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  • How do you access the value of an SQL count () query in a Java program

    - by Ankur
    I want to get to the value I am finding using the COUNT command of SQL. Normally I enter the column name I want to access into the getInt() getString() method, what do I do in this case when there is no specific column name. I have used 'AS' in the same manner as is used to alias a table, I am not sure if this is going to work, I would think not. Statement stmt3 = con.createStatement(); ResultSet rs3 = stmt3.executeQuery("SELECT COUNT(*) FROM "+lastTempTable+") AS count"); while(rs3.next()){ count = rs3.getInt("count"); }

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  • Authorization engine in java

    - by eltados
    In the course of my work i need to develop an authorization engine ( i'm already authenticated and i check access of a user to an action ) in order to store all the authorization logic inside a same place and be able to reuse it and i have created the mini library. http://github.com/eltados/canny what do you think about it? Is there any lightweight Authorization engine library i could have a look at?

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  • Well written open source java projects

    - by Algorist
    I want to improve my design and programming skills by understanding design & code of open source projects. I downloaded hadoop,groovy but they are very difficult to follow. I am not having a clue of how to follow this code without having a high level overview of the design. Any suggestions?? Thank you.

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  • Java BufferedReader behavior in CSV vs TXT file

    - by Gabriel
    If i try to read a CSV file called csv_file.csv. The problem is that when i read lines with BufferedReader.readLine() it skips the first line with months. But when i rename the file to csv_file.txt it reads it allright and it's not skipping the first line. Is there an undocumented "feature" of BufferedReader that i'm not aware? Example of file: Months, SEP2010, OCT2010, NOV2010 col1, col2, col3, col4, col5 aaa,,sdf,"12,456",bla bla bla, xsaffadfafda and so on, and so on, "10,00", xxx, xxx The code: FileInputStream stream = new FileInputStream(UploadSupport.TEMPORARY_FILES_PATH+fileName); BufferedReader br = new BufferedReader(new InputStreamReader(stream, "UTF-8")); String line = br.readLine(); String months[] = line.split(","); while ((line=br.readLine())!=null) { /*parse other lines*/ }

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  • List all files from a directory recursively with Java

    - by Hultner
    Okay I got this function who prints the name of all files in a directory recursively problem is that it's very slow and it gets the stuff from a network device and with my current code it has to access the device time after time. What I would want is to first load all the files from the directory recursively and then after that go through all files with the regex to filter out all the files I don't want. Unless anyone got a better suggestion. I've never before done anything like this. public static printFnames(String sDir){  File[] faFiles = new File(sDir).listFiles();  for(File file: faFiles){ if(file.getName().matches("^(.*?)")){   System.out.println(file.getAbsolutePath()); }   if(file.isDirectory()){     printFnames(file.getAbsolutePath());   }  } } This is just a test later on I'm not going to use the code like this, instead I'm going to add the path and modification date of every file which matches an advanced regex to an array.

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  • Java Beginner question about String[] args in the main method

    - by happysoul
    So I just tried excluding String[] args from the main method It compiled alright ! But JVM is showing an exception Why did it compile when String[] args HAS to be included every time ? What is going on here ? Why won't it show a compilation error ? typing this made me think that may be compiler did not see it as THE main method ..is that so ?

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  • Java serialization testing

    - by Jeff Storey
    Does anyone know if there is a library that exists to help test if an object graph is fully serializable? It would probably be as simple as writing it out and reading it back in, but I figured someone must have abstracted this already - I just can't find it.

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  • object construct a class of objects in java

    - by Mgccl
    There is a super class, A, and there are many subclasses, B,C,D... people can write more subclasses. Each of the class have the method dostuff(), each is different in some way. I want an object that constructs any object that belong to A or any of it's subclass. For example I can pass the name of the subclass, or a object of that class, and it will construct another object of the class. Of course I can write A construct(A var){ stuff = var.dostuff(); domorestuff(stuff) return new A(stuff); } B construct(B var){ stuff = var.dostuff(); domorestuff(stuff) return new B(stuff); } C construct(C var){ stuff = var.dostuff(); domorestuff(stuff) return new C(stuff); } but this is not efficient. I have to write a few new lines every time I make a new subclass. It seems I can't use generics either. Because I can't use dostuff() on objects not in any of the subclass of A. What should I do in this situation?

