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  • How to find an XPath query to Element/Element without namespaces (XmlSerializer, fragment)?

    - by Veksi
    Assume this simple XML fragment in which there may or may not be the xml declaration and has exactly one NodeElement as a root node, followed by exactly one other NodeElement, which may contain an assortment of various number of different kinds of elements. <?xml version="1.0"> <NodeElement xmlns="xyz"> <NodeElement xmlns=""> <SomeElement></SomeElement> </NodeElement> </NodeElement> How could I go about selecting the inner NodeElement and its contents without the namespace? For instance, "//*[local-name()='NodeElement/NodeElement[1]']" (and other variations I've tried) doesn't seem to yield results. As for in general the thing that I'm really trying to accomplish is to Deserialize a fragment of a larger XML document contained in a XmlDocument. Something like the following var doc = new XmlDocument(); doc.LoadXml(File.ReadAllText(@"trickynodefile.xml")); //ReadAllText to avoid Unicode trouble. var n = doc.SelectSingleNode("//*[local-name()='NodeElement/NodeElement[1]']"); using(var reader = XmlReader.Create(new StringReader(n.OuterXml))) { var obj = new XmlSerializer(typeof(NodeElementNodeElement)).Deserialize(reader); I believe I'm missing just the right XPath expression, which seem to be rather elusive. Any help much appreciated!

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  • MapView EXC_BAD_ACCESS (SIGSEGV) and KERN_INVALID_ADDRESS

    - by user768113
    I'm having some 'issues' with my application... well, it crashes in an UIViewController that is presented modally, there the user enters information through UITextFields and his location is tracked by a MapView. Lets call this view controller "MapViewController" When the user submits the form, I call a different ViewController - modally again - that processes this info and a third one answers accordingly, then go back to a MenuVC using unwinding segues, which then calls MapViewController and so on. This sequence is repeated many times, but it always crashes in MapViewController. Looking at the crash log, I think that the MapView can be the problem of this or some element in the UI (because of the UIKit framework). I tried to use NSZombie in order to track a memory issue but it doesn't give me a clue about whats happening. Here is the crash log Hardware Model: iPad3,4 Process: MyApp [2253] OS Version: iOS 6.1.3 (10B329) Report Version: 104 Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x00000044 Crashed Thread: 0 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 IMGSGX554GLDriver 0x328b9be0 0x328ac000 + 56288 1 IMGSGX554GLDriver 0x328b9b8e 0x328ac000 + 56206deallocated instance 2 IMGSGX554GLDriver 0x328bc2f2 0x328ac000 + 66290 3 IMGSGX554GLDriver 0x328baf44 0x328ac000 + 61252 4 libGPUSupportMercury.dylib 0x370f86be 0x370f6000 + 9918 5 GLEngine 0x34ce8bd2 0x34c4f000 + 629714 6 GLEngine 0x34cea30e 0x34c4f000 + 635662 7 GLEngine 0x34c8498e 0x34c4f000 + 219534 8 GLEngine 0x34c81394 0x34c4f000 + 205716 9 VectorKit 0x3957f4de 0x394c7000 + 754910 10 VectorKit 0x3955552e 0x394c7000 + 582958 11 VectorKit 0x394d056e 0x394c7000 + 38254 12 VectorKit 0x394d0416 0x394c7000 + 37910 13 VectorKit 0x394cb7ca 0x394c7000 + 18378 14 VectorKit 0x394c9804 0x394c7000 + 10244 15 VectorKit 0x394c86a2 0x394c7000 + 5794 16 QuartzCore 0x354a07a4 0x35466000 + 239524 17 QuartzCore 0x354a06fc 0x35466000 + 239356 18 IOMobileFramebuffer 0x376f8fd4 0x376f4000 + 20436 19 IOKit 0x344935aa 0x34490000 + 13738 20 CoreFoundation 0x33875888 0x337e9000 + 575624 21 CoreFoundation 0x338803e4 0x337e9000 + 619492 22 CoreFoundation 0x33880386 0x337e9000 + 619398 23 CoreFoundation 0x3387f20a 0x337e9000 + 614922 24 CoreFoundation 0x337f2238 0x337e9000 + 37432 25 CoreFoundation 0x337f20c4 0x337e9000 + 37060 26 GraphicsServices 0x373ad336 0x373a8000 + 21302 27 UIKit 0x3570e2b4 0x356b7000 + 357044 28 MyApp 0x000ea12e 0xe9000 + 4398 29 MyApp 0x000ea0e4 0xe9000 + 4324 I think thats all, additionally, I would like to ask you: if you are using unwind segues then you are releasing view controllers from the memory heap, right? Meanwhile, performing segues let you instantiate those controllers. Technically, MenuVC should be the only VC alive in the heap during the app life cycle if you understand me.

