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  • Safe to pass objects to C functions when working in JNI Invocation API?

    - by bubbadoughball
    I am coding up something using the JNI Invocation API. A C program starts up a JVM and makes calls into it. The JNIenv pointer is global to the C file. I have numerous C functions which need to perform the same operation on a given class of jobject. So I wrote helper functions which take a jobject and process it, returning the needed data (a C data type...for example, an int status value). Is it safe to write C helper functions and pass jobjects to them as arguments? i.e. (a simple example - designed to illustrate the question): int getStatusValue(jobject jStatus) { return (*jenv)->CallIntMethod(jenv,jStatus,statusMethod); } int function1() { int status; jobject aObj = (*jenv)->NewObject (jenv, aDefinedClass, aDefinedCtor); jobject j = (*jenv)->CallObjectMethod (jenv, aObj, aDefinedObjGetMethod) status = getStatusValue(j); (*jenv)->DeleteLocalRef(jenv,aObj); (*jenv)->DeleteLocalRef(jenv,j); return status; } Thanks.

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  • c# delegate and abstract class

    - by BeraCim
    Hi all: I currently have 2 concrete methods in 2 abstract classes. One class contains the current method, while the other contains the legacy method. E.g. // Class #1 public abstract class ClassCurrent<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllRootNodes(int i) { //some code } } // Class #2 public abstract class MyClassLegacy<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllLeafNodes(int j) { //some code } } I want the corresponding method to run in their relative scenarios in the app. I'm planning to write a delegate to handle this. The idea is that I can just call the delegate and write logic in it to handle which method to call depending on which class/project it is called from (at least thats what I think delegates are for and how they are used). However, I have some questions on that topic (after some googling): 1) Is it possible to have a delegate that knows the 2 (or more) methods that reside in different classes? 2) Is it possible to make a delegate that spawns off abstract classes (like from the above code)? (My guess is a no, since delegates create concrete implementation of the passed-in classes) 3) I tried to write a delegate for the above code. But I'm being technically challenged: public delegate List GetAllNodesDelegate(int k); GetAllNodesDelegate del = new GetAllNodesDelegate(ClassCurrent.GetAllRootNodes); I got the following error: An object reference is required for the non-static field, method, property ClassCurrent<BaseNode>.GetAllRootNodes(int) I might have misunderstood something... but if I have to manually declare a delegate at the calling class, AND to pass in the function manually as above, then I'm starting to question whether delegate is a good way to handle my problem. Thanks.

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  • Accessing Members of Containing Objects from Contained Objects.

    - by Bunkai.Satori
    If I have several levels of object containment (one object defines and instantiates another object which define and instantiate another object..), is it possible to get access to upper, containing - object variables and functions, please? Example: class CObjectOne { public: CObjectOne::CObjectOne() { Create(); }; void Create(); std::vector<ObjectTwo>vObejctsTwo; int nVariableOne; } bool CObjectOne::Create() { CObjectTwo ObjectTwo(this); vObjectsTwo.push_back(ObjectTwo); } class CObjectTwo { public: CObjectTwo::CObjectTwo(CObjectOne* pObject) { pObjectOne = pObject; Create(); }; void Create(); CObjectOne* GetObjectOne(){return pObjectOne;}; std::vector<CObjectTrhee>vObjectsTrhee; CObjectOne* pObjectOne; int nVariableTwo; } bool CObjectTwo::Create() { CObjectThree ObjectThree(this); vObjectsThree.push_back(ObjectThree); } class CObjectThree { public: CObjectThree::CObjectThree(CObjectTwo* pObject) { pObjectTwo = pObject; Create(); }; void Create(); CObjectTwo* GetObjectTwo(){return pObjectTwo;}; std::vector<CObjectsFour>vObjectsFour; CObjectTwo* pObjectTwo; int nVariableThree; } bool CObjectThree::Create() { CObjectFour ObjectFour(this); vObjectsFour.push_back(ObjectFour); } main() { CObjectOne myObject1; } Say, that from within CObjectThree I need to access nVariableOne in CObjectOne. I would like to do it as follows: int nValue = vObjectThree[index].GetObjectTwo()->GetObjectOne()->nVariable1; However, after compiling and running my application, I get Memory Access Violation error. What is wrong with the code above(it is example, and might contain spelling mistakes)? Do I have to create the objects dynamically instead of statically? Is there any other way how to achieve variables stored in containing objects from withing contained objects?

