was doing at the time, getting fully immersed in their task again might take up to 15-20 minutes. Enough interruptions might even cause a knowledge worker to mentally call it a day. According to this article interruptions can consume about 28% of a knowledge worker’s time, translating in a $588 billion loss for US companies each year. Looking for a new developer to join your team? Ever thought about optimizing your team’s environment and the way they work instead? Making non knowledge workers aware You can’t. Well, I haven’t succeeded yet. And believe me: I’ve tried. When you’ve got a simple way to really increase your productivity (’give me 2 hours of uninterrupted time a day’) it wouldn’t be right not to tell your boss or team-leader about it. The problem is: only productive knowledge workers seem to understand this. People who don’t fall into this category just seem to think you’re joking, being arrogant or anti-social when you tell them the interruptions can really have an impact on your productivity. Also, knowledge workers often work in a very concentrated mental state which is described here as: It is the same mindfulness as ecstatic lovemaking, the merging of two into a fluidly harmonious one. The hallmark of flow is a feeling of spontaneous joy, even rapture, while performing a task. Yes, coding can be addictive and if you’re interrupting a programmer at the wrong moment, you’re effectively bringing down a junkie from his high in just a few seconds. This can result in seemingly arrogant, almost aggressive reactions. How to make people aware of the production-cost they’re inflicting: I’ve been often pondering that question myself. The article suggests that solutions based on that question never seem to work. To be honest: I’ve never even been able to find a half decent solution for this question. People who are not in this situations just don’t understand the issue, no matter how you try to explain it. Fun (?) thing I’ve noticed: Programmers or IT people in general who don’t get this are often the kind of people who just don’t get anything done. Interrupt handling (interruption management?) IRL Have non-urgent questions handled in a non-interruptive way It helps a bit to educate people into using non-interruptive ways to ask questions: “duh, I have no idea, but I’m a bit busy here now could you put it in an email so I don’t forget?”. Eventually, a considerable amount of people will skip interrupting you and just send an email right away. Some stubborn-headed people however will continue to just interrupt you, saying “you’re 10 meters from my desk, why can’t we just talk?”. Just remember to disable your email notifications, it can be hard to resist opening your email client when you know a new email just arrived. Use Do Not Disturb signals When working in a group of programmers, often the unofficial sign you can only be interrupted for something important is to put on headphones. And when the environment is quiet enough, often people aren’t even listening to music. Otherwise music can help to block the indirect distractions (someone else talking on the phone or tapping their feet). You might get a “they’re all just surfing and listening to music”-reaction from outsiders though. Peopleware talks about a team where the no-interruption sign was placing a shawl on the desk. If I remember correctly, I am unable to locate my copy of this really excellent must-read book. If you have all standardized on the same IM tool, maybe that tool has a ‘do not disturb’ setting. Also some phone-systems have a ‘DND’ (do not disturb) setting. Hide Brian offers a number of good suggestions, some obvious like: hide away somewhere they can’t find you. Not sure how long it’ll be till someone thinks you’re just taking a nap somewhere though. Also, this often isn’t possible or your boss might not understand this. And if you really get caught taking a nap, make sure to explain that your were powernapping. Counter-act interruptions Another suggestion he offers is when you’re being interrupted to just hold up your hand, blocking the interruption, and at least giving you time to finish your sentence or your block/line of code. The last suggestion works more as a way to make it obvious to the interruptor that they really are interrupting your work and to offload some of the cost on the interruptor. In practice, this can also helps you cool down a bit so you don’t start saying nasty things to the interruptor. Unfortunately I’ve sometimes been confronted with people who just ignore this signal and keep talking, as if they’re sure that whatever they’ve got to say is really worth listening to and without a doubt more important than anything you might be doing. This behaviour usually leaves me speechless (not good when someone just asked a question). I’ve noticed that these people are usually also the first to complain when being interrupted themselves. They’re generally not very liked as colleagues, so try not to imitate their behaviour. TDD as a way to minimize recovery time I don’t like Test Driven Development. Mainly for only one reason: It interrupts flow. At least, that’s what it does for me, but maybe I’m just not grown used to TDD yet. BUT a positive effect TDD has on me when I have to work in an interruptive environment and can’t really get into the ‘flow’ (also supposedly called ‘the zone’ by software developers, although I’ve never heard it 1st hand), TDD helps me to concentrate on the tasks at hand and helps me to get back at work after an interruption. I feel when using TDD, I can get by without the need for being totally ‘in’ the project and I can be reasonably productive without obtaining ‘flow’. Do you have a suggestion on how to make people aware of the concept of ‘flow’ and the cost of interruptions? (without looking like an arrogant ass or a weirdo)

