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  • Best Design for creating Historic Reports on GAE

    - by charming30
    My App requires Daily reports based on various user activities. My current design does not sum the daily totals in database, which means I must compute them everytime. For example A report that shows Top 100 users based on the number of submissions they have made on a given day. For such a report If I have 50,000 users, what is the best way to create daily report? How to create monthly and yearly report with such data? If this is not a good design, then how to deal with such design decision when the metrics of the report are not clear during db design and by the time it is clear we already have huge data with limited parameters (fields). Please advice.

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  • Java program runs smoothly in Netbeans but slowly in Eclipse and as an executed jar. WTF?

    - by comp sci balla
    A java program that does frequent swing/awt painting animation (but nothing more advanced than g.fillOval(...)) runs at a consistent 60fps in Netbeans, and at about 6fps when ran in Eclipse or executed as a jar file from a unix terminal. The program was developed in Netbeans and is run-of-the-mill desktop application (not webstart or japplet or ...). This is occurring in Ubuntu 10 with java 1.6. How is this possible? The universe no longer makes sense to me.

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  • Why are Java primitive types' modifiers `public`, `abstract`, & `final`?

    - by oconnor0
    In the process of doing some reflection on Java types, I came across an oddity that I do not understand. Inspecting int for its modifiers returns public, abstract, and final. I understand public and final, but the presence of abstract on a primitive type is non-obvious to me. Why is this the case? Edit: I am not reflecting on Integer but on int: import java.lang.reflect.Modifier; public class IntegerReflection { public static void main(final String[] args) { System.out.println(String.format("int.class == Integer.class -> %b", int.class == Integer.class)); System.out.println(String.format("int.class modifiers: %s", Modifier.toString(int.class.getModifiers()))); System.out.println(String.format("Integer.class modifiers: %s", Modifier.toString(Integer.class.getModifiers()))); } } The output when run: int.class == Integer.class -> false int.class modifiers: public abstract final Integer.class modifiers: public final

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  • How can I compress jpeg images in Java without losing any metadata in that image?

    - by guitarpoet
    I want compress jpeg files using Java. I do it like this: Read the image as BufferedImage Write the image to another file with compression rate. OK, that seems easy, but I find the ICC color profile and the EXIF information are gone in the new file and the DPI of the image is dropped from 240 to 72. It looks different from the origin image. I use a tool like preview in OS X. It can perfectly change the quality of the image without affecting other information. Can I done this in Java? At least keep the ICC color profile and let the image color look the same as the origin photo?

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  • How to assess the risk of a java version upgrade?

    - by Roy Tang
    I'm being asked to assess whether we can safely upgrade the java version on one of our production-deployed webapps. The codebase is fairly large and we want to avoid having to regression test everything (no automated tests sadly), but we've already encountered at least one problem during some manual testing (XmlStringReader.getLocalName now throws an IllegalStateExeption when it just used to return null) and higher-ups are pretty nervous about the upgrade. The current suggested approach is to do a source compare of the JDK sources for each version and assess those changes to see which ones might have impact, but it seems there's a lot of changes to go through (and as mentioned the codebase is kinda large). Is it safe and easier to just review the java version changes for each version? Or is there an easier way to conduct this assessment? Edit: I forgot to mention the version upgrade being considered is a minor version upgrade, i.e. 1.6.10 to 1.6.33

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  • Simple Java Sound Applet won't work!!! ARG!!!

    - by William
    import java.applet.*; /** * SoundApplet.java - a simple applet that plays the "gong.au" sound file. */ public class AppletGame extends Applet { public void init() { super.init(); resize(0,0); AudioClip gong = getAudioClip(getDocumentBase(), "test0.au"); gong.play(); } } In Eclipse applet viewer it loads and doesn't play sound. In html it doesn't load and says start not initalized. I've tried calling it outside of init, and all that someone help me!!!

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  • What are the latest options in Java logging frameworks?