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  • WCF RIA Services Custom Type with Collection of Custom Types

    - by Blakewell
    Is it possible to have a custom type within a custom type and have the result returned via WCF RIA services? I have the following two classes below, but I can't gain access to the Verticies property within the Polygon class. I assume it is because it is a custom class, or something to do with it being a List collection. Polygon Class public class Polygon { public Polygon() { _vertices = new List<Location>(); } private int _id; [Key] public int Id { get; set; } private List<Location> _vertices; public List<Location> Vertices { get { return _vertices; } set { _vertices = value; } } } Location Class public class Location { public Location() { } /// <summary> /// Default constructor for creating a Location object /// </summary> /// <param name="latitude"></param> /// <param name="longitude"></param> public Location( double latitude, double longitude ) { _latitude = latitude; _longitude = longitude; } private int _id; [Key] public int Id { get { return _id; } set { _id = value; } } private double _latitude; /// <summary> /// Latitude coordinate of the location /// </summary> public double Latitude { get { return _latitude; } set { _latitude = value; } } private double _longitude; /// <summary> /// Longitude coordiante of the location /// </summary> public double Longitude { get { return _longitude; } set { _longitude = value; } } }

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  • How to implement an ID field on a POCO representing an Identity field in MS SQL?

    - by Dr. Zim
    If I have a Domain Model that has an ID that maps to a SQL identity column, what does the POCO look like that contains that field? Candidate 1: Allows anyone to set and get the ID. I don't think we want anyone setting the ID except the Repository, from the SQL table. public class Thing { public int ID {get;set;} } Candidate 2: Allows someone to set the ID upon creation, but we won't know the ID until after we create the object (factory creates a blank Thing object where ID = 0 until we persist it). How would we set the ID after persisting? public class Thing { public Thing () : This (ID: 0) {} public Thing (int ID) { this.ID = ID } private int _ID; public int ID { get { return this.ID;}; } Candidate 3: Methods to set ID? Somehow we would need to allow the Repository to set the ID without allowing the consumer to change it. Any ideas? Is this barking up the wrong tree? Do we send the object to the Repository, save it, throw it away, then create a new object from the loaded version and return that as a new object?

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  • ListBox and Listview problem

    - by Anu
    Hi, I have listbox in my applcation and corresponding coding.. XAML: <DataTemplate x:Key="menuItemTemplate"> <WrapPanel> <TextBlock Text="{Binding Path = Menu}" /> </WrapPanel> </DataTemplate> <ListBox x:Name="menubox" ItemsSource="{Binding}" ItemTemplate="{StaticResource menuItemTemplate}" Margin="0,5,0,0"> .CS : public void Add(string[] menu) { ItemList items = ItemList.Load(menu); DataContext = items; } It works fine.Later i add Listview for another purpose and i coded like the same way of listbox XAML: <DataTemplate x:Key="ListItemTemplate"> <WrapPanel> <TextBlock Text="{Binding Path = Title}" /> </WrapPanel> </DataTemplate> <ListView ItemsSource="{Binding}" ItemTemplate="{StaticResource ListItemTemplate}" Name="listView1" /> .cs coding: public void SetTree(string Title,int BoxNo ) { TreeList items1 = TreeList.Load(Title,BoxNo); DataContext = items1; } After adding Listview,what happended this ListView show data,but Listbox didnot show anything.When i click the listbox it perfectly executing the clicking event of listbox.Only problem it doesnot display the text.What can i do for that. Here i added corresponding list class pls see tht. namespace Tabcontrol { public class TreeList : Collection<TreeItems> { public int size; public TreeList() { size = 0; } public int Count { get { return size; } } public static TreeList Load(string pmenu,int Box) { TreeList result = new TreeList(); TreeItems item = TreeItems.Load(pmenu,Box); result.Add(item); return result; } } } The ItemList class also the same thing, only variable names are getting differred.

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  • Help in J2ME for creating image and parse it

    - by HAMED
    Can anyone tell me how i can parse a png image into many png images in J2ME??? for examole:I just wnat to have a source image 150*150 pixel and parse it to 10 image with 15*15 pixel. I write an elemantary code that have exeption. This is my code: public class HelloMIDlet extends MIDlet implements CommandListener { private boolean midletPaused = false; private Command exitCommand; private Form form; private StringItem stringItem; Image im , im2; Form form1 = null; public HelloMIDlet() { try { // create source image im = Image.createImage("/image1.JPG"); int height = im.getHeight() ; int width = im.getWidth() ; int x = 0 ; int y = 0 ; while ( y < height ){ while ( x < width ){ // create 15*15 pixel of source image im2 = im.createImage(im, x, y, 15, 15, Sprite.TRANS_NONE) ; x += 15 ; } y += 15 ; x = 0 ; } } catch (IOException ex) { ex.printStackTrace(); } } please help me to make it right....It's emergency! Thanks a lot guys...

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  • What's the most efficient query?

