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  • Setup database for Unit tests with Spring, Hibernate and Spring Transaction Support

    - by Michael Bulla
    I want to test integration of dao-layer with my service-layer in a unit-test. So I need to setup some data in my database (hsql). For this setup I need an own transaction at the begining of my testcase to ensure that all my setup is really commited to database before starting my testcase. So here's what I want to achieve: // NotTranactional public void doTest { // transaction begins setup database // commit transaction service.doStuff() // doStuff is annotated @Transactional(propagation=Propagation.REQUIRED) } Here is my not working code: @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations={"/asynchUnit.xml"}) @DirtiesContext(classMode=ClassMode.AFTER_EACH_TEST_METHOD) public class ReceiptServiceTest implements ApplicationContextAware { @Autowired(required=true) private UserHome userHome; private ApplicationContext context; @Before @Transactional(propagation=Propagation.REQUIRED) public void init() throws Exception { User user = InitialCreator.createUser(); userHome.persist(user); } @Test public void testDoSomething() { ... } } Leading to this exception: org.hibernate.HibernateException: No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here at org.springframework.orm.hibernate3.SpringSessionContext.currentSession(SpringSessionContext.java:63) at org.hibernate.impl.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:687) at de.diandan.asynch.modell.GenericHome.getSession(GenericHome.java:40) at de.diandan.asynch.modell.GenericHome.persist(GenericHome.java:53) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:196) at $Proxy28.persist(Unknown Source) at de.diandan.asynch.service.ReceiptServiceTest.init(ReceiptServiceTest.java:63) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27) at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74) at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83) at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71) at org.junit.runners.ParentRunner.run(ParentRunner.java:236) at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) I dont know whats the right way to get the transaction around setup database. What I tried: @Before @Transactional(propagation=Propagation.REQUIRED) public void setup() { setup database } - Spring seems not to start transaction in @Before-annotated methods. Beyond that, thats not what I really want, cause there are a lot merhods in my testclass which needs a slightly differnt setup, so I need several of that init-methods. @Transactional(propagation=Propagation.REQUIRED) public void setup() { setup database } public void doTest { init(); service.doStuff() // doStuff is annotated @Transactional(propagation=Propagation.REQUIRED) } -- init seems not to get started in transaction What I dont want to do: public void doTest { // doing my own transaction-handling setup database // doing my own transaction-handling service.doStuff() // doStuff is annotated @Transactional(propagation=Propagation.REQUIRED) } -- start mixing springs transaction-handling and my own seems to get pain in the ass. @Transactional(propagation=Propagation.REQUIRED) public void doTest { setup database service.doStuff() } -- I want to test as real as possible situation, so my service should start with a clean session and no transaction opened So whats the right way to setup database for my testcase?

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  • java-COM interop: Implement COM interface in Java

    - by mdma
    How can I implement a vtable COM interface in java? In the old days, I'd use the Microsft JVM, which had built in java-COM interop. What's the equivalent for a modern JRE? Answers to a similar SO question proposed JACOB. I've looked at JACOB, but that is based on IDispatch, and is aimed at controlling Automation serers. The COM interfaces I need are custom vtable (extend IUnknown), e.g. IPersistStream, IOleWindow, IContextMenu etc. For my use case, I could implement all the COM specifics in JNI, and have the JNI layer call corresponding interfaces in java. But I'm hoping for a less painful solution. It's for an open source project, so open source alternatives are preferred.

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  • 3D Web Sites and Applications

    - by Scott Evernden
    I have for the last several years been struggling to understand why the Internet has so few actually useful 3D web applications. It's 2009 and still everything looks like pages from a Sears catalog. You can turn on your TV and find flying logos every night. After that you can get nostalgic and flip on ol' N-64 and play some Zelda or Mario Kart. On the PC, Sims 2 is approaching 6 years old already.. And then there's WoW. Current generation of users - the Facebook crowd, let's say - has ~no~ problem dealing with multi-dimensional environments.. And yet, nothing really immersive seems to happen on the web. I've been hearing about VRML and X3D for at least 10 years and ... pffft .. - nothing earth shaking going on there. Java 3D ? .. cool ! .. but ...... Still .... waiting and waiting. Do you think it will take a killer-web app before people become accustomed-to or will seek to use what could more more engaging web experiences? I am not talking about Second Life and other dedicated downloaded applications. I probably am more focused on apps like Lively or SceneCaster or Hangout or a half dozen others that are delivered 'painlessly' directly into web pages. My own particular interest is in the domain of virtual stores and immersive shopping. Its been a challenge trying to understand why an average user would not want to browse and wander a changing mall-space - like in the real world -- entertained by unexpected discovery. Is the 3D web always going to be 5 years in the future ?