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  • Why do browsers encode special characters differently with ajax requests?

    - by Andrei Oniga
    I have a web application that reads the values of a few input fields (alphanumeric) and constructs a very simple xml that is passes to the server, using jQuery's $.ajax() method. The template for that xml is: <request> <session>[some-string]</session> <space>[some-string]</space> <plot>[some-string]</plot> ... </request> Sending such requests to the server when the inputs contain Finnish diacritical characters (such as ä or ö) raises a problem in terms of character encoding with different browsers. For instance, if I add the word Käyttötarkoitus" in one of the inputs, here's how Chrome and Firefox send EXACTLY the same request to the server: Chrome: <request> <session>{string-hidden}</session> <space>2080874</space> <plot>Käyttötarkoitus</plot> ... </request> FF 12.0: <request> <session>{string-hidden}</session> <space>2080874</space> <plot>Käyttötarkoitus</plot> ... </request> And here is the code fragment that I use to send the requests: $.ajax({ type: "POST", url: url, dataType: 'xml;charset=UTF-8', data: xml, success: function(xml) { // }, error: function(jqXHR, textStatus, errorThrown) { // } }); Why do I get different encodings and how do I get rid of this difference? I need to fix this problem because it's causing other on the server-side.

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  • Remote connection to SQL Server Express fails

    - by worlds-apart89
    I have two computers that share the same Internet IP address. Using one of the computers, I can remotely connect to a SQL Server database on the other. Here is my connection string: SqlConnection connection = new SqlConnection(@"Data Source=192.168.1.101\SQLEXPRESSNI,1433;Network Library=DBMSSOCN;Initial Catalog=FirstDB;Persist Security Info=True;User ID=username;Password=password;"); 192.168.1.101 is the server, SQLEXPRESSNI is the SQL Server instance name, and FirstDB is the name of the database. Now, I have another computer with a different Internet IP address. I want to connect to the server above using the third computer that does not belong to my local area network. I dont have access to that third computer at the moment, so I want to use (if possible) the client computer in LAN again. SqlConnection connection = new SqlConnection(@"Data Source=SharedInternetIP\SQLEXPRESSNI,1433;Network Library=DBMSSOCN;Initial Catalog=FirstDB;Persist Security Info=True;User ID=username;Password=password;"); Does not work Note that I am a beginner, so I am not quite sure what I am doing even though I know what I want to do. By passing the Internet IP to the SqlConnection object rather than the local IP address, how can I successfully connect to the server computer, using the client computer in the same network? Also note that my ultimate goal is to connect to the server with an external client, but I don't have access to that computer right now. I'd appreciate any help.

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  • could not execute a stored procedure(using DAAB) from a client(aspx page) to a wcf service

    - by user1144695
    i am trying to store data to sql database from a asp.net client website through a stored procedure(using DAAB) in a wcf service hosted in a asp.net empty website.When i try to store data to the DB i get the following error: ** - The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the <serviceDebug> configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework SDK documentation and inspect the server trace logs. ** When i try to debug i get the following exception: Activation error occured while trying to get instance of type Database, key "" in the code-- Database db = EnterpriseLibraryContainer.Current.GetInstance<Database>("MyInstance"); where my app.config is <?xml version="1.0"?> <configuration> <configSections> <section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true"/> </configSections> <dataConfiguration defaultDatabase="MyInstance"/> <connectionStrings> <add name="MyInstance" connectionString="Data Source=BLRKDAS307581\KD;Integrated Security=True;User ID=SAPIENT\kdas3;Password=ilove0LINUX" providerName="System.Data.SqlClient" /> </connectionStrings> <startup> <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> </startup> </configuration> Can anyone help me with it? Thanks in advance...

