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  • Method hiding with interfaces

    - by fearofawhackplanet
    interface IFoo { int MyReadOnlyVar { get; } } class Foo : IFoo { int MyReadOnlyVar { get; set; } } public IFoo GetFoo() { return new Foo { MyReadOnlyVar = 1 }; } Is the above an acceptable way of implementing a readonly/immutable object? The immutability of IFoo can be broken with a temporary cast to Foo. In general (non-critical) cases, is hiding functionality through interfaces a common pattern? Or is it considered lazy coding? Or even an anti-pattern?

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  • How to get the running of time of my program with gettimeofday()

    - by Mechko
    So I get the time at the beginning of the code, run it, and then get the time. struct timeval begin, end; gettimeofday(&begin, NULL); //code to time gettimeofday(&end, NULL); //get the total number of ms that the code took: unsigned int t = end.tv_usec - begin.tv_usec; Now I want to print it out in the form "**code took 0.007 seconds to run" or something similar. So two problems: 1) t seems to contain a value of the order 6000, and I KNOW the code didn't take 6 seconds to run. 2) How can I convert t to a double, given that it's an unsigned int? Or is there an easier way to print the output the way I wanted to?

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  • BuiltIn Function to Convert from Hex String to Byte

    - by Ngu Soon Hui
    This question is similar to the one here. One can easily convert from hex string to byte via the following formula: public static byte[] HexStringToBytes(string hex) { byte[] data = new byte[hex.Length /2]; int j = 0; for (int i = 0; i < hex.Length; i+=2) { data[ j ] = Convert.ToByte(hex.Substring(i, 2), 16); ++j; } return data; } But is there a built-in function ( inside .net framework) for this?

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  • InvalidOperationException When XML Serializing Inherited Class

    - by Nick
    I am having an issue serializing a c# class to an XML file that has a base class... here is a simple example: namespace Domain { [Serializable] public class ClassA { public virtual int MyProperty { get; set; } } } namespace Derived { public class ClassA : Domain.ClassA { public override int MyProperty { get { return 1; } set { /* Do Nothing */ } } } } When I attempt to serialize an instance of Derived.ClassA, I receive the following exception: InvalidOperationException(Types 'Domain.ClassA' and 'Derived.ClassA' both use the XML type name 'ClassA', from the namespace ". Use XML attributes to specify a unique XML name and/or namespace for the type.) The problem is that I want to create a single base class that simply defines the structure of the XML file, and then allow anyone else to derive from that class to insert business rules, but that the formatting will come through from the base. Is this possible, and if so, how do I attribute the base class to allow this?

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  • How can I clip strings in Java2D and add ... in the end?

    - by Jonas
    I'm trying to print Invoices in a Java Swing applications. I do that by extending Printable and implement the method public int print(Graphics g, PageFormat pf, int page). I would like to draw strings in columns, and when the string is to long I want to clip it and let it end with "...". How can I measure the string and clip it at the right position? Some of my code: Font headline = new Font("Times New Roman", Font.BOLD, 14); g2d.setFont(headline); FontMetrics metrics = g2d.getFontMetrics(headline); g2d.drawString(myString, 0, 20); I.e How can I limit myString to be max 120px? I could use metrics.stringWidth(myString), but I don't get the position where I have to clip the string. Expected results could be: A longer string that exc... A shorter string. Another long string, but OK

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  • Why does C# exit when calling the Ada elaboration routine using debug?

