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• Regularly update database without browser/user

  - by Chris M

  I currently have a MySQL database which I was hoping to use to store regularly updated data from a temperature sensor connected to the internet. I currently have a page that, when opened, will grab the current temperature and the current timestamp and add it as an entry to the database, but I was looking for a way to do that without me refreshing the page every 5 seconds. Detail: The data comes from an Arduino Ethernet, posted to an IP address. Currently, I'm using cURL to grab the data from the IP, add a timestamp and save it to the DB. Obviously only updates when the page is refreshed (it uses PHP). Here is a live feed of the data - http://wetdreams.org.uk/ChrisProject/UI/live_graph_two.html TL;DR - Basically I need a middle man to grab the data from the IP and post it to a MySQL Edit: Thanks for all the advice. There might be a little bit of confusion, I'm looking for a solution that (ideally) doesn't require a computer to be on at all (other than the Server containing Database). Since I'm looking to store data over long periods of time (weeks), I'd like to set it up and leave a script running on the server (or Arduino) that gets the temp and posts it to the Database. In my head I would like to have a page on the server that automatically (without any browser open, or any other prompting other than a timer) calls a PHP script. Hope that clears things up!

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• Unexpected behaviour of Process.MainWindowHandle

  - by Ed Guiness

  I've been trying to understand Process.MainWindowHandle. According to MSDN; "The main window is the window that is created when the process is started. After initialization, other windows may be opened, including the Modal and TopLevel windows, but the first window associated with the process remains the main window." (Emphasis added) But while debugging I noticed that MainWindowHandle seemed to change value... which I wasn't expecting, especially after consulting the documentation above. To confirm the behaviour I created a standalone WinForms app with a timer to check the MainWindowHandle of the "DEVENV" (Visual Studio) process every 100ms. Here's the interesting part of this test app... IntPtr oldHWnd = IntPtr.Zero; void GetMainwindowHandle() { Process[] processes = Process.GetProcessesByName("DEVENV"); if (processes.Length!=1) return; IntPtr newHWnd = processes[0].MainWindowHandle; if (newHWnd != oldHWnd) { oldHWnd = newHWnd; textBox1.AppendText(processes[0].MainWindowHandle.ToString("X")+"\r\n"); } } private void timer1Tick(object sender, EventArgs e) { GetMainwindowHandle(); } You can see the value of MainWindowHandle changing when you (for example) click on a drop-down menu inside VS. Perhaps I've misunderstood the documentation. Can anyone shed light?

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• How to encrypt a RSAKey using another RSAKey?

  - by Tom Brito

  I know its not the usual thing to do. But the specification I'm implementing is discribed this way, and I cannot run out. I was trying to encrypt the modulus and exponent of the private key, but the following test code raises an exception because the byte array is 1 byte larger then the maximum allowed by RSA block: import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.Cipher; import org.apache.commons.lang.ArrayUtils; public class TEST { public static KeyPair generateKeyPair() throws NoSuchAlgorithmException, NoSuchProviderException { KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC"); keyPairGenerator.initialize(1024); return keyPairGenerator.generateKeyPair(); } public static void main(String[] args) throws Exception { KeyPair keyPair = generateKeyPair(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); System.out.println("Priv modulus len = " + privateKey.getModulus().bitLength()); System.out.println("Priv exponent len = " + privateKey.getPrivateExponent().bitLength()); System.out.println("Priv modulus toByteArray len = " + privateKey.getModulus().toByteArray().length); byte[] byteArray = privateKey.getModulus().toByteArray(); // the byte at index 0 have no value (in every generation it is always zero) byteArray = ArrayUtils.subarray(byteArray, 1, byteArray.length); System.out.println("byteArray size: " + byteArray.length); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); Cipher cipher = Cipher.getInstance("RSA", "BC"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); byte[] encryptedBytes = cipher.doFinal(byteArray); System.out.println("Success!"); } } (obs. its just a test, i would never encrypt the private key with its pair public key) The byte array is 128 bytes, the exactly maximum allowed by a RSA block, so why the exception? And how to fix it?

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• OSGi bundle imports packages from non-bundle jars: create bundles for them?