    - by Aaron Carlino
    I have a table named Projects that has the following relationships: has many Contributions has many Payments In my result set, I need the following aggregate values: Number of unique contributors (DonorID on the Contribution table) Total contributed (SUM of Amount on Contribution table) Total paid (SUM of PaymentAmount on Payment table) Because there are so many aggregate functions and multiple joins, it gets messy do use standard aggregate functions the the GROUP BY clause. I also need the ability to sort and filter these fields. So I've come up with two options: Using subqueries: SELECT Project.ID AS PROJECT_ID, (SELECT SUM(PaymentAmount) FROM Payment WHERE ProjectID = PROJECT_ID) AS TotalPaidBack, (SELECT COUNT(DISTINCT DonorID) FROM Contribution WHERE RecipientID = PROJECT_ID) AS ContributorCount, (SELECT SUM(Amount) FROM Contribution WHERE RecipientID = PROJECT_ID) AS TotalReceived FROM Project; Using a temporary table: DROP TABLE IF EXISTS Project_Temp; CREATE TEMPORARY TABLE Project_Temp (project_id INT NOT NULL, total_payments INT, total_donors INT, total_received INT, PRIMARY KEY(project_id)) ENGINE=MEMORY; INSERT INTO Project_Temp (project_id,total_payments) SELECT `Project`.ID, IFNULL(SUM(PaymentAmount),0) FROM `Project` LEFT JOIN `Payment` ON ProjectID = `Project`.ID GROUP BY 1; INSERT INTO Project_Temp (project_id,total_donors,total_received) SELECT `Project`.ID, IFNULL(COUNT(DISTINCT DonorID),0), IFNULL(SUM(Amount),0) FROM `Project` LEFT JOIN `Contribution` ON RecipientID = `Project`.ID GROUP BY 1 ON DUPLICATE KEY UPDATE total_donors = VALUES(total_donors), total_received = VALUES(total_received); SELECT * FROM Project_Temp; Tests for both are pretty comparable, in the 0.7 - 0.8 seconds range with 1,000 rows. But I'm really concerned about scalability, and I don't want to have to re-engineer everything as my tables grow. What's the best approach?

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  • How to embed XBase expressions in an Xtext DSL

    - by Marcus Mathioudakis
    I am writing a simple little DSL for specifying constraints on messages, and Have been trying without success for a while to embed XBase expressions into the language. The Grammar looks like this: grammar org.xtext.businessrules.BusinessRules with org.eclipse.xtext.xbase.Xbase //import "http://www.eclipse.org/xtext/xbase/Xbase" as xbase import "http://www.eclipse.org/xtext/common/JavaVMTypes" as jvmTypes generate businessRules "http://www.xtext.org/businessrules/BusinessRules" Start: rules+=Constraint*; Constraint: {Constraint} 'FOR' 'PAYLOAD' payload=PAYLOAD 'ELEMENT' element=ID 'CONSTRAINED BY' constraint=XExpression; PAYLOAD: "SimulationSessionEvents" |"stacons" |"any" ; Range: 'above' min=INT ('below' max=INT)? |'below' max=INT ('above' min=INT)? ; When trying to parse a file such as: FOR PAYLOAD SimulationSessionEvents ELEMENT matrix CONSTRAINED BY ... I can't get it to work for ... = any kind of Arithmetic expression, although it works for ...= loop or if expression, or even just a number. As soon as I do something like '-5' or '4-5' it says Couldn't resolve reference to JvmIdentifiableElement '-', even though the Xbase.xtext Grammar looks like it allows these expressions. I don't think I'm missing any Jars, as it doesn't complain when I run the mwe workflow, but only when trying to parse the input file. Any help would be much appreciated.

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  • Delay in displaying contents in JDialog