    - by erict
    I have a DLL created in Ada using GPS. I am dynamically loading it and calling it successfully both from Ada and from C++. But when I try to call it from C#, the program exits on the call to Elaboration init. What am I missing? The exact same DLL is perfectly happy getting called from C++ and Ada. Edit: If I start the program without Debugging, it also works with C#. But if I run it with the Debugger, then it exits on the call to ElaborationInit. There are no indications in any of the Windows event logs. If the Ada DLL is Pure, and I skip the elaboration init call, the actual function DLL is called correctly, so it has something to do with the elaboration. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; namespace CallingDLLfromCS { class Program { [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern IntPtr LoadLibrary(string dllToLoad); [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true)] public static extern IntPtr GetProcAddress(IntPtr hModule, string procedureName); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern bool FreeLibrary(IntPtr hModule); [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate int AdaCallable2_dlgt(int val); static AdaCallable2_dlgt fnAdaCallable2 = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void ElaborationInit_dlgt(); static ElaborationInit_dlgt ElaborationInit = null; [UnmanagedFunctionPointer(CallingConvention.StdCall)] delegate void AdaFinal_dlgt(); static AdaFinal_dlgt AdaFinal = null; static void Main(string[] args) { int result; bool fail = false; // assume the best IntPtr pDll2 = LoadLibrary("libDllBuiltFromAda.dll"); if (pDll2 != IntPtr.Zero) { // Note the @4 is because 4 bytes are passed. This can be further reduced by the use of a DEF file in the DLL generation. IntPtr pAddressOfFunctionToCall = GetProcAddress(pDll2, "AdaCallable@4"); if (pAddressOfFunctionToCall != IntPtr.Zero) { fnAdaCallable2 = (AdaCallable2_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaCallable2_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdainit"); if (pAddressOfFunctionToCall != IntPtr.Zero) { ElaborationInit = (ElaborationInit_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(ElaborationInit_dlgt)); } else fail = true; pAddressOfFunctionToCall = GetProcAddress(pDll2, "DllBuiltFromAdafinal"); if (pAddressOfFunctionToCall != IntPtr.Zero) AdaFinal = (AdaFinal_dlgt)Marshal.GetDelegateForFunctionPointer(pAddressOfFunctionToCall, typeof(AdaFinal_dlgt)); else fail = true; if (!fail) { ElaborationInit.Invoke(); // ^^^^^^^^^^^^^^^^^^^^^^^^^ FAILS HERE result = fnAdaCallable2(50); Console.WriteLine("Return value is " + result.ToString()); AdaFinal(); } FreeLibrary(pDll2); } } } }

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  • Copy Rows in a One to Many with LINQ (2 SQL)

    - by Refracted Paladin
    I have a table that stores a bunch of diagnosis for a single plan. When the users create a new plan I need to copy over all existing diagnosis's as well. I had thought to try the below but this is obviously not correct. I am guessing that I will need to loop through my oldDiagnosis part, but how? Thanks! My Attempt so far... public static void CopyPlanDiagnosis(int newPlanID, int oldPlanID) { using (var context = McpDataContext.Create()) { var oldDiagnosis = from planDiagnosi in context.tblPlanDiagnosis where planDiagnosi.PlanID == oldPlanID select planDiagnosi; var newDiagnosis = new tblPlanDiagnosi { PlanID = newPlanID, DiagnosisCueID = oldDiagnosis.DiagnosisCueID, DiagnosisOther = oldDiagnosis.DiagnosisOther, AdditionalInfo = oldDiagnosis.AdditionalInfo, rowguid = Guid.NewGuid() }; context.tblPlanDiagnosis.InsertOnSubmit(newDiagnosis); context.SubmitChanges(); } }

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  • Use Automapper to flatten sub-class of property

    - by Neil
    Given the classes: public class Person { public string Name { get; set; } } public class Student : Person { public int StudentId { get; set; } } public class Source { public Person Person { get; set; } } public class Dest { public string PersonName { get; set; } public int? PersonStudentId { get; set; } } I want to use Automapper to map Source - Dest. This test obviously fails: Mapper.CreateMap<Source, Dest>(); var source = new Source() { Person = new Student(){ Name = "J", StudentId = 5 }}; var dest = Mapper.Map<Source, Dest>(source); Assert.AreEqual(5, dest.PersonStudentId); What would be the best approach to mapping this given that "Person" is actually a heavily used data-type throughout our domain model.

