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  • Image creation performance / image caching

    - by Kilnr
    Hello, I'm writing an application that has a scrollable image (used to display a map). The map background consists of several tiles (premade from a big JPG file), that I draw on a Graphics object. I also use a cache (Hashtable), to prevent from having to create every image when I need it. I don't keep everything in memory, because that would be too much. The problem is that when I'm scrolling through the map, and I need an image that wasn't cached, it takes about 60-80 ms to create it. Depending on screen resolution, tile size and scroll direction, this can occur multiple times in one scroll operation (for different tiles). In my case, it often happens that this needs to be done 4 times, which introduces a delay of more than 300 ms, which is extremely noticeable. The easiest thing for me would be that there's some way to speed up the creation of Images, but I guess that's just wishful thinking... Besides that, I suppose the most obvious thing to do is to load the tiles predictively (e.g. when scrolling to the right, precache the tiles to the right), but then I'm faced with the rather difficult task of thinking up a halfway decent algorithm for this. My actual question then is: how can I best do this predictive loading? Maybe I could offload the creation of images to a separate thread? Other things to consider? Thanks in advance.

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  • Correct usage of "<T extends SuperClass>"

    - by yusaku
    I am not familiar with "Generics". Is it a correct use of "<T extends SuperClass>" ? And do you agree that the codes after using generics are better? Before using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected void doProcessY(SubASample subASample) { // Nothing to do } protected void doProcessY(SubBSample subBSample) { // Nothing to do } } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected void doProcessY(SubASample subASample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } } After using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected abstract <T extends SuperSample> void doProcessY(T subSample); } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected <T extends SuperSample> void doProcessY(T subSample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } }

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  • how to test this portion of code

    - by Gandalf StormCrow
    Hello I'm writting junit test how can I test this method .. this is only part of this method : public MyClass{ public void myMethod(){ List<myObject> list = readData(); } } How will I make the test for this? ReadData is a private method inside MyClass?

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  • Hibernate Session flush behaviour [ and Spring @Transactional ]

    - by EugeneP
    I use Spring and Hibernate in a web-app, SessionFactory is injected into a DAO bean, and then this DAO is used in a Servlet through webservicecontext. DAO methods are transactional, inside one of the methods I use ... getCurrentSession().save(myObject); One servlet calls this method with an object passed. The update seems to not be flushed at once, it takes about 5 seconds to see the changes in the database. The servlet's method in which that DAO's update method is called, takes a fraction of second to complete. After the @Transactional method of DAO is completed, flushing may NOT happen ? It does not seem to be a rule [ I already see it ]. Then the question is this: what to do to force the session to flush after every DAO method? It may not be a good thing to do, but talking about a Service layer, some methods must end with immediate flush, and Hibernate Session behavior is not predictable. So what to do to guarantee that my @Transactional method persists all the changes after the last line of that method code? getCurrentSession().flush() is the only solution? p.s. I read somewhere that @Transactional IS ASSOCIATED with a DB Transaction. Method returns, transaction must be committed. I do not see this happens.

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  • Object reference case study

    - by Skogen
    When person 1 become partner with person 3, person 2 should no longer have person 1 as partner. How should I solve this? public class Person { private String name; private Person partner; public Person(String name){ this.name = name; } public void setPartner(Person partner){ this.partner = partner; partner.partner = this; } public static void main(String[] args) { Person one = new Person("1"); Person two = new Person("2"); Person three = new Person("3"); Person four = new Person("4"); one.setPartner(two); three.setPartner(four); one.setPartner(three); //Person two is still partner with person 1 }

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  • A hard Question ?

    - by the-ifl
    Hi Guys , I try To find a solution to a question .... we have a number , example : 20 ... and we have 6 number :{ a ,b , c , d , e , f} < 20 , t try to find all values of these numbers , but only if we can combinate (whit + or -) whit 2 of this numbers and getting all the value below to 20 : for example we choose 31 : a = 22 b = 21 c = 14 d = 11 e = 9 f = 5 we have : 22 - 21 = 1 ; 11 - 9 = 2 ; 14 - 11 = 3 ; 9 - 5 = 4 ; f = 5 ; 11 - 5 = 6 ; 21 - 14 = 7 ; .... .... .... .... .... 21 + 9 = 30 ; 9 + 22 = 31 ;

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  • how do you find the exact variable of a null pointer exception

    - by OVERTONE
    I've been at this one for a bit now. I've got a null pointer exception so im guessing somethings not been initialized. AdminMessages.inbox1.setText(messageRsetArray[0]); thats my code where its targetting. but i cant find what inside it hasnt been initiazed. AdminMessages is a class which contains a JTextField called inbox1, messageRsetArray is an array which has taken variables from an array. also inbox1 is static. i coulndt get the getters and setter to work. i know its bad practice though.

