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  • Can foreground threads be aborted on application shutdown in C#.Net?

    - by Cartman
    I inherited a c# winforms app (.NET 2.0) which creates a thread upon startup in a singleton class. This thread handles messages from a messaging topic (Tibco EMS). When the app is shutdown, the thread doesn't remain the the background? How is this possible? Is there something else happening that can abort this thread? Code snippet: public class Startup { public static void main(string [] args) { MySingletonClass.Instance.Init(); // do other things below Application.Run(new MainForm()); } public class MySingletonClass { // singleton code //.. //.. private Thread t; public void Init() { t = new Thread(new ThreadStart(poll)); } private void poll() { while(true} { // listen for messages and process but there is no break clause // exceptions are also handled within to ensure control doesnt go out } } Pls. don't write to tell me this is bad code. I know it and i was going to refactor it when i realised that the app actually shutdowns correctly inspite of this aberration. So i want to understand how this is possible. Thanks for your help

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  • Technical details for Server 2012 de-duplication feature

    - by syneticon-dj
    Now that Windows Server 2012 comes with de-duplication features for NTFS volumes I am having a hard time finding technical details about it. I can deduce from the TechNet documentation that the de-duplication action itself is an asynchronous process - not unlike how the SIS Groveler used to work - but there is virtually no detail about the implementation (algorithms used, resources needed, even the info on performance considerations is nothing but a bunch rule-of-thumb-style recommendations). Insights and pointers are greatly appreciated, a comparison to Solaris' ZFS de-duplication efficiency for a set of scenarios would be wonderful.

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  • Flex/Flash: Don't show 'bar' cursor when dragging over a TextField/TextArea?

    - by David Wolever
    As the title suggests, how can I prevent the "bar" cursor from appearing when I click-and-drag over a TextField? For example, consider this interaction: I'd like to prevent the cursor changing to the "bar" in step "2". How can I do that? I've tried fiddling with the selectable flag: protected static function fixMouseOverAfordance(field:TextField):void { var iOwnClick:Boolean = false; function handleMouseOver(event:MouseEvent):void { if (event.buttonDown) { field.selectable = iOwnClick; } else { field.selectable = true; iOwnClick = false; } } field.addEventListener(MouseEvent.MOUSE_OVER, handleMouseOver, false, EventPriority.CURSOR_MANAGEMENT+1); field.addEventListener(MouseEvent.ROLL_OVER, handleMouseOver, false, EventPriority.CURSOR_MANAGEMENT+1); field.addEventListener(MouseEvent.MOUSE_MOVE, handleMouseOver, false, EventPriority.CURSOR_MANAGEMENT+1); field.addEventListener(MouseEvent.MOUSE_DOWN, function(event:MouseEvent):void { iOwnClick = true; field.selectable = true; }); } But the "bar" cursor still appears the first time the mouse is moved over the text field (however, after it has been moved out then moved back in, it does the right thing).

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  • Manipulating original elements with qTip

    - by pjotr
    I have a bunch of divs on my page and each of them has only the class attribute. In the divs there are some spans, which are set up to display a tooltip with the help of qTip. The tooltip should contain three items: Up: anchor, which should move the OuterDiv up (probably something like this: move up/down in jquery) Down: anchor, which should move the OuterDiv down Delete: anchor, which should remove the calling OuterDiv My code so far: <body> <div class="OuterDiv"> <div class="InnerDiv"> <span class="Position">Position 1</span> </div> </div> <div class="OuterDiv"> <div class="InnerDiv"> <span class="Position">Position 2</span> </div> </div> </body> And scripts: $(document).ready(function () { var qTipContent = '<a href="javascript:void(0)" onclick="">&uarr;</a>&nbsp;&nbsp;&nbsp;'; qTipContent = qTipContent + '<a href="javascript:void(0)" onclick="">&darr;</a>&nbsp;&nbsp;&nbsp;'; qTipContent = qTipContent + '<a href="javascript:void(0)" onclick="">X</a>'; $('.Position').each(function () { $(this).qtip({ content: qTipContent, hide: { fixed: true } }) }); }); How should the onclick function in the qTip content look like?