    - by sanity
    This question gets asked periodically, but I've long felt that existing Java logging frameworks were overcomplicated and over-engineered, and I want to see what's new. I have a more critical issue on my current project as we've standardized on JSON as our human-readable data encoding, and most logging frameworks I've seen require XML. I would really rather avoid using JSON for 95% of my apps configuration, and XML for the rest just because of the logging framework (truth be told, I hate XML used for anything other than text markup, its original intended purpose). Are there any hot new Java logging frameworks that are actively maintained, reasonably powerful, have a maven repo, can be reconfigured without restarting your app, and don't tie you to XML?

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  • Whats the best to way convert a set of Java objects to another set of objects?

    - by HDave
    Basic Java question here from a real newbie. I have a set of Java objects (of class "MyClass") that implement a certain interface (Interface "MyIfc"). I have a set of these objects stored in a private variable in my class that is declared as follows: protected Set<MyClass> stuff = new HashSet<MyClass>(); I need to provide a public method that returns this set as a collection of objects of type "MyIfc". public Collection<MyIfc> getMyStuff() {...} How do I do the conversion? The following line gives me an error that it can't do the conversion. I would have guessed the compiler knew that objects of class MyClass implemented MyIfc and therefore would have handled it. Collection<MyIfc> newstuff = stuff; Any enlightenment is appreciated.

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  • Memory allocation patterns in C++

    - by Mahatma
    I am confused about the memory allocation in C++ in terms of the memory areas such as Const data area, Stack, Heap, Freestore, Heap and Global/Static area. I would like to understand the memory allocation pattern in the following snippet. Can anyone help me to understand this. If there any thing more apart from the variable types mentioned in the example to help understand the concept better please alter the example. class FooBar { int n; //Stored in stack? public: int pubVar; //stored in stack? void foo(int param) //param stored in stack { int *pp = new int; //int is allocated on heap. n = param; static int nStat; //Stored in static area of memory int nLoc; //stored in stack? string str = "mystring"; //stored in stack? .. if(CONDITION) { static int nSIf; //stored in static area of memory int loopvar; //stored in stack .. } } } int main(int) { Foobar bar; //bar stored in stack? or a part of it? Foobar *pBar; //pBar is stored in stack pBar = new Foobar(); //the object is created in heap? What part of the object is stored on heap } EDIT: What confuses me is, if pBar = new Foobar(); stores the object on the heap, how come int nLoc; and int pubVar;, that are components of the object stored on stack? Sounds contradictory to me. Shouldn't the lifetime of pubvar and pBar be the same?

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  • GAE JCache NumberFormatException, will I need to write Java to avoid?

    - by Jasper
    This code below produces a NumberFormatException in this line: val cache = cf.createCache(Collections.emptyMap()) Do you see any errors? Will I need to write a Java version to avoid this, or is there a Scala way? ... import java.util.Collections import net.sf.jsr107cache._ object QueryGenerator extends ServerResource { private val log = Logger.getLogger(classOf[QueryGenerator].getName) } class QueryGenerator extends ServerResource { def getCounter(cache:Cache):long = { if (cache.containsKey("counter")) { cache.get("counter").asInstanceOf[long] } else { 0l } } @Get("html") def getHtml(): Representation = { val cf = CacheManager.getInstance().getCacheFactory() val cache = cf.createCache(Collections.emptyMap()) val counter = getCounter(cache) cache.put("counter", counter + 1) val q = QueueFactory.getQueue("query-generator") q.add(TaskOptions.Builder.url("/tasks/query-generator").method(Method.GET).countdownMillis(1000L)) QueryGenerator.log.warning(counter.toString) new StringRepresentation("QueryGenerator started!", MediaType.TEXT_HTML) } } Thanks!

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  • java-maven2: How to include the a jar as depedency in pom so that I will be able to access test clas

    - by flavour-of-bru
    Hi, I have a set of functional jars(more than 3) that tests my source code. These jars just contains test classes and assisting asserter classes. I am creating a new performance jar that would import all the functional tests from these jars so that all can be run simultaneously. But when I include them as test dependencies in pom of current jar, what all I get to see is the classes in src/main/java. How can I include these functional jars as dependent jars so that I can also reference classes in src/test/java. In other words, how do I reference the test classes in other jars. In what way should I include the dependency as. Thanks for your support.