  - by John Simmons

  I am new to OSGi, and am using Equinox. I have done several searches and can find no answer to this. The discussion at OSGI - handling 3rd party JARs required by a bundle helps somewhat, but does not fully answer my question. I have obtained a jar file, rabbitmq-client.jar, that is already packaged as an OSGi bundle (with Bundle-Name and other such properties in its MANIFEST.MF), that I would like to install as a bundle. This jar imports packages org.apache.commons.io and org.apache.commons.io.input from commons-io-1.2.jar. The RabbitMQ client 2.7.1 distribution also includes commons-cli-1.1.jar, so I presume that it is required as well. I examined the manifests of these commons jars and found that they do not appear to be packaged as bundles. That is, their manifests have none of the standard bundle properties. My specific question is: if I install rabbitmq-client.jar as a bundle, what is the proper way to get access to the packages that it needs to import from the commons jars? There are only three alternatives that I can think of, without rebuilding rabbitmq-client.jar. The packages from the commons jars are already included in the Equinox global classpath, and rabbitmq-client.jar will get them automatically from there. I must make another bundle with the two commons jars, export the needed packages, and install that bundle in Equinox. I must put these two commons jars in the global classpath when I start Equinox, and they will be available to rabbitmq-client.jar from there. I have read that one normally does not use the global classpath in an OSGi container. I am not clear on whether items from the global classpath are even available when building individual bundle classpaths. However, I note that rabbitmq-client.jar also imports other packages such as javax.net, which I presume come from the global classpath. Or is there some other bundle that exports them? Thanks for any assistance!

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• Strange performance behaviour

  - by plastilino

  I'm puzzled with this. In my machine Direct calculation: 375 ms Method calculation: 3594 ms, about TEN times SLOWER If I place the method calulation BEFORE the direct calculation, both times are SIMILAR. Woud you check it in your machine? class Test { static long COUNT = 50000 * 10000; private static long BEFORE; /*--------METHOD---------*/ public static final double hypotenuse(double a, double b) { return Math.sqrt(a * a + b * b); } /*--------TIMER---------*/ public static void getTime(String text) { if (BEFORE == 0) { BEFORE = System.currentTimeMillis(); return; } long now = System.currentTimeMillis(); long elapsed = (now - BEFORE); BEFORE = System.currentTimeMillis(); if (text.equals("")) { return; } String message = "\r\n" + text + "\r\n" + "Elapsed time: " + elapsed + " ms"; System.out.println(message); } public static void main(String[] args) { double a = 0.2223221101; double b = 122333.167; getTime(""); /*--------DIRECT CALCULATION---------*/ for (int i = 1; i < COUNT; i++) { Math.sqrt(a * a + b * b); } getTime("Direct: "); /*--------METHOD---------*/ for (int k = 1; k < COUNT; k++) { hypotenuse(a, b); } getTime("Method: "); } }

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• Action listener for JButton array

  - by user530809

  Let's say I have a program with 2D array of buttons, and when you click one of them it turns red. I didn't want to declare every single button seperately so I just created JButton[][] array for them. The problem is that I don't know how to use action listener on any of the buttons in the array so it would change the color of this particular button, and none of related questions is relevant to this. I tried to use "for" but it doesn't help: package appli; import javax.swing.*; import java.awt.*; import java.awt.event.*; public class MainW extends JFrame implements ActionListener { public MainW(){ setSize(640,480); setTitle("title"); setLayout(null); JButton[][] btnz = new JButton[5][5]; for(Integer i=0;i<5;i++) { for(Integer j=0;j<5;j++) { btnz[i][j]= new JButton(""); btnz[i][j].setBackground(Color.WHITE); btnz[i][j].setBounds(10+20*i,10+20*j,20,20); add(btnz[i][j]); btnz[i][j].addActionListener(this); } } setDefaultCloseOperation(EXIT_ON_CLOSE); setVisible(true); } public void actionPerformed(ActionEvent e){ for(Integer i=0;i<5;i++) { for(Integer j=0;j<5;j++) { if (e.getSource()==btnz[i][j]); { btnz[i][j].setBackground(Color.RED); } } } } }

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• python script problem once build and package it