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  • Make Java parent class not part of the interface

    - by Bart van Heukelom
    (This is a hypothetical question for discussion, I have no actual problem). Say that I'm making an implementation of SortedSet by extending LinkedHashMap: class LinkedHashSortedMapThing extends LinkedHashMap implements SortedSet { ... } Now programmers who use this class may do LinkedHashMap x = new LinkedHashSortedMapThing(); But what if I consider the extending of LinkedHashMap an implementation detail, and do not want it to be a part of the class' contract? If people use the line above, I can no longer freely change this detail without worrying about breaking existing code. Is there any way to prevent this sort of thing, other than favouring composition over inheritance (which is not always possible due to private/protected members)?

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  • Java Web App: Passing form parameters across multiple pages

    - by digiarnie
    Hi, what is the best practice or best way of passing form parameters from page to page in a flow? If I have a flow where a user enters data in a form and hits next and repeats this process until they get to an approval page, what ways could I approach this problem to make the retention of data as simple as possible over the flow? I guess you could put all the information as you go in the session but could you get into memory issues if a lot of people are using your app and going through the flow at the same time?

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  • Ajax file uploading with java back end?

    - by Joren
    I don't want to use flash. I've found multiple jquery libraries that do this. Right now I'm using this one: http://demo.webdeveloperplus.com/ajax-file-upload/ The problem is they all use PHP. I tried just pointing it at my servlet instead of the PHP file, but it never gets called.

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  • Should I use Flash or Java?

    - by cable729
    I want to make some 2d games that I may want to submit to a game site, such as newgrounds.com. Even if I decide not to submit, I'd still like to know which is a better choice. Which has a faster startup time? Which performs faster in a 2d game? Which IDE should I use? Thanks in advance!

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  • java will this threading setup work or what can i be doing wrong

    - by Erik
    Im a bit unsure and have to get advice. I have the: public class MyApp extends JFrame{ And from there i do; MyServer = new MyServer (this); MyServer.execute(); MyServer is a: public class MyServer extends SwingWorker<String, Object> { MyServer is doing listen_socket.accept() in the doInBackground() and on connection it create a new class Connection implements Runnable { I have the belove DbHelper that are a singleton. It holds an Sqlite connected. Im initiating it in the above MyApp and passing references all the way in to my runnable: class Connection implements Runnable { My question is what will happen if there are two simultaneous read or `write? My thought here was the all methods in the singleton are synchronized and would put all calls in the queue waiting to get a lock on the synchronized method. Will this work or what can i change? public final class DbHelper { private boolean initalized = false; private String HomePath = ""; private File DBFile; private static final String SYSTEM_TABLE = "systemtable"; Connection con = null; private Statement stmt; private static final ContentProviderHelper instance = new ContentProviderHelper (); public static ContentProviderHelper getInstance() { return instance; } private DbHelper () { if (!initalized) { initDB(); initalized = true; } } private void initDB() { DBFile = locateDBFile(); try { Class.forName("org.sqlite.JDBC"); // create a database connection con = DriverManager.getConnection("jdbc:sqlite:J:/workspace/workComputer/user_ptpp"); } catch (SQLException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } private File locateDBFile() { File f = null; try{ HomePath = System.getProperty("user.dir"); System.out.println("HomePath: " + HomePath); f = new File(HomePath + "/user_ptpp"); if (f.canRead()) return f; else { boolean success = f.createNewFile(); if (success) { System.out.println("File did not exist and was created " + HomePath); // File did not exist and was created } else { System.out.println("File already exists " + HomePath); // File already exists } } } catch (IOException e) { System.out.println("Maybe try a new directory. " + HomePath); //Maybe try a new directory. } return f; } public String getHomePath() { return HomePath; } private synchronized String getDate(){ SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = new Date(); return dateFormat.format(date); } public synchronized String getSelectedSystemTableColumn( String column) { String query = "select "+ column + " from " + SYSTEM_TABLE ; try { stmt = con.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY); ResultSet rs = stmt.executeQuery(query); while (rs.next()) { String value = rs.getString(column); if(value == null || value == "") return ""; else return value; } } catch (SQLException e ) { e.printStackTrace(); return ""; } finally { } return ""; } }

