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  • FileConnection Blackberry memory usage

    - by Dean
    Hello, I'm writing a blackberry application that reads ints and strings out of a database. This is my first time dealing with reading/writing on the blackberry, so forgive me if this is a dumb question. The database file I'm reading is only about 4kB I open the file with the following code fconn = (FileConnection) Connector.open("file_path_here", Connector.READ); if(fconn.exists()==false){fconn.close();return;} is = fconn.openDataInputStream(); while(!eof){ //etc... } is.close(); fconn.close(); The problem is, this code appears to be eating a LOT of memory. Using breakpoints and the "Memory Statistics" view, I determined the following: calling "Connector.open" creates 71 objects and changes "RAM Bytes in use" by 5376 calling "fconn.openDataInputStream();" increases RAM usage by a whopping 75920 Is this normal? Or am I doing something wrong? And how can I fix this? 75MB of RAM is a LOT of memory to waste on a handheld device, especially when the file I'm reading is only 4kB and I haven't even begun reading any data! How is this even possible?

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  • Is it a good idea to close and open hibernate sessions frequently?

    - by Gaurav
    Hi, I'm developing an application which requires that state of entities be read from a database at frequent intervals or triggers. However, once hibernate reads the state, it doesn't re-read it unless I explicitly close the session and read the entity in a new session. Is it a good idea to open a session everytime I want to read the entity and then close it afterwards? How much of an overhead does this put on the application and the database (we use a c3p0 connection pool also)? Will it be enough to simply evict the entity from the session before reading it again?

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  • what can cause large discrepancy between minor GC time and total pause time?

    - by cxcg
    We have a latency-sensitive application, and are experiencing some GC-related pauses we don't fully understand. We occasionally have a minor GC that results in application pause times that are much longer than the reported GC time itself. Here is an example log snippet: 485377.257: [GC 485378.857: [ParNew: 105845K-621K(118016K), 0.0028070 secs] 136492K-31374K(1035520K), 0.0028720 secs] [Times: user=0.01 sys=0.00, real=1.61 secs] Total time for which application threads were stopped: 1.6032830 seconds The total pause time here is orders of magnitude longer than the reported GC time. These are isolated and occasional events: the immediately preceding and succeeding minor GC events do not show this large discrepancy. The process is running on a dedicated machine, with lots of free memory, 8 cores, running Red Hat Enterprise Linux ES Release 4 Update 8 with kernel 2.6.9-89.0.1EL-smp. We have observed this with (32 bit) JVM versions 1.6.0_13 and 1.6.0_18. We are running with these flags: -server -ea -Xms512m -Xmx512m -XX:+UseConcMarkSweepGC -XX:NewSize=128m -XX:MaxNewSize=128m -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCApplicationStoppedTime -XX:-TraceClassUnloading Can anybody offer some explanation as to what might be going on here, and/or some avenues for further investigation?

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  • How can I add a .jar to my build path in Eclipse?

    - by Roman
    I try to do it the following way: Right click on the name of the project. Click on Build Path in the drop dawn menu. Click on "Configure Build Path" And then I do not know what to do. Should I select "Source", "Projects", "Libraries", "Order and Export"? In "Libraries" I have "Add JARs..." and "Add External JARs...". What should I select? (I have already a .jar file in the lib folder of my project.) ADDED: If I click on "Add JARs" in the "Libraries" tab, I see the "lib" sub-folder but if I go there I do not see my .jar file there (and I know that it is there).

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  • Is it possible to apply inheritance to a Singleton class?