    - by Yohan
    Please have a look at the following code import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.util.List; import java.util.ArrayList; public class SendEmailForm extends JDialog { private JLabel to, cc, bcc, subject, account; private JTextField toTxt, ccTxt, bccTxt, subjectTxt; private JTextArea messageTxt; private JButton send; private JComboBox accountBox; private JScrollPane scroll; private GridBagLayout gbl; private GridBagConstraints gbc; public SendEmailForm() { //Declaring instance variables to = new JLabel("To: "); cc = new JLabel("CC: "); bcc = new JLabel("BCC: "); subject = new JLabel("Subject: "); account = new JLabel("Select an Account: "); toTxt = new JTextField(20); ccTxt = new JTextField(20); bccTxt = new JTextField(20); subjectTxt = new JTextField(20); messageTxt = new JTextArea(20, 50); messageTxt.setLineWrap(true); scroll = new JScrollPane(messageTxt); scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED); scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER); accountBox = new JComboBox(); accountBox.addItem("Yahoo"); accountBox.addItem("GMail"); accountBox.addItem("MSN"); //accountBox.addItem("Yahoo"); //accountBox.addItem("Yahoo"); JPanel buttonPanel = new JPanel(); buttonPanel.setLayout(new FlowLayout()); send = new JButton("Send"); send.addActionListener(new SendButtonAction()); buttonPanel.add(send); //Creating thr GUI //GUI CREATION IS REMOVED IN THIS POST this.setTitle("Send Emails"); this.setVisible(true); this.pack(); this.setLocationRelativeTo(null); this.validate(); } private class SendButtonAction implements ActionListener { public void actionPerformed(ActionEvent ae) { ProgressMonitor pm = new ProgressMonitor(); //Retreiving the user name and password List userData = new ArrayList(); EmailDBConnector emailCon = new EmailDBHandler(); userData = emailCon.getUserNameAndPassword( accountBox.getSelectedItem().toString().trim()); String userName = userData.get(0).toString(); String password = userData.get(1).toString(); System.out.println(userName); System.out.println(password); pm.setVisible(true); SendEmail sendEmail = new SendEmail(toTxt.getText(), userName.trim(), bccTxt.getText(), ccTxt.getText(), accountBox.getSelectedItem().toString().trim(), messageTxt.getText().trim(), password.trim(), subjectTxt.getText()); String result = sendEmail.send(); //pm.dispose(); JOptionPane.showMessageDialog(null, result); } } private class ProgressMonitor extends JDialog { public ProgressMonitor() { this.setLayout(new BorderLayout()); JLabel text = new JLabel("Sending..Please wait..."); this.add(text, "Center"); this.pack(); this.validate(); this.setLocationRelativeTo(null); } } } First, this is an email program. In here, when the JDialog is called, it just opens as a 100% blank window. I have added a JLabel, but it is not there when it is displaying. Anyway, it takes sometime to send the email, after the email is sent, I can see the JLabel in the JDialog. If I take my issue into one sentence, I am calling the JDialog before the email is sent, but it appears blank, after the email is sent, it's content are there! Why is this? Please help!

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  • C++ find largest BST in a binary tree

    - by fonjibe
    what is your approach to have the largest BST in a binary tree? I refer to this post where a very good implementation for finding if a tree is BST or not is bool isBinarySearchTree(BinaryTree * n, int min=std::numeric_limits<int>::min(), int max=std::numeric_limits<int>::max()) { return !n || (min < n->value && n->value < max && isBinarySearchTree(n->l, min, n->value) && isBinarySearchTree(n->r, n->value, max)); } It is quite easy to implement a solution to find whether a tree contains a binary search tree. i think that the following method makes it: bool includeSomeBST(BinaryTree* n) { if(!isBinarySearchTree(n)) { if(!isBinarySearchTree(n->left)) return isBinarySearchTree(n->right); } else return true; else return true; } but what if i want the largest BST? this is my first idea, BinaryTree largestBST(BinaryTree* n) { if(isBinarySearchTree(n)) return n; if(!isBinarySearchTree(n->left)) { if(!isBinarySearchTree(n->right)) if(includeSomeBST(n->right)) return largestBST(n->right); else if(includeSomeBST(n->left)) return largestBST(n->left); else return NULL; else return n->right; } else return n->left; } but its not telling the largest actually. i struggle to make the comparison. how should it take place? thanks

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  • Is private members hacking a defined behaviour ?

    - by ereOn
    Hi, Lets say I have the following class: class BritneySpears { public: int getValue() { return m_value; }; private: int m_value; }; Which is an external library (that I can't change). I obviously can't change the value of m_value, only read it. Even subclassing BritneySpears won't work. What if I define the following class: class AshtonKutcher { public: int getValue() { return m_value; }; public: int m_value; }; And then do: BritneySpears b; // Here comes the ugly hack AshtonKutcher* a = reinterpret_cast<AshtonKutcher*>(&b); a->m_value = 17; // Print out the value std::cout << b.getValue() << std::endl; I know this is a bad practice. But just for curiosity: is this guaranted to work ? Is it a defined behaviour ? Bonus question: Have you ever had to use such an ugly hack ? Thanks !

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  • How do i change this method to get strings instead of ints

    - by David
    here is the original code: public static int getInt () { Scanner in = new Scanner (System.in) ; if (in.hasNextInt()) { int a = in.nextInt() ; return a ; } else { System.out.println ("try again:") ; return getInt () ; } } This checks and sees if the input it receives is an int. If it is then it returns the int, if not it tells you to try again and re-runs. This is what i tried to do to change it: public static String getIns () { Scanner in = new Scanner (System.in) ; if (in.hasNextString()) { String a = in.nextString() ; return a ; } else { System.out.println ("try again:") ; return getIns () ; } } This doesn't work though. I looked through the documentation for the scanner class and i think the problem is that there is no such method as in.hasNextString or in.nextString What methods from the scanner class can i use to do what i intend these to do?

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  • How to play extracted wave file byte array in C#?