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  • Advise about quick/full format

    - by ile
    Is it virus-safe to do quick format of hard drive? I want to format disk that was infected and install windows 7 on it, but I am not sure if Quick Format is secure enough. I am aware that it does not delete data but pointers to it, so I wonder if it is possible that virus activates from that data? Thanks

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  • Android - save/restore state of custom class

    - by user1209216
    I have some class for ssh support - it uses jsch internally. I use this class on main activity, this way: public class MainActivity extends Activity { SshSupport ssh = new SshSupport(); ..... @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); //Handle events for ssh ssh.eventHandler = new ISshEvents() { @Override public void SshCommandExecuted(SshCommandsEnum commandType, String result) { } //other overrides here } //Ssh operations on gui item click @Override public void onItemClick(AdapterView<?> arg0, View v, int position, long arg3) { if (ssh.IsConnected() == false) { try { ssh.ConnectAsync(/*parameters*/); } catch (Exception e) { e.printStackTrace(); } } try { ssh.ExecuteCommandAsync(SshCommandsEnum.values()[position]); } catch (Exception e) { e.printStackTrace(); } } }); } It works very well. My application connects to ssh, performs all needed operation in background thread and results are reported to gui, via events as shown above. But nothing works after user change device orientation. It's clear for me - activity is re-created and all state is lost. Unfortunately, my SshSupport class object is lost as well. It's pretty easy to store gui state for dynamically changed/added objects (using put/get serializable etc methods). But I have no idea how to prevent my ssh object, ssh connected session being lost. Since my class is not serializable, I can't save it to bundle. Also, even if I make my SshSupport class serializable, jsch objects it uses still are not serializable. So what is the best way to solve this?

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  • Accessing Instance Variables from NSTimer selector

    - by Timbo
    Firstly newbie question: What's the difference between a selector and a method? Secondly newbie question (who would have thought): I need to loop some code based on instance variables and pause between loops until some condition (of course based on instance variables) is met. I've looked at sleep, I've looked at NSThread. In both discussions working through those options many asked why don't I use NSTimer, so here I am. Ok so it's simple enough to get a method (selector? ) to fire on a schedule. Problem I have is that I don't know how to see instance variables I've set up outside the timer from within the code NSTimer fires. I need to see those variables from the NSTimer selector code as I 1) will be updating their values and 2) will set labels based on those values. Here's some code that shows the concept… eventually I'd invalidate the timers based on myVariable too, however I've excluded that for code clarity. MyClass *aMyClassInstance = [MyClass new]; [aMyClassInstance setMyVariable:0]; [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(doStuff) userInfo:nil repeats:YES]; [NSTimer scheduledTimerWithTimeInterval:5.0 target:self selector:@selector(doSomeOtherStuff) userInfo:nil repeats:YES]; - (void) doStuff { [aMyClassInstance setMyVariable:11]; // don't actually have access to set aMyClassInstance.myVariable [self updateSomeUILabel:[NSNumber numberWithInt:aMyClassInstance.myVariable]]; // don't actually have access to aMyClassInstance.myVariable } - (void) doSomeOtherStuff { [aMyClassInstance setMyVariable:22]; // don't actually have access to set aMyClassInstance.myVariable [self updateSomeUILabel:[NSNumber numberWithInt:aMyClassInstance.myVariable]]; // don't actually have access to aMyClassInstance.myVariable } - (void) updateSomeUILabel:(NSNumber *)arg{ int value = [arg intValue]; someUILabel.text = [NSString stringWithFormat:@"myVariable = %d", value]; // Updates the UI with new instance variable values }

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  • Attempted GCF app for Android

    - by Aaron
    I am new to Android and am trying to create a very basic app that calculates and displays the GCF of two numbers entered by the user. Here is a copy of my GCF.java: package com.example.GCF; import java.util.Arrays; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class GCF extends Activity { private TextView mAnswer; private EditText mA, mB; private Button ok; private String A, B; private int iA, iB; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mA = (EditText) findViewById(R.id.entry); mB = (EditText) findViewById(R.id.entry1); ok = (Button) findViewById(R.id.ok); mAnswer = (TextView) findViewById(R.id.answer1); ok.setOnClickListener(new OnClickListener() { public void onClick(View v) { A = mA.getText().toString(); B = mB.getText().toString(); } }); // the String to int conversion happens here iA = Integer.parseInt(A.trim()); iB = Integer.parseInt(B.trim()); while (iA != iB) { int[] nums={ iA, iB, Math.abs(iA-iB) }; Arrays.sort(nums); iA=nums[0]; iB=nums[1]; } updateDisplay(); } private void updateDisplay() { mAnswer.setText( new StringBuilder().append(iA)); } } Any Suggestions? Thank you!

