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• How to avoid exceptions catches copy-paste in .NET

  - by Budda

  Working with .NET framework I have a service with a set of methods that can generates several types of exceptions: MyException2, MyExc1, Exception... To provide proper work for all methods, each of them contains following sections: void Method1(...) { try { ... required functionality } catch(MyException2 exc) { ... process exception of MyException2 type } catch(MyExc1 exc) { ... process exception of MyExc1 type } catch(Exception exc) { ... process exception of Exception type } ... process and return result if necessary } It is very boring to have exactly same stuff in EACH service method with exactly same exceptions processing functionality... Is there any possibility to "group" these catch-sections and use only one line (something similar to C++ macros)? Probably something new in .NET 4.0 is related to this topic? Thanks. P.S. Any thoughts are welcome.

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• Force IOException during file reading

  - by DixonD

  I have the piece of code that reads data from file. I want to force IOException in this code for testing purpose (I want to check if code throws correct custom exception in this case). Is there a some way to create a file which is protected from being read, for example? Maybe dealing with some security checks can help? Please, note that passing name to not-existent file cannot help, because FileNotFoundException has separate catch clause. Here peace of code for better undestanding of question: BufferedReader reader = null; try { reader = new BufferedReader(new FileReader(csvFile)); String rawLine; while ((rawLine = reader.readLine()) != null) { // some work is done here } } catch (FileNotFoundException e) { throw new SomeCustomException(); } catch (IOException e) { throw new SomeCustomException(); } finally { // close the input stream if (reader != null) { try { reader.close(); } catch (IOException e) { // ignore } } }

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• Strange Java Socket Behavior (Connects, but Doesn't Send)

  - by Donald Campbell

  I have a fairly complex project that boils down to a simple Client / Server communicating through object streams. Everything works flawlessly for two consecutive connections (I connect once, work, disconnect, then connect again, work, and disconnect). The client connects, does its business, and then closes. The server successfully closes both the object output stream and the socket, with no IO errors. When I try to connect a third time, the connection appears to go through (the ServerSocket.accept() method goes through and an ObjectOutputStream is successfully created). No data is passed, however. The inputStream.readUnshared() method simply blocks. I have taken the following memory precautions: When it comes time to close the sockets, all running threads are stopped, and all objects are nulled out. After every writeUnshared() method call, the ObjectOutputBuffer is flushed and reset. Has anyone encountered a similar problem, or does anyone have any suggestions? I'm afraid my project is rather large, and so copying code is problematic. The project boils down to this: SERVER MAIN ServerSocket serverSocket = new ServerSocket(port); while (true) { new WorkThread(serverSocket.accept()).start(); } WORK THREAD (SERVER) public void run() { ObjectInputBuffer inputBuffer = new ObjectInputBuffer(new BufferedInputStream(socket.getInputStream())); while (running) { try { Object myObject = inputBuffer.readUnshared(); // do work is not specified in this sample doWork(myObject); } catch (IOException e) { running = false; } } try { inputBuffer.close(); socket.close(); } catch (Exception e) { System.out.println("Could not close."); } } CLIENT public Client() { Object myObject; Socket mySocket = new Socket(address, port); try { ObjectOutputBuffer output = new ObjectOutputBuffer(new BufferedOutputStream(mySocket.getOutputStream())); output.reset(); output.flush(); } catch (Exception e) { System.out.println("Could not get an input."); mySocket.close(); return; } // get object data is not specified in this sample. it simply returns a serializable object myObject = getObjectData(); while (myObject != null) { try { output.writeUnshared(myObject); output.reset(); output.flush(); } catch (Exception e) { e.printStackTrace(); break; } // catch } // while try { output.close(); socket.close(); } catch (Exception e) { System.out.println("Could not close."); } } Thank you to everyone who may be able to help!

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• non blocking client server chat application in java using nio

  - by Amith

  I built a simple chat application using nio channels. I am very much new to networking as well as threads. This application is for communicating with server (Server / Client chat application). My problem is that multiple clients are not supported by the server. How do I solve this problem? What's the bug in my code? public class Clientcore extends Thread { SelectionKey selkey=null; Selector sckt_manager=null; public void coreClient() { System.out.println("please enter the text"); BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in)); SocketChannel sc = null; try { sc = SocketChannel.open(); sc.configureBlocking(false); sc.connect(new InetSocketAddress(8888)); int i=0; while (!sc.finishConnect()) { } for(int ii=0;ii>-22;ii++) { System.out.println("Enter the text"); String HELLO_REQUEST =stdin.readLine().toString(); if(HELLO_REQUEST.equalsIgnoreCase("end")) { break; } System.out.println("Sending a request to HelloServer"); ByteBuffer buffer = ByteBuffer.wrap(HELLO_REQUEST.getBytes()); sc.write(buffer); } } catch (IOException e) { e.printStackTrace(); } finally { if (sc != null) { try { sc.close(); } catch (Exception e) { e.printStackTrace(); } } } } public void run() { try { coreClient(); } catch(Exception ej) { ej.printStackTrace(); }}} public class ServerCore extends Thread { SelectionKey selkey=null; Selector sckt_manager=null; public void run() { try { coreServer(); } catch(Exception ej) { ej.printStackTrace(); } } private void coreServer() { try { ServerSocketChannel ssc = ServerSocketChannel.open(); try { ssc.socket().bind(new InetSocketAddress(8888)); while (true) { sckt_manager=SelectorProvider.provider().openSelector(); ssc.configureBlocking(false); SocketChannel sc = ssc.accept(); register_server(ssc,SelectionKey.OP_ACCEPT); if (sc == null) { } else { System.out.println("Received an incoming connection from " + sc.socket().getRemoteSocketAddress()); printRequest(sc); System.err.println("testing 1"); String HELLO_REPLY = "Sample Display"; ByteBuffer buffer = ByteBuffer.wrap(HELLO_REPLY.getBytes()); System.err.println("testing 2"); sc.write(buffer); System.err.println("testing 3"); sc.close(); }}} catch (IOException e) { e.printStackTrace(); } finally { if (ssc != null) { try { ssc.close(); } catch (IOException e) { e.printStackTrace(); } } } } catch(Exception E) { System.out.println("Ex in servCORE "+E); } } private static void printRequest(SocketChannel sc) throws IOException { ReadableByteChannel rbc = Channels.newChannel(sc.socket().getInputStream()); WritableByteChannel wbc = Channels.newChannel(System.out); ByteBuffer b = ByteBuffer.allocate(1024); // read 1024 bytes while (rbc.read(b) != -1) { b.flip(); while (b.hasRemaining()) { wbc.write(b); System.out.println(); } b.clear(); } } public void register_server(ServerSocketChannel ssc,int selectionkey_ops)throws Exception { ssc.register(sckt_manager,selectionkey_ops); }} public class HelloClient { public void coreClientChat() { Clientcore t=new Clientcore(); new Thread(t).start(); } public static void main(String[] args)throws Exception { HelloClient cl= new HelloClient(); cl.coreClientChat(); }} public class HelloServer { public void coreServerChat() { ServerCore t=new ServerCore(); new Thread(t).start(); } public static void main(String[] args) { HelloServer st= new HelloServer(); st.coreServerChat(); }}