    - by user261924
    At the moment i have managed to separate the left and right channel of a WAVE file and have included the header in a byte[] array. My next step is to be about to play both channels. How can this be done? Here is a code snippet: byte[] song_left = new byte[fa.Length]; byte[] song_right = new byte[fa.Length]; int p = 0; for (int c = 0; c < 43; c++) { song_left[p] = header[c]; p++; } int q = 0; for (s = startByte; s < length; s = s + 3) { song_left[s] = sLeft[q]; q++; s++; song_left[s] = sLeft[q]; q++; } p = 0; for (int c = 0; c < 43; c++) { song_right[p] = header[c]; p++; } This part is reading the header and data from both the right and light channel and saving it to array sLeft[] and sRight[]. This part is working perfectly. Once I obtained the byte arrays, I did the following: System.IO.File.WriteAllBytes("c:\\left.wav", song_left); System.IO.File.WriteAllBytes("c:\\right.wav", song_right); Added a button to play the saved wave file: private void button2_Click(object sender, EventArgs e) { spWave = new SoundPlayer("c:\\left.wav"); spWave.Play(); } Once I hit the play button, this error appers: An unhandled exception of type 'System.InvalidOperationException' occurred in System.dll Additional information: The wave header is corrupt. Any ideas?

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  • non static method cannot be referenced from a static context.

    - by David
    First some code: import java.util.*; ... class TicTacToe { ... public static void main (String[]arg) { Random Random = new Random() ; toerunner () ; // this leads to a path of methods that eventualy gets us to the rest of the code } ... public void CompTurn (int type, boolean debug) { ... boolean done = true ; int a = 0 ; while (!done) { a = Random.nextInt(10) ; if (debug) { int i = 0 ; while (i<20) { System.out.print (a+", ") ; i++; }} if (possibles[a]==1) done = true ; } this.board[a] = 2 ; } ... } //to close the class Here is the error message: TicTacToe.java:85: non-static method nextInt(int) cannot be referenced from a static context a = Random.nextInt(10) ; ^ What exactly went wrong? What does that error message "non static method cannot be referenced from a static context" mean?

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  • Configurable Values in Enum

    - by Omer Akhter
    I often use this design in my code to maintain configurable values. Consider this code: public enum Options { REGEX_STRING("Some Regex"), REGEX_PATTERN(Pattern.compile(REGEX_STRING.getString()), false), THREAD_COUNT(2), OPTIONS_PATH("options.config", false), DEBUG(true), ALWAYS_SAVE_OPTIONS(true), THREAD_WAIT_MILLIS(1000); Object value; boolean saveValue = true; private Options(Object value) { this.value = value; } private Options(Object value, boolean saveValue) { this.value = value; this.saveValue = saveValue; } public void setValue(Object value) { this.value = value; } public Object getValue() { return value; } public String getString() { return value.toString(); } public boolean getBoolean() { Boolean booleanValue = (value instanceof Boolean) ? (Boolean) value : null; if (value == null) { try { booleanValue = Boolean.valueOf(value.toString()); } catch (Throwable t) { } } // We want a NullPointerException here return booleanValue.booleanValue(); } public int getInteger() { Integer integerValue = (value instanceof Number) ? ((Number) value).intValue() : null; if (integerValue == null) { try { integerValue = Integer.valueOf(value.toString()); } catch (Throwable t) { } } return integerValue.intValue(); } public float getFloat() { Float floatValue = (value instanceof Number) ? ((Number) value).floatValue() : null; if (floatValue == null) { try { floatValue = Float.valueOf(value.toString()); } catch (Throwable t) { } } return floatValue.floatValue(); } public static void saveToFile(String path) throws IOException { FileWriter fw = new FileWriter(path); Properties properties = new Properties(); for (Options option : Options.values()) { if (option.saveValue) { properties.setProperty(option.name(), option.getString()); } } if (DEBUG.getBoolean()) { properties.list(System.out); } properties.store(fw, null); } public static void loadFromFile(String path) throws IOException { FileReader fr = new FileReader(path); Properties properties = new Properties(); properties.load(fr); if (DEBUG.getBoolean()) { properties.list(System.out); } Object value = null; for (Options option : Options.values()) { if (option.saveValue) { Class<?> clazz = option.value.getClass(); try { if (String.class.equals(clazz)) { value = properties.getProperty(option.name()); } else { value = clazz.getConstructor(String.class).newInstance(properties.getProperty(option.name())); } } catch (NoSuchMethodException ex) { Debug.log(ex); } catch (InstantiationException ex) { Debug.log(ex); } catch (IllegalAccessException ex) { Debug.log(ex); } catch (IllegalArgumentException ex) { Debug.log(ex); } catch (InvocationTargetException ex) { Debug.log(ex); } if (value != null) { option.setValue(value); } } } } } This way, I can save and retrieve values from files easily. The problem is that I don't want to repeat this code everywhere. Like as we know, enums can't be extended; so wherever I use this, I have to put all these methods there. I want only to declare the values and that if they should be persisted. No method definitions each time; any ideas?