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  • uploading database file in assets not returning a record

    - by Alexander
    I have a problem with a database file not being read I have added the database file in assets called mydb but when i run my code it says its not being located. It is calling this toast Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show(); This is being called because no records are being returned. This is an example form Android Application Development book. public class DatabaseActivity extends Activity { /** Called when the activity is first created. */ TextView quest, response1, response2; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView quest = (TextView) findViewById(R.id.quest); try { String destPath = "/data/data/" + getPackageName() + "/databases/MyDB"; File f = new File(destPath); if (!f.exists()) { CopyDB( getBaseContext().getAssets().open("mydb"), new FileOutputStream(destPath)); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } DBAdapter db = new DBAdapter(this); //---get a contact--- db.open(); Cursor c = db.getContact(2); if (c.moveToFirst()) DisplayContact(c); else Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show(); db.close(); } public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException { //---copy 1K bytes at a time--- byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer)) > 0) { outputStream.write(buffer, 0, length); } inputStream.close(); outputStream.close(); } public void DisplayContact(Cursor c) { quest.setText(String.valueOf(c.getString(1))); //quest.setText(String.valueOf("this is a text string")); } }

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  • How to filter and intercept Linux packets by using net_dev_add() API?

    - by Khajavi
    I'm writing ethernet network driver for linux. I want to receive packets, edit and resend them. I know how to edit the packet in packet_interceptor function, but how can I drop incoming packets in this function?? #include <linux/netdevice.h> #include <linux/skbuff.h> #include <linux/ip.h> #include <net/sock.h> struct packet_type my_proto; int packet_interceptor(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev) { // I dont want certain packets go to upper in net_devices for further processing. // How can I drop sk_buff here?! return 0; } static int hello_init( void ) { printk(KERN_INFO "Hello, world!\n"); my_proto.type = htons(ETH_P_ALL); my_proto.dev = NULL; my_proto.func = packet_interceptor; dev_add_pack(&my_proto); return 0; } static void hello_exit(void) { dev_remove_pack(&my_proto); printk(KERN_INFO "Bye, world\n"); } module_init(hello_init); module_exit(hello_exit);

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  • AudioRecord - empty buffer

    - by Arxas
    I' m trying to record some audio using AudioRecord class. Here is my code: int audioSource = AudioSource.MIC; int sampleRateInHz = 44100; int channelConfig = AudioFormat.CHANNEL_IN_MONO; int audioFormat = AudioFormat.ENCODING_PCM_16BIT; int bufferSizeInShorts = 44100; int bufferSizeInBytes = 2*bufferSizeInShorts; short Data[] = new short[bufferSizeInShorts]; Thread recordingThread; AudioRecord audioRecorder = new AudioRecord(audioSource, sampleRateInHz, channelConfig, audioFormat, bufferSizeInBytes); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } public void startRecording(View arg0) { audioRecorder.startRecording(); recordingThread = new Thread(new Runnable() { public void run() { while (Data[bufferSizeInShorts-1] == 0) audioRecorder.read(Data, 0, bufferSizeInShorts); } }); audioRecorder.stop(); } Unfortunately my short array is empty after the recording is over. May I kindly ask you to help me figure out what's wrong?

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  • How to write curiously recurring templates with more than 2 layers of inheritance?

    - by Kyle
    All the material I've read on Curiously Recurring Template Pattern seems to one layer of inheritance, ie Base and Derived : Base<Derived>. What if I want to take it one step further? #include <iostream> using std::cout; template<typename LowestDerivedClass> class A { public: LowestDerivedClass& get() { return *static_cast<LowestDerivedClass*>(this); } void print() { cout << "A\n"; } }; template<typename LowestDerivedClass> class B : public A<LowestDerivedClass> { public: void print() { cout << "B\n"; } }; class C : public B<C> { public: void print() { cout << "C\n"; } }; int main() { C c; c.get().print(); // B b; // Intentionally bad syntax, // b.get().print(); // to demonstrate what I'm trying to accomplish return 0; } How can I rewrite this code to compile without errors (and output "C\nB\n")?