  - by Apache

  hi expert, I've written python script to scan wifi and send data to the server, I set interval value, so it keep on scanning and send the data, it read from config.txt file where i set the interval value to scan, I also add yes/no in my config file, so is 'no' it will scan only once and if 'yes' it will scan according to the interval level, my code as below import time,..... from threading import Event, Thread class RepeatTimer(Thread): def __init__(self, interval, function, iterations=0, args=[], kwargs={}): Thread.__init__(self) self.interval = interval self.function = function self.iterations = iterations self.args = args self.kwargs = kwargs self.finished = Event() def run(self): count = 0 while not self.finished.is_set() and (self.iterations <= 0 or count < self.iterations): self.finished.wait(self.interval) if not self.finished.is_set(): self.function(*self.args, **self.kwargs) count += 1 def cancel(self): self.finished.set() def scanWifi(self): #scanning process and sending data done here obj = JW() if status == "yes": t = RepeatTimer(int(intervalTime),obj.scanWifi) t.start() else: obj.scanWifi() once I package my code, its only run when I set my config file set to 'no' where it scan only once, but when I set my config file to 'yes', there is no progress at all, so I found that there is problem with my class RepeatTimer(Timer) once build, but don't know how to solve can anyone help me thanks

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• How can I change jtable height at runtime

  - by wniroshan

  I hava a JFrame with multiple JPanels of similar width aligned one below other. I use one of these JPanels to display a JTable which is the last JPanel of the lot. This JPanel has a JScrollpane as a child component. This is where I try to add my table dynamically. Initial height of this JScrollpane is set to 40. I designed above template using Netbeans 6.8 Now I'm trying to add the table to the JPanel. When a button is pressed below code snippet is called. The class which includes this code extends javax.swing.JFrame class. I am expecting below code would adjust table height according to the row count and display the table. SearchTable = new JTable(RowData, DisplayNames) { @Override public boolean isCellEditable(int rowIndex, int vColIndex) { return false; } }; // if row count is less than 10 then display all the rows without a scroll bar if (SearchTable.getRowCount() < 10) { pnl_tblpanel.setPreferredSize(new Dimension(625, SearchTable.getRowHeight() * (SearchTable.getRowCount() + 4))); scr_tblholder.setPreferredSize(new Dimension(625, SearchTable.getRowHeight() * (SearchTable.getRowCount() + 4))); } else {// if row count is more than 10 display first 10 rows and add a scroll bar pnl_tblpanel.setPreferredSize(new Dimension(625, SearchTable.getRowHeight() * (10 + 2))); scr_tblholder.setAutoscrolls(true); } //pnl_tblpanel.add(scr_tblholder); scr_tblholder.setViewportView(SearchTable); //pnl_tblpanel.repaint(); pnl_tblpanel.validate(); this.validate(); //this.repaint(); pnl_tblpanel.setVisible(true); this.pack(); The table displays, but the table height is not changed according to the row count. It stays its default value. I have been trying many combinations of validate and repaint but nothing worked. (More in desperation) Can anyone shed some light on this Thank you

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• Build OpenGL model in parallel?

  - by Brendan Long

  I have a program which draws some terrain and simulates water flowing over it (in a cheap and easy way). Updating the water was easy to parallelize using OpenMP, so I can do ~50 updates per second. The problem is that even with a small amounts of water, my draws per second are very very low (starts at 5 and drops to around 2 once there's a significant amount of water). It's not a problem with the video card because the terrain is more complicated and gets drawn so quickly that boost::timer tells me that I get infinity draws per second if I turn the water off. It may be related to memory bandwidth though (since I assume the model stays on the card and doesn't have to be transfered every time). What I'm concerned about is that on every draw, I'm calling glVertex3f() about a million times (max size is 450*600, 4 vertices each), and it's done entirely sequentially because Glut won't let me call anything in parallel. So.. is if there's some way of building the list in parallel and then passing it to OpenGL all at once? Or some other way of making it draw this faster? Am I using the wrong method (besides the obvious "use less vertices")?