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  • Method having an abstract class as a parameter

    - by Ferhat
    I have an abstract class A, where I have derived the classes B and C. Class A provides an abstract method DoJOB(), which is implemented by both derived classes. There is a class X which has methods inside, which need to call DoJOB(). The class X may not contain any code like B.DoJOB() or C.DoJOB(). Example: public class X { private A foo; public X(A concrete) { foo = concrete; } public FunnyMethod() { foo.DoJOB(); } } While instantiating class X I want to decide which derived class (B or C) must be used. I thought about passing an instance of B or C using the constructor of X. X kewl = new X(new C()); kewl.FunnyMethod(); //calls C.DoJOB() kewl = new X(new B()); kewl.FunnyMethod(); // calls B.DoJOB() My test showed that declaring a method with a parameter A is not working. Am I missing something? How can I implement this correctly? (A is abstract, it cannot be instantiated)

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  • Java: using generic wildcards with subclassing

    - by gibberish
    Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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  • getSharedPreferences not working for me with concerns to ListPreferences and Integers

    - by ideagent
    I'm stuck at a point where I'm trying to get my project to read a preference value (from a ListPreference listing) and then use that value in a basic mathematical subtraction instance. The problem is that the "seek" preference is not being seen by my Java code, and yet the default value is (I've tried the default value with 3000 and now 0). Am i missing something, is there a bug here, known or unknown? Java code chunk where the issues manifests itself: public static final String PREF_FILE_NAME = "preferences"; seekback.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View view) { try { SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE); Integer storedPreference = preferences.getInt("seek", 0); (mediaPlayer.getCurrentPosition()-storedPreference); } catch (Exception e) { e.printStackTrace(); } } }); Here are some other code bits for my project: From preferences file: <ListPreference android:entries="@array/seconds" android:entryValues="@array/seconds_values" android:summary="sets the seek interval for the seekback and seekforward buttons" android:title="Seek Interval" android:defaultValue="5000" android:key="@string/seek" From strings file: seek From an array file: Five seconds Fifteen seconds Thirty seconds Sixty seconds 5000 15000 30000 60000 let me know if you need to see more code to figure this one out Thanks in advance for any help that can be offered. I've worked over this issue now for a few hours and I'm burnt, a second pair of eyes on it would be very much appreciated. Arg, not sure how to get the code and plain text to format nicely here, even tried the options, like Code Sample, no luck AndroidCoder

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  • invalid scalar hex value 0x8000000 and over

    - by kioto
    Hi. I found a problem getting hex value from yaml file. It couldn't get hex value 0x80000000 and over. Following is a sample C++ program. // ymlparser.cpp #include <iostream> #include <fstream> #include "yaml-cpp/yaml.h" int main(void) { try { std::ifstream fin("hex.yaml"); YAML::Parser parser(fin); YAML::Node doc; parser.GetNextDocument(doc); int num1; doc["hex1"] >> num1; printf("num1 = 0x%x\n", num1); int num2; doc["hex2"] >> num2; printf("num2 = 0x%x\n", num2); return 0; } catch(YAML::ParserException& e) { std::cout << e.what() << "\n"; } } hex.yaml hex1: 0x7FFFFFFF hex2: 0x80000000 Error message is here. $ ./ymlparser num1 = 0x7fffffff terminate called after throwing an instance of 'YAML::InvalidScalar' what(): yaml-cpp: error at line 2, column 7: invalid scalar Aborted Environment yaml-cpp : getting from svn, March.22.2010 or v0.2.5 OS : Ubuntu 9.10 i386 I need to get hex the value on yaml-cpp now, but I have no idea. Please tell me how to get it another way. Thanks,

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  • Can anyone get app-engine plugin working with Grails on mac os x?

    - by tim
    I have been trying for 4 days to get app-engine and grails working together on my mac to no avail. I am using latest groovy/grails and appengine sdk versions. Im following the app-engine plugin step by step on the grails site.. http://grails.org/plugin/app-engine Groovy Version: 1.7.1 JVM: 1.5.0_22 Grails 1.3.0.RC1 echo $APPENGINE_HOME reveals /Users/markstim/appengine-java-sdk-1.3.2 I perform the following steps 1. grails create-app myapp 2. cd myapp; grails list-plugins reveals hibernate 1.3.0.RC1 -- Hibernate for Grails tomcat 1.3.0.RC1 -- Apache Tomcat plugin for Grails add the following line to Config.groovy google.appengine.application="myapp" install the plugin for app-engine grails install-plugin app-engine and answer 'jpa' when asked (no errors yet) installed plugins list now looks like app-engine 0.8.9 -- Grails AppEngine plugin gorm-jpa 0.7.1 -- GORM-JPA Plugin then grails run-app and get this error as the server is coming up... [java] WARNING: Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is org.codehaus.groovy.grails.exceptions.NewInstanceCreationException: Could not create a new instance of class [GormJpaGrailsPlugin]!: [java] java.lang.NoClassDefFoundError: org.grails.jpa.JpaPluginSupport then if i navigate to localhost:8080 I get HTTP ERROR: 503 Problem accessing /myapp. Reason: SERVICE_UNAVAILABLE Powered by Jetty://