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  • Why do bind1st and bind2nd require constant function objects?

    - by rlbond
    So, I was writing a C++ program which would allow me to take control of the entire world. I was all done writing the final translation unit, but I got an error: error C3848: expression having type 'const `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>' would lose some const-volatile qualifiers in order to call 'void `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>::operator ()(const point::Point &,const int &)' with [ T=SideCounter, BinaryFunction=std::plus<int> ] c:\program files (x86)\microsoft visual studio 9.0\vc\include\functional(324) : while compiling class template member function 'void std::binder2nd<_Fn2>::operator ()(point::Point &) const' with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] c:\users\****\documents\visual studio 2008\projects\TAKE_OVER_THE_WORLD\grid_divider.cpp(361) : see reference to class template instantiation 'std::binder2nd<_Fn2>' being compiled with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] I looked in the specifications of binder2nd and there it was: it took a const AdaptibleBinaryFunction. So, not a big deal, I thought. I just used boost::bind instead, right? Wrong! Now my take-over-the-world program takes too long to compile (bind is used inside a template which is instantiated quite a lot)! At this rate, my nemesis is going to take over the world first! I can't let that happen -- he uses Java! So can someone tell me why this design decision was made? It seems like an odd decision. I guess I'll have to make some of the elements of my class mutable for now...

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  • SQL Query Math Gymnastics

    - by keruilin
    I have two tables of concern here: users and race_weeks. User has many race_weeks, and race_week belongs to User. Therefore, user_id is a fk in the race_weeks table. I need to perform some challenging math on fields in the race_weeks table in order to return users with the most all-time points. Here are the fields that we need to manipulate in the race_weeks table. races_won (int) races_lost (int) races_tied (int) points_won (int, pos or neg) recordable_type(varchar, Robots can race, but we're only concerned about type 'User') Just so that you fully understand the business logic at work here, over the course of a week a user can participate in many races. The race_week record represents the summary results of the user's races for that week. A user is considered active for the week if races_won, races_lost, or races_tied is greater than 0. Otherwise the user is inactive. So here's what we need to do in our query in order to return users with the most points won (actually net_points_won): Calculate each user's net_points_won (not a field in the DB). To calculate net_points, you take (1000 * count_of_active_weeks) - sum(points__won). (Why 1000? Just imagine that every week the user is spotted a 1000 points to compete and enter races. We want to factor-out what we spot the user because the user could enter only one race for the week for 100 points, and be sitting on 900, which we would skew who actually EARNED the most points.) This one is a little convoluted, so let me know if I can clarify further.

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  • From where starts the process' memory space and where does it end?

    - by nhaa123
    Hi, I'm trying to dump memory from my application where the variables lye. Here's the function: void MyDump(const void *m, unsigned int n) { const unsigned char *p = reinterpret_cast<const unsigned char *(m); char buffer[16]; unsigned int mod = 0; for (unsigned int i = 0; i < n; ++i, ++mod) { if (mod % 16 == 0) { mod = 0; std::cout << " | "; for (unsigned short j = 0; j < 16; ++j) { switch (buffer[j]) { case 0xa: case 0xb: case 0xd: case 0xe: case 0xf: std::cout << " "; break; default: std::cout << buffer[j]; } } std::cout << "\n0x" << std::setfill('0') << std::setw(8) << std::hex << (long)i << " | "; } buffer[i % 16] = p[i]; std::cout << std::setw(2) << std::hex << static_cast<unsigned int(p[i]) << " "; if (i % 4 == 0 && i != 1) std::cout << " "; } } Now, how can I know from which address starts my process memory space, where all the variables are stored? And how do I now, how long the area is? For instance: MyDump(0x0000 /* <-- Starts from here? */, 0x1000 /* <-- This much? */); Best regards, nhaa123

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  • Windows Form hangs when running threads