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  • Using Java, can I have one JVM spawn another, and then have the original one exit?

    - by CarlG
    I have a need to have a running JVM start another JVM and then exit. I'm currently trying to do this via Runtime.getRuntime().exec(). The other JVM starts, but my original JVM won't exit until the "child" JVM process stops. It appears that using Runtime.getRuntime().exec() creates a parent-child relationship between the processes. Is there some way to de-couple the spawned process so that the parent can die, or some other mechanism to spawn a process without any relationship to the creating process? Note that this seems exactly like this question: http://stackoverflow.com/questions/2566502/using-java-to-spawn-a-process-and-keep-it-running-after-parent-quits but the accepted answer there doesn't actually work, at least not on my system (Windows 7, Java 5 and 6). It seems that maybe this is a platform-dependent behavior. I'm looking for a platform independent way to reliably invoke the other process and let my original process die.

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  • Can you get the previous value of a variable in Java?

    - by The Special One
    Say way have a variable (let's say String Str) and the value of Str starts of as " " then as some code is running it is set to "test" then somewhere else in the code it is changed again to say "tester". Now in the program I want to find out what the previous value of Str was. Is this possible in Java? So I am saying that the variable gets changed twice, and you want to find out what Str was before it got changed for the second time. So in the example above the latest value of Str would be "tester" but I wanted to find out what Str was before this (assuming you had no idea what it was before it was changed to tester) in this case I would want to be able to find out that Str was "test". Is it at all possible to do this in Java?

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  • Make sure bad patterns don't come back after refactoring

    - by Let_Me_Be
    I'm refactoring an old C code. The code has absolutely no layered architecture (everything is being accessed by everything) and I'm trying to change that. I would like to cut direct access to structure members (at least write for now) and only allow access through access functions. Is there some tool (or perhaps directly the compiler) that could check this rule for me? I need this since I'm maintaining a fork and the upstream isn't very concerned with code quality.

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  • What is the equivalent of Java's .length for arrays in C#?

    - by Michael Loftus
    I'm new to C#, and I'm trying to convert this code from java into C#. static public double euclidean_2(double[] x, double[] y) { if (x.length != y.length) throw new RuntimeException("Arguments must have same number of dimensions."); double cumssq = 0.0; for (int i = 0; i < x.length; i++) cumssq += (x[i] - y[i]) * (x[i] - y[i]); return cumssq; } I know java uses .length but what is the equivalent in C# since I keep getting an error Thanks

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  • Is there any image converter through which I connect with java?

    - by Nitz
    Hey guys I had ask one question here but i don't get exactly as i want. So, now bcz of unsupported image in ImageIO, so i thought why don't I give other way to use it , by converting Unsupported images. So, is their any open-source image converter in java or is there any website or any tool , through which I can connect with my java application and then that tool or website convert my jpg image to jpg or png image and then store that image on some place. So that if their any image unsupported in ImageIO then also i can store that image by converting it. This whole process should be done automatically means user should not have to open that website or tool and convert it manually.

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  • How do I determine the video file size on youtube in Java?

    - by user1753343
    I am using the youtube-API to gather different information about videos. The only missing attribute until now is size. The API itself doesn't provide any functionality. I googled, but didn't found any solution. Indirect way My next idea was to get the path to the video-file itself and make a get-request. In the response-headers I could check for the file size. So I searched for "video / download / youtube / java". Some time ago youtube used get_video_info but this doesn't work today. I also found an application called JavaYoutubeDownloader but it seems VERY complicated for just getting the file size and it doesn't work either (just prints finish, without downloading anything). So is there a way to get the filesize of a video on youtube by using Java? If not, what would be a practical solution for this problem (a list of video_ids exists)?

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