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  • Java reading xml element without prefix but within the scope of a namespace

    - by wsxedc
    Functionally, the two blocks should be the same <soapenv:Body> <ns1:login xmlns:ns1="urn:soap.sof.com"> <userInfo> <username>superuser</username> <password>qapass</password> </userInfo> </ns1:login> </soapenv:Body> ----------------------- <soapenv:Body> <ns1:login xmlns:ns1="urn:soap.sof.com"> <ns1:userInfo> <ns1:username>superuser</ns1:username> <ns1:password>qapass</ns1:password> </ns1:userInfo> </ns1:login> </soapenv:Body> However, how when I read using AXIS2 and I have tested it with java6 as well, I am having a problem. MessageFactory factory = MessageFactory.newInstance(); SOAPMessage soapMsg = factory.createMessage(new MimeHeaders(), SimpleTest.class.getResourceAsStream("LoginSoap.xml")); SOAPBody body = soapMsg.getSOAPBody(); NodeList nodeList = body.getElementsByTagNameNS("urn:soap.sof.com", "login"); System.out.println("Try to get login element" + nodeList.getLength()); // I can get the login element Node item = nodeList.item(0); NodeList elementsByTagNameNS = ((Element)item).getElementsByTagNameNS("urn:soap.sof.com", "username"); System.out.println("try to get username element " + elementsByTagNameNS.getLength()); So if I replace the 2nd getElementsByTagNameNS with ((Element)item).getElementsByTagName("username");, I am able to get the username element. Doesn't username have ns1 namespace even though it doesn't have the prefix? Am I suppose to keep track of the namespace scope to read an element? Wouldn't it became nasty if my xml elements are many level deep? Is there a workaround where I can read the element in ns1 namespace without knowing whether a prefix is defined?

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  • Java Generic Type and Reflection

    - by Tom Tucker
    I have some tricky generic type problem involving reflection. Here's the code. public @interface MyConstraint { Class<? extends MyConstraintValidator<?>> validatedBy(); } public interface MyConstraintValidator<T extends Annotation> { void initialize(T annotation); } /** @param annotation is annotated with MyConstraint. */ public void run(Annotation annotation) { Class<? extends MyConstraintValidator<? extends Annotation>> validatorClass = annotation.annotationType().getAnnotation(MyConstraint.class).validatedBy(); validatorClass.newInstance().initialize(annotation) // will not compile! } The run() method above will not compile because of the following error. The method initialize(capture#10-of ? extends Annotation) in the type MyConstraintValidator<capture#10-of ? extends Annotation> is not applicable for the arguments (Annotation) If I remove the wild cards, then it compiles and works fine. What would be the propert way to declare the type parameter for the vairable validatorClass? Thanks.

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  • EhCache default cache in java

    - by user349302
    Hello I have this configuration for ehCache: <ehcache> <defaultCache name="defaut" maxElementsInMemory="5" eternal="false" timeToIdleSeconds="20" timeToLiveSeconds="20" overflowToDisk="false" diskPersistent="false" memoryStoreEvictionPolicy="LRU" /> </ehcache> How can I get access to default cache of EhCache? CacheManager.getInstance().getCache("default") - returns null thank you

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  • Java/Hibernate using interfaces over the entities.