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• How to analyze evenness/oddness of numbers in Java

  - by appreciation

  I have to write a program which reads in 3 numbers (using input boxes), and depending on their values it should write one of these messages: All 3 numbers are odd OR All 3 numbers are even OR 2 numbers are odd and 1 is even OR 1 number is odd and 2 are even This is what I have so far: import javax.swing.JOptionPane; class program3 { public static void main(String[] args) { String num1 = JOptionPane.showInputDialog("Enter first number."); String num2 = JOptionPane.showInputDialog("Enter second number."); String num3 = JOptionPane.showInputDialog("Enter third number."); boolean newnum1 = Integer.parseInt(num1); boolean newnum2 = Integer.parseInt(num2); boolean newnum3 = Integer.parseInt(num3); } } This is where I am stuck. I am not sure how to use the MOD to display the messages. I think I have to also use an IF Statement too...But I'm not too sure. Please help! :D

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• Indy client receive string

  - by Eszee

  Im writing an Indy chat app, and am wondering if there is a way for the server component to tell the client that there is a string waiting, or even a way for the client to have an "OnExecute" like event. This is what i have now: server: procedure TServer.ServerExecute(AContext: TIdContext); var sResponse: string; I: Integer; list: Tlist; begin List := Server.Contexts.LockList; sResponse:= AContext.Connection.Socket.ReadLn; try for I := 0 to List.Count-1 do begin try TIdContext(List[I]).Connection.IOHandler.WriteLn(sResponse); except end; end; finally Server.Contexts.UnlockList; end; end; Client: procedure TForm1.Button1Click(Sender: TObject); var sMsg : string; begin Client.Socket.WriteLn(edit1.Text); sMsg := Client.Socket.ReadLn; Memo1.Lines.Add(sMsg); end; The problem is when i have 2 or more clients running the messages keep stacking because the button only processes 1 message a time. I'd like a way for the client to wait for messages and when it is triggered it processes those messages, like it does now under the button procedure. I've tried to put the "readln" part under a timer, but that causes some major problems. Im Using Delphi 2010 and Indy 10

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• Running a process at the Windows 7 Welcome Screen

  - by peelman

  So here's the scoop: I wrote a tiny C# app a while back that displays the hostname, ip address, imaged date, thaw status (we use DeepFreeze), current domain, and the current date/time, to display on the welcome screen of our Windows 7 lab machines. This was to replace our previous information block, which was set statically at startup and actually embedded text into the background, with something a little more dynamic and functional. The app uses a Timer to update the ip address, deepfreeze status, and clock every second, and it checks to see if a user has logged in and kills itself when it detects such a condition. If we just run it, via our startup script (set via group policy), it holds the script open and the machine never makes it to the login prompt. If we use something like the start or cmd commands to start it off under a separate shell/process, it runs until the startup script finishes, at which point Windows seems to clean up any and all child processes of the script. We're currently able to bypass that using psexec -s -d -i -x to fire it off, which lets it persist after the startup script is completed, but can be incredibly slow, adding anywhere between 5 seconds and over a minute to our startup time. We have experimented with using another C# app to start the process, via the Process class, using WMI Calls (Win32_Process and Win32_ProcessStartup) with various startup flags, etc, but all end with the same result of the script finishing and the info block process getting killed. I tinkered with rewriting the app as a service, but services were never designed to interact with the desktop, let alone the login window, and getting things operating in the right context never really seemed to work out. So for the question: Does anybody have a good way to accomplish this? Launch a task so that it would be independent of the startup script and run on top of the welcome screen?

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• How to Check Authenticity of an AJAX Request

  - by Alex Reisner

  I am designing a web site in which users solve puzzles as quickly as they can. JavaScript is used to time each puzzle, and the number of milliseconds is sent to the server via AJAX when the puzzle is completed. How can I ensure that the time received by the server was not forged by the user? I don't think a session-based authenticity token (the kind used for forms in Rails) is sufficient because I need to authenticate the source of a value, not just the legitimacy of the request. Is there a way to cryptographically sign the request? I can't think of anything that couldn't be duplicated by a hacker. Is any JavaScript, by its exposed, client-side nature, subject to tampering? Am I going to have to use something that gets compiled, like Flash? (Yikes.) Or is there some way to hide a secret key? Or something else I haven't thought of? Update: To clarify, I don't want to penalize people with slow network connections (and network speed should be considered inconsistent), so the timing needs to be 100% client-side (the timer starts only when we know the user can see the puzzle). Also, there is money involved so no amount of "trusting the user" is acceptable.