    - by Bragaadeesh
    Hi, Today I faced one question in interview. Is it possible to apply inheritance concept on Singleton Classes. I said since the constructor is private, we cannot extend that Singleton class (can someone please validate this). Next thing he asked me is to apply inheritance on that Singleton class. So, I made the Singleton's constructor as protected thinking that child's constructor also has be protected. But I was wrong the child can have a modifier either equal to or higher than that. So, I asked him to give a real world example on such a case. He was not able to give me one and said that I cant ask questions and wanted me to tell whether this scenario is possible or not. I went kind of blank. My question here is, Is this possible? Even if its possible, what is the use of it? What real world scenario would demand such a use. Thanks

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  • How do you make sure your pakcet is delivered to right client using public ip address

    - by TemporaryNickName
    So private IP addresses are 192.168.00 ~ 192.168.255.255 or 10.0.0.0 or 172.16.0.0 ~ 172.31.255.255 If I accepted a client to my serversocket, I can get the client's remoteIp address by using socket.getremotesocketaddress(); But I suspect the IP address that I'm getting from this method is only the public IP address and it must have more than one client using same public IP as this one (one like you see when you go on to the website www.whatismyip.com). So if I want to make sure that my packet is delivered to the right person using some IP address or otherthing that uniquely identifies a person, what should I have to do?

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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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  • toString() Method question

    - by cdominguez13
    I've been working on this assignemnt here's code: public class Student { private String fname; private String lname; private String studentId; private double gpa; public Student(String studentFname,String studentLname,String stuId,double studentGpa) { fname = studentFname; lname = studentLname; studentId = stuId; gpa = studentGpa; } public double getGpa() { return gpa; } public String getStudentId() { return studentId; } public String getName() { return lname + ", " + fname; } public void setGpa(double gpaReplacement) { if (gpaReplacement >= 0.0 && gpaReplacement <= 4.0) gpa = gpaReplacement; else System.out.println("Invalid GPA! Please try again."); System.exit(0); } } Now I need to create a toString() method that returns a String formatted something like this: Name: Wilson, Mary Ann ID number: 12345 GPA: 3.5

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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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  • 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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  • 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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  • What is the fastest findByName query with hibernate?

    - by Karussell
    I am sure I can improve the performance of the following findByName query of hibernate: public List<User> findByName(String name) { session.createCriteria(User.class).add(Restrictions.eq("name", name)).list(); } In which way should I improve it or even more important: in which ways should I improve it first? I will need the full object with all the collections (layz or not) and deps of this class.

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  • prefix and postfix increments while comparing variables

    - by miatech
    could someone explain why this code output is not equals not equals 2 in the first if statement it seems that a = 0 b/c is a postfix increment; therefore a will not increase untile next line; however, the two a's are not equal why? and in the second if when I run the debugger the value of a is 2, but the test is false, why? public static void main (String[] args) { int a = 0; if (a++ == a++) { System.out.println("equals"); } else { System.out.println("not equals"); } if (++a == 2) { System.out.println("equals 2"); } else { System.out.println("not equals 2"); } }

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  • wifi disconnect event

    - by user986474
    when i get disconnect event by this code : public class WifiReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { String ssid="someSsidName"; ConnectivityManager conMan = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE); NetworkInfo netInfo = conMan.getActiveNetworkInfo(); WifiInfo wifiInfo = null; if (netInfo.getType() == ConnectivityManager.TYPE_WIFI) { //android connect to wifi } else{ //do somthing } } } i try to know what the ssid name when android disconnect. i mean when android disconnect from wifi i need to know it (this i can know by my code) but what i missing is the ssid name android just disconnect from. there is a way to do that? (i know i can save the name when android connect to wifi and use this name when disconnect but this not the way i want...) thanks in advance!

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  • issue of JSTL forEach iterate from arrayList

    - by Mickey
    In my code, I have used ArrayList which stores the number format like '$0.00 to $1,000,000.00' in each index of array list. while iterate in JSP through tag, its values are printing like $0.00 to $1 as a first string, 000 as a second string and 000.00 as a thrid string. but it has to print like '$0.00 to $1,000,000.00'. what will be the problem is? Thanks in advance

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  • Creating a fancy search bar with Swing components

    - by Kavon Farvardin
    I'm trying to come up with an elegant recreation of the search bar component in Thunderbird. The clear button doesn't appear until there is text in the box, so that screen-shot is a bit inaccurate. Should I use a layered pane and get some buttons to float above the box? (but then getting the text to not appear below the buttons would be hacky) Maybe just put buttons at the ends of the search bar and have it somehow blend in? Any ideas or maybe a style reconsideration is welcome, thank you.

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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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  • 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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  • 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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  • 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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