    - by Dennetik
    I am using annoted Hibernate, and I'm wondering whether the following is possible. I have to set up a series of interfaces representing the objects that can be persisted, and an interface for the main database class containing several operations for persisting these objects (... an API for the database). Below that, I have to implement these interfaces, and persist them with Hibernate. So I'll have, for example: public interface Data { public String getSomeString(); public void setSomeString(String someString); } @Entity public class HbnData implements Data, Serializable { @Column(name = "some_string") private String someString; public String getSomeString() { return this.someString; } public void setSomeString(String someString) { this.someString = someString; } } Now, this works fine, sort of. The trouble comes when I want nested entities. The interface of what I'd want is easy enough: public interface HasData { public Data getSomeData(); public void setSomeData(Data someData); } But when I implement the class, I can follow the interface, as below, and get an error from Hibernate saying it doesn't know the class "Data". @Entity public class HbnHasData implements HasData, Serializable { @OneToOne(cascade = CascadeType.ALL) private Data someData; public Data getSomeData() { return this.someData; } public void setSomeData(Data someData) { this.someData = someData; } } The simple change would be to change the type from "Data" to "HbnData", but that would obviously break the interface implementation, and thus make the abstraction impossible. Can anyone explain to me how to implement this in a way that it will work with Hibernate?

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  • [java] Returning the element number of the longest string in an array

    - by JohnRoberts
    Hoookay, so. I'm trying to get the longestS method to take the user-inputted array of strings, then return the element number of the longest string in that array. I got it to the point where I was able to return the number of chars in the longest string, but I don't believe that will work for what I need. My problem is that I keep getting incompatible type errors when trying to figure this out. I don't understand the whole data type thing with strings yet. It's confusing me how I go about return a number of the array yet the array is of strings. The main method is fine, I got stuck on the ???? part. { public static void main(String [] args) { Scanner inp = new Scanner( System.in ); String [] responseArr= new String[4]; for (int i=0; i<4; i++) { System.out.println("Enter string "+(i+1)); responseArr[i] = inp.nextLine(); } int highest=longestS(responseArr); } public static int longestS(String[] values) { int largest=0 for( int i = 1; i < values.length; i++ ) { if ( ????? ) } return largest; } }

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  • Should I avoid using Java Label Statements?

    - by Kamikaze Mercenary
    Today I had a coworker suggest I refactor my code to use a label statement to control flow through 2 nested for loops I had created. I've never used them before because personally I think they decrease the readability of a program. I am willing to change my mind about using them if the argument is solid enough however. What are people's opinions on label statements?

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  • Java Thread - Memory consistency errors

    - by Yatendra Goel
    I was reading a Sun's tutorial on Concurrency. But I couldn't understand exactly what memory consistency errors are? I googled about that but didn't find any helpful tutorial or article about that. I know that this question is a subjective one, so you can provide me links to articles on the above topic. It would be great if you explain it with a simple example.

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  • Why are (almost) all the on-line games written in ActionScript (Flash) not Java?

    - by MasterPeter
    I absolutely love good defender games (e.g. Gemcraft, Protector: reclaiming the throne) as they can be intellectually quite challenging; it's like playing chess but a little less thinking a bit more action. Sadly, there are not that many good ones out there and I thought I would create one myself and share it with the rest of the world by making it available on-line. I have never worked with ActionScript but when it comes to on-line games, this is the main choice. I have tried to find a decent 2D game in the form of a Java applet but to no avail. Why is this so? I could write the game, most comfortably, in Delphi for Win32 but then people would need to download the executable, which could deter some form downloading it, and also it would only work on Windows. I am also familiar with Java, having worked with Java for the last four years or so. Although I don't have much experience with games programming. Should I note be deterred by the fact that all online games are written for in Flash and create my defender game as a Java applet, or should I consider learning ActionScript and games development for the ActionScript Virtual Machine (AS3 looks very much like Java... but still, it's an entirely new technology to me and I might never use it professionally.) Could you, please, just answer the the question in the title? Why Flash, not Java applets? Is it only 'politics'?

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