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• Ping remote server and wait to get data

  - by infinity

  Hi I'm building my first application for android and I've reached a point where I can't find a solution even have no idea what to search for in Google. So the problem: I am pinging a remote server with GET request through the application passing some parameters like file_id. Then the server gives back confirmation if the file exists or error otherwise, both in plain text. The error string is $$$ERROR$$$. Actually the confirmation is JSON string that holds the path to the file. If the file doesn't exists on the server it generated the error message and start downloading the file and processing it which normally takes 10-30 seconds. What would be the best way to check if the file is ready for download? I have DownloadFile class that extends AsyncTask but before I reach the point to download the file I need the URL which is dependant on the previous request which is in the main class in the UI thread. Here is some code: public class MainActivity extends Activity { private String getInfo() { // Create a new HttpClient and Post Header HttpClient httpClient = new DefaultHttpClient(); HttpGet httpPost = new HttpGet(infoUrl); StringBuilder sb = null; String data; JSONObject jObject = null; try { HttpResponse response = httpClient.execute(httpPost); // This might be equal "$$$ERROR$$$" if no file exists sb = inputStreamToString(response.getEntity().getContent()); } catch(ClientProtocolException e) { // TODO Auto-generated catch block Log.v("Error: pushItem ClientProtocolException: ", e.toString()); } catch (IOException e) { // TODO Auto-generated catch block Log.v("Error: pushItem IOException: ", e.toString()); } // Clean the data to be complaint JSON format data = sb.toString().replace("info = ", ""); try { jObject = new JSONObject(data); data = jObject.getString("h"); fileTitle = jObject.getString("title"); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } downloadUrl = String.format(downloadUrl, fileId, data); return downloadUrl; } } So my idea was to get the content and if equal to $$$ERROR$$$ go into loop until JSON data is passed but I guess there is better solution. Note: I don't have control over the server output so have to deal with what I have.

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• How can I tell what events fire from GXT?

  - by CoverosGene

  I cannot seem to find any documentation of what events fire and when in GXT. The API docs have lists of all the events that could fire (in Events). And it describes how to handle events that you catch. But I'm interested in the opposite side, which events are fired when I take a certain action. I can set some listeners for various different components, or I can use addListener with a specific event code to catch individual events. That's spotty, and I seem to be using trial-and-error to guess what I might want to catch. Is there a way to log all the events that are firing? Or catch all of them so I could look at them in a debugger? Or is there some documentation I am missing that has the information? Something along the lines of "when you click on a widget, a ButtonEvent is fired. Events.x is fired on the hover, Events.y on the click."

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• Question about Transact SQL syntax

  - by Yousui

  Hi guys, The following code works like a charm: BEGIN TRY BEGIN TRANSACTION COMMIT TRANSACTION END TRY BEGIN CATCH IF @@TRANCOUNT > 0 ROLLBACK; DECLARE @ErrorMessage NVARCHAR(4000), @ErrorSeverity int; SELECT @ErrorMessage = ERROR_MESSAGE(), @ErrorSeverity = ERROR_SEVERITY(); RAISERROR(@ErrorMessage, @ErrorSeverity, 1); END CATCH But this code gives an error: BEGIN TRY BEGIN TRANSACTION COMMIT TRANSACTION END TRY BEGIN CATCH IF @@TRANCOUNT > 0 ROLLBACK; RAISERROR(ERROR_MESSAGE(), ERROR_SEVERITY(), 1); END CATCH Why?

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• Must JDBC Resultsets and Statements be closed separately although the Connection is closed afterwards?

  - by Mulmoth

  It is said to be a good habit to close all JDBC resources after usage. But if I have the following code, is it necessary to close the Resultset and the Statement? Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; try { conn = // Retrieve connection stmt = conn.prepareStatement(// Some SQL); rs = stmt.executeQuery(); } catch { // Error Handling } finally { try { if (rs != null) rs.close(); } catch (Exception e) {}; try { if (stmt != null) stmt.close(); } catch (Exception e) {}; try { if (conn != null) conn.close(); } catch (Exception e) {}; } The question is if the closing of the connection does the job or if it leaves some resources in use.