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  • Converting a generic list into JSON string and then handling it in java script

    - by Jalpesh P. Vadgama
    We all know that JSON (JavaScript Object Notification) is very useful in case of manipulating string on client side with java script and its performance is very good over browsers so let’s create a simple example where convert a Generic List then we will convert this list into JSON string and then we will call this web service from java script and will handle in java script. To do this we need a info class(Type) and for that class we are going to create generic list. Here is code for that I have created simple class with two properties UserId and UserName public class UserInfo { public int UserId { get; set; } public string UserName { get; set; } } Now Let’s create a web service and web method will create a class and then we will convert this with in JSON string with JavaScriptSerializer class. Here is web service class. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Services; namespace Experiment.WebService { /// <summary> /// Summary description for WsApplicationUser /// </summary> [WebService(Namespace = "http://tempuri.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] [System.ComponentModel.ToolboxItem(false)] // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. [System.Web.Script.Services.ScriptService] public class WsApplicationUser : System.Web.Services.WebService { [WebMethod] public string GetUserList() { List<UserInfo> userList = new List<UserInfo>(); for (int i = 1; i <= 5; i++) { UserInfo userInfo = new UserInfo(); userInfo.UserId = i; userInfo.UserName = string.Format("{0}{1}", "J", i.ToString()); userList.Add(userInfo); } System.Web.Script.Serialization.JavaScriptSerializer jSearializer = new System.Web.Script.Serialization.JavaScriptSerializer(); return jSearializer.Serialize(userList); } } } Note: Here you must have this attribute here in web service class ‘[System.Web.Script.Services.ScriptService]’ as this attribute will enable web service to call from client side. Now we have created a web service class let’s create a java script function ‘GetUserList’ which will call web service from JavaScript like following function GetUserList() { Experiment.WebService.WsApplicationUser.GetUserList(ReuqestCompleteCallback, RequestFailedCallback); } After as you can see we have inserted two call back function ReuqestCompleteCallback and RequestFailedCallback which handle errors and result from web service. ReuqestCompleteCallback will handle result of web service and if and error comes then RequestFailedCallback will print the error. Following is code for both function. function ReuqestCompleteCallback(result) { result = eval(result); var divResult = document.getElementById("divUserList"); CreateUserListTable(result); } function RequestFailedCallback(error) { var stackTrace = error.get_stackTrace(); var message = error.get_message(); var statusCode = error.get_statusCode(); var exceptionType = error.get_exceptionType(); var timedout = error.get_timedOut(); // Display the error. var divResult = document.getElementById("divUserList"); divResult.innerHTML = "Stack Trace: " + stackTrace + "<br/>" + "Service Error: " + message + "<br/>" + "Status Code: " + statusCode + "<br/>" + "Exception Type: " + exceptionType + "<br/>" + "Timedout: " + timedout; } Here in above there is a function called you can see that we have use ‘eval’ function which parse string in enumerable form. Then we are calling a function call ‘CreateUserListTable’ which will create a table string and paste string in the a div. Here is code for that function. function CreateUserListTable(userList) { var tablestring = '<table ><tr><td>UsreID</td><td>UserName</td></tr>'; for (var i = 0, len = userList.length; i < len; ++i) { tablestring=tablestring + "<tr>"; tablestring=tablestring + "<td>" + userList[i].UserId + "</td>"; tablestring=tablestring + "<td>" + userList[i].UserName + "</td>"; tablestring=tablestring + "</tr>"; } tablestring = tablestring + "</table>"; var divResult = document.getElementById("divUserList"); divResult.innerHTML = tablestring; } Now let’s create div which will have all html that is generated from this function. Here is code of my web page. We also need to add a script reference to enable web service from client side. Here is all HTML code we have. <form id="form1" runat="server"> <asp:ScriptManager ID="myScirptManger" runat="Server"> <Services> <asp:ServiceReference Path="~/WebService/WsApplicationUser.asmx" /> </Services> </asp:ScriptManager> <div id="divUserList"> </div> </form> Now as we have not defined where we are going to call ‘GetUserList’ function so let’s call this function on windows onload event of javascript like following. window.onload=GetUserList(); That’s it. Now let’s run it on browser to see whether it’s work or not and here is the output in browser as expected. That’s it. This was very basic example but you can crate your own JavaScript enabled grid from this and you can see possibilities are unlimited here. Stay tuned for more.. Happy programming.. Technorati Tags: JSON,Javascript,ASP.NET,WebService

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  • How important do you find exception safety to be in your C++ code?

