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  • problem in extending a class

    - by Vineeth
    there are two classes public class Account { public Acconut() { //constructor } } public class SavingsAccount extends Account { } while doing the inheritance i have got an error message "cannont find symbol Symbol: constructor Account()" what might be the error in my code...??

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  • Create a new log file every time my program is run

    - by Bernhard V
    Hi, I am using the Apache commons logging library and log4j to generate my log files. Now I want to create a new file every time I run my program. The current count should be appended to the log file's name. For example: program_1.log program_2.log program_3.log Do you know how I could achieve this?

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  • converting result set to list

    - by akshay
    how can i conver result set to list? i am using following code but its not working properly private List<User> convertToList(ResultSet rs) { List<User> userList = new ArrayList(); User user = new User(); try { while (rs.next()) { user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); user.setFname(rs.getString("fname")); user.setLname(rs.getString("lname")); user.setUsertype(rs.getInt("usertype")); user.setPasswd(rs.getString("passwd")); user.setEmail(rs.getString("email")); userList.add(user); } } catch (SQLException ex) { Logger.getLogger(UserDAO.class.getName()).log(Level.SEVERE, null, ex); } finally { closeConnection(); } return userList; }

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  • Auto injecting logger with guice

    - by koss
    With reference to Guice's custom injections article, its TypeListener performs a check for InjectLogger.class annotation - which can be optional. Removing that check will inject to all Logger.class types. class Log4JTypeListener implements TypeListener { public <T> void hear(TypeLiteral<T> typeLiteral, TypeEncounter<T> typeEncounter) { for (Field field : typeLiteral.getRawType().getDeclaredFields()) { if (field.getType() == Logger.class && field.isAnnotationPresent(InjectLogger.class)) { typeEncounter.register(new Log4JMembersInjector<T>(field)); } } } } I'm tempted to remove "&& field.isAnnotationPresent(InjectLogger.class)" from the listener. If we're using Guice to inject all instances of our Logger, is there any reason not to do it automatically (without need to annotate)?

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  • NullPointerException when adding to BigDecimal

    - by Dan
    String[] toppings = new String[10]; BigDecimal toppingsPrice = null; toppings[0] = req.getParameter("extraCheese"); toppings[1] = req.getParameter("moreTomatoes"); toppings[2] = req.getParameter("extraOnions"); // ... for(int i = 0; i < toppings.length; i++) { if(toppings[i] != null) { toppingsPrice.add(new BigDecimal("0.99")); // <-- NPE is caused here. toppingsPrice = toppingsPrice.setScale(2, BigDecimal.ROUND_HALF_EVEN); } } I am getting a NullPointerException in the above code when adding 0.99 to toppingsPrice. I am working with money values, so I have used BigDecimal. Is there something wrong with how I am adding the 0.99c price?

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  • Generate URL for File

    - by Don
    The default output of File.toURL() is file:/c:/foo/bar These don't appear to work on windows, and need to be changed to file:///c:/foo/bar Does the format file:/c:/foo/bar work correctly on Unix (I don't have a Unix machine to test on)? Is there a library that can take care of generating a URL from a File that is in the correct format for the current environment?

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  • Twitter4J - Looking up profile details without logging in

    - by wvd
    Hello all, I've been using Twitter4J for a quite a while now, but I can't seem to find this particular feature. I want to be able to search on a name, and when the certain user is on twitter, I want to retrieve basic information such as tweets, followers (like you can access via http) - but how to do is in Twitter4J? Neither the code examples or the source could help me. Thanks, William van Doorn

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  • Sleep a thread until an event is attended in another thread from a different class

    - by Afro Genius
    I have an application that fires 2 threads, the 1st launches another class to do some processing which in turn launches a 3rd class to do yet more processing. The 2nd thread in the main class should wait until some event in the 3rd class completes before it performs its job. How can this be achieved? I had tried implementing a wait/notify to share a lock object between the two threads but technically this will not work as I found the hard way. Can I share a lock between classes? Note, an instance of the 3rd class is declared in the 1st class and passed as parameter to the 2nd class. Also I tried creating boolean value in 3rd class that tells when event is complete then poll 2nd thread till this value is true. This worked but is not very desirable. Also is actionListner a better approach to this problem?