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  • How to focus a control in an MDIParent when all child windows have closed?

    - by Tim Gradwell
    I have a control in my parent mdi form which I wish to be given the focus if all mdi children have closed. I've tried hooking into the child form's FormClosed event and setting the focus from there but when I test it, my control is not left with focus when I close the mdi child. Can anyone tell me what I'm missing? In the sample below, "first focus" gets hit and does its job correctly (if I comment out the first focus line, my tree does not get focus on startup, so it must be doing its job, right?) Unfortunately, even though "second focus" gets hit, my tree does not end up with the focus when I close the child window. Sample using System; using System.Windows.Forms; namespace mdiFocus { class ParentForm : Form { public ParentForm() { IsMdiContainer = true; tree = new TreeView(); tree.Nodes.Add("SomeNode"); tree.Dock = DockStyle.Left; Controls.Add(tree); } protected override void OnShown(EventArgs e) { Form child = new Form(); child.MdiParent = this; child.Show(); child.FormClosed += new FormClosedEventHandler(child_FormClosed); tree.Focus(); // first focus works ok } void child_FormClosed(object sender, FormClosedEventArgs e) { tree.Focus(); // second focus doesn't seem to work, even though it is hit :( } TreeView tree; } static class Program { [STAThread] static void Main() { Application.Run(new ParentForm()); } } }

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  • c# template member functions

    - by user3730583
    How can I define a template member function in C# For instance I will fill any collection which supports an Add(...) member function, please check out the sample code below public class CInternalCollection { public static void ExternalCollectionTryOne<T<int>>(ref T<int> ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } public static void ExternalCollectionTryTwo<T>(ref T ext_col, int para_selection = 0) { foreach (int int_value in m_int_col) { if (int_value > para_selection) ext_col.Add(int_value); } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; } The ExternalCollectionTryOne<...(...) would be the preferred kind, because the int type can be explicit defined, but results in an error: Type parameter declaration must be an identifier not a type The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) The ExternalCollectionTryTwo<...(...) results in an error: 'T' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'T' could be found (are you missing a using directive or an assembly reference?)... I hope the problem is clear – any suggestions? ----------------------------- edit -------------------------- The answers with the interface ICollection<.. without a template member works fine and thanks all for this hint, but I still cannot define successfully a member template(generic) function So a more simpler example ... how can I define this public class CAddCollectionValues { public static void AddInt<T>(ref T number, int selection) { T new_T = new T(); //this line is just an easy demonstration to get a compile error with type T foreach (int i_value in m_int_col) { if (i_value > selection) number += i_value; //again the type T cannot be used } } static int[] m_int_col = { 0, -1, -3, 5, 7, -8 }; }

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  • gwt get array button value

    - by graybow
    My gwt project have flexTable show data of image and button on each row and coll. But my button won't work properly. this is my current code: private Button[] b = new Button[]{new Button("a"),...,new Button("j")}; private int z=0; ... public void UpdateTabelGallery(JsArray str){ for(int i=0; i str.length(); i++){ b[i].setText(str.gettitle()); UpdateTabelGallery(str.get(i)); } } public void UpdateTabelGallery(GalleryData str){ Image img = new Image(); img.setUrl(str.getthumburl()); HTML himage= new HTML("a href="+str.geturl()+""+ img +"/a" + b[z] ); TabelGaleri.setWidget(y, x, himage); //is here th right place? b[z].addClickHandler(new ClickHandler(){ @Override public void onClick(ClickEvent event) { Window.alert("I wan to show the clicked button text" + b[z].getText()); } }); z++; } I'm still confuse where I should put my button handler. With this current code seems the clickhandler didn't work inside a looping. And if I put it outside loop its not working because I need to know which button clicked. I need to get my index button.but how? Is there any option than array button? thanks

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  • Reducing Duplicated Code

    - by cam
    I have some code that works on the color structure like this public void ChangeColor() { thisColor.R = thisColor.R + 5; } Now I need to make a method that changes a different variable depending on what it is passed. Here is what the code looks like now. public void ChangeColor(int RGBValue) { switch(RGBValue) { case 1: thisColor.R = thisColor.R + 5; break; case 2: thiscolor.B = thisColor.B + 5; break; } } Now, this is something I would normally never question, I'd just throw a #region statement around it and call it a day, but this is just an example of what I have, the actual function is quite long. I want it to look like this: public void ChangeColor(int RGBValue) { thiscolor.RGBValue = thiscolor.RGBValue; } So essentially the value would refer to the variable being used. Is there a name for this? Is this what Reflection is for? Or something like that... Is there a way to do this?

