Search Results

Search found 41993 results on 1680 pages for 'java db'.

Page 850/1680 | < Previous Page | 846 847 848 849 850 851 852 853 854 855 856 857  | Next Page >

  • Inheritance or identifier

    - by Lina
    Hi! Does anyone here have opinions about when to user inheritance and when to use an identifier instead? Inheritance example: class Animal { public int Name { get; set; } } class Dog : Animal {} class Cat : Animal {} Identifier example: class Animal { public int Name { get; set; } public AnimalType { get; set; } } In what situations should i prefer which solution and what are the pros and cons for them? /Lina

    Read the article

  • Properly removing an Integer from a List<Integer>

    - by Yuval A
    Here's a nice pitfall I just encountered. Consider a list of integers: List<Integer> list = new ArrayList<Integer>(); list.add(5); list.add(6); list.add(7); list.add(1); Any educated guess on what happens when you execute list.remove(1)? What about list.remove(new Integer(1))? This can cause some nasty bugs. What is the proper way to differentiate between remove(int index), which removes an element from given index and remove(Object o), which removes an element by reference, when dealing with lists of integers? The main point to consider here is the one @Nikita mentioned - exact parameter matching takes precedence over auto-boxing.

    Read the article

  • JavaME - LWUIT images eat up all the memory

    - by Marko
    Hi, I'm writing a MIDlet using LWUIT and images seem to eat up incredible amounts of memory. All the images I use are PNGs and are packed inside the JAR file. I load them using the standard Image.createImage(URL) method. The application has a number of forms and each has a couple of labels an buttons, however I am fairly certain that only the active form is kept in memory (I know it isn't very trustworthy, but Runtime.freeMemory() seems to confirm this). The application has worked well in 240x320 resolution, but moving it to 480x640 and using appropriately larger images for UI started causing out of memory errors to show up. What the application does, among other things, is download remote images. The application seems to work fine until it gets to this point. After downloading a couple of PNGs and returning to the main menu, the out of memory error is encountered. Naturally, I looked into the amount of memory the main menu uses and it was pretty shocking. It's just two labels with images and four buttons. Each button has three images used for style.setIcon, setPressedIcon and setRolloverIcon. Images range in size from 15 to 25KB but removing two of the three images used for every button (so 8 images in total), Runtime.freeMemory() showed a stunning 1MB decrease in memory usage. The way I see it, I either have a whole lot of memory leaks (which I don't think I do, but memory leaks aren't exactly known to be easily tracked down), I am doing something terribly wrong with image handling or there's really no problem involved and I just need to scale down. If anyone has any insight to offer, I would greatly appreciate it.

    Read the article

  • Are there any reasons to make all fields and variables final?

    - by Roman
    In my current project I noticed that all class fields and variable inside methods are declared with final modifier whenever it's possible. Just like here: private final XMLStreamWriter _xmlStreamWriter; private final Marshaller _marshaller; private final OutputStream _documentStream; private final OutputStream _stylesStream; private final XMLStreamWriter _stylesStreamWriter; private final StyleMerger _styleMerger; public DocumentWriter(PhysicalPackage physicalPackage) throws IOException { final Package pkg = new Package(physicalPackage); final Part wordDocumentPart = pkg.createPart( "/word/document.xml", "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"); // styles.xml final Pair<Part, String> wordStylesPart = wordDocumentPart.createRelatedPart(...); ... } Are there any reasons to do so? p.s. As I know project is not supposed to be multithreaded (at least I've heard nothing about it).

    Read the article

  • How to add a jar build by a project to the project in eclipse?

    - by Xetius
    I have a project which as part of the build process creates an XMLBeans jar file (stbSchemas.jar) which I want to include and reference in this project. Is this the best way to go about this (Single project) or should I have a child project which is built from the parent project? I am building this using Maven2 inside Eclipse. Is there a better way to do this so that I can maintain the integrity of the projects and stability of the builds.

    Read the article

  • Bulding an multi-platform SWT application using Ant

    - by Mridang Agarwalla
    I'm writing an SWT application which can be used on Windows (32/64 bit) and Mac OSX (32/64 bit). Apart from the JRE I rely on the SWT library found here. I can find four versions of the SWT library depending upon my target platforms (as mentioned above). When building my application, how can I compile using the correct SWT Jar? If possible, I'd like to try and avoid hard-coding the Jar version, platform and architecture. The SWT Jars are named like this: swt-win32-x86_64.jar swt-win32-x86_32.jar swt-macosx-x86_32.jar swt-macosx-x86_64.jar (My project will be an open source project. I'd like people to be able to download the source and build it and therefore I've thought of including all the four versions of the SWT Jars in the source distribution. I hope this is the correct approach of publishing code relying on third-part libraries.) Thanks everyone.

    Read the article

  • What can cause my code to run slower when the server JIT is activated?

    - by durandai
    I am doing some optimizations on an MPEG decoder. To ensure my optimizations aren't breaking anything I have a test suite that benchmarks the entire codebase (both optimized and original) as well as verifying that they both produce identical results (basically just feeding a couple of different streams through the decoder and crc32 the outputs). When using the "-server" option with the Sun 1.6.0_18, the test suite runs about 12% slower on the optimized version after warmup (in comparison to the default "-client" setting), while the original codebase gains a good boost running about twice as fast as in client mode. While at first this seemed to be simply a warmup issue to me, I added a loop to repeat the entire test suite multiple times. Then execution times become constant for each pass starting at the 3rd iteration of the test, still the optimized version stays 12% slower than in the client mode. I am also pretty sure its not a garbage collection issue, since the code involves absolutely no object allocations after startup. The code consists mainly of some bit manipulation operations (stream decoding) and lots of basic floating math (generating PCM audio). The only JDK classes involved are ByteArrayInputStream (feeds the stream to the test and excluding disk IO from the tests) and CRC32 (to verify the result). I also observed the same behaviour with Sun JDK 1.7.0_b98 (only that ist 15% instead of 12% there). Oh, and the tests were all done on the same machine (single core) with no other applications running (WinXP). While there is some inevitable variation on the measured execution times (using System.nanoTime btw), the variation between different test runs with the same settings never exceeded 2%, usually less than 1% (after warmup), so I conclude the effect is real and not purely induced by the measuring mechanism/machine. Are there any known coding patterns that perform worse on the server JIT? Failing that, what options are available to "peek" under the hood and observe what the JIT is doing there?

    Read the article

  • Children in Enumeration

    - by marionmaiden
    Hello I have a enumeration for elements in a JTree When I find some specific element in this JTree, I want to check it's children. Do the method children() in a Enumeration check it's grandcildren too? For example, let's supose this JTree, considering the identation as new levels of the tree: Fruits apple grape orange peach pineapple strawberry banana If I get the children of grape, will I have just orange and peach or will I get peach children (pineaple) too?

    Read the article

  • KeyStore, HttpClient, and HTTPS: Can someone explain this code to me?

    - by stormin986
    I'm trying to understand what's going on in this code. KeyStore trustStore = KeyStore.getInstance(KeyStore.getDefaultType()); FileInputStream instream = new FileInputStream(new File("my.keystore")); try { trustStore.load(instream, "nopassword".toCharArray()); } finally { instream.close(); } SSLSocketFactory socketFactory = new SSLSocketFactory(trustStore); Scheme sch = new Scheme("https", socketFactory, 443); httpclient.getConnectionManager().getSchemeRegistry().register(sch); My Questions: trustStore.load(instream, "nopassword".toCharArray()); is doing what exactly? From reading the documentation load() will load KeyStore data from an input stream (which is just an empty file we just created), using some arbitrary "nopassword". Why not just load it with null as the InputStream parameter and an empty string as the password field? And then what is happening when this empty KeyStore is being passed to the SSLSocketFactory constructor? What's the result of such an operation? Or -- is this simply an example where in a real application you would have to actually put a reference to an existing keystore file / password?

    Read the article

  • OPTICS Clustering algorithm. How to get the best epsilon

    - by Marco Galassi
    I am implementing a project which needs to cluster geographical points. OPTICS algorithm seems to be a very nice solution. It needs just 2 parameters as input(MinPts and Epsilon), which are, respectively, the minimum number of points needed to consider them as a cluster, and the distance value used to compare if two points are in can be placed in same cluster. My problem is that, due to the extreme variety of the points, I can't set a fixed epsilon. Just look at the image below. The same points structure but in a different scale would result very different. Suppose to set MinPts=2 and epsilon = 1Km. On the left, the algorithm would create 2 clusters(red and blue), but on the right it would create one single cluster containing all of the points(red), but I would like to obtain 2 clusters even on the right. So my question is: is there any kind of way to calculate dynamically the epsilon value to get this result? Thank you very much and excuse my for my poor english. Marco

    Read the article

  • Prevent an Activity from being killed by the OS while starting a child activity

    - by Martin Marinov
    I have a main activity which calls a child one via Intent I = new Intent(this, Child.class); startActivityForResult(I, 0); But as soon as Child becomes visible the main activity gets its onStop and immediately after that onDestroy method triggered. And as soon as I call finish() within the Child activity or press the back button, the Child activity closes and the home screen shows (instead of the main activity). How can I prevent the main activity from being destroyed? :\

    Read the article

  • How to perform a non-polymorphic HQL query in Hibernate?

    - by Eli Acherkan
    Hi all, I'm using Hibernate 3.1.1, and in particular, I'm using HQL queries. According to the documentation, Hibernate's queries are polymorphic: A query like: from Cat as cat returns instances not only of Cat, but also of subclasses like DomesticCat. How can I query for instances of Cat, but not of any of its subclasses? I'd like to be able to do it without having to explicitly mention each subclass. I'm aware of the following options, and don't find them satisfactory: Manually filtering the instances after the query, OR: Manually adding a WHERE clause on the discriminator column. It would make sense for Hibernate to allow the user to decide whether a query should be polymorphic or not, but I can't find such an option. Thanks in advance!

    Read the article

  • how to handle result set data

    - by ashwani66476
    Hello All I am getting lacks of records in my Result Set. My concerns are : How Result Set handle these records internally? and How a programmer can handle those records in batches So that memory problem would not occur.? waiting for your answers .. Many Thanks

    Read the article

  • BigDecimal, division & MathContext - very strange behaviour

    - by blackliteon
    CentOs 5.4, OpenJDK Runtime Environment (build 1.6.0-b09) MathContext context = new MathContext(2, RoundingMode.FLOOR); BigDecimal total = new BigDecimal("200.0", context); BigDecimal goodPrice = total.divide(BigDecimal.valueOf(3), 2, RoundingMode.FLOOR); System.out.println("divided price=" + goodPrice.toPlainString()); // prints 66.66 BigDecimal goodPrice2 = total.divide(BigDecimal.valueOf(3), new MathContext(2, RoundingMode.FLOOR)); System.out.println("divided price2=" + goodPrice2.toPlainString()); // prints 66 BUG ?

    Read the article

  • JBoss RMI Transaction

    - by EasyName
    Hi, How can i can achieve remote transaction while using Remote EJB (over RMI/IIOP or RMI/JRMP). Is that JBoss 4.0 support this kind of transaction or should i use jotm or atomikos? Thanks in advance

    Read the article

  • Relation many-to-many with attributes : how ?

    - by mada
    Hi, Excuse me for my poor english in advance as it is not my mother tongue. Like in this example: http://www.xylax.net/hibernate/manytomany.html But i have in the table foo-bar 2 attributes which are not part of the primary or foreign keys.: one boolean(A) & one string(B). I know how to map it without attributes but not in this case. I have not found an answer in the documentation. I need to know please how to map it & what kind of collection i have to declare in my class Foo. Thanks in advance for your answer. I really appreciate the time given by you.

    Read the article

  • Tower of Hanoi, stop sliding

    - by ArtWorkAD
    Hi, I developed a solution for the Tower of Hanoi problem: public static void bewege(int h, char quelle, char ablage, char ziel) { if(h > 0){ bewege(h - 1, quelle, ziel, ablage); System.out.println("Move "+ h +" from " + quelle + " to " + ziel); bewege(h - 1, ablage, quelle, ziel); } } It works fine. Now i want to limit the number of slides and throw an exception if a certain limit is reached. I tried it with a counter but it does not work: class HanoiNK{ public static void main(String args[]){ Integer n = Integer.parseInt(args[0]); Integer k = Integer.parseInt(args[1]); try{ bewege(k, n, 'A', 'B', 'C'); }catch(Exception e){ System.out.println(e); } } public static void bewege(int c, int h, char quelle, char ablage, char ziel) throws Exception{ if(h > 0){ if(counter != 0){ bewege(c, h - 1, quelle, ziel, ablage); c--; System.out.println("Move "+ h +" from " + quelle + " to " + ziel); bewege(c, h - 1, ablage, quelle, ziel); c--; }else{ throw new Exception("stop sliding"); } } } } The exception is never thrown. Any ideas?

    Read the article

  • Is it possible to use flashvars with JBoss?

    - by Aikanaro
    Hi, I'm part of a team developing a product using JSF 2.0 and I was asked to investigate the possibility of including FusionCharts free in the app. I have tried different ways of inserting a simple chart in a JSF page but with no luck. On of the methods involves using the elements OBJECT and EMBED but hhen I try to use them I get a "null source" error from JBoss. From what I could find online (through Google), I am under the impression that 'flashvars' isn't quite compatible with JBoss. Is anyone here able to confirm this? If this is the case, what workaround would you suggest me? Other ways I also found online didn't show the chart not even an error message. Thanks in advance.

    Read the article

< Previous Page | 846 847 848 849 850 851 852 853 854 855 856 857  | Next Page >