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  • Oval collision detection not working properly

    - by William
    So I'm trying to implement a test where a oval can connect with a circle, but it's not working. edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); and here is the full code (requires Slick2D): import org.newdawn.slick.AppGameContainer; import org.newdawn.slick.BasicGame; import org.newdawn.slick.Color; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Input; import org.newdawn.slick.SlickException; public class ColTest extends BasicGame{ float px = 50; float py = 50; float pheight = 50; float pwidth = 50; float bx = 200; float by = 200; float bsize = 200; float edist; float pspeed = 3; Input input; public ColTest() { super("ColTest"); } @Override public void init(GameContainer gc) throws SlickException { } @Override public void update(GameContainer gc, int delta) throws SlickException { input = gc.getInput(); try{ if(input.isKeyDown(Input.KEY_UP)) py-=pspeed; if(input.isKeyDown(Input.KEY_DOWN)) py+=pspeed; if(input.isKeyDown(Input.KEY_LEFT)) px-=pspeed; if(input.isKeyDown(Input.KEY_RIGHT)) px+=pspeed; } catch(Exception e){} } public void render(GameContainer gc, Graphics g) throws SlickException { g.setColor(new Color(255,255,255)); g.drawString("col: " + col(), 10, 10); g.drawString("edist: " + edist + " dist: " + dist, 10, 100); g.fillRect(px, py, pwidth, pheight); g.setColor(new Color(255,0,255)); g.fillOval(px, py, pwidth, pheight); g.setColor(new Color(255,255,255)); g.fillOval(200, 200, 200, 200); } public boolean col(){ edist = (float) Math.sqrt(Math.pow((px + ((pwidth/2) )) - (bx + (bsize/2)), 2) + Math.pow(-((py + ((pwidth/2)) ) - (bx + (bsize/2))), 2)); if(edist <= (bsize/2) + (px + (pwidth/2))) return true; else return false; } public float rotate(float x, float y, float ox, float oy, float a, boolean b) { float dst = (float) Math.sqrt(Math.pow(x-ox,2.0)+ Math.pow(y-oy,2.0)); float oa = (float) Math.atan2(y-oy,x-ox); if(b) return (float) Math.cos(oa + Math.toRadians(a))*dst+ox; else return (float) Math.sin(oa + Math.toRadians(a))*dst+oy; } public static void main(String[] args) throws SlickException { AppGameContainer app = new AppGameContainer( new ColTest() ); app.setShowFPS(false); app.setAlwaysRender(true); app.setTargetFrameRate(60); app.setDisplayMode(800, 600, false); app.start(); } }

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  • Hibernate Exception Fixed By Alt+Tab

    - by Lee Theobald
    Hi all, I've got a very curious problem in Hibernate that I would like some opinions on. In my code if I do the following: Go to page A Click a link on page A to be taken to page B Click on data item on page B Exception thrown I get an error telling me: failed to lazily initialize a collection of role: XYZ, no session or session was closed Fair enough. But when I do the same thing but add an alt+tab in the middle, everything is fine. E.g. Go to page A Click a link on page A to be taken to page B Hit ALt+Tab to switch to another application Hit ALt+Tab to switch back to the web browser Click on data item on page B Everything is fine. I'm a little confused as to how switching focus from my application makes it act as I want it to. Does anyone have any light to shine on the subject? I don't think it's a locking issue as even if I do the second set of steps quicker than the first, still no error. It's a Seam application using Hibernate 3.3.2.GA & 3.4.0.GA.

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  • Implementing Unowned relationship Google App Engine

    - by nwallman
    My question is more of a best practices question on how to implement unowned relationships with Google App Engine. I am using JDO to do my persistence and like recommended in the google docs I'm persisting my list of unowned relationships like so: @PersistenceCapable(identityType = IdentityType.APPLICATION) public class User implements Serializable, UserDetails { ... @Persistent private List<Key> groups; ... } Now I came across my predicament when I went to query that list of objects using they Key object. So when I get my list of group keys in order to actually return a list of Group objects I have to do a look up on that key to get the object. My question is what is the recommended way of doing a unowned look up on a model object? Should I have an instance of the PersistanceManagerFactory on my Model object so I can do a lookup? Should I have an instance of my GroupDAO object on my Model object so I can do a look up? Should I have a Utility to do this type of lookup? I'm new to this so I just want to know which is the best way to do this. Thanks.