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  • How to Object Array to List

    - by Peter Black
    (C#) I have 2 classes. 1 is called Employee. The other is my "main". I am trying to take a list and assign each value in list to an array of Employee object. //Inside "Main" class int counter = NameList.Count; Employee[] employee = new Employee[counter]; for (int i = 0; i <= counter; i++) { employee[i].Name = NameList[i]; employee[i].EmpNumber = EmpNumList[i]; employee[i].DateOfHire = DOHList[i]; employee[i].Salary = SalaryList[i]; employee[i].JobDescription = JobDescList[i]; employee[i].Department = DeptList[i]; } This returns the error: An unhandled exception of type 'System.NullReferenceException' occurred in Pgm4.exe Additional information: Object reference not set to an instance of an object. I think this means that I am not calling the list properly. Any help would be much appreciated. Thank you.

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  • ADO.NET DataTable/DataRow Thread Safety

    - by Allen E. Scharfenberg
    Introduction A user reported to me this morning that he was having an issue with inconsistent results (namely, column values sometimes coming out null when they should not be) of some parallel execution code that we provide as part of an internal framework. This code has worked fine in the past and has not been tampered with lately, but it got me to thinking about the following snippet: Code Sample lock (ResultTable) { newRow = ResultTable.NewRow(); } newRow["Key"] = currentKey; foreach (KeyValuePair<string, object> output in outputs) { object resultValue = output.Value; newRow[output.Name] = resultValue != null ? resultValue : DBNull.Value; } lock (ResultTable) { ResultTable.Rows.Add(newRow); } (No guarantees that that compiles, hand-edited to mask proprietery information.) Explanation We have this cascading type of locking code other places in our system, and it works fine, but this is the first instance of cascading locking code that I have come across that interacts with ADO .NET. As we all know, members of framework objects are usually not thread safe (which is the case in this situation), but the cascading locking should ensure that we are not reading and writing to ResultTable.Rows concurrently. We are safe, right? Hypothesis Well, the cascading lock code does not ensure that we are not reading from or writing to ResultTable.Rows at the same time that we are assigning values to columns in the new row. What if ADO .NET uses some kind of buffer for assigning column values that is not thread safe--even when different object types are involved (DataTable vs. DataRow)? Has anyone run into anything like this before? I thought I would ask here at StackOverflow before beating my head against this for hours on end :) Conclusion Well, the consensus appears to be that changing the cascading lock to a full lock has resolved the issue. That is not the result that I expected, but the full lock version has not produced the issue after many, many, many tests. The lesson: be wary of cascading locks used on APIs that you do not control. Who knows what may be going on under the covers!

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  • Fastest XML parser for small, simple documents in Java

    - by Varkhan
    I have to objectify very simple and small XML documents (less than 1k, and it's almost SGML: no namespaces, plain UTF-8, you name it...), read from a stream, in Java. I am using JAXP to process the data from my stream into a Document object. I have tried Xerces, it's way too big and slow... I am using Dom4j, but I am still spending way too much time in org.dom4j.io.SAXReader. Does anybody out there have any suggestion on a faster, more efficient implementation, keeping in mind I have very tough CPU and memory constraints? [Edit 1] Keep in mind that my documents are very small, so the overhead of staring the parser can be important. For instance I am spending as much time in org.xml.sax.helpers.XMLReaderFactory.createXMLReader as in org.dom4j.io.SAXReader.read [Edit 2] The result has to be in Dom format, as I pass the document to decision tools that do arbitrary processing on it, like switching code based on the value of arbitrary XPaths, but also extracting lists of values packed as children of a predefined node. [Edit 3] In any case I eventually need to load/parse the complete document, since all the information it contains is going to be used at some point. (This question is related to, but different from, http://stackoverflow.com/questions/373833/best-xml-parser-for-java )