    - by Kai
    Every time I consider making my code strongly exception safe, I justify not doing it because it would be so time consuming. Consider this relatively simple snippet: Level::Entity* entity = new Level::Entity(); entity->id = GetNextId(); entity->AddComponent(new Component::Position(x, y)); entity->AddComponent(new Component::Movement()); entity->AddComponent(new Component::Render()); allEntities.push_back(entity); // std::vector entityById[entity->id] = entity; // std::map return entity; To implement a basic exception guarantee, I could use a scoped pointer on the new calls. This would prevent memory leaks if any of the calls were to throw an exception. However, let's say I want to implement a strong exception guarantee. At the least, I would need to implement a shared pointer for my containers (I'm not using Boost), a nothrow Entity::Swap for adding the components atomically, and some sort of idiom for atomically adding to both the Vector and Map. Not only would these be time consuming to implement, but they would be expensive since it involves a lot more copying than the exception unsafe solution. Ultimately, it feels to me like that time spent doing all of that wouldn't be justified just so that the a simple CreateEntity function is strongly exception safe. I probably just want the game to display an error and close at that point anyway. How far do you take this in your own game projects? Is it generally acceptable to write exception unsafe code for a program that can just crash when there is an exception?

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  • How to simulate inner join on very large files in java (without running out of memory)