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• game currency convert: math efficient

  - by Comradsky

  For variables:4 text views named diamondText, goldText, silverText, and bronzeText;money variable unsigned int money;and an NSTimer, every .1 sec,runs function: -(void)updateMoney{ money++; bronzeText.text = [NSString stringWithFormat:@"%d",money]; silverText.text = [NSString stringWithFormat:@"%d",money%10]; goldText.text = [NSString stringWithFormat:@"%d",money%100]; diamondText.text= [NSString stringWithFormat:@"%d",money%1000]; } Given that my currency is diamond = 10 gold = 10 silver = 10 bronze = 1; What would be most efficient way to calculate and display the money labels? How would you store this variable, with GameCenter and NSDictionary or GameCenter and something else? More details are below if you don't understand. To clarify: bronze has the last 2 numbers, silver has the next 2 numbers, and so on. I understand I could use 4 ints or an array, but i would rather try to use this method, unless theres a much more efficient way. Example: When money = 1000;bronzeText = nothing, silverText = 10,goldText = nothing, diamondText = nothing; What other ways would you do this that you think would be more efficient? I will be calling a function (void)collisionDetector that detects if my player.frame crosses with a flyingObject.frame, and if that object is a coin it gives an added value to money and then calls (void)updateMoney. Im just using the timer to test this and spawn these flying objects.

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• ASP.NET javascript embed in template column

  - by Mahesh

  Hi, I am developing a web page in which a rad grid displays the list of exams. I included a template column which shows count down timer when the exam is going to expire. Code is as given below: <telerik:RadGrid ID="radGrid" runat="server" AutoGenerateColumns="false"> <MasterTableView> <Columns> <telerik:GridTemplateColumn HeaderText="template" DataField="Date"> <ItemTemplate> <script language="JavaScript" type="text/javascript"> TargetDate = '<%# Eval("Date") %>'; BackColor = "white"; ForeColor = "black"; CountActive = true; CountStepper = -1; LeadingZero = true; DisplayFormat = "%%D%% Days, %%H%% Hours, %%M%% Minutes, %%S%% Seconds."; FinishMessage = "It is finally here!"; </script> <script language="JavaScript" src="http://scripts.hashemian.com/js/countdown.js" type="text/javascript"></script> </ItemTemplate> </telerik:GridTemplateColumn> </Columns> </MasterTableView> </telerik:RadGrid> I am giving DataTable as datasource to this grid. But my problem is , the template column is showing data only for the first record and the value taken is from the last row in the DataTable. For Ex: If I give data as given below, I can see 3 records but with only the first record displaying the counter with last value(10/10/2010 05:43 PM). 02/02/2011 01:00 AM 08/09/2010 11:00 PM 10/10/2010 05:43 PM Could you please help in this?? Thanks, Mahesh

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• how to find by date from timestamp column in JPA criteria

  - by Kre Toni

  I want to find a record by date. In entity and database table datatype is timestamp. I used Oracle database. @Entity public class Request implements Serializable { @Id private String id; @Version private long version; @Temporal(TemporalType.TIMESTAMP) @Column(name = "CREATION_DATE") private Date creationDate; public Request() { } public Request(String id, Date creationDate) { setId(id); setCreationDate(creationDate); } public String getId() { return id; } public void setId(String id) { this.id = id; } public long getVersion() { return version; } public void setVersion(long version) { this.version = version; } public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } } in mian method public static void main(String[] args) { RequestTestCase requestTestCase = new RequestTestCase(); EntityManager em = Persistence.createEntityManagerFactory("Criteria").createEntityManager(); em.getTransaction().begin(); em.persist(new Request("005",new Date())); em.getTransaction().commit(); Query q = em.createQuery("SELECT r FROM Request r WHERE r.creationDate = :creationDate",Request.class); q.setParameter("creationDate",new GregorianCalendar(2012,12,5).getTime()); Request r = (Request)q.getSingleResult(); System.out.println(r.getCreationDate()); } in oracle database record is ID CREATION_DATE VERSION 006 05-DEC-12 05.34.39.200000 PM 1 Exception is Exception in thread "main" javax.persistence.NoResultException: getSingleResult() did not retrieve any entities. at org.eclipse.persistence.internal.jpa.EJBQueryImpl.throwNoResultException(EJBQueryImpl.java:1246) at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getSingleResult(EJBQueryImpl.java:750) at com.ktrsn.RequestTestCase.main(RequestTestCase.java:29)

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• Inheritance concept java..help

  - by max

  Hi everyone. I'd be very grateful if someone could help me to understand the inheritance concept in Java. Is the following code an example of that? I mean the class WavPanel is actually a subclass of JPanel which acts as a superclass. Is that correct? If so it means that "what JPanel has, also WavPanel but it is more specific since through its methods you can do something else". Am I wrong? thank you. Max import javax.swing.JPanel; class WavPanel extends JPanel { List<Byte> audioBytes; List<Line2D.Double> lines; public WavPanel() { super(); setBackground(Color.black); resetWaveform(); } public void resetWaveform() { audioBytes = new ArrayList<Byte>(); lines = new ArrayList<Line2D.Double>(); repaint(); } }

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• Are there concurrency problems when using -performSelector:withObject:afterDelay: ?