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  • Specifying character

    - by danutenshu
    So below I have a code in C++ that is supposed to invert the arguments in a vector, but not the sequence. I have listed my problems as sidenotes in the code below. The invert function is supposed to invert each argument, and then the main function just outputs the inverted words in same order For instance, program("one two three four")=ruof eerth owt eno #include <iostream> #include <string> using namespace std; int invert(string normal) { string inverted; for (int num=normal.size()-1; num>=0; num--) { inverted.append(normal[num]); //I don't know how to get each character //I need another command for append } return **inverted**; <---- } int main(int argc, char* argv[]) { string text; for (int a=1; a<argc; a++) { text.append(invert(argv[a])); //Can't run the invert function text.append(" "); } cout << text << endl; return 0; }

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  • How to design authentication in a thick client, to be fail safe?

    - by Jay
    Here's a use case: I have a desktop application (built using Eclipse RCP) which on start, pops open a dialog box with 'UserName' and 'Password' fields in it. Once the end user, inputs his UserName and Password, a server is contacted (a spring remote-servlet, with the client side being a spring httpclient: similar to the approaches here.), and authentication is performed on the server side. A few questions related to the above mentioned scenario: If said this authentication service were to go down, what would be the best way to handle further proceedings? Authentication is something that I cannot do away with. Would running the desktop client in a "limited" mode be a good idea? For instance, important features/menus/views will be disabled, rest of the application will be accessible? Should I have a back up authentication service running on a different machine, working as a backup? What are the general best-practices in this scenario? I remember reading about google gears and how it would let you edit and do stuff offline - should something like this be designed? Please let me know your design/architectural comments/suggestions. Appreciate your help.

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  • Python program to search for specific strings in hash values (coding help)

    - by Diego
    Trying to write a code that searches hash values for specific string's (input by user) and returns the hash if searchquery is present in that line. Doing this to kind of just learn python a bit more, but it could be a real world application used by an HR department to search a .csv resume database for specific words in each resume. I'd like this program to look through a .csv file that has three entries per line (id#;applicant name;resume text) I set it up so that it creates a hash, then created a string for the resume text hash entry, and am trying to use the .find() function to return the entire hash for each instance. What i'd like is if the word "gpa" is used as a search query and it is found in s['resumetext'] for three applicants(rows in .csv file), it prints the id, name, and resume for every row that has it.(All three applicants) As it is right now, my program prints the first row in the .csv file(print resume['id'], resume['name'], resume['resumetext']) no matter what the searchquery is, whether it's in the resumetext or not. lastly, are there better ways to doing this, by searching word documents, pdf's and .txt files in a folder for specific words using python (i've just started reading about the re module and am wondering if this may be the route, rather than putting everything in a .csv file.) def find_details(id2find): resumes_f=open("resume_data.csv") for each_line in resumes_f: s={} (s['id'], s['name'], s['resumetext']) = each_line.split(";") resumetext = str(s['resumetext']) if resumetext.find(id2find): return(s) else: print "No data matches your search query. Please try again" searchquery = raw_input("please enter your search term") resume = find_details(searchquery) if resume: print resume['id'], resume['name'], resume['resumetext']

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  • Database Programming in C#, returning output from Stored Proc

    - by jpavlov
    I am working at gaining an understanding at how to interface stored procedures with applications. My example is simple, but it doesn't display my columns and rows in the command prompt, instead it display System.Data.SqlClient.SqlDataReader. How do I display the rows from my stored procudure? ----Stored Proc-- ALTER PROCEDURE dbo.SelectID AS SELECT * FROM tb_User; ----- Below is the code: using System; using System.Data.SqlClient; using System.IO; namespace ExecuteStoredProc { class Program { static void Main(string[] args) { SqlConnection cnnUserMan; SqlCommand cmmUser; //SqlDataReader drdUser; //Instantiate and open the connection cnnUserMan = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=c:\\Program Files\\Microsoft SQL Server\\MSSQL10.SQLEXPRESS\\MSSQL\\DATA\\UserDB.mdf; Integrated Security=True;Connect Timeout=30;User Instance=True"); cnnUserMan.Open(); //Instantiate and initialize command cmmUser = new SqlCommand("SelectID", cnnUserMan); cmmUser.CommandType = System.Data.CommandType.StoredProcedure; //drdUser = cmmUser.ExecuteReader(); Console.WriteLine(cmmUser.ExecuteReader()); Console.ReadLine(); } } } Thanks.