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  • Error in Android's clearCheck() for RadioGroup?

    - by Manuel R. Ciosici
    I'm having an issue with RadioGroup's clearChecked(). I'm displaying a multiple choice question to the user and after the user selects an answer I check the answer, give him some feedback and then move to the next question. In the process of moving to the next question I clearCheck on the RadioGroup. Can anyone explain to me why the onCheckedChanged method is called 3 times? Once when the change actually occurs (with the user changes), once when I clearCheck(with -1 as the selected id) and once in between (with the user changes again)? As far as I could tell the second trigger is provoked by clearCheck. Code below: private void checkAnswer(RadioGroup group, int checkedId){ // this makes sure it doesn't blow up when the check is cleared // also we don't check the answer when there is no answer if (checkedId == -1) return; if (group.getCheckedRadioButtonId() == -1) return; // check if correct answer if (checkedId == validAnswerId){ score++; this.giveFeedBack(feedBackType.GOOD); } else { this.giveFeedBack(feedBackType.BAD); } // allow for user to see feedback and move to next question h.postDelayed(this, 800); } private void changeToQuestion(int questionNumber){ if (questionNumber >= this.questionSet.size()){ // means we are past the question set // we're going to the score activity this.goToScoreActivity(); return; } //clearing the check gr.clearCheck(); // give change the feedback back to question imgFeedback.setImageResource(R.drawable.question_mark); //OTHER CODE HERE } and the run method looks like this public void run() { questionNumber++; changeToQuestion(questionNumber); }

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  • JLabel transparency problem

    - by Rendicahya
    I have a dark-gray JPanel with a JLabel on it. I set new Color(0, 0, 0, .5f) (tranparent) as the background of the JLabel and I change the text several times using a button. The problem is, everytime the text is changed, the previous text still remains behind the new text. I change the text from "123456789" to "1234567", "12345" and "123". Here is the screenshot: How do I get rid of this "shadow"? Here's the code: public class TransparentJLabel extends JFrame { private int i = 0; private String[] value = {"123456789", "1234567", "12345", "123", "1"}; public TransparentJLabel() { setSize(300, 160); setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); setLayout(null); JPanel panel = new JPanel(); panel.setBackground(new Color(102, 102, 102)); panel.setLayout(null); panel.setBounds(0, 0, 300, 160); final JLabel label = new JLabel(); label.setText(value[0]); label.setFont(new Font("Times New Roman", 1, 36)); label.setForeground(new Color(255, 255, 255)); label.setBackground(new Color(0, 0, 0, .5f)); label.setHorizontalAlignment(SwingConstants.CENTER); label.setOpaque(true); label.setBounds(10, 10, 270, 70); JButton button = new JButton(); button.setText("Change"); button.setBounds(100, 90, 90, 25); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { label.setText(value[++i]); } }); panel.add(label); panel.add(button); add(panel); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { new TransparentJLabel().setVisible(true); } }); } }

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  • Draggable cards (touch enumeration) issue