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  • Hibernate is performing unwanted SELECTs on call to saveOrUpdate

    - by digiarnie
    Let's say I have a House entity which maps to many Person entities. I then load an existing House which has 20 occupants. beginTransaction(); House house = houseDao.find(1L); commitTransaction(); Later in the code, I can then add a new Person to the House: ... List<Person> people = house.getPeople(); people.add(new Person("Dilbert")); .... When I make the call: session.saveOrUpdate(house); Hibernate performs 21 queries: 1 to SELECT the House and 20 to SELECT each existing Person in the House. I'm sure it's a small issue on my part, however, what should I do so that I can add a new Person to the house without having such a heavy hit on the database in this situation? This is all done within the same session.

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  • Tomcat does not persist Session during restart

    - by mabuzer
    How to force Tomcat to serialize Session so that the user is kept logged in when Tomcat has restarted? Right now the user has to login again everytime. Added the following lines into web-app context.xml: <Manager className="org.apache.catalina.session.PersistentManager"> <Store className="org.apache.catalina.session.FileStore"/> </Manager> but still I see login page after Tomcat restart, I use Tomcat 6.0.24

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  • Whats wrong with this method?

    - by David
    Here's the method: public static String CPUcolor () { System.out.println ("What color am I?") ; String s = getIns() ; System.out.println ("are you sure I'm "+s+"? (Y/N)") ; String a = getIns() ; while (!((a.equals ("y")) || (a.equals ("Y")) || (a.equals ("n")) || (a.equals ("N")))) { System.out.println ("try again") ; a = getIns () ; } if (a.equals ("n") || a.equals("N")) {CPUcolor() ;} System.out.println ("I am "+s) ; return s ; } here is a possible output of this method (y's and n's are user inputs): What color am I? red are you sure I'm red? (Y/N) N What color am I? blue are you sure I'm blue? (Y/N) N What color am I? Yellow are you sure I'm Yellow? (Y/N) y I am Yellow I am blue I am red Why is it that the line's "I am blue" and "I am Blue" printed? Why are they printed in reverse order with red, the first entered, printed last?

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  • A member variable's hashCode() value is different

    - by Jacques René Mesrine
    There's a piece of code that looks like this. The problem is that during bootup, 2 initialization takes place. (1) Some method does a reflection on ForumRepository & performs a newInstance() purely to invoke #setCacheEngine. (2) Another method following that invokes #start(). I am noticing that the hashCode of the #cache member variable is different sometimes in some weird scenarios. Since only 1 piece of code invokes #setCacheEngine, how can the hashCode change during runtime (I am assuming that a different instance will have a different hashCode). Is there a bug here somewhere ? public class ForumRepository implements Cacheable { private static CacheEngine cache; private static ForumRepository instance; public void setCacheEngine(CacheEngine engine) { cache = engine; } public synchronized static void start() { instance = new ForumRepository(); } public synchronized static void addForum( ... ) { cache.add( .. ); System.out.println( cache.hashCode() ); // snipped } public synchronized static void getForum( ... ) { ... cache.get( .. ); System.out.println( cache.hashCode() ); // snipped } }

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  • Why baseclass calls method of subclass?

    - by twlkyao
    I encounter some code like the following: BaseClass: public class BaseClass { String name = "Base"; public BaseClass() { printName(); } public void printName() { System.out.println(name + "——Base"); } } DrivedClass: public class SubClass extends BaseClass { String name = "Sub"; public SubClass() { printName(); } public void printName() { System.out.println(name + "——Sub"); } public static void main(String[] args) { new SubClass(); } } When run the code, the output is: null——Sub Sub——Sub while it should be: Base——Base Sub——Sub I wonder why the BaseClass constructor calls the SubClass method, can anybody explain this? Thanks in advance.

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  • playing two streams on android

    - by Yanush
    Hello, I'm looking for a way (or at least to be pointed in the right direction) to play two streams of audio on android simultaneously but each on a different channel (e.g one in the speaker and one through the headphones) I'm not even sure its possible hardware wise. Any thoughts, clues ? Y

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