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  • C++ Linux getpeername IP family

    - by gln
    hi In my Linux C++ application I'm using getpeername in order to get the peer IP. my problem is: when I enable the IPv6 on my machine the IP I got from the peer is with family IF_INET6 although it is IPv4. code: int GetSockPeerIP( int sock) { struct sockaddr_storage ss; struct socklen_t salen = sizeof(ss); struct sockaddr *sa; memset(&ss,0,salen); sa = (sockaddr *)&ss; if(getpeername(sock,sa,&salen) != 0) { return -1; } char * ip=NULL: if(sa->sa_family == AF_INET) { ip = inet_ntoa((struct sockaddr_in *)sa)->sin_addr); } else { //ip = how to convert IPv6 to char IP? } return 0; } how can I fix it? thanks1

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  • how to get output of a variable as float value

    - by jaskirat
    hi..i m having the follwing problem.. want to get the result in float suppose int a= convert.toint32(textbox1.text); int b= convert.toint32(textbox2.text); float ans= math.sqrt(a*b); label1.text= ans.tostring(); output.. a=7 b=3 ans should be= 4.582 but i get an error cannot implicitly convert type 'double' to 'float'. pls help..how can i get the float ans...

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  • Assigning an @Annotation enum a value

    - by h2g2java
    I created enum Restrictions{ none, enumeration, fractionDigits, length, maxExclusive, maxInclusive, maxLength, minExclusive, minInclusive, minLength, pattern, totalDigits, whiteSpace; public Restrictions setValue(int value){ this.value = value; return this; } public int value; } So that I could happily do something like this, which is perfectly legal syntax. Restrictions r1 = Restrictions.maxLength.setValue(64); The reason being is, I am using enum to restrict the type of restriction that could be used, and be able to assign a value to that restriction. However, my actual motivation is to use that restriction in an @annotation. @Retention(RetentionPolicy.RUNTIME) @Target({ElementType.TYPE, ElementType.FIELD, ElementType.METHOD}) public @interface Presentable { Restrictions[] restrictions() default Restrictions.none; } So that, I intended to do this: @Presentable(restrictions=Restrictions.maxLength.setValue(64)) public String userName; to which, the compiler croaks The value for annotation enum attribute must be an enum constant expression. Is there a way to accomplish what I wish to accomplish

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  • Dynamically formatting a string

    - by TofuBeer
    Before I wander off and roll my own I was wondering if anyone knows of a way to do the following sort of thing... Currently I am using MessageFormat to create some strings. I now have the requirement that some of those strings will have a variable number of arguments. For example (current code): MessageFormat.format("{0} OR {1}", array[0], array[1]); Now I need something like: // s will have "1 OR 2 OR 3" String s = format(new int[] { 1, 2, 3 }); and: // s will have "1 OR 2 OR 3 OR 4" String s = format(new int[] { 1, 2, 3, 4 }); There are a couple ways I can think of creating the format string, such as having 1 String per number of arguments (there is a finite number of them so this is practical, but seems bad), or build the string dynamically (there are a lot of them so this could be slow). Any other suggestions?

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  • long integer problem

    - by hopefulLLl
    hello friends,, m a beginner at c language.. m using turbo c ++ compiler 16 bit. nw the max answer obtained by me is aaround 32000.. nw if i want a number larger that that then i use long int.. if i execute the following programme.. #include <stdio.h> void main() { long int x; x=40000; printf("%d", x); } then i get error that constant value is long in function main().. kindly tell me how to get an answer more that 32000 by getting rid of this error! thnx..

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  • Change Layout Of Text Created In Java [Android]

    - by Dan
    Ok right , i asked how to create a random number from 1-100 for android and i came to this TextView tv = new TextView(this); int random = (int)Math.ceil(Math.random()*101); tv.setText("Your Number Is..."+ random ); What this does is create the default kinda "hello world" style text view and says "Your Number Is.... [Then Random Number] My problem is that i cant change the layout of this text , because it is not defined in XML, if someone could tell me how to change the style , or like make the random number into a string so i could use it for any Textview layout that would be great .. Thanks :)

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  • Stored procedure error when use computed column for ID