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  • How to implement Administrator rights in Java Application?

    - by Yatendra Goel
    I am developing a Data Modeling Software that is implemented in Java. This application converts the textual data (stored in a database) to graphical form so that users can interpret the data in a more efficient form. Now, this application will be accessed by 3 kinds of persons: 1. Managers (who can fill the database with data and they can also view the visual form of the data after entering the data into the database) 2. Viewers (who can only view the visual form of data that has been filled by managers) 3. Administrators (who can create and manage other administrators, managers and viewers) Now, how to implement 3 diff. views of the same application. Note: Managers, Viewers and Administrators can be located in any part of the world and should access the application through internet. One idea that came in my mind is as follows: Step1: Code all the business logic in EJBs so that it can be used in distributed environment (means which can be accessed by several users through internet) Step2: Code 3 Swing GUI Clients: One for administrators, one for managers and one for viewers. These 3 GUI clients can access business logic written in EJBs. Step3: Distribute the clients corresponding to their users. For instance, manager client to managers. =================================QUESTIONS======================================= Q1. Is the above approach is correct? Q2. This is very common functionality that various softwares have. So, Do they implement this kind of functionality through this way or any other way? Q3. If any other approach would be more better, then what is that approach?

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  • Which isolation level should I use for the following insert-if-not-present transaction?

    - by Steve Guidi
    I've written a linq-to-sql program that essentially performs an ETL task, and I've noticed many places where parallelization will improve its performance. However, I'm concerned about preventing uniquness constraint violations when two threads perform the following task (psuedo code). Record CreateRecord(string recordText) { using (MyDataContext database = GetDatabase()) { Record existingRecord = database.MyTable.FirstOrDefault(record.KeyPredicate()); if(existingRecord == null) { existingRecord = CreateRecord(recordText); database.MyTable.InsertOnSubmit(existingRecord); } database.SubmitChanges(); return existingRecord; } } In general, this code executes a SELECT statement to test for record existance, followed by an INSERT statement if the record doesn't exist. It is encapsulated by an implicit transaction. When two threads run this code for the same instance of recordText, I want to prevent them from simultaneously determining that the record doesn't exist, thereby both attempting to create the same record. An isolation level and explicit transaction will work well, except I'm not certain which isolation level I should use -- Serializable should work, but seems too strict. Is there a better choice?

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  • Java - Removing duplicates in an ArrayList

    - by Will
    I'm working on a program that uses an ArrayList to store Strings. The program prompts the user with a menu and allows the user to choose an operation to perform. Such operations are adding Strings to the List, printing the entries etc. What I want to be able to do is create a method called removeDuplicates().This method will search the ArrayList and remove any duplicated values. I want to leave one instance of the duplicated value(s) within the list. I also want this method to return the total number of duplicates removed. I've been trying to use nested loops to accomplish this but I've been running into trouble because when entries get deleted, the indexing of the ArrayList gets altered and things don't work as they should. I know conceptually what I need to do but I'm having trouble implementing this idea in code. Here is some pseudo code: start with first entry; check each subsequent entry in the list and see if it matches the first entry; remove each subsequent entry in the list that matches the first entry; after all entries have been examined, move on to the second entry; check each entry in the list and see if it matches the second entry; remove each entry in the list that matches the second entry; repeat for entry in the list Here's the code I have so far: public int removeDuplicates() { int duplicates = 0; for ( int i = 0; i < strings.size(); i++ ) { for ( int j = 0; j < strings.size(); j++ ) { if ( i == j ) { // i & j refer to same entry so do nothing } else if ( strings.get( j ).equals( strings.get( i ) ) ) { strings.remove( j ); duplicates++; } } } return duplicates; }

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  • In what order should the Python concepts be explained to absolute beginners?

    - by Tomaž Pisanski
    I am teaching Python to undergraduate math majors. I am interested in the optimal order in which students should be introduced to various Python concepts. In my view, at each stage the students should be able to solve a non-trivial programming problem using only the tools available at that time. Each new tool should enable a simpler solution to a familiar problem. A selection of numerous concepts available in Python is essential in order to keep students focused. They should also motivated and should appreciate each newly mastered tool without too much memorization. Here are some specific questions: For instance, my predecessor introduced lists before strings. I think the opposite is a better solution. Should function definitions be introduced at the very beginning or after mastering basic structured programming ideas, such as decisions (if) and loops (while)? Should sets be introduced before dictionaries? Is it better to introduce reading and writing files early in the course or should one use input and print for most of the course? Any suggestions with explanations are most welcome.