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  • java util iterator but cannot import java.util.iterator

    - by qwertzuiop13
    Given this Code import java.util.Iterator; private static List<String> someList = new ArrayList<String>(); public static void main(String[] args) { someList.add("monkey"); someList.add("donkey"); //Code works when I change Iterator to java.util.Iterator, but import //is not possible? for(Iterator<String> i = someList.iterator(); i.hasNext(); ) { String item = i.next(); System.out.println(item); } } I receive the error: The type Iterator is not generic; it cannot be parameterized with arguments Eclipse tells me that the import java.util.iterator conflicts with a type defined in the same file. lol... ?

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  • Java tool to remove warnings from code developed in java 1.4

    - by Nitin Ware
    Hi All, I am working on a soucre code which was developed using java 1.4 but now we want to migrate it to java 6. I was able to compile it but there are tons of warnings related to use of java generics wherever we have made use of collections framework. It is possible to remove them by manually make changes to them, but I wanna know if is there any tool which can run on the source code and remove all the warnings by making necessary changes ot the code. Any help will be highly appreciated. Cheers, Nitin Ware

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  • MyClass cannot be cast to java.lang.Comparable: java.lang.ClassCastException

    - by user2234225
    I am doing a java project and I got this problem and don't know how to fix it. The classes in my project (simplified): public class Item { private String itemID; private Integer price; public Integer getPrice() { return this.price; } } public class Store { private String storeID; private String address; } public class Stock { private Item item; private Store store; private Integer itemCount; public Integer getInventoryValue() { return this.item.getPrice() * this.itemCount; } } Then I try to sort an ArrayList of Stock so I create another class called CompareByValue public class CompareByValue implements Comparator<Stock> { @Override public int compare(Stock stock1, Stock stock2) { return (stock1.getInventoryValue() - stock2.getInventoryValue()); } } When I try to run the program, it gives the error: Exception in thread "main" java.lang.ClassCastException: Stock cannot be cast to java.lang.Comparable Anyone know what's wrong?

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  • How to run java code using Java code?

    - by Nitz
    Hey Guys i want to do basically two things 1)I want to know is there any way that i can run the java code, using some java code. 2 ) and if it is possible then , and whatever the out put is then it should get that out put [ maybe output or error or exception ] and show on my screen, so i need to get that also. I know this is possible bcz one of my senior had done that..but i don't know how? May be with using the java's inbuilt classes. Note: user will write the code in some text file and then i will store that file content in some variable and then may be run that code.

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  • Java and gstreamer-java initialisation error

    - by Mark
    I am building a small app which will play streaming audio from the internet in java (mainly internet radio stations). I have decided to use the gstreamer-java library for the sound, which uses JNA. I would like to include a check in the code, to see whether the gstreamer library has been initialised. When I have left the "Gst.init()" code out (to mimic when the library has not been initialised correctly), the application throws out the following messages: (process:21888): GLib-GObject-CRITICAL **: /build/buildd/glib2.0-2.22.3/gobject/gtype.c:2458: initialization assertion failed, use IA__g_type_init() prior to this function (process:21888): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed The app calls the gstreamer-java library. The error messages appear but the thread continues to run, hogging the CPU. Is there any way to catch the error or to add a check to prevent it from happening? An alternative would be to put the "Gst.init()" in the main class, but I am not sure if this would always guarantee the gstreamer library is initialised.

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  • Reverse-projection 2D points into 3D

    - by ehsan baghaki
    Suppose we have a 3d Space with a plane on it with an arbitary equation : ax+by+cz+d=0 now suppose that we pick 3 random points on that plane: (x0,y0,z0) (x1,y1,z1) (x1,y1,z1) now i have a different point of view(camera) for this plane. i mean i have a different camera that will look at this plane from a different point of view. From that camera point of view these points have different locations. for example (x0,y0,z0) will be (x0',y0') and (x1,y1,z1) will be (x1',y1') and (x2,y2,z2) will be (x2',y2') from the new camera point of view. So here is my a little hard question! I want to pick a point for example (X,Y) from the new camera point of view and tell where it will be on that plane. All i know is that 3 points and their locations on 3d space and their projection locations on the new camera view. Do you know the coefficients of the plane-equation and the camera positions (along with the projection), or do you only have the six points? - Nils i know the location of first 3 points. therefore we can calculate the coefficients of the plane. so we know exactly where the plane is from (0,0,0) point of view. and then we have the camera that can only see the points! So the only thing that camera sees is 3 points and also it knows their locations in 3d space (and for sure their locations on 2d camera view plane). and after all i want to look at camera view, pick a point (for example (x1,y1)) and tell where is that point on that plane. (for sure this (X,Y,Z) point should fit on the plane equation). Also i know nothing about the camera location.