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• how to retrive String from DatagramPacket

  - by sajith

  the following code prints [B@40545a60,[B@40545a60abc exp but i want to print abc,so that i can retrive the correct message from the receiving system public class Operation { InetAddress ip; DatagramSocket dsock; DatagramPacket pack1; byte[] bin,bout; WifyOperation(InetAddress Systemip) { ip=Systemip; try { dsock=new DatagramSocket(); } catch (SocketException e) { // TODO Auto-generated catch block e.printStackTrace(); } } void sendbyte() { String senddata="abc"+"123"; bout=senddata.getBytes(); pack1=new DatagramPacket(bout,bout.length,ip,3322); try { dsock.send(pack1); Log.d(pack1.getData().toString(),"abc exp"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } how i retrieve string instead of byte from the packet pack1

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• How do I close a file after catching an IOException in java?

  - by DimDom

  All, I am trying to ensure that a file I have open with BufferedReader is closed when I catch an IOException, but it appears as if my BufferedReader object is out of scope in the catch block. public static ArrayList readFiletoArrayList(String fileName, ArrayList fileArrayList) { fileArrayList.removeAll(fileArrayList); try { //open the file for reading BufferedReader fileIn = new BufferedReader(new FileReader(fileName)); // add line by line to array list, until end of file is reached // when buffered reader returns null (todo). while(true){ fileArrayList.add(fileIn.readLine()); } }catch(IOException e){ fileArrayList.removeAll(fileArrayList); fileIn.close(); return fileArrayList; //returned empty. Dealt with in calling code. } } Netbeans complains that it "cannot find symbol fileIn" in the catch block, but I want to ensure that in the case of an IOException that the Reader gets closed. How can I do that without the ugliness of a second try/catch construct around the first? Any tips or pointers as to best practise in this situation is appreciated,

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• Functioning Socket read no longer works when called in AsyncTask

  - by bibismcbryde

  I'm making an app that sends a string to a server over a socket and then reads the output after the server has processed that data. It worked perfectly when it was my foreground task, but I have since used AsyncTask to show a process dialog while the socket communication runs in the background, and things start breaking after I read the output from the server and then try to close the socket. private class Progressor extends AsyncTask<String, Void, Void> { ProgressDialog dialog; protected void onPreExecute() { dialog = ProgressDialog.show(ClearTalkInputActivity.this, "Loading..", "Analyzing Text", true, false); } protected Void doInBackground(String... strings) { String language = strings[0].toLowerCase(); String the_text = strings[1]; Socket socket = null; DataOutputStream dos = null; DataInputStream dis = null; try { socket = new Socket(my_ip, port); dos = new DataOutputStream(socket.getOutputStream()); dis = new DataInputStream(socket.getInputStream()); dos.writeUTF(language+"****"+the_text); String in = ""; while (in.indexOf("</content>") < 0) { in += dis.readUTF(); } socket.close(); save_str(OUTPUT_KEY, in); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (socket != null) { try { socket.close(); } catch (IOException e) { e.printStackTrace(); } } } if (dos != null) { try { dos.close(); } catch (IOException e) { e.printStackTrace(); } } if (dis != null) { try { dis.close(); } catch (IOException e) { e.printStackTrace(); } } return null; } protected void onPostExecute() { if (dialog.isShowing()) dialog.dismiss(); startActivity(new Intent (output_intent)); } }

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• Exceptions confusion

  - by Misiur

  Hi there. I'm trying to build site using OOP in PHP. Everyone is talking about Singleton, hermetization, MVC, and using exceptions. So I've tried to do it like this: Class building whole site: class Core { public $is_core; public $theme; private $db; public $language; private $info; static private $instance; public function __construct($lang = 'eng', $theme = 'default') { if(!self::$instance) { try { $this->db = new sdb(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(PDOException $e) { throw new CoreException($e->getMessage()); } try { $this->language = new Language($lang); } catch(LangException $e) { throw new CoreException($e->getMessage()); } try { $this->theme = new Theme($theme); } catch(ThemeException $e) { throw new CoreException($e->getMessage()); } } return self::$instance; } public function getSite($what) { return $this->language->getLang(); } private function __clone() { } } Class managing themes class Theme { private $theme; public function __construct($name = 'default') { if(!is_dir("themes/$name")) { throw new ThemeException("Unable to load theme $name"); } else { $this->theme = $name; } } public function getTheme() { return $this->theme; } public function display($part) { if(!is_file("themes/$this->theme/$part.php")) { throw new ThemeException("Unable to load theme part: themes/$this->theme/$part.php"); } else { return 'So far so good'; } } } And usage: error_reporting(E_ALL); require_once('config.php'); require_once('functions.php'); try { $core = new Core(); } catch(CoreException $e) { echo 'Core Exception: '.$e->getMessage(); } echo $core->theme->getTheme(); echo "<br />"; echo $core->language->getLang(); try { $core->theme->display('footer'); } catch(ThemeException $e) { echo $e->getMessage(); } I don't like those exception handlers - i don't want to catch them like some pokemons... I want to use things simple: $core-theme-display('footer'); And if something is wrong, and debug mode is enabled, then aplication show error. What should i do?

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• Secure WS client with UsernameToken(SOAP security header)

  - by user79163

  Hi, I'm trying to secure my WS client to be able to call the WS. My code looks like this: SendSmsService smsService = new SendSmsService(); SendSms sendSMS = smsService.getSendSms(); BindingProvider stub = (BindingProvider)sendSMS; //Override endpoint with local copy of wsdl. String URL ="";//here is the wsdl url Map<String,Object> requestContext = stub.getRequestContext(); requestContext.put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, URL); //Set usernametoken URL fileURL = loader.getResource("client-config.xml"); File file = new File(fileURL.getFile()); FileInputStream clientConfig = null; try { clientConfig = new FileInputStream(file); } catch (FileNotFoundException e) { e.printStackTrace(); } XWSSecurityConfiguration config = null; try { config = SecurityConfigurationFactory.newXWSSecurityConfiguration(clientConfig); } catch (Exception e) { e.printStackTrace(); log.warn("Exception: "+e.getMessage()); } requestContext.put(XWSSecurityConfiguration.MESSAGE_SECURITY_CONFIGURATION, config); //Invoke the web service String requestId = null; try { requestId = sendSMS.sendSms(addresses, senderName, charging, message, receiptRequest); } catch (PolicyException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ServiceException e) { // TODO Auto-generated catch block e.printStackTrace(); } and the config file looks like this: <xwss:JAXRPCSecurity xmlns:xwss="http://java.sun.com/xml/ns/xwss/config" optimize="true"> <xwss:Service> <xwss:SecurityConfiguration dumpMessages="true" xmlns:xwss="http://java.sun.com/xml/ns/xwss/config"> <xwss:UsernameToken name="username" password="password> </xwss:SecurityConfiguration> </xwss:Service> <xwss:SecurityEnvironmentHandler> util.SecurityEnvironmentHandler </xwss:SecurityEnvironmentHandler> </xwss:JAXRPCSecurity> The SecurityEnviromentHandler is a dummy class that implements javax.security.auth.callback.CallbackHandler. Authentication must be in compliance with Oasis Web Services Security Username Token Profile 1.0. But I'm constantly getting "Security header not valid" error. Where am I going wrong, can anyone tell me. I used wsimport(JAX_WS 2.1 to generate classes for my client) Note:Only thing I know about this WS is WSDL URL and user&pass for authentication

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• Java program will read from database, but not write to it

  - by ck1221

  I have a Java program that successfully connects to a mysql database that is hosted on godaddy's server. I can read from that db with out issue, however, when I try to write to it with INSERT or UPDATE for example, the query does not execute. I am using the 'admin' account that I set up through godaddy, I realize this is not the root account. I have checked and verified that the connection is not read only, and have logged out of phpmyadmin while the query ran. I'm not sure what else I can try or if anyone has experienced this issue. Maybe a setting to the connection I have failed to set? Or maybe its not possible since the db is hosted on godaddy's servers? Any help is great! Thanks. Here is some relevant code: Connection to db: Connection con; public DBconnection(String url, String user, String pass) { try { Class.forName("com.mysql.jdbc.Driver").newInstance(); con = DriverManager.getConnection (url,user,pass); if(!con.isClosed()) System.out.println("connecton open"); } catch (InstantiationException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (ClassNotFoundException e) {e.printStackTrace();} catch (SQLException e) {e.printStackTrace();} } Send Query: public ResultSet executeQuery(String query) { ResultSet rs = null; try { Statement stmt = (Statement) con.createStatement(); rs = stmt.executeQuery(query); //while(rs.next()) //System.out.println(rs.getString("ticket_num")); } catch (SQLException e) {} return rs; } Insert Query (works in phpmyadmin): conn.executeQuery("INSERT INTO tickets VALUES(55555,'12/01/2012','me','reports','test','','','0','Nope')");

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• Java File Handling, what did I do wrong?

  - by Urda

  Wrote up a basic file handler for a Java Homework assignment, and when I got the assignment back I had some notes about failing to catch a few instances: Buffer from file could have been null. File was not found File stream wasn't closed Here is the block of code that is used for opening a file: /** * Create a Filestream, Buffer, and a String to store the Buffer. */ FileInputStream fin = null; BufferedReader buffRead = null; String loadedString = null; /** Try to open the file from user input */ try { fin = new FileInputStream(programPath + fileToParse); buffRead = new BufferedReader(new InputStreamReader(fin)); loadedString = buffRead.readLine(); fin.close(); } /** Catch the error if we can't open the file */ catch(IOException e) { System.err.println("CRITICAL: Unable to open text file!"); System.err.println("Exiting!"); System.exit(-1); } The one comment I had from him was that fin.close(); needed to be in a finally block, which I did not have at all. But I thought that the way I have created the try/catch it would have prevented an issue with the file not opening. Let me be clear on a few things: This is not for a current assignment (not trying to get someone to do my own work), I have already created my project and have been graded on it. I did not fully understand my Professor's reasoning myself. Finally, I do not have a lot of Java experience, so I was a little confused why my catch wasn't good enough.

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• hibernate: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException

  - by user121196

  when saving an object to database using hibernate, sometimes it fails because certain fields of the object exceed the maximum varchar length defined in the database. There force I am using the following approach: 1. attempt to save 2. if getting an DataException, then I truncate the fields in the object to the max length specified in the db definition, then try to save again. However, in the second save after truncation. I'm getting the following exception: hibernate: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails here's the relevant code, what's wrong? public static void saveLenientObject(Object obj){ try { save2(rec); } catch (org.hibernate.exception.DataException e) { // TODO Auto-generated catch block e.printStackTrace(); saveLenientObject(rec, e); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } private static void saveLenientObject(Object rec, DataException e) { Util.truncateObject(rec); System.out.println("after truncation "); save2(rec); } public static void save2(Object obj) throws Exception{ try{ beginTransaction(); getSession().save(obj); commitTransaction(); }catch(Exception e){ e.printStackTrace(); rollbackTransaction(); //closeSession(); throw e; }finally{ closeSession(); } }

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• Converting text into numeric in xls using Java

  - by Work World

  When I create excel sheet through java ,the column which has number datatype in the oracle table, get converted to text format in excel.I want it to remain in the number format.Below is my code snippet for excel creation. FileWriter fw = new FileWriter(tempFile.getAbsoluteFile(),true); // BufferedWriter bw = new BufferedWriter(fw); HSSFWorkbook wb = new HSSFWorkbook(); HSSFSheet sheet = wb.createSheet("Excel Sheet"); //Column Size of excel for(int i=0;i<10;i++) { sheet.setColumnWidth((short) i, (short)8000); } String userSelectedValues=result; HSSFCellStyle style = wb.createCellStyle(); ///HSSFDataFormat df = wb.createDataFormat(); style.setFillForegroundColor(HSSFColor.GREY_25_PERCENT.index); style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND); //style.setDataFormat(df.getFormat("0")); HSSFFont font = wb.createFont(); font.setColor(HSSFColor.BLACK.index); font.setBoldweight((short) 700); style.setFont(font); int selecteditems=userSelectedValues.split(",").length; // HSSFRow rowhead = sheet.createRow((short)0); //System.out.println("**************selecteditems************" +selecteditems); for(int k=0; k<selecteditems;k++) { HSSFRow rowhead = sheet.createRow((short)k); if(userSelectedValues.contains("O_UID")) { HSSFCell cell0 = rowhead.createCell((short) k); cell0.setCellValue("O UID"); cell0.setCellStyle(style); k=k+1; } ///some columns here.. } int index=1; for (int i = 0; i<dataBeanList.size(); i++) { odb=(OppDataBean)dataBeanList.get(i); HSSFRow row = sheet.createRow((short)index); for(int j=0;j<selecteditems;j++) { if(userSelectedValues.contains("O_UID")) { row.createCell((short)j).setCellValue(odb.getUID()); j=j+1; } } index++; } FileOutputStream fileOut = null; try { fileOut = new FileOutputStream(path.toString()+"/temp.xls"); } catch (FileNotFoundException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } try { wb.write(fileOut); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { fileOut.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

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• How to structure code with 2 methods, one after another, which throw the same two exceptions?

  - by dotnetdev

  Hi, I have two methods, one called straight after another, which both throw the exact same 2 exceptions (IF an erroneous condition occurs, not stating that I'm getting exceptions). For this, should I write seperate try and catch blocks with the one statement in each try block and catch both exceptions (Both of which I can handle as I checked MSDN class library reference and there is something I can do, eg, re-open SqlConnection or run a query and not a stored proc which does not exist). So code like this: try { obj.Open(); } catch (SqlException) { // Take action here. } catch (InvalidOperationException) { // Take action here. } And likewise for the other method I call straight after. This seems like a very messy way of coding. The other way is to code with the exception variable (that is ommited as I am using AOP to log the exception details, using a class-level attribute). Doing this, this could aid me in finding out which method caused an exception and then taking action accordingly. Is this the best approach or is there another best practise altogether? I also assume that, as only these two methods are thrown, I do not need to catch Exception as that would be for an exception I cannot handle (causes way out of my control). Thanks

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• Best way to get a date in .NET?

  - by frenchie

  I'm getting a string back from my page and I want to make sure it's a date. This is what I have so far (it works) and I just want to know if this is the "best" way to do it. I'm using .NET 4. int TheMonth =0; int TheDay = 0; int TheYear = 0; DateTime NewDate; var TheIncomingParam = Request.Params.Get("__EVENTARGUMENT").ToString(); char[] TheBreak = { '/' }; string[] TheOutput = TheIncomingParam.Split(TheBreak); try { TheMonth = Convert.ToInt32(TheOutput[0]); } catch { } try { TheDay = Convert.ToInt32(TheOutput[1]); } catch { } try { TheYear = Convert.ToInt32(TheOutput[2]); } catch { } if (TheMonth!=0 && TheDay!=0 && TheYear!=0) { try { NewDate = new DateTime(TheYear, TheMonth, TheDay); } catch { var NoDate = true; } }

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• Android while getting HTTP response to file how to know it wasn't fully loaded?

  - by Stan

  I'm using this approach to store a big-sized response from server to parse it later: final HttpClient client = new DefaultHttpClient(new BasicHttpParams()); final HttpGet mHttpGetRequest = new HttpGet(strUrl); mHttpGetRequest.setHeader("Content-Type", "application/x-www-form-urlencoded"); FileOutputStream fos = null; try { final HttpResponse response = client.execute(mHttpGetRequest); final StatusLine statusLine = response.getStatusLine(); lastHttpErrorCode = statusLine.getStatusCode(); lastHttpErrorMsg = statusLine.getReasonPhrase(); if (lastHttpErrorCode == 200) { HttpEntity entity = response.getEntity(); fos = new FileOutputStream(reponseFile); entity.writeTo(fos); entity.consumeContent(); fos.flush(); } } catch (ClientProtocolException e) { e.printStackTrace(); lastHttpErrorMsg = e.toString(); return null; } catch (final ParseException e) { e.printStackTrace(); lastHttpErrorMsg = e.toString(); return null; } catch (final UnknownHostException e) { e.printStackTrace(); lastHttpErrorMsg = e.toString(); return null; } catch (IOException e) { e.printStackTrace(); lastHttpErrorMsg = e.toString(); } finally{ if (fos!=null) try{ fos.close(); } catch (IOException e){} } now how could I ensure the response was completely received and thus saved to file? Assume client's device lost Internet connection while this code was running. So the app received only some part of real response. And I'm pretty sure it happens cuz I got parsing exceptions like "tag not closed", "unexpected end of file" etc. So I need to detect somehow this situation to prevent code from parsing partial response but can't see how. Is it possible at all and how to do it? Or has it has to raise IOException in such cases?

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• How to make a VB exception handling for no value in a Textbox

  - by Twocold

  I want to catch an exception when user enter no value in a Textbox and try to process further by press a button, I know I can use "If else" statement to make it. but in terms of "Try and Catch" block, I dont know how. Here is the code sample. Dim NameString As String Try NameString = OperatorNameTextBox.Text Catch ex As ArgumentException MessageBox.Show("Enter a String Value") End Try

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• No class def find error

  - by John Smith

  I have the following piece of code which helps me to read the paths of all the files in a directory and its subdirectories : File dir = new File("directory path"); try { System.out.println("Getting all files in " + dir.getCanonicalPath() + " including those in subdirectories"); } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } List<File> files = (List<File>) FileUtils.listFiles(dir, TrueFileFilter.INSTANCE, TrueFileFilter.INSTANCE); for (File file : files) { try { System.out.println("file: " + file.getCanonicalPath()); } catch (IOException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } } The problem is that I get a java.lang.NoClassDefFoundError: org/apache/commons/io/filefilter/TrueFileFilter error. I've imported the necessary libraries. I mention that I work on a plugin project. This code runs in a class with main function. I don't understand why it gave me this error. Thank you !

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• Oracle Coherence & Oracle Service Bus: REST API Integration

  - by Nino Guarnacci

  This post aims to highlight one of the features found in Oracle Coherence which allows it to be easily added and integrated inside a wider variety of projects.  The features in question are the REST API exposed by the Coherence nodes, with which you can interact in the wider mode in memory data grid.Oracle Coherence and Oracle Service Bus are natively integrated through a feature found in the Oracle Service Bus, which allows you to use the coherence grid cache during the configuration phase of a business service. This feature allows you to use an intermediate layer of cache to retrieve the answers from previous invocations of the same service, without necessarily having to invoke the real business service again. Directly from the web console of Oracle Service Bus, you can decide the policies of eviction of the objects / answers and define the discriminating parameters that identify their uniqueness.The coherence REST APIs, however, allow you to integrate both products for other necessities enabling realization of new architectures design.  Consider coherence’s node as a simple service which interoperates through the stardard services and in particular REST (with JSON and XML). Thinking of coherence as a company’s shared service, able to have an implementation of a centralized “map and reduce” which you can access  by a huge variety of protocols (transport and envelopes).An amazing step forward for those who still imagine connectors and code. This type of integration does not require writing custom code or complex implementation to be self-supported. The added value is made unique by the incredible value of both products independently, and still more out of their simple and robust integration.As already mentioned this scenario discovers a hidden new door behind the columns of these two products. The door leads to new ideas and perspectives for enterprise architectures that increasingly wink to next-generation applications: simple and dynamic, perhaps towards the mobile and web 2.0.Below, a small and simple demo useful to demonstrate how easily is to integrate these two products using the Coherence REST API. This demo is also intended to imagine new enterprise architectures using this approach.The idea is to create a centralized system of alerting, fed easily from any company’s application, regardless of the technology with which they were built . Then use a representation standard protocol: RSS, using a service exposed by the service bus; So you can browse and search only the alerts that you are interested on, by category, author, title, date, etc etc.. The steps needed to implement this system are very simple and very few. Here they are listed below and described to be easily replicated within your environment. I would remind you that the demo is only meant to demonstrate how easily is to integrate Oracle Coherence and the Oracle Service Bus, and stimulate your imagination to new technological approaches.1) Install the two products: In this demo used (if necessary, consult the installation guides of 2 products)  - Oracle Service Bus ver. 11.1.1.5.0 http://www.oracle.com/technetwork/middleware/service-bus/downloads/index.html - Oracle Coherence ver. 3.7.1 http://www.oracle.com/technetwork/middleware/coherence/downloads/index.html 2) Because you choose to create a centralized alerting system, we need to define a structure type containing some alerting attributes useful to preserve and organize the information of the various alerts sent by the different applications. Here, then it was built a java class named Alert containing the canonical properties of an alarm information:- Title- Description- System- Time- Severity 3) Therefore, we need to create two configuration files for the coherence node, in order to save the Alert objects within the grid, through the rest/http protocol (more than the native API for Java, C + +, C,. Net). Here are the two minimal configuration files for Coherence:coherence-rest-config.xml resty-server-config.xml This minimum configuration allows me to use a distributed cache named "alerts" that can  also be accessed via http - rest on the host "localhost" over port "8080", objects are of type “oracle.cohsb.Alert”. 4) Below  a simple Java class that represents the type of alert messages: 5) At this point we just need to startup our coherence node, able to listen on http protocol to manage the “alerts” cache, which will receive incoming XML or JSON objects of type Alert. Remember to include in the classpath of the coherence node, the Alert java class and the following coherence libraries and configuration files:  At this point, just run the coherence class node “com.tangosol.net.DefaultCacheServer”advising you to set the following parameters:-Dtangosol.coherence.log.level=9 -Dtangosol.coherence.log=stdout -Dtangosol.coherence.cacheconfig=[PATH_TO_THE_FILE]\resty-server-config.xml 6) Let's create a procedure to test our configuration of Coherence and in order to insert some custom alerts in our cache. The technology with which you want to achieve this functionality is fully not considerable: Javascript, Python, Ruby, Scala, C + +, Java.... Because the protocol to communicate with Coherence is simply HTTP / JSON or XML. For this little demo i choose Java: A method to send/put the alert to the cache: A method to query and view the content of the cache: Finally the main method that execute our methods:  No special library added in the classpath for our class (json struct static defined), when it will be executed, it asks some information such as title, description,... in order to compose and send an alert to the cache and then it will perform an inquiry, to the same cache. At this point, a good exercise at this point, may be to create the same procedure using other technologies, such as a simple html page containing some JavaScript code, and then using Python, Ruby, and so on.7) Now we are ready to start configuring the Oracle Service Bus in order to integrate the two products. First integrate the internal alerting system of Oracle Service Bus with our centralized alerting system based on coherence node. This ensures that by monitoring, or directly from within our Proxy Message Flow, we can throw alerts and save them directly into the Coherence node. To do this I choose to use the jms technology, natively present inside the Oracle Weblogic / Service Bus. Access to the Oracle WebLogic Administration console and create and configure a new JMS connection factory and a new jms destination (queue). Now we should create a new resource of type “alert destination” within our Oracle Service Bus project. The new “alert destination” resource should be configured using the newly created connection factory jms and jms destination. Finally, in order to withdraw the message alert enqueued in our JMS destination and send it to our coherence node, we just need to create a new business service and proxy service within our Oracle Service Bus project.Our business service is responsible for sending a message to our REST service Coherence using as a method action: PUT Finally our proxy service have to collect all messages enqueued on the destination, execute an xquery transformation on those messages  in order to translate them into valid XML / alert objects useful to be sent to our coherence service, through the newly created business service. The message flow pipeline containing the xquery transformation: Incredibly,  we just did a basic first integration between the native alerting system of Oracle Service Bus and our centralized alerting system by simply configuring our coherence node without developing anything.It's time to test it out. To do this I create a proxy service able to generate an alert using our "alert destination", whenever the proxy is invoked. After some invocation to our proxy that generates fake alerts, we could open an Internet browser and type the URL  http://localhost: 8080/alerts/  so we could see what has been inserted within the coherence node. 8) We are ready for the final step.  We would create a new message flow, that can be used to search and display the results in standard mode. To do this I choosen the standard representation of RSS, to display a formatted result on a huge variety of devices such as readers for the iPhone and Android. The inquiry may be defined already at the time of the request able to return only feed / items related to our needs. To do this we need to create a new business service, a new proxy service, and finally a new XQuery Transformation to take care of translating the collection of alerts that will be return from our coherence node in a nicely formatted RSS standard document.So we start right from this resource (xquery), which has the task of transforming a collection of alerts / xml returned from the node coherence in a type well-formatted feed RSS 2.0 our new business service that will search the alerts on our coherence node using the Rest API. And finally, our last resource, the proxy service that will be exposed as an RSS / feeds to various mobile devices and traditional web readers, in which we will intercept any search query, and transform the result returned by the business service in an RSS feed 2.0. The message flow with the transformation phase (Alert TO Feed Items): Finally some little tricks to follow during the routing to the business service, - check for any queries present in the url to require a subset of alerts  - the http header "Accept" to help get an answer XML instead of JSON: In our little demo we also static added some coherence parameters to the request:sort=time:desc;start=0;count=100I would like to get from Coherence that the results will be sorted by date, and starting from 1 up to a maximum of 100.Done!!Just incredible, our centralized alerting system is ready. Inheriting all the qualities and capabilities of the two products involved Oracle Coherence & Oracle Service Bus: - RASP (Reliability, Availability, Scalability, Performance)Now try to use your mobile device, or a normal Internet browser by accessing the RSS just published: Some urls you may test: Search for the last 100 alerts : http://localhost:7001/alarmsSearch for alerts that do not have time set to null (time is not null):http://localhost:7001/alarms?q=time+is+not+nullSearch for alerts that the system property is “Web Browser” (system = ‘Web Browser’):http://localhost:7001/alarms?q=system+%3D+%27Web+Browser%27Search for alerts that the system property is “Web Browser” and the severity property is “Fatal” and the title property contain the word “Javascript”  (system = ‘Web Broser’ and severity = ‘Fatal’ and title like ‘%Javascript%’)http://localhost:8080/alerts?q=system+%3D+%27Web+Browser%27+AND+severity+%3D+%27Fatal%27+AND+title+LIKE+%27%25Javascript%25%27 To compose more complex queries about your need I would suggest you to read the chapter in the coherence documentation inherent the Cohl language (Coherence Query Language) http://download.oracle.com/docs/cd/E24290_01/coh.371/e22837/api_cq.htm . Some useful links: - Oracle Coherence REST API Documentation http://download.oracle.com/docs/cd/E24290_01/coh.371/e22839/rest_intro.htm - Oracle Service Bus Documentation http://download.oracle.com/docs/cd/E21764_01/soa.htm#osb - REST explanation from Wikipedia http://en.wikipedia.org/wiki/Representational_state_transfer At this URL could be downloaded the whole materials of this demo http://blogs.oracle.com/slc/resource/cosb/coh-sb-demo.zip Author: Nino Guarnacci.