    - by Constantin
    I am trying to simulate SQL joins using java and very large text files (INNER, RIGHT OUTER and LEFT OUTER). The files have already been sorted using an external sort routine. The issue I have is I am trying to find the most efficient way to deal with the INNER join part of the algorithm. Right now I am using two Lists to store the lines that have the same key and iterate through the set of lines in the right file once for every line in the left file (provided the keys still match). In other words, the join key is not unique in each file so would need to account for the Cartesian product situations ... left_01, 1 left_02, 1 right_01, 1 right_02, 1 right_03, 1 left_01 joins to right_01 using key 1 left_01 joins to right_02 using key 1 left_01 joins to right_03 using key 1 left_02 joins to right_01 using key 1 left_02 joins to right_02 using key 1 left_02 joins to right_03 using key 1 My concern is one of memory. I will run out of memory if i use the approach below but still want the inner join part to work fairly quickly. What is the best approach to deal with the INNER join part keeping in mind that these files may potentially be huge public class Joiner { private void join(BufferedReader left, BufferedReader right, BufferedWriter output) throws Throwable { BufferedReader _left = left; BufferedReader _right = right; BufferedWriter _output = output; Record _leftRecord; Record _rightRecord; _leftRecord = read(_left); _rightRecord = read(_right); while( _leftRecord != null && _rightRecord != null ) { if( _leftRecord.getKey() < _rightRecord.getKey() ) { write(_output, _leftRecord, null); _leftRecord = read(_left); } else if( _leftRecord.getKey() > _rightRecord.getKey() ) { write(_output, null, _rightRecord); _rightRecord = read(_right); } else { List<Record> leftList = new ArrayList<Record>(); List<Record> rightList = new ArrayList<Record>(); _leftRecord = readRecords(leftList, _leftRecord, _left); _rightRecord = readRecords(rightList, _rightRecord, _right); for( Record equalKeyLeftRecord : leftList ){ for( Record equalKeyRightRecord : rightList ){ write(_output, equalKeyLeftRecord, equalKeyRightRecord); } } } } if( _leftRecord != null ) { write(_output, _leftRecord, null); _leftRecord = read(_left); while(_leftRecord != null) { write(_output, _leftRecord, null); _leftRecord = read(_left); } } else { if( _rightRecord != null ) { write(_output, null, _rightRecord); _rightRecord = read(_right); while(_rightRecord != null) { write(_output, null, _rightRecord); _rightRecord = read(_right); } } } _left.close(); _right.close(); _output.flush(); _output.close(); } private Record read(BufferedReader reader) throws Throwable { Record record = null; String data = reader.readLine(); if( data != null ) { record = new Record(data.split("\t")); } return record; } private Record readRecords(List<Record> list, Record record, BufferedReader reader) throws Throwable { int key = record.getKey(); list.add(record); record = read(reader); while( record != null && record.getKey() == key) { list.add(record); record = read(reader); } return record; } private void write(BufferedWriter writer, Record left, Record right) throws Throwable { String leftKey = (left == null ? "null" : Integer.toString(left.getKey())); String leftData = (left == null ? "null" : left.getData()); String rightKey = (right == null ? "null" : Integer.toString(right.getKey())); String rightData = (right == null ? "null" : right.getData()); writer.write("[" + leftKey + "][" + leftData + "][" + rightKey + "][" + rightData + "]\n"); } public static void main(String[] args) { try { BufferedReader leftReader = new BufferedReader(new FileReader("LEFT.DAT")); BufferedReader rightReader = new BufferedReader(new FileReader("RIGHT.DAT")); BufferedWriter output = new BufferedWriter(new FileWriter("OUTPUT.DAT")); Joiner joiner = new Joiner(); joiner.join(leftReader, rightReader, output); } catch (Throwable e) { e.printStackTrace(); } } } After applying the ideas from the proposed answer, I changed the loop to this private void join(RandomAccessFile left, RandomAccessFile right, BufferedWriter output) throws Throwable { long _pointer = 0; RandomAccessFile _left = left; RandomAccessFile _right = right; BufferedWriter _output = output; Record _leftRecord; Record _rightRecord; _leftRecord = read(_left); _rightRecord = read(_right); while( _leftRecord != null && _rightRecord != null ) { if( _leftRecord.getKey() < _rightRecord.getKey() ) { write(_output, _leftRecord, null); _leftRecord = read(_left); } else if( _leftRecord.getKey() > _rightRecord.getKey() ) { write(_output, null, _rightRecord); _pointer = _right.getFilePointer(); _rightRecord = read(_right); } else { long _tempPointer = 0; int key = _leftRecord.getKey(); while( _leftRecord != null && _leftRecord.getKey() == key ) { _right.seek(_pointer); _rightRecord = read(_right); while( _rightRecord != null && _rightRecord.getKey() == key ) { write(_output, _leftRecord, _rightRecord ); _tempPointer = _right.getFilePointer(); _rightRecord = read(_right); } _leftRecord = read(_left); } _pointer = _tempPointer; } } if( _leftRecord != null ) { write(_output, _leftRecord, null); _leftRecord = read(_left); while(_leftRecord != null) { write(_output, _leftRecord, null); _leftRecord = read(_left); } } else { if( _rightRecord != null ) { write(_output, null, _rightRecord); _rightRecord = read(_right); while(_rightRecord != null) { write(_output, null, _rightRecord); _rightRecord = read(_right); } } } _left.close(); _right.close(); _output.flush(); _output.close(); } UPDATE While this approach worked, it was terribly slow and so I have modified this to create files as buffers and this works very well. Here is the update ... private long getMaxBufferedLines(File file) throws Throwable { long freeBytes = Runtime.getRuntime().freeMemory() / 2; return (freeBytes / (file.length() / getLineCount(file))); } private void join(File left, File right, File output, JoinType joinType) throws Throwable { BufferedReader leftFile = new BufferedReader(new FileReader(left)); BufferedReader rightFile = new BufferedReader(new FileReader(right)); BufferedWriter outputFile = new BufferedWriter(new FileWriter(output)); long maxBufferedLines = getMaxBufferedLines(right); Record leftRecord; Record rightRecord; leftRecord = read(leftFile); rightRecord = read(rightFile); while( leftRecord != null && rightRecord != null ) { if( leftRecord.getKey().compareTo(rightRecord.getKey()) < 0) { if( joinType == JoinType.LeftOuterJoin || joinType == JoinType.LeftExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, leftRecord, null); } leftRecord = read(leftFile); } else if( leftRecord.getKey().compareTo(rightRecord.getKey()) > 0 ) { if( joinType == JoinType.RightOuterJoin || joinType == JoinType.RightExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, null, rightRecord); } rightRecord = read(rightFile); } else if( leftRecord.getKey().compareTo(rightRecord.getKey()) == 0 ) { String key = leftRecord.getKey(); List<File> rightRecordFileList = new ArrayList<File>(); List<Record> rightRecordList = new ArrayList<Record>(); rightRecordList.add(rightRecord); rightRecord = consume(key, rightFile, rightRecordList, rightRecordFileList, maxBufferedLines); while( leftRecord != null && leftRecord.getKey().compareTo(key) == 0 ) { processRightRecords(outputFile, leftRecord, rightRecordFileList, rightRecordList, joinType); leftRecord = read(leftFile); } // need a dispose for deleting files in list } else { throw new Exception("DATA IS NOT SORTED"); } } if( leftRecord != null ) { if( joinType == JoinType.LeftOuterJoin || joinType == JoinType.LeftExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, leftRecord, null); } leftRecord = read(leftFile); while(leftRecord != null) { if( joinType == JoinType.LeftOuterJoin || joinType == JoinType.LeftExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, leftRecord, null); } leftRecord = read(leftFile); } } else { if( rightRecord != null ) { if( joinType == JoinType.RightOuterJoin || joinType == JoinType.RightExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, null, rightRecord); } rightRecord = read(rightFile); while(rightRecord != null) { if( joinType == JoinType.RightOuterJoin || joinType == JoinType.RightExclusiveJoin || joinType == JoinType.FullExclusiveJoin || joinType == JoinType.FullOuterJoin ) { write(outputFile, null, rightRecord); } rightRecord = read(rightFile); } } } leftFile.close(); rightFile.close(); outputFile.flush(); outputFile.close(); } public void processRightRecords(BufferedWriter outputFile, Record leftRecord, List<File> rightFiles, List<Record> rightRecords, JoinType joinType) throws Throwable { for(File rightFile : rightFiles) { BufferedReader rightReader = new BufferedReader(new FileReader(rightFile)); Record rightRecord = read(rightReader); while(rightRecord != null){ if( joinType == JoinType.LeftOuterJoin || joinType == JoinType.RightOuterJoin || joinType == JoinType.FullOuterJoin || joinType == JoinType.InnerJoin ) { write(outputFile, leftRecord, rightRecord); } rightRecord = read(rightReader); } rightReader.close(); } for(Record rightRecord : rightRecords) { if( joinType == JoinType.LeftOuterJoin || joinType == JoinType.RightOuterJoin || joinType == JoinType.FullOuterJoin || joinType == JoinType.InnerJoin ) { write(outputFile, leftRecord, rightRecord); } } } /** * consume all records having key (either to a single list or multiple files) each file will * store a buffer full of data. The right record returned represents the outside flow (key is * already positioned to next one or null) so we can't use this record in below while loop or * within this block in general when comparing current key. The trick is to keep consuming * from a List. When it becomes empty, re-fill it from the next file until all files have * been consumed (and the last node in the list is read). The next outside iteration will be * ready to be processed (either it will be null or it points to the next biggest key * @throws Throwable * */ private Record consume(String key, BufferedReader reader, List<Record> records, List<File> files, long bufferMaxRecordLines ) throws Throwable { boolean processComplete = false; Record record = records.get(records.size() - 1); while(!processComplete){ long recordCount = records.size(); if( record.getKey().compareTo(key) == 0 ){ record = read(reader); while( record != null && record.getKey().compareTo(key) == 0 && recordCount < bufferMaxRecordLines ) { records.add(record); recordCount++; record = read(reader); } } processComplete = true; // if record is null, we are done if( record != null ) { // if the key has changed, we are done if( record.getKey().compareTo(key) == 0 ) { // Same key means we have exhausted the buffer. // Dump entire buffer into a file. The list of file // pointers will keep track of the files ... processComplete = false; dumpBufferToFile(records, files); records.clear(); records.add(record); } } } return record; } /** * Dump all records in List of Record objects to a file. Then, add that * file to List of File objects * * NEED TO PLACE A LIMIT ON NUMBER OF FILE POINTERS (check size of file list) * * @param records * @param files * @throws Throwable */ private void dumpBufferToFile(List<Record> records, List<File> files) throws Throwable { String prefix = "joiner_" + files.size() + 1; String suffix = ".dat"; File file = File.createTempFile(prefix, suffix, new File("cache")); BufferedWriter writer = new BufferedWriter(new FileWriter(file)); for( Record record : records ) { writer.write( record.dump() ); } files.add(file); writer.flush(); writer.close(); }