  - by mystify

  For example, I often use this: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:someDelay]; Now, lets say I call this 10 times to perform at the exact same delay, like: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; - (void)doSomethingAfterDelay:(id)someObject { /* access an array, read stuff, write stuff, do different things that would suffer in multithreaded environments .... all operations are nonatomic! */ } I have observed pretty strange behavior when doing things like this. For my understanding, this method schedules a timer to fire on the current thread, so in this case the main thread. But since it doesn't create new threads, it actually should not be possible to run into concurrency problems, right?

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• Are there concurrency problems when using -performSelector:withObject:afterDelay: ?

  - by mystify

  For example, I often use this: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:someDelay]; Now, lets say I call this 10 times to perform at the exact same delay, like: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; - (void)doSomethingAfterDelay:(id)someObject { /* access an array, read stuff, write stuff, do different things that would suffer in multithreaded environments .... all operations are nonatomic! */ } I have observed pretty strange behavior when doing things like this. For my understanding, this method schedules a timer to fire on the current thread, so in this case the main thread. But since it doesn't create new threads, it actually should not be possible to run into concurrency problems, right?

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• Storing same type but still getting an ArrayStoreException

  - by Firefoxx Pwnass

  I have strange problem. I have three classes. Book ( abstract ), and two subclasses ( Fiction, Nonfiction). I have created array of Book references. That array can hold both subclasse's objects. I'have following code for Fiction class. public class Fiction extends Book{ public Fiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 24.99; } } And the "same" code for Nonfiction class public class Nonfiction extends Book{ public Nonfiction(String title) { super(title); setPrice(); } public void setPrice() { super.price = 37.99; } } And this is Main program. import javax.swing.JOptionPane; public class Main { public static void main(String[] args) { Book[] book = new Fiction[6]; for(int i = 0; i<book.length; i++) { if(i<4) { String title = JOptionPane.showInputDialog("Enter fiction book, no "+i); book[i] = new Fiction(title); } else { String title = JOptionPane.showInputDialog("Enter non fiction book, no "+i); book[i] = new Nonfiction(title); } } for(int x = 0; x<book.length; x++) { System.out.println("Book named "+book[x].getTitle()+" costs "+book[x].getPrice()); } } } For any reason i'm getting ArrayStoreException on this line.. book[i] = new Nonfiction(title); But same code works for Fiction class. I checked java documentation and it says that this exception is thrown when i'm trying to store different objects in array ( like String and Int ), but in this case they are all the same objects. Both classes are children of superclass, that means, they are of the same type. I'm confsued. A little help here please?

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• jquery small error

  - by HeinekenBluess

  Hi, i am very new at jquery and code, here i am trying to get the setTimeout event to be inside the .mouseout event but i'm not sure how to do that as i keep getting syntax error in my editor. Here's what i have: jQuery(document).ready(function() { $('.slidedown').hide(); $('.trigger').hover( function(){ // enter animation $('.slidedown').stop(true,true).animate({ height: ['toggle', 'swing'], }, 600, function() { /* animation done */ }); }, function(){ // leave animation $('.slidedown').mouseout() setTimeout( function(){ $('.slidedown').stop(true,true).animate({ height: '0px', }, 600, function() { /* animation done */ }); }, 1000 ); }); }); A small nuance, in this code the user mouses over a div, then another div bellow it slides down. Moving the mouse to the .slidedown div should keep it open until the mouse is removed. But will this code collapse the .slidedown div if the user doesn't mouse over .slidedown after .trigger but instead moves the mouse directly from .trigger to another area of page? I.e i need some kind of 'setTimeout' that is trigged only if the user doesn't move mouse over .slidedown after hovering over .trigger. Hope i make sense. Thanks for your help!