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• Evil DRY

  - by StefanSteinegger

  DRY (Don't Repeat Yourself) is a basic software design and coding principle. But there is just no silver bullet. While DRY should increase maintainability by avoiding common design mistakes, it could lead to huge maintenance problems when misunderstood. The root of the problem is most probably that many developers believe that DRY means that any piece of code that is written more then once should be made reusable. But the principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." So the important thing here is "knowledge". Nobody ever said "every piece of code". I try to give some examples of misusing the DRY principle. Code Repetitions by Coincidence There is code that is repeated by pure coincidence. It is not the same code because it is based on the same piece of knowledge, it is just the same by coincidence. It's hard to give an example of such a case. Just think about some lines of code the developer thinks "I already wrote something similar". Then he takes the original code, puts it into a public method, even worse into a base class where none had been there before, puts some weird arguments and some if or switch statements into it to support all special cases and calls this "increasing maintainability based on the DRY principle". The resulting "reusable method" is usually something the developer not even can give a meaningful name, because its contents isn't anything specific, it is just a bunch of code. For the same reason, nobody will really understand this piece of code. Typically this method only makes sense to call after some other method had been called. All the symptoms of really bad design is evident. Fact is, writing this kind of "reusable methods" is worse then copy pasting! Believe me. What will happen when you change this weird piece of code? You can't say what'll happen, because you can't understand what the code is actually doing. So better don't touch it anymore. Maintainability just died. Of course this problem is with any badly designed code. But because the developer tried to make this method as reusable as possible, large parts of the system get dependent on it. Completely independent parts get tightly coupled by this common piece of code. Changing on the single common place will have effects anywhere in the system, a typical symptom of too tight coupling. Without trying to dogmatically (and wrongly) apply the DRY principle, you just had a system with a weak design. Now you get a system which just can't be maintained anymore. So what can you do against it? When making code reusable, always identify the generally reusable parts of it. Find the reason why the code is repeated, find the common "piece of knowledge". If you have to search too far, it's probably not really there. Explain it to a colleague, if you can't explain or the explanation is to complicated, it's probably not worth to reuse. If you identify the piece of knowledge, don't forget to carefully find the place where it should be implemented. Reusing code is never worth giving up a clean design. Methods always need to do something specific. If you can't give it a simple and explanatory name, you did probably something weird. If you can't find the common piece of knowledge, try to make the code simpler. For instance, if you have some complicated string or collection operations within this code, write some general-purpose operations into a helper class. If your code gets simple enough, its not so bad if it can't be reused. If you are not able to find anything simple and reasonable, copy paste it. Put a comment into the code to reference the other copies. You may find a solution later. Requirements Repetitions by Coincidence Let's assume that you need to implement complex tax calculations for many countries. It's possible that some countries have very similar tax rules. These rules are still completely independent from each other, since every country can change it of its own. (Assumed that this similarity is actually by coincidence and not by political membership. There might be basic rules applying to all European countries. etc.) Let's assume that there are similarities between an Asian country and an African country. Moving the common part to a central place will cause problems. What happens if one of the countries changes its rules? Or - more likely - what happens if users of one country complain about an error in the calculation? If there is shared code, it is very risky to change it, even for a bugfix. It is hard to find requirements to be repeated by coincidence. Then there is not much you can do against the repetition of the code. What you really should consider is to make coding of the rules as simple as possible. So this independent knowledge "Tax Rules in Timbuktu" or wherever should be as pure as possible, without much overhead and stuff that does not belong to it. So you can write every independent requirement short and clean. DRYing try-catch and using Blocks This is a technical issue. Blocks like try-catch or using (e.g. in C#) are very hard to DRY. Imagine a complex exception handling, including several catch blocks. When the contents of the try block as well as the contents of the individual catch block are trivial, but the whole structure is repeated on many places in the code, there is almost no reasonable way to DRY it. try { // trivial code here using (Thingy thing = new thingy) { //trivial, but always different line of code } } catch(FooException foo) { // trivial foo handling } catch (BarException bar) { // trivial bar handling } catch { // trivial common handling } finally { // trivial finally block } The key here is that every block is trivial, so there is nothing to just move into a separate method. The only part that differs from case to case is the line of code in the body of the using block (or any other block). The situation is especially interesting if the many occurrences of this structure are completely independent: they appear in classes with no common base class, they don't aggregate each other and so on. Let's assume that this is a common pattern in service methods within the whole system. Examples of Evil DRYing in this situation: Put a if or switch statement into the method to choose the line of code to execute. There are several reasons why this is not a good idea: The close coupling of the formerly independent implementation is the strongest. Also the readability of the code and the use of a parameter to control the logic. Put everything into a method which takes a delegate as argument to call. The caller just passes his "specific line of code" to this method. The code will be very unreadable. The same maintainability problems apply as for any "Code Repetition by Coincidence" situations. Enforce a base class to all the classes where this pattern appears and use the template method pattern. It's the same readability and maintainability problem as above, but additionally complex and tightly coupled because of the base class. I would call this "Inheritance by Coincidence" which will not lead to great software design. What can you do against it: Ideally, the individual line of code is a call to a class or interface, which could be made individual by inheritance. If this would be the case, it wouldn't be a problem at all. I assume that it is no such a trivial case. Consider to refactor the error concept to make error handling easier. The last but not worst option is to keep the replications. Some pattern of code must be maintained in consistency, there is nothing we can do against it. And no reason to make it unreadable. Conclusion The DRY-principle is an important and basic principle every software developer should master. The key is to identify the "pieces of knowledge". There is code which can't be reused easily because of technical reasons. This requires quite a bit flexibility and creativity to make code simple and maintainable. It's not the problem of the principle, it is the problem of blindly applying a principle without understanding the problem it should solve. The result is mostly much worse then ignoring the principle.

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• XNA Masking Mayhem

  - by TropicalFlesh

  I'd like to start by mentioning that I'm just an amateur programmer of the past 2 years with no formal training and know very little about maximizing the potential of graphics hardware. I can write shaders and manipulate a multi-layered drawing environment, but I've basically stuck to minimalist pixel shaders. I'm working on putting dynamic point light shadows in my 2d sidescroller, and have had it working to a reasonable degree. Just chucking it in without working on serious optimizations outside of basic culling, I can get 50 lights or so onscreen at once and still hover around 100 fps. The only issue is that I'm on a very high end machine and would like to target the game at as many platforms I can, low and high end. The way I'm doing shadows involves a lot of masking before I can finally draw the light to my light layer. Basically, my technique to achieveing such shadows is as follows. See pics in this album http://imgur.com/a/m2fWw#0 The dark gray represents the background tiles, the light gray represents the foreground tiles, and the yellow represents the shadow-emitting foreground tile. I'll draw the light using a radial gradient and a color of choice I'll then exclude light from the mask by drawing some geometry extending through the tile from my point light. I actually don't mask the light yet at this point, but I'm just illustrating the technique in this image Finally, I'll re-include the foreground layer in my mask, as I only want shadows to collect on the background layer and finally multiply the light with it's mask to the light layer My question is simple - How can I go about reducing the amount of render target switches I need to do to achieve the following: a. Draw mask to exclude shadows from the foreground to it's own target once per frame b. For each light that emits shadows, -Begin light mask as full white -Render shadow geometry as transparent with an opaque blendmode to eliminate shadowed areas from the mask -Render foreground mask back over the light mask to reintroduce light to the foreground c. Multiply light texture with it's individual mask to the main light layer.

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