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  • WCF sending the same exception even if the service endpoint address is valid

    - by ALexr111
    Hi, I'm running into a really strange problem with WCF. I need to implement some recovery behavior for WCF service if not reachable endpoint IP address received or service can not bind. The flow is simple if the application fail on exception on service creation it terminate it and request from user another IP address and perform another attempt to create the service. (The code snippet below). If the address is not valid I get "A TCP error (10049: The requested address is not valid in its context) occurred while listening on IP Endpoint=.121.10.11.11" exception, but for any reason if I try the second attempt with valid address I've got the same exception with wrong IP address from previous attempt. Here is a code: ServiceHost service = null; try { Uri[] uris = { new Uri(Constants.PROTOCOL + "://" + address + ":" + port) }; service = new ServiceHost(typeof(IRemoteService), uris); NetTcpBinding tcpBinding = WcfTcpRemoteServicesManager.LessLimitedNewNetTcpBinding(int.MaxValue, int.MaxValue, int.MaxValue); ServiceEndpoint ep = service.AddServiceEndpoint(implementedContract.FullName, tcpBinding, serviceName); var throttle = service.Description.Behaviors.Find<ServiceThrottlingBehavior>(); if (throttle == null) { throttle = new ServiceThrottlingBehavior { MaxConcurrentCalls = Constants.MAX_CONCURRENT_CALLS, MaxConcurrentSessions = Constants.MAX_CONCURRENT_SESSIONS, MaxConcurrentInstances = Constants.MAX_CONCURRENT_INSTANCES }; service.Description.Behaviors.Add(throttle); } service.Open(); } catch (Exception e) { _debugLog.WriteLineMessage( "Failed to open or create service exception. Exception message:" + e.Message); if (service!=null) { try { service.Close(); } catch (Exception) { service.Abort(); service.Close(); throw e; } } } Thanks

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  • handling java exception

    - by Noona
    This questions is related to java exception, why are there some cases that when an exception thrown the program exits even though the exception was caught and there was no exit() statement? my code looks something like this void bindProxySocket(DefaultHttpClientConnection proxyConnection, String hostName, HttpParams params) { if (!proxyConnection.isOpen()) { Socket socket = null; try { socket = new Socket(hostName, 80); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { proxyConnection.bind(socket, params); } catch(IOException e) { System.err.println ("couldn't bind socket"); e.printStackTrace(); } } } and then I call this method like this: bindProxySocket(proxyConn, hostName, params1); but, the program exits, although I want to handle the exception by doing something else, can it be because I didn't enclose the method call within a try catch clause? what happens if I catch the exception again even though it's already in the method? and what should I do if i want to clean resources only if an exception occurs and otherwise I want to continue with the program? I am guessing in this case I have to include the whole piece of code until I can clean the resources with in a try statement or can I do it in the handle exception statement? some of these questions are on this specific case, but I would like to get a thorough answer to all my questions for future reference. thanks

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  • Dealing with Try/Catch Exceptions in Java bytecode? ("stack height inconsistent")

    - by Cogwirrel
    I am trying to do some error handling in java bytecode. I first tried to implement some catch-like subroutines, where I would check for the error condition, and jump to the appropriate subroutine, a little like: iconst_1 iconst_0 dup ifeq calldiverr goto enddivtest calldiverr: jsr divError enddivtest: idiv ...More instructions... divError: getstatic java/lang/System/out Ljava/io/PrintStream; ldc "Oh dear you divided by 0!" invokevirtual java/io/PrintStream/print(Ljava/lang/String;)V The problem with the above is that when I have multiple instructions that jump to this subroutine, I get an error message when running the bytecode, saying that the stack height is inconsistent. Perhaps using exceptions is the best way to get around this? From some googling I have found that you can create instances of Exception classes and initialise them with something like: new java/lang/Exception dup ldc "exception message!" invokespecial java/lang/Exception/<init>(Ljava/lang/String;)V I have also found that you can throw them with athrow and this seems ok. What is confusing me however is exactly how exceptions are caught. There seems to be a magical "Exception table" which glues the throwing and catching of exceptions together, but I do not know how to define one of these when writing bytecode from scratch (and assembling using Jasmin). Can somebody tell me the secret of creating an exception table? And possibly give me an example of exception handling that will assemble with jasmin?

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  • When does an ARM7 processor increase its PC register?

    - by Summer_More_More_Tea
    Hi everyone: I'm thinking about this question for a time: when does an ARM7(with 3 pipelines) processor increase its PC register. I originally thought that after an instruction has been executed, the processor first check is there any exception in the last execution, then increase PC by 2 or 4 depending on current state. If an exception occur, ARM7 will change its running mode, store PC in the LR of current mode and begin to process current exception without modifying the PC register. But it make no sense when analyzing returning instructions. I can not work out why PC will be assigned LR when returning from an undefined-instruction-exception while LR-4 from prefetch-abort-exception, don't both of these exceptions happened at the decoding state? What's more, according to my textbook, PC will always be assigned LR-4 when returning from prefetch-abort-exception no matter what state the processor is(ARM or Thumb) before exception occurs. However, I think PC should be assigned LR-2 if the original state is Thumb, since a Thumb-instruction is 2 bytes long instead of 4 bytes which an ARM-instruction holds, and we just wanna roll-back an instruction in current state. Is there any flaws in my reasoning or something wrong with the textbook. Seems a long question. I really hope anyone can help me get the right answer. Thanks in advance.

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  • Very strange Application.ThreadException behaviour.

    - by Brann
    I'm using the Application.ThreadException event to handle and log unexpected exceptions in my winforms application. Now, somewhere in my application, I've got the following code (or rather something equivalent, but this dummy code is enough to reproduce my issue) : try { throw new NullReferenceException("test"); } catch (Exception ex) { throw new Exception("test2", ex); } I'm clearly expecting my Application_ThreadException handler to be passed the "test2" exception, but this is not always the case. Typically, if another thread marshals my code to the UI, my handler receives the "test" exception, exactly as if I hadn't caught "test" at all. Here is a short sample reproducing this behavior. I have omitted the designer's code. static class Program { [STAThread] static void Main() { Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException); Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e) { Console.WriteLine(e.Exception.Message); } } public partial class Form1 : Form { public Form1() { InitializeComponent(); button1.Click+=new EventHandler(button1_Click); System.Threading.Thread t = new System.Threading.Thread(new System.Threading.ThreadStart(ThrowEx)); t.Start(); } private void button1_Click(object sender, EventArgs e) { try { throw new NullReferenceException("test"); } catch (Exception ex) { throw new Exception("test2", ex); } } void ThrowEx() { this.BeginInvoke(new EventHandler(button1_Click)); } } The output of this program on my computer is : test ... here I click button1 test2 I've reproduced this on .net 2.0,3.5 and 4.0. Does someone have a logical explanation ?

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  • Initialising vals which might throw an exception

    - by Paul Butcher
    I need to initialise a set of vals, where the code to initialise them might throw an exception. I'd love to write: try { val x = ... generate x value ... val y = ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But this (obviously) doesn't work because x and y aren't in scope outside of the try. It's easy to solve the problem by using mutable variables: var x: Whatever = _ var y: Whatever = _ try { x = ... generate x value ... y = ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But that's not exactly very nice. It's also easy to solve the problem by duplicating the exception handling: val x = try { ... generate x value ... } catch { ... exception handling ... } val y = try { ... generate y value ... } catch { ... exception handling ... } ... use x and y ... But that involves duplicating the exception handling. There must be a "nice" way, but it's eluding me.

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  • Catching exception in Main() method

    - by Corvin
    Consider the following simple application: a windows form created by a "new C# windows application" sequence in VS that was modified in a following way: public static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); try { Application.Run(new Form1()); } catch (Exception ex) { MessageBox.Show("An unexpected exception was caught."); } } Form1.cs contains the following modifications: private void Form1_Load(object sender, EventArgs e) { throw new Exception("Error"); } If I press F5 in IDE, then, as I expect, I see a message box saying that exception was caught and the application quits. If I go to Debug(or Release)/bin and launch the executable, I see the standard "Unhandled exception" window, meaning that my exception handler doesn't work. Obviously, that has something to do with exception being thrown from a different thread that Application.Run is called from. But the question remains - why the behavior differs depending on whether the application has been run from IDE or from command line? What is the best practice to ensure that no exceptions remain unhandled in the application?

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  • auto-document exceptions on methods in C#/.NET

    - by Sarah Vessels
    I would like some tool, preferably one that plugs into VS 2008/2010, that will go through my methods and add XML comments about the possible exceptions they can throw. I don't want the <summary> or other XML tags to be generated for me because I'll fill those out myself, but it would be nice if even on private/protected methods I could see which exceptions could be thrown. Otherwise I find myself going through the methods and hovering on all the method calls within them to see the list of exceptions, then updating that method's <exception list to include those. Maybe a VS macro could do this? From this: private static string getConfigFilePath() { return Path.Combine(Environment.CurrentDirectory, CONFIG_FILE); } To this: /// <exception cref="System.ArgumentException"/> /// <exception cref="System.ArgumentNullException"/> /// <exception cref="System.IO.IOException"/> /// <exception cref="System.IO.DirectoryNotFoundException"/> /// <exception cref="System.Security.SecurityException"/> private static string getConfigFilePath() { return Path.Combine(Environment.CurrentDirectory, CONFIG_FILE); } Update: it seems like the tool would have to go through the methods recursively, e.g., method1 calls method2 which calls method3 which is documented as throwing NullReferenceException, so both method2 and method1 are documented by the tool as also throwing NullReferenceException. The tool would also need to eliminate duplicates, like if two calls within a method are documented as throwing DirectoryNotFoundException, the method would only list <exception cref="System.IO.DirectoryNotFoundException"/> once.

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  • shipping and handling fee calculation

    - by Newb
    Here is the question: Many companies normally charge a shipping and handling fee for purchases. Create a Web page that allows a user to enter a purchase price into a text box - include a JavaScript function that calculates shipping and handling. Add functionality to the script that adds a minimum shipping and handling fee of $1.50 for any purchase that is less than or equal to $25.00. For any orders over $25.00, add 10% to the total purchase price for shipping and handling, but do not include the $1.50 minimum shipping and handling fee. After you determine the total cost of the order (purchase plus shipping and handling), display it in an alert dialog box. I am beginner at JavaScript and struggling to get my code to work. It does display an alert box with the value entered by the user but doesn't add anything. Although, I don't know why the formula doesn't work. Please help. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Calculating Shipping & Handling</title> <script type="text/javascript"> /* <![CDATA[ */ var price=[]; var shipping=[]; var total=price+shipping; function calculateShipping(){ if (price <= 25){ shipping = (price + 1.5); } else { shipping = (price * 10 / 100); } window.alert("The purchase price with shipping is " + document.calculate.ent.value); } /* ]]> */ </script> </head> <body> <form name ="calculate" action="" > <p>Enter Purchase Price</p> <input type="text" name="ent" > <input type="button" name="button" value="Submit" onClick="calculateShipping()" /> </form> </body> </html>