    - by glitch
    I'm trying to let a player tap, drag and release a card from a fanned stack on the screen to a 4x4 field on the board. My cards are instantiated from a custom class that inherits from the UIImageView class. I started with the Touches sample app, and I modified the event handlers for touches to iterate over my player's card hand instead of the 3 squares the sample app allows you to move on screen. Everything works, until that is, I move the card I'm dragging near another card. I'm really drawing a blank here for the logic to get the cards to behave properly. Here's my code: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSUInteger numTaps = [[touches anyObject] tapCount]; if(numTaps = 1) { for (UITouch *touch in touches) { [self dispatchFirstTouchAtPoint:[touch locationInView: self.boardCardView] forEvent:nil]; } } } -(void) dispatchFirstTouchAtPoint:(CGPoint)touchPoint forEvent:(UIEvent *)event { for (int i = 0; i<5; i++) { UIImageView *touchedCard = boardBuffer[i]; if (CGRectContainsPoint([touchedCard frame], touchPoint)) { [self animateFirstTouchAtPoint:touchPoint forView:touchedCard]; } } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { NSUInteger touchCount = 0; for (UITouch *touch in touches){ [self dispatchTouchEvent:[touch view] toPosition:[touch locationInView:self.boardCardView]]; touchCount++; } } My questions are: How do I get the touch logic to disallow other cards from being picked up by a dragging finger? Is there anyway I can only enumerate the objects that are directly below a player's finger and explicitly disable other objects from responding? Thanks!

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  • Removing Item from Collection / Changing field of Object

    - by x Nuclear 213
    public void searchOwner(List<Appointments> appts, String owner) { Appointments theOne = null; for (Appointments temp : appts) { if (owner.equalsIgnoreCase(temp.owner.name)) { System.out.println(temp.data); temp.setResolved(true); } } } public void checkRemoval() { for (Appointments appts : appointments) { if (appts.resolved == true) { appointments.remove(appts); } //Iterator method used before enhanced for-loop public void checkRemovalI(){ Iterator<Appointments> it = appointments.iterator(); while(it.hasNext()){ if(it.next().resolved = true){ it.remove(); } } } So far this is where I am encountering my problem. I am trying to check the arrayList of Appointments and see if the field (resolved) is set to true, however I am receiving an ConcurrentModification exception during the searchOwner method when trying to set resolved = to true. I've tried using an Iterator in checkRemoval instead of an enhanced for-loop however that didn't help either. I really only need to get the part where the appointment is set to true to work, the checkRemoval seemed to be working early before implementing the changing of the boolean resolved. Any help will be greatly appreciated, thank you.

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  • Writing my own implementation of stl-like Iterator in C++.

    - by Negai
    Good evening everybody, I'm currently trying to understand the intrinsics of iterators in various languages i.e. the way they are implemented. For example, there is the following class exposing the list interface. template<class T> class List { public: virtual void Insert( int beforeIndex, const T item ) throw( ListException ) =0 ; virtual void Append( const T item ) =0; virtual T Get( int position ) const throw( ListException ) =0; virtual int GetLength() const =0; virtual void Remove( int position ) throw( ListException ) =0; virtual ~List() =0 {}; }; According to GoF, the best way to implement an iterator that can support different kinds of traversal is to create the base Iterator class (friend of List) with protected methods that can access List's members. The concrete implementations of Iterator will handle the job in different ways and access List's private and protected data through the base interface. From here forth things are getting confusing. Say, I have class LinkedList and ArrayList, both derived from List, and there are also corresponding iterators, each of the classes returns. How can I implement LinkedListIterator? I'm absolutely out of ideas. And what kind of data can the base iterator class retrieve from the List (which is a mere interface, while the implementations of all the derived classes differ significantly) ? Sorry for so much clutter. Thanks.

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  • How to draw mutiple rectangles using c#

    - by Nivas
    I have drawn and saved the Rectangle on the image i loaded in the picture box. How i like to draw multiple rectangles for that i tried array in the rectangle but it gives error ("Object reference not set to an instance of an object." (Null reference Exception was unhandled). enter code here private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { if (mybitmap == null) { mybitmap = new Bitmap(sz.Width, sz.Height); } rect = new Rectangle(e.X, e.Y, 0, 0); this.Invalidate(); } private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { if (stayToolStripMenuItem.Checked == true) { switch (e.Button) { case MouseButtons.Left: { rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top); pictureBox1.Invalidate(); break; } } } } private void pictureBox1_Paint(object sender, PaintEventArgs e) { if (stayToolStripMenuItem.Checked == true) { button1.Visible = true; button2.Visible = true; if (mybitmap == null) { return; } using (g = Graphics.FromImage(mybitmap)) { using (Pen pen = new Pen(Color.Red, 2)) { //g.Clear(Color.Transparent); e.Graphics.DrawRectangle(pen, rect); label1.Top = rect.Top; label1.Left = rect.Left; label1.Width = rect.Width; label1.Height = rect.Height; if (label1.TextAlign == ContentAlignment.TopLeft) { e.Graphics.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawRectangle(pen, rect); } } } } } How can i do this.....