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  • Which way to go in Linux 3D programming?

    - by Tek
    I'm looking for some answers for a project I'm thinking of. I've searched and from what I understand (correct me if I'm wrong) the only way the program I want to make will work is through 3D application. Let me explain. I plan to make a studio production program but it's unique in the fact that I want to be able to make it fluid. Let me explain. Imagine Microsoft's Surface program where you're able to touch and drag pictures across the screen. Instead of pictures I want them to be sound samples (wavs,mp3,etc). Of course instead the input will be with the mouse but if I ever do finish the project I would totally add touch screen input compatibility! Anyway, I'm guessing there's "physics" to do with it which is why I'm thinking that even though it'll be a 2D application I'll need to code it in a 3D environment. Assuming that I'm correct in how I want to approach my project, where can I start learning about 3D programming? I actually come from PHP programming which will make C++ easier for me to learn. But I don't even know where to start. If I'm not wrong OpenGL is the most up to date API as far as I know. Anyway, please give me your insights guys. I could really use some guidance here since I could totally be wrong in everything that I wrote :)

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  • when to choose ruby on rails over java [closed]

    - by Dany Y
    I have been working with Java EE for 6 years, and I have mostly used it even for simple applications like data-entry to database). I heard Ruby on Rails is superior to Java in this domain. What are the actual advantages of Ruby. and should I switch ? P.S : I know this is a subjective question, and the most probable answer is "depends on what you'll use it for", but this is exactly what I want to know when to use what. Thank you

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  • Oracle Sun Java Roadshow

    - by Lajos Sárecz
    Jövo héten, május 20-án Oracle Sun Java Roadshow konferencia lesz Ramada Plaza Budapest Hotel helszínnel. Hogy jön ide a blog-ba egy Java konferencia kedvcsinálója? A tervezett program ismeretében talán már nem olyan meglepo. Ugyanis az egyik eloadás a közelmúltban megjelent Oracle Berkeley újdonságairól fog szólni. Bár az Oracle már 2006 februárjában felvásárolta a Berkeley DB-t, azóta Magyarországon nem volt olyan Oracle rendezvény, ahol érdemben szó esett volna róla, így mindenkit bíztatok, hogy ne hagyja ki ezt a lehetoséget.

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  • JavaOne 2012 - Java Generics

    - by Sharon Zakhour
    At JavaOne 2012, Venkat Subramaniam of Agile Developer, Inc, presented a conference session titled "The Good, The Bad, and the Ugly of Java Generics." Dr Subramaniam discussed the use of generics, what to watch out for when using generics, and best practices. To learn more about working with generics, see the Generics trail in the Java Tutorials. The trail was recently expanded and coverage added for the following topics: Generics, Inheritance, and Subtypes Guidelines for Wildcard Use Restrictions on Generics Wildcard Capture and Helper Methods Effects of Type Erasure and Bridge Methods

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  • Installed Sun Java 6 - configuration problem when running as sudo

    - by HorusKol
    I have install Sun Java 6 on an Ubuntu server and set an environment variable in the default profile as per the instructions at http://www.edugate.ie/workshop-guides/shibboleth-2-identity-provider-installation-linux-debian-or-ubuntu I then try to run an installer for a Java servlet - but when I run it as myself, it cannot create the required directory in /opt. When I run it as sudo, I am told that JAVA_HOME is not correct and it doesn't even start the installer - shouldn't this be coming from /etc/profile like it is for my normal user?

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  • Zombiewood for your Java ME tech-enabled Nokia C3

    - by hinkmond
    Zombies... Zoooombies... Here come the zombies in the new Zombiewood game for your Java ME technology-enabled Nokia C3. Watch the video to check it out. See: Zombiewood on Java ME Nokia C3 If you had two handguns and a couple sticks of dynamite, I'm sure you'd be looking to shoot zombies and collect giant floating gold coins spinning on the sidewalk. 'Cause that's what you do in that situation, right? Hinkmond

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  • ubuntu 12.10 can't find java, but it's exists!