    - by Hari
    I got the error: Procedure or function usp_User_Info3 has too many arguments specified When I run the program. I don't know the error in SP or in C# code. I have to display the Vendor_ID after the user clicks the submit button. Where the thing going wrong here ? Table structure : CREATE TABLE User_Info3 ( SNo int Identity (2000,1) , Vendor_ID AS 'VEN' + CAST(SNo as varchar(16)) PERSISTED PRIMARY KEY, UserName VARCHAR(16) NOT NULL, User_Password VARCHAR(12) NOT NULL, User_ConPassword VARCHAR(12) NOT NULL, User_FirstName VARCHAR(25) NOT NULL, User_LastName VARCHAR(25) SPARSE NULL, User_Title VARCHAR(35) NOT NULL, User_EMail VARCHAR(35) NOT NULL, User_PhoneNo VARCHAR(14) NOT NULL, User_MobileNo VARCHAR(14)NOT NULL, User_FaxNo VARCHAR(14)NOT NULL, UserReg_Date DATE DEFAULT GETDATE() ) Stored Procedure : ALTER PROCEDURE [dbo].[usp_User_Info3] @SNo INT OUTPUT, @Vendor_ID VARCHAR(10) OUTPUT, @UserName VARCHAR(30), @User_Password VARCHAR(12), @User_ConPassword VARCHAR(12), @User_FirstName VARCHAR(25), @User_LastName VARCHAR(25), @User_Title VARCHAR(35), @User_OtherEmail VARCHAR(30), @User_PhoneNo VARCHAR(14), @User_MobileNo VARCHAR(14), @User_FaxNo VARCHAR(14) AS BEGIN SET NOCOUNT ON; INSERT INTO User_Info3 (UserName,User_Password,User_ConPassword,User_FirstName, User_LastName,User_Title,User_OtherEmail,User_PhoneNo,User_MobileNo,User_FaxNo) VALUES (@UserName,@User_Password,@User_ConPassword,@User_FirstName,@User_LastName, @User_Title,@User_OtherEmail,@User_PhoneNo,@User_MobileNo,@User_FaxNo) SET @SNo = Scope_Identity() SELECT Vendor_ID From User_Info3 WHERE SNo = @SNo END C# Code : protected void BtnUserNext_Click(object sender, EventArgs e) { cmd.CommandType = CommandType.StoredProcedure; cmd.CommandText = "usp_User_Info3"; System.Data.SqlClient.SqlParameter SNo=cmd.Parameters.Add("@SNo",System.Data.SqlDbType.Int); System.Data.SqlClient.SqlParameter Vendor_ID=cmd.Parameters.Add("@Vendor_ID", System.Data.SqlDbType.VarChar,10); cmd.Parameters.Add("@UserName", SqlDbType.VarChar).Value = txtUserName.Text; cmd.Parameters.Add("@User_Password", SqlDbType.VarChar).Value = txtRegPassword.Text; cmd.Parameters.Add("@User_ConPassword", SqlDbType.VarChar).Value = txtRegConPassword.Text; cmd.Parameters.Add("@User_FirstName", SqlDbType.VarChar).Value = txtRegFName.Text; cmd.Parameters.Add("@User_LastName", SqlDbType.VarChar).Value = txtRegLName.Text; cmd.Parameters.Add("@User_Title", SqlDbType.VarChar).Value = txtRegTitle.Text; cmd.Parameters.Add("@User_OtherEmail", SqlDbType.VarChar).Value = txtOtherEmail.Text; cmd.Parameters.Add("@User_PhoneNo", SqlDbType.VarChar).Value =txtRegTelephone.Text; cmd.Parameters.Add("@User_MobileNo", SqlDbType.VarChar).Value =txtRegMobile.Text; cmd.Parameters.Add("@User_FaxNo", SqlDbType.VarChar).Value =txtRegFax.Text; cmd.Connection = SqlCon; try { Vendor_ID.Direction = System.Data.ParameterDirection.Output; SqlCon.Open(); cmd.ExecuteNonQuery(); string VendorID = cmd.ExecuteScalar() as string; } catch (Exception ex) { throw new Exception(ex.Message); } finally { string url = "../CompanyBasicInfo.aspx?Parameter=" + Server.UrlEncode(" + VendorID + "); SqlCon.Close(); } }

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  • Longest keyword chain?

    - by pg-robban
    As I was typing some constants in Java I noticed I had used 4 keywords in a row, which Eclipse highlighted for me: public static final int. I then took a break from my regular coding and asked myself (and google with no relevant results) what the longest chain of keywords I can use and still have valid code. After a while, the best I could come up with was this method definition: public synchronized static final strictfp int a() { ... which is 6 keywords in Java. Is it possible to go 7, or even higher? What about other languages?

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  • Help me understand this C code

    - by Benjamin
    INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved? If you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a warning under embedded visual c++ 4.0, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code, and am trying to learn, is it possible the original author made a mistake on this line? The *pRoot should point to HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match?

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  • LINQ DefaultIfEmpty(), generating inferred argument error

    - by Refracted Paladin
    I am trying to get the below linq query to return -1 if there isn't any current value. I was looking at this article on MSDN, here, and it seemed that DefaultIfEmpty() was what I wanted. Unfortunately, I am getting a The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly. error. I guess I am not sure what that means or what it is telling me to do. Can someone explain, please. public static int CheckForDRIID(int personID) { using (var context = ConnectDataContext.Create()) { var masterIndex = (from applicationAssociation in context.tblApplicationAssociations where applicationAssociation.ApplicationID == 1 && applicationAssociation.PersonID == personID select applicationAssociation.PersonApplicationID).DefaultIfEmpty(-1).Single(); return Convert.ToInt32(masterIndex); } }

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  • Using free function as pseudo-constructors to exploit template parameter deduction

    - by Poita_
    Is it a common pattern/idiom to use free functions as pseudo-constructors to avoid having to explicitly specify template parameters? For example, everyone knows about std::make_pair, which uses its parameters to deduce the pair types: template <class A, class B> std::pair<A, B> make_pair(A a, B b) { return std::pair<A, B>(a, b); } // This allows you to call make_pair(1, 2), // instead of having to type pair<int, int>(1, 2) // as you can't get type deduction from the constructor. I find myself using this quite often, so I was just wondering if many other people use it, and if there is a name for this pattern?

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  • WiX: Extracting Binary-string in Custom Action yields string like "???good data"

    - by leiflundgren
    I just found a weird behaviour when attempting to extract a string from the Binary-table in the MSI. I have a file containing "Hello world", the data I get is "???Hello world". (Literary question mark.) Is this as intended? Will it always be exactly 3 characters in the beginning? Regards Leif Sample code: [CustomAction] public static ActionResult CustomAction2(Session session) { View v = session.Database.OpenView("SELECT `Name`,`Data` FROM `Binary`"); v.Execute(); Record r = v.Fetch(); int datalen = r.GetDataSize("Data"); System.IO.Stream strm = r.GetStream("Data"); byte[] rawData = new byte[datalen]; int res = strm.Read(rawData, 0, datalen); strm.Close(); String s = System.Text.Encoding.ASCII.GetString(rawData); // s == "???Hello World" return ActionResult.Success; }

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  • Android: Creating custom class of resources