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  • java.net.URISyntaxException

    - by aayushi soni
    Hi, I have get this exception. but this exception is not reproduced again. I want to get the cause of this Exception Caught while Checking tag in XMLjava.net.URISyntaxException: Illegal character in opaque part at index 2: C:\Documents and Settings\All Users\.SF\config\sd.xml stacktrace net.sf.saxon.trans.XPathException. Why this exception occured. How to deal with so it will not reproduce.

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  • Getting custom attribute from an Exception thrown during testing

    - by Amit Bhargava
    I'm using JUnit4 to test my code. Now, I'm aware that the following annotation allows me to expect an exception of a certain type @Test(expected = NipException.class) However, I have an 'errorCode' property in my exception class which I would also like to verify. This is because the same exception is thrown at three places in the same method with different error codes. How do I access 'errorCode' of the thrown exception?

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  • throw exception

    - by Unknown
    Why can't you throw an InterruptedException in the following way: try { System.in.wait(5) //Just an example } catch (InterruptedException exception) { exception.printStackTrace(); //On this next line I am confused as to why it will not let me throw the exception throw exception; } I went to http://java24hours.com, but it didn't tell me why I couldn't throw an InterruptedException. If anyone knows why, PLEASE tell me! I'm desperate! :S

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  • Invoke target throwing invalid cross-thread operate exception

    - by sqwerty
    MethodInfo mi = typeof(NotifyIcon).GetMethod("ShowContextMenu", BindingFlags.Instance | BindingFlags.NonPublic); mi.Invoke(notify, null); This throws the following exception: {"Exception has been thrown by the target of an invocation."} With the following inner exception: "Cross-thread operation not valid: Control '' accessed from a thread other than the thread it was created on." If I comment out a line of code that sets the images for the context menu entries then it stops throwing the exception. Any ideas?

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  • Handling keyboard and mouse input (Win API)

    - by Deluxe
    There is a number of ways to catch mouse or keyboard under Windows. So I tried some of them, but every of them has some advantages and drawbacks. I want to ask you: Which method do use? I've tried these: WM_KEYDOWN/WM_KEYUP - Main disadvantage is that, I can't distinguish between left and right-handed keys like ALT, CONTROL or SHIFT. GetKeyboardState - This solves problem of first method, but there is new one. When I get that the Right-ALT key is pressed, I also get that the Left-Control key is down. This behaviour happens only when using localized keyboard layout (Czech - CS). WM_INPUT (Raw Input) - This method also doesn't distinguish left and right-handed keys (if I can remember) and for mouse movement sometimes generates message with zero delta values of mouse position.

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  • Try and catch error trapping. why is it so significant

    - by oded
    sorry if it sounds dumb ' as i am i a process of learnning java i try to understand , why on earth i should "try" a method to catch errors. it looks to me like the concept is:- ' letting a process run assuming its not properly developed. should i always assume that a program based on classes and inheritance is bound for unexpected errors, which i should handle with such a heavy tools like try catch throw throws ? should all java programs be included withing try catch framework? Thanks Oded.

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  • Bash history handling with multiple terminals

    - by zetah
    I use mainly Terminator, and it's usually opened with 3 split terminal windows. I also use Gnome terminal for various reasons. I'm wondering how is bash history handled in this case as I sometimes miss previously issued commands when I run history For example, my prompt shows current bash history line (\!) and if I launch Terminator with 3 split terminal windows I get same history line (let's say 100) on all terminals. Which history will be saved? Also launching Gnome Terminal after using Terminator I get line 100 at startup regardless all commands issued before in Terminator

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  • Handling special characters with FOR XML PATH('')

    - by Rob Farley
    Because I hate seeing &gt; or &amp; in my results… Since SQL Server 2005, we’ve been able to use FOR XML PATH('') to do string concatenation. I’ve blogged about it before several times. But I don’t think I’ve blogged about the fact that it all goes a bit wrong if you have special characters in the strings you’re concatenating. Generally, I don’t even worry about this. I should, but I don’t, particularly when the solution is so easy. Suppose I want to concatenate the list of user databases...(read more)

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