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• Dereferencing possible null pointer in java

  - by Nealio

  I am just starting to get into graphics and when I am trying to get the graphics, I get the error"Exception in thread "Thread-2" java.lang.NullPointerException" and I have no clue on what is going on! Any help is greatly appreciated. //The display class for the game //Crated: 10-30-2013 //Last Modified: 10-30-2013 package gamedev; import gamedev.Graphics.Render; import gamedev.Graphics.Screen; import java.awt.Canvas; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import java.awt.image.DataBufferInt; import javax.swing.JFrame; private void tick() { } private void render() { System.out.println("display.render"); BufferStrategy bs = this.getBufferStrategy(); if (bs == null) { createBufferStrategy(3); } for (int i = 0; i < GAMEWIDTH * GAMEHEIGHT; i++) { pixels[i] = screen.PIXELS[i]; } screen.Render(); //The line of code that is the problem Graphics g = bs.getDrawGraphics(); //end problematic code g.drawImage(img, 0, 0, GAMEWIDTH, GAMEHEIGHT, null); g.dispose(); bs.show(); }

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• How to handle exceptions from an image-generating Servlet?

  - by ssahmed555

  I have a simple (Servlet, JSP, and JSTL) web app whose main functionality is displaying images retrieved from a back-end server. The controller servlet forwards the user to a JSP that in turn uses another Servlet to display the resulting image on that same JSP. Further down, the JSP has a line similar to: <a href="<c:out value='${imageURL}'/>"><img src="<c:out value='${imageURL}'/>" alt="image view" border="1"></a> which invokes a GET request on the image-generating servlet causing it to generate the image. My question is: how do I handle Exceptions thrown by this image-generating servlet? I already have an error page defined (in web.xml) to handle ServletException within my web app but this doesn't work for this image-generating Servlet, and results in the following errors showing up in my Tomcat server logs: SEVERE: Exception Processing ErrorPage[exceptionType=javax.servlet.ServletException, location=/WEB-INF/ExceptionPage.jsp] java.lang.IllegalStateException: Cannot reset buffer after response has been committed What's my recourse in this situation? I'd like to be able to handle Exceptions thrown from this image-generating Servlet, and display some error on the main UI or forward the user to another error page.

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• autoreload webpage on new release

  - by user3726562

  I have a website in PHP which is completely ajax-based. There is an index.php, but a part from it, all the other page are never rendered directly into the browser. Instead, all the post and get request are done tfrom javascript through ajax. So basically, if you go to /contact.php you will not see anything. All the pages are rendered inside index.php. So, there are a lot of people that use this page that are not very good in using the web. Asking them to "refresh" the page makes them to wonder what we are talking about. Unfortunately. The biggest issue happens when we do a new release. Especially the javascript code (but not only) can be the old one in a client's webpage as they maybe havent refreshed the page for some week (lol). S I do an svn-update and the new code is on the server. I just refresh my page and see the new features. However, the poor guys that dont really know how to make a refresh, will not see anything. I have added a big button on the page with the text "refresh". Which makes a location.reload. Hopefully this can help a few of them. But my question is: how to "force" the browser to reload itself when a new svn-version has been released? Hopefully in a simple way, without needing some node.js, javascript timer or stuff like that. It is also quite important to not refresh the page when the user is doing something with the page (maybe writing a mail in the UI, and then suddenly the page get refreshed: not so good).

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• Can't access a property with <html:checkbox property="..."> when iterating a list

  - by Bernhard V

  Hi. In my Struts form I've got a list. In a JSP I iterate over it like this: <c:forEach items="${MyForm.auspraegungen}" var="auspraegung"> <tr> <td>${auspraegung.name}</td> <td>${auspraegung.forced}</td> <td>${auspraegung.cbx_uebernehmen}</td> <html:checkbox property="auspraegung.cbx_uebernehmen" /> </tr> </c:forEach> Now the <html:checkbox isn't working. I'm always getting the following error: Caused by: javax.servlet.jsp.JspException: No getter method for property auspraegung.cbx_uebernehmen of bean org.apache.struts.taglib.html.BEAN But actually there is a getter for this property in my form class. It's written like this: public Boolean getCbx_uebernehmen() { return cbx_uebernehmen; } When I remove the checkbox it's also possible to display the property as in the <td>-tag above so I don't know where the problem is. Maybe I'm accessing it in the wrong way?

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