    - by Sebastian
    Hi, R class on android has it's limitations. You can't use the resources dynamically for loading audio, pictures or whatever. If you wan't for example, load a set of audio files for a choosen object you can't do something like: R.raw."string-upon-choosen-object" I'm new to android and at least I didn't find how you could do that, depending on what objects are choosen or something more dynamic than that. So, I thought about making it dynamic with a little of memory overhead. But, I'm in doubt if it's worth it or just working different with external resources. The idea is this: Modify the ant build xml to execute my own task. This task, is a java program that parses the R.java file building a set of HashMaps with it's pair (key, value). I have done this manually and It's working good. So I need some experts voice about it. This is how I will manage the whole thing: Generate a base Application class, e.g. MainApplicationResources that builds up all the require methods and attributes. Then, you can access those methods invoking getApplication() and then the desired method. Something like this: package [packageName] import android.app.Application; import java.util.HashMap; public class MainActivityResources extends Application { private HashMap<String,Integer> [resNameObj1]; private HashMap<String,Integer> [resNameObj2]; ... private HashMap<String,Integer> [resNameObjN]; public MainActivityResources() { super(); [resNameObj1] = new HashMap<String,Integer>(); [resNameObj1].put("[resNameObj1_Key1]", new Integer([resNameObj1_Value1])); [resNameObj1].put("[resNameObj1_Key2]", new Integer([resNameObj1_Value2])); [resNameObj2] = new HashMap<String,Integer>(); [resNameObj2].put("[resNameObj2_Key1]", new Integer([resNameObj2_Value1])); [resNameObj2].put("[resNameObj2_Key2]", new Integer([resNameObj2_Value2])); ... [resNameObjN] = new HashMap<String,Integer>(); [resNameObjN].put("[resNameObjN_Key1]", new Integer([resNameObjN_Value1])); [resNameObjN].put("[resNameObjN_Key2]", new Integer([resNameObjN_Value2])); } public int get[ResNameObj1](String resourceName) { return [resNameObj1].get(resourceName).intValue(); } public int get[ResNameObj2](String resourceName) { return [resNameObj2].get(resourceName).intValue(); } ... public int get[ResNameObjN](String resourceName) { return [resNameObjN].get(resourceName).intValue(); } } The question is: Will I add too much memory use of the device? Is it worth it? Regards,

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  • How the simples GUI countdown is supposed to work?

    - by Roman
    I am trying to write the simples GUI countdown. I found in Internet some code but it is already too fancy for me. I am trying to keep it as simple as possible. So, I just want to have a window saying "You have 10 second left". The number of second should decrease every second from 10 to 0. I wrote a code. And I think I am close to the working solution. But I still missing something. Could you pleas help me to find out what is wrong? Here is my code: import javax.swing.*; public class Countdown { static JLabel label; // Method which defines the appearance of the window. private static void showGUI() { JFrame frame = new JFrame("Simple Countdown"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JLabel label = new JLabel("Some Text"); frame.add(label); frame.pack(); frame.setVisible(true); } // Define a new thread in which the countdown is counting down. static Thread counter = new Thread() { public void run() { for (int i=10; i>0; i=i-1) { updateGUI(i,label); try {Thread.sleep(1000);} catch(InterruptedException e) {}; } } }; // A method which updates GUI (sets a new value of JLabel). private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater(new Runnable(i,label) { public Runnable(int i, JLabel label) { this.i = i; this.label = label; } public void run() { label.setText("You have " + i + " seconds."); } }); } // The main method (entry point). public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { showGUI(); //counter.start(); } }); //counter.start(); } } And I have several concrete question about this code: Where should I place the counter.start();? (In my code I put it on 2 places. Which one is correct?) Why compiler complains about the constructor for Runnable? It says that I have an invalid method declaration and I need to specify the returned type. ADDED: I made the suggested corrections. And then I execute the code and get: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at Worker.run(Worker.java:12) In the Worker.java in the line 12 I have: label.setText("You have " + i + " seconds.");.

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  • What is the purpose of Java's unary plus operator?

    - by Syntactic
    Java's unary plus operator appears to have come over from C, via C++. As near as I can tell, it has the following effects: promotes its operand to int, if it's not already an int or wider unboxes its operand, if it's a wrapper object complicates slightly the parsing of evil expressions containing large numbers of consecutive plus signs It seems to me that there are better (or, at least, clearer) ways to do all of these things. In this SO question, concerning the counterpart operator in C#, someone said that "It's there to be overloaded if you feel the need." But in Java, one cannot overload any operator. So does this operator exist in Java just because it existed in C++?

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  • What does the '&' operator do in C++?

    - by rascher
    n00b question. I am a C guy and I'm trying to understand some C++ code. I have the following function declaration: int foo(const string &myname) { cout << "called foo for: " << myname << endl; return 0; } How does the function signature differ from the equivalent C: int foo(const char *myname) Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers? Similarly: const string &GetMethodName() { ... } What is the & doing here? Is there some website that explains how & is used differently in C vs C++?

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