    - by Benjamin Ortuzar
    JI have written a .NET C# Windows Form app in Visual Studio 2008 that uses a Semaphore to run multiple jobs as threads when the Start button is pressed. It’s experiencing an issue where the Form goes into a comma after being run for 40 minutes or more. The log files indicate that the current jobs complete, it picks a new job from the list, and there it hangs. I have noticed that the Windows Form becomes unresponsive when this happens. The form is running in its own thread. This is a sample of the code I am using: protected void ProcessJobsWithStatus (Status status) { int maxJobThreads = Convert.ToInt32(ConfigurationManager.AppSettings["MaxJobThreads"]); Semaphore semaphore = new Semaphore(maxJobThreads, maxJobThreads); // Available=3; Capacity=3 int threadTimeOut = Convert.ToInt32(ConfigurationManager.AppSettings["ThreadSemaphoreWait"]);//in Seconds //gets a list of jobs from a DB Query. List<Job> jobList = jobQueue.GetJobsWithStatus(status); //we need to create a list of threads to check if they all have stopped. List<Thread> threadList = new List<Thread>(); if (jobList.Count > 0) { foreach (Job job in jobList) { logger.DebugFormat("Waiting green light for JobId: [{0}]", job.JobId.ToString()); if (!semaphore.WaitOne(threadTimeOut * 1000)) { logger.ErrorFormat("Semaphore Timeout. A thread did NOT complete in time[{0} seconds]. JobId: [{1}] will start", threadTimeOut, job.JobId.ToString()); } logger.DebugFormat("Acquired green light for JobId: [{0}]", job.JobId.ToString()); // Only N threads can get here at once job.semaphore = semaphore; ThreadStart threadStart = new ThreadStart(job.Process); Thread thread = new Thread(threadStart); thread.Name = job.JobId.ToString(); threadList.Add(thread); thread.Start(); } logger.Info("Waiting for all threads to complete"); //check that all threads have completed. foreach (Thread thread in threadList) { logger.DebugFormat("About to join thread(jobId): {0}", thread.Name); if (!thread.Join(threadTimeOut * 1000)) { logger.ErrorFormat("Thread did NOT complete in time[{0} seconds]. JobId: [{1}]", threadTimeOut, thread.Name); } else { logger.DebugFormat("Thread did complete in time. JobId: [{0}]", thread.Name); } } } logger.InfoFormat("Finished Processing Jobs in Queue with status [{0}]...", status); } //form methods private void button1_Click(object sender, EventArgs e) { buttonStop.Enabled = true; buttonStart.Enabled = false; ThreadStart threadStart = new ThreadStart(DoWork); workerThread = new Thread(threadStart); serviceStarted = true; workerThread.Start(); } private void DoWork() { EmailAlert emailAlert = new EmailAlert (); // start an endless loop; loop will abort only when "serviceStarted" flag = false while (serviceStarted) { emailAlert.ProcessJobsWithStatus(0); // yield if (serviceStarted) { Thread.Sleep(new TimeSpan(0, 0, 1)); } } // time to end the thread Thread.CurrentThread.Abort(); } //job.process() public void Process() { try { //sets the status, DateTimeStarted, and the processId this.UpdateStatus(Status.InProgress); //do something logger.Debug("Updating Status to [Completed]"); //hits, status,DateFinished this.UpdateStatus(Status.Completed); } catch (Exception e) { logger.Error("Exception: " + e.Message); this.UpdateStatus(Status.Error); } finally { logger.Debug("Relasing semaphore"); semaphore.Release(); } I have tried to log what I can into a file to detect where the problem is happening, but so far I haven't been able to identify where this happens. Losing control of the Windows Form makes me think that this has nothing to do with processing the jobs. Any ideas?

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  • Generic FSM for game in C++ ?

    - by Mr.Gando
    Hello, I was wondering if there's a way I could code some kind of "generic" FSM for a game with C++?. My game has a component oriented design, so I use a FSM Component. my Finite State Machine (FSM) Component, looks more or less this way. class gecFSM : public gecBehaviour { public: //Constructors gecFSM() { state = kEntityState_walk; } gecFSM(kEntityState s) { state = s; } //Interface void setRule(kEntityState initialState, int inputAction, kEntityState resultingState); void performAction(int action); private: kEntityState fsmTable[MAX_STATES][MAX_ACTIONS]; }; I would love to hear your opinions/ideas or suggestions about how to make this FSM component, generic. With generic I mean: 1) Creating the fsmTable from an xml file is really easy, I mean it's just a bunch of integers that can be loaded to create an MAX_STATESxMAX_ACTION matrix. void gecFSM::setRule(kEntityState initialState, int inputAction, kEntityState resultingState) { fsmTable[initialState][inputAction] = resultingState; } 2) But what about the "perform Action" method ? void gecFSM::performAction(int action) { switch( smTable[ ownerEntity->getState() ][ action ] ) { case WALK: /*Walk action*/ break; case STAND: /*Stand action*/ break; case JUMP: /*Jump action*/ break; case RUN: /*Run action*/ break; } } What if I wanted to make the "actions" and the switch generic? This in order to avoid creating a different FSM component class for each GameEntity? (gecFSMZombie, gecFSMDryad, gecFSMBoss etc ?). That would allow me to go "Data Driven" and construct my generic FSM's from files for example. What do you people suggest?