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  • create and insert values using mysql JDBC

    - by S.PRATHIBA
    Hi all, I have the sample code. public void UpdateTable1() { for(int t=0;t<20;t++) { if(consumer==1 && number==1 && provider1==31 && feedback==1) { try{ Class.forName(driverName); con = DriverManager.getConnection(url+dbName,"root","mysql"); try { Statement st = con.createStatement(); int val = st.executeUpdate("INSERT Consumer1 VALUES ("+31+","+"'Printer'"+", "+1+" "+")"); System.out.println("1 row affected"); } catch (SQLException s) { System.out.println("SQL statement is not executed!"); } con.close(); } I want to insert the same set of values(31,printer,1) into the table consumer2,consumer3.Is it possible without using another try catch statements...Please help me.

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  • what's the difference between DEFAULT_SIZE and PREFERRED_SIZE?

    - by CD1
    hi, I'm using Swing GroupLayout and I'm confused about the values GroupLayout.DEFAULT_SIZE and GroupLayout.PREFERRED_SIZE. I never know when to use each one of them in methods like GroupLayout.addComponent(Component, int, int, int). suppose I have this code: GroupLayout l = ...; l.setHorizontalGroup(l.createSequentialGroup() .addComponent(tf1) .addComponent(tf2)); l.setVerticalGroup(l.createParallelGroup() .addComponent(tf1) .addComponent(tf2)); there are two JTextFields on a single line laid out with GroupLayout (one sequential group horizontally and one parallel group vertically). if I resize the window now, both components get the available space (50% each). but I want only the first text field to grow/shrink horizontally and only the second text field to grow/shrink vertically. what values of min, pref and max should I use to accomplish that? I know I can just try it and see what combination works but I'd like to know the reasoning behind this problem.

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  • How to add response headers based on Content-type; getting Content-type before the response is commi

    - by Bozho
    I want to set the Expires header for all image/* and text/css. I'm doing this in a Filter. However: before calling chain.doFilter(..) the Content-type is not yet "realized" after calling chain.doFilter(..) the Content-type is set, but so is content-length, which forbids adding new headers (at least in Tomcat implementation) I can use the extensions of the requested resource, but since some of the css files are generated by richfaces by taking them from inside jar-files, the name of the file isn't x.css, but is /xx/yy/zz.xcss/DATB/.... So, is there a way to get the Content-type before the response is committed.

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  • How to deal with unknown entity references?

    - by Chris
    I'm parsing (a lot of) XML files that contain entity references which i dont know in advance (can't change that fact). For example: xml = "<tag>I'm content with &funny; &entity; &references;.</tag>" when i try to parse this using the following code: final DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); final DocumentBuilder db = dbf.newDocumentBuilder(); final InputSource is = new InputSource(new StringReader(xml)); final Document d = db.parse(is); i get the following exception: org.xml.sax.SAXParseException: The entity "funny" was referenced, but not declared. but, what i do want to achieve is, that the parser replaces every entity that is not declared (unknown to the parser) with an empty String ''. Or even better, is there a way to pass a map to the parser like: Map<String,String> entityMapping = ... entityMapping.put("funny","very"); entityMapping.put("entity","important"); entityMapping.put("references","stuff"); so that i could do the following: final DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); final DocumentBuilder db = dbf.newDocumentBuilder(); final InputSource is = new InputSource(new StringReader(xml)); db.setEntityResolver(entityMapping); final Document d = db.parse(is); if i would obtain the text from the document using this example code i should receive: I'm content with very important stuff. Any suggestions? Of course, i already would be happy to just replace the unknown entity's with empty strings. Thanks,

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  • When accessing ResultSets in JDBC, is there an elegant way to distinguish between nulls and actual z

    - by Uri
    When using JDBC and accessing primitive types via a result set, is there a more elegant way to deal with the null/0 than the following: int myInt = rs.getInt(columnNumber) if(rs.wasNull())? { // Treat as null } else { // Treat as 0 } I personally cringe whenever I see this sort of code. I fail to see why ResultSet was not defined to return the boxed integer types (except, perhaps, performance) or at least provide both. Bonus points if anyone can convince me that the current API design is great :) My solution was to write a wrapper that returns an Integer (I care more about elegance of client code than performance), but I'm wondering if I'm missing a better way to do this.

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  • output image is not displayed

    - by gerry chocolatos
    so, im doing an image detection which i have to process on each red, green, n blue element to get the edge map and combine them become one to show the output. but it doesnt show my output image would anyone pls be kind enough to help me? here is my code so far. //get the red element process_red = new int[width * height]; counter = 0; for(int i = 0; i < 256; i++) { for(int j = 0; j < 256; j++) { int clr = buff_red.getRGB(j, i); int red = (clr & 0x00ff0000) >> 16; red = (0xFF<<24)|(red<<16)|(red<<8)|red; process_red[counter] = red; counter++; } } //set threshold value for red element int threshold = 100; for (int x = 0; x < width; x++) { for (int y = 0; y < height; y++) { int bin = (buff_red.getRGB(x, y) & 0x000000ff); if (bin < threshold) bin = 0; else bin = 255; buff_red.setRGB(x,y, 0xff000000 | bin << 16 | bin << 8 | bin); } } and i do the same way for my green n blue elements. and then i wanted to get to combination of the three by doing it this way: //combine the three elements process_combine = new int[width * height]; counter = 0; for(int i = 0; i < 256; i++) { for(int j = 0; j < 256; j++) { int clr_a = buff_red.getRGB(j, i); int ar = clr_a & 0x000000ff; int clr_b = buff_green.getRGB(j, i); int bg = clr_b & 0x000000ff; int clr_c = buff_blue.getRGB(j, i); int cb = clr_b & 0x000000ff; int alpha = 0xff000000; int combine = alpha|(ar<<16)|(bg<<8)|cb; process_combine[counter] = combine; counter++; } } buff_rgb = new BufferedImage(width,height, BufferedImage.TYPE_INT_ARGB); Graphics rgb; rgb = buff_rgb.getGraphics(); rgb.drawImage(output_rgb, 0, 0, null); rgb.dispose(); repaint(); and to show the output whic is from the combining process, i use a draw method: g.drawImage(buff_rgb,800,100,this); but still it doesnt show the image. can anyone pls help me? ur help is really appreciated. thanks.

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  • Unsure how to modify userDetailsService to allow for custom userDetails but keep datasource

    - by adam2510
    what i am trying to do is i'm following this http://www.theserverside.com/tip/-Spring-Security-Customizing-Your-User-and-Authorization-in website to attempt to customise the UserDetails so i can retrieve more fields regarding to the user... as far as implementing the UserDetails, where i am confused is the UserDetailsService at the moment i only have the code for the userDetailsService that is in the website linked above i'm just not sure on how to go about doing it

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  • how to configure jetty 7 to use syslog or log4j

    - by egemen ozden
    I am looking for a way to direct all the jetty 7 logging to syslog. My current configuration dumps everything to JETTY_HOME/logs/.. After some initial ivestigation, it seems I should change JETTY_HOME/etc/jetty-logging.xml, but this does not look straightforward. It looks like I should create a new PrintStream implementation which sends its output to syslog and redirecting stderr and stdout to that class in jetty-logging.xml. any easier way to do that or to make jetty log directly to log4j ? Thanks

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  • Can we instantiate abstract class?

    - by satheesh.droid
    I don't understand whether we can instantiate abstract class by any means because I have read we can inherit the abstract class but in have found we can create an object by calling method of other class.For example LocationProvider is an abstract class but we can create object for the same by calling getProvider() function in LocationManager class. By the following code LocationManager lm=getSystemService(Context.LOCATION_PROVIDER) LocationProvider lp=lm.getProvider("gps");

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