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  • transmit a java.lang.reflect.Proxy over a network

    - by panzi
    Is there a convenient way to transmit an object including its code (the class) over a network (not just the instance data)? Don't ask me why I want to do this. It's in an assignment. I asked several times if that is really what they meant and the didn't rephrase their answer so I guess they really want us to transmit code (not just the field data) over a network. To be honest I have no clue why we need a Proxy in this assignment anyway, just writing a simple class would do IMO. The assignment says that we should instantiate the proxy on the server and transmit it to the client (and yes, they talk about a java.lang.reflect.Proxy, they name this class). Because there is no class file for a proxy I can't deploy that. I guess I would have to somehow read out the bytecode of the generated Proxy, transmit it to the client and then load it. Which makes absolutely no sense at all, but this seems what they want us to do. I don't get why.

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  • Scala path dependent return type from parameter

    - by Rich Oliver
    In the following code using 2.10.0M3 in Eclipse plugin 2.1.0 for 2.10M3. I'm using the default setting which is targeting JVM 1.5 class GeomBase[T <: DTypes] { abstract class NewObjs { def newHex(gridR: GridBase, coodI: Cood): gridR.HexRT } class GridBase { selfGrid => type HexRT = HexG with T#HexTr def uniformRect (init: NewObjs) { val hexCood = Cood(2 ,2) val hex: HexRT = init.newHex(selfGrid, hexCood)// won't compile } } } Error message: Description Resource Path Location Type type mismatch; found: GeomBase.this.GridBase#HexG with T#HexTr required: GridBase.this.HexRT (which expands to) GridBase.this.HexG with T#HexTr GeomBase.scala Why does the compiler think the method returns the type projection GridBase#HexG when it should be this specific instance of GridBase? Edit transferred to a simpler code class in responce to comments now getting a different error message. package rStrat class TestClass { abstract class NewObjs { def newHex(gridR: GridBase): gridR.HexG } class GridBase { selfGrid => def uniformRect (init: NewObjs) { val hex: HexG = init.newHex(this) //error here } class HexG { val test12 = 5 } } } . Error line 11:Description Resource Path Location Type type mismatch; found : gridR.HexG required: GridBase.this.HexG possible cause: missing arguments for method or constructor TestClass.scala /SStrat/src/rStrat line 11 Scala Problem Update I've switched to 2.10.0M4 and updated the plug-in to the M4 version on a fresh version of Eclipse and switched to JVM 1.6 (and 1.7) but the problems are unchanged.

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  • Wrapper class that creates objects at runtime and stores data in an array.

    - by scriptingalias
    I tried making a wrapper class that encapsulates an object, a string (for naming and differentiating the object instance), and an array to store data. The problem I'm having now is accessing this class using methods that determine the "name" of the object and also reading the array containing some random variables. import java.util.Arrays; import java.util.Random; public class WrapperClass { String varName; Object varData; int[] array = new int[10]; public WrapperClass(String name, Object data, int[] ARRAY) { varName = name; varData = data; array = ARRAY; } public static void getvalues() { } public static void main(String[] args) { int[] array = new int[10]; Random random = new Random(3134234); for(int i = 0; i < 10; i++) { for (int c = 0; c < 10; c++) { array[c] = random.nextInt();//randomly creates data } WrapperClass w = new WrapperClass("c" + i, new Object(),array); } } }

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  • Conditional insert as a single database transaction in HSQLDB 1.8?

    - by Kevin Pauli
    I'm using a particular database table like a "Set" data structure, i.e., you can attempt to insert the same row several times, but it will only contain one instance. The primary key is a natural key. For example, I want the following series of operations to work fine, and result in only one row for Oklahoma: insert into states_visited (state_name) values ('Oklahoma'); insert into states_visited (state_name) values ('Texas'); insert into states_visited (state_name) values ('Oklahoma'); I am of course getting an error due to the duplicate primary key on subsequent inserts of the same value. Is there a way to make the insert conditional, so that these errors are not thrown? I.e. only do the the insert if the natural key does not already exist? I know I could do a where clause and a subquery to test for the row's existence first, but it seems that would be expensive. That's 2 physical operations for one logical "conditional insert" operation. Anything like this in SQL? FYI I am using HSQLDB 1.8

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