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  • File Hierarchy system with a web application logic question: List searching

    - by molleman
    I need to search through a list of folders that could have more folders inside it, and add a new folder depending what folder is its parent.(the path is stored as a String for eg = "root/MyCom/home/") Then i fill in a field with a new folder name and add it to the final folder(eg "home/"). Below as you can see , I can navigate to the right location and add the new folder to a current folder, My trouble is that i cannot ensure that currentFolder element is placed back in the list it came from how could i add a folder to a list of folders, that could be within a list of folders,that could be within a list of folders and endless more? YFUser user = (YFUser)getSession().getAttribute(SESSION_USER); Folder newFolder = new Folder(); newFolder.setFolderName(foldername); // this is the path string (root/MyCom/home/) split in the different folder names String folderNames[] = folderLocationString.split("/"); int folderNamesLength = folderNames.length; Folder root = user.getRoot(); Folder currentFolder = root; for(int i=0;i<=folderNamesLength; i++){ // because root is folderNames[i] String folderName = folderNames[i++]; int currentFolderSize = currentFolder.getChildren.getSize(); for(int o=1; o<= currentFolderSize ; o++){ if(currentFolder.getChildren().get(o) instanceof Folder){ if(folderName.equals(currentFolder.getChildren().get(o).getFolderName())){ currentFolder = currentFolder.getChildren().get(o); if (i == counter){ //now i am inside the correct folder and i add it to the list of folders within it //the trouble is knowing how to re add this changed folder back to the list before it currentFolder.getChildren.add(newFolder); } } } } }

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  • how to close a java frame with threads

    - by user261002
    I have a java frame that I want to close it automatically after 3 or 4 seconds. I found out I must used threads. but I dont know how exactly to do it, this a dumy part of my code : package intro; import java.awt.*; import java.io.IOException; //import view.LangMenu; public class IntroClass extends Frame { private int _screenWidth = 0; private int _screenHeight = 0; private int _screenCenterx = 0; private int _screenCentery = 0; //private static final String SOUND_PATH="/sounds/introSound.midi"; public IntroClass() { Toolkit thisScreen = Toolkit.getDefaultToolkit(); Dimension thisScrrensize = thisScreen.getScreenSize(); _screenWidth = thisScrrensize.width; _screenHeight = thisScrrensize.height; _screenCenterx = _screenWidth / 2; _screenCentery = _screenHeight / 2; setBackground(Color.pink); Label lbl = new Label("Welcome To Dots Game. Samaneh Khaleghi", Label.CENTER); add(lbl); setUndecorated(true); setLocation((_screenCenterx*50)/100,_screenCentery-(_screenCentery*50)/100); setSize((_screenWidth * 50) / 100, (_screenHeight * 50) / 100); WaitClass r = new WaitClass(); r.start(); view.DotsBoardFrame d=new view.DotsBoardFrame(); main.Main.showScreen(d); } class WaitClass extends Thread { boolean running = true; public void run() { while (running) { try { Thread.sleep(50); } catch (InterruptedException ex) { ex.printStackTrace(); } } } } }

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  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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  • Passing a list of files to javac

    - by Robert Menteer
    How can I get the javac task to use an existing fileset? In my build.xml I have created several filesets to be used in multiple places throughout build file. Here is how they have been defined: <fileset dir = "${src}" id = "java.source.all"> <include name = "**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.examples"> <include name = "**/Examples/**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.tests"> <include name = "**/Tests/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.project"> <include name = "**/*.java" /> <exclude name = "**/Examples/**/*.java" /> <exclude name = "**/Tests/**/*.java" /> </fileset> I have also used macrodef to compile the java files so the javac task does not need to be repeated multiple times. The macro looks like this: <macrodef name="compile"> <attribute name="sourceref"/> <sequential> <javac srcdir = "${src}" destdir = "${build}" classpathref = "classpath" includeantruntime = "no" debug = "${debug}"> <filelist dir="." files="@{sourceref}" /> <-- email is about this </javac> </sequential> What I'm trying to do is compile only the classes that are needed for specific targets not all the targets in the source tree. And do so without having to specify the files every time. Here are how the targets are defined: <target name = "compile-examples" depends = "init"> <compile sourceref = "${toString:java.source.examples}" /> </target> <target name = "compile-project" depends = "init"> <compile sourceref = "${toString:java.source.project}" /> </target> <target name = "compile-tests" depends = "init"> <compile sourceref = "${toString:java.source.tests}" /> </target> As you can see each target specifies the java files to be compiled as a simi-colon separated list of absolute file names. The only problem with this is that javac does not support filelist. It also does not support fileset, path or pathset. I've tried using but it treats the list as a single file name. Another thing I tried is sending the reference directly (not using toString) and using but include does not have a ref attribute. SO THE QUESTION IS: How do you get the javac task to use a reference to a fileset that was defined in another part of the build file? I'm not interested in solutions that cause me to have multiple javac tasks. Completely re-writting the macro is acceptable. Changes to the targets are also acceptable provided redundant code between targets is kept to a minimum. p.s. Another problem is that fileset wants a comma separated list. I've only done a brief search for a way to convert semi-colons to commas and haven't found a way to do that. p.p.s. Sorry for the yelling but some people are too quick to post responses that don't address the subject.

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