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  • Write file need to optimised for heavy traffic part 2

    - by Clayton Leung
    For anyone interest to see where I come from you can refer to part 1, but it is not necessary. write file need to optimised for heavy traffic Below is a snippet of code I have written to capture some financial tick data from the broker API. The code will run without error. I need to optimize the code, because in peak hours the zf_TickEvent method will be call more than 10000 times a second. I use a memorystream to hold the data until it reaches a certain size, then I output it into a text file. The broker API is only single threaded. void zf_TickEvent(object sender, ZenFire.TickEventArgs e) { outputString = string.Format("{0},{1},{2},{3},{4}\r\n", e.TimeStamp.ToString(timeFmt), e.Product.ToString(), Enum.GetName(typeof(ZenFire.TickType), e.Type), e.Price, e.Volume); fillBuffer(outputString); } public class memoryStreamClass { public static MemoryStream ms = new MemoryStream(); } void fillBuffer(string outputString) { byte[] outputByte = Encoding.ASCII.GetBytes(outputString); memoryStreamClass.ms.Write(outputByte, 0, outputByte.Length); if (memoryStreamClass.ms.Length > 8192) { emptyBuffer(memoryStreamClass.ms); memoryStreamClass.ms.SetLength(0); memoryStreamClass.ms.Position = 0; } } void emptyBuffer(MemoryStream ms) { FileStream outStream = new FileStream("c:\\test.txt", FileMode.Append); ms.WriteTo(outStream); outStream.Flush(); outStream.Close(); } Question: Any suggestion to make this even faster? I will try to vary the buffer length but in terms of code structure, is this (almost) the fastest? When memorystream is filled up and I am emptying it to the file, what would happen to the new data coming in? Do I need to implement a second buffer to hold that data while I am emptying my first buffer? Or is c# smart enough to figure it out? Thanks for any advice

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  • C++ creating generic template function specialisations

    - by Fire Lancer
    I know how to specialise a template function, however what I want to do here is specialise a function for all types which have a given method, eg: template<typename T> void foo(){...} template<typename T, if_exists(T::bar)>void foo(){...}//always use this one if the method T::bar exists T::bar in my classes is static and has different return types. I tried doing this by having an empty base class ("class HasBar{};") for my classes to derive from and using boost::enable_if with boost::is_base_of on my "specialised" version. However the problem then is that for classes that do have bar, the compiler cant resolve which one to use :(. template<typename T> typename boost::enable_if<boost::is_base_of(HasBar, T>, void>::type f() {...} I know that I could use boost::disable_if on the "normal" version, however I do not control the normal version (its provided by a third party library and its expected for specialisations to be made, I just don't really want to make explicit specialisations for my 20 or so classes), nor do I have that much control over the code using these functions, just the classes implementing T::bar and the function that uses it. Is there some way to tell the compiler to "always use this version if possible no matter what" without altering the other versions?

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  • Strange overloading rules in C++

    - by bucels
    I'm trying to compile this code with GCC 4.5.0: #include <algorithm> #include <vector> template <typename T> void sort(T, T) {} int main() { std::vector<int> v; sort(v.begin(), v.end()); } But it doesn't seem to work: $ g++ -c nm.cpp nm.cpp: In function ‘int main()’: nm.cpp:9:28: error: call of overloaded ‘sort(std::vector<int>::iterator, std::vector<int>::iterator)’ is ambiguous nm.cpp:4:28: note: candidates are: void sort(T, T) [with T = __gnu_cxx::__normal_iterator<int*, std::vector<int> >] /usr/lib/gcc/i686-pc-linux-gnu/4.5.0/../../../../include/c++/4.5.0/bits/stl_algo.h:5199:69: note: void std::sort(_RAIter, _RAIter) [with _RAIter = __gnu_cxx::__normal_iterator<int*, std::vector<int> >] Comeau compiles this code without errors. (4.3.10.1 Beta2, strict C++03, no C++0x) Is this valid C++?

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