    - by William
    I installed ZendStudio 5.5.1 on Ubuntu 12.04 and it runs well , no problem. Today, I download Ubuntu 12.10 and intalled it on my / but keep the /home partition. And now, I can't run the ZendStudio any more, it gives me this error: strings: '/lib/libc.so.6': No such file ./ZDE: 1714: exec: /home/william/Zend/ZendStudio-5.5.1/jre/bin/java: not found But the java file exist! What's wrong? Thanks!

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  • Custom Java Web Development vs Spreadsheet

    - by jacktrades
    Need some arguments why a small business should prefer a custom web developed solution using relational database (e.g. Java Servlet + MySQL) over standard Spreadsheet user programs like Excel. Specially now in these days that Office 365 is available in the cloud. As a Java programmer need good arguments to convince clients that this approach is better (if it really is) This is a generic situation, I understand that each case is different. Nevertheless answers so far has pinpointed right answers.

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  • Super constructor must be a first statement in Java constructor [closed]

    - by Val
    I know the answer: "we need rules to prevent shooting into your own foot". Ok, I make millions of programming mistakes every day. To be prevented, we need one simple rule: prohibit all JLS and do not use Java. If we explain everything by "not shooting your foot", this is reasonable. But there is not much reason is such reason. When I programmed in Delphy, I always wanted the compiler to check me if I read uninitializable. I have discovered myself that is is stupid to read uncertain variable because it leads unpredictable result and is errorenous obviously. By just looking at the code I could see if there is an error. I wished if compiler could do this job. It is also a reliable signal of programming error if function does not return any value. But I never wanted it do enforce me the super constructor first. Why? You say that constructors just initialize fields. Super fields are derived; extra fields are introduced. From the goal point of view, it does not matter in which order you initialize the variables. I have studied parallel architectures and can say that all the fields can even be assigned in parallel... What? Do you want to use the unitialized fields? Stupid people always want to take away our freedoms and break the JLS rules the God gives to us! Please, policeman, take away that person! Where do I say so? I'm just saying only about initializing/assigning, not using the fields. Java compiler already defends me from the mistake of accessing notinitialized. Some cases sneak but this example shows how this stupid rule does not save us from the read-accessing incompletely initialized in construction: public class BadSuper { String field; public String toString() { return "field = " + field; } public BadSuper(String val) { field = val; // yea, superfirst does not protect from accessing // inconstructed subclass fields. Subclass constr // must be called before super()! System.err.println(this); } } public class BadPost extends BadSuper { Object o; public BadPost(Object o) { super("str"); this. o = o; } public String toString() { // superconstructor will boom here, because o is not initialized! return super.toString() + ", obj = " + o.toString(); } public static void main(String[] args) { new BadSuper("test 1"); new BadPost(new Object()); } } It shows that actually, subfields have to be inilialized before the supreclass! Meantime, java requirement "saves" us from writing specializing the class by specializing what the super constructor argument is, public class MyKryo extends Kryo { class MyClassResolver extends DefaultClassResolver { public Registration register(Registration registration) { System.out.println(MyKryo.this.getDepth()); return super.register(registration); } } MyKryo() { // cannot instantiate MyClassResolver in super super(new MyClassResolver(), new MapReferenceResolver()); } } Try to make it compilable. It is always pain. Especially, when you cannot assign the argument later. Initialization order is not important for initialization in general. I could understand that you should not use super methods before initializing super. But, the requirement for super to be the first statement is different. It only saves you from the code that does useful things simply. I do not see how this adds safety. Actually, safety is degraded because we need to use ugly workarounds. Doing post-initialization, outside the constructors also degrades safety (otherwise, why do we need constructors?) and defeats the java final safety reenforcer. To conclude Reading not initialized is a bug. Initialization order is not important from the computer science point of view. Doing initalization or computations in different order is not a bug. Reenforcing read-access to not initialized is good but compilers fail to detect all such bugs Making super the first does not solve the problem as it "Prevents" shooting into right things but not into the foot It requires to invent workarounds, where, because of complexity of analysis, it is easier to shoot into the foot doing post-initialization outside the constructors degrades safety (otherwise, why do we need constructors?) and that degrade safety by defeating final access modifier When there was java forum alive, java bigots attecked me for these thoughts. Particularly, they dislaked that fields can be initialized in parallel, saying that natural development ensures correctness. When I replied that you could use an advanced engineering to create a human right away, without "developing" any ape first, and it still be an ape, they stopped to listen me. Cos modern technology cannot afford it. Ok, Take something simpler. How do you produce a Renault? Should you construct an Automobile first? No, you start by producing a Renault and, once completed, you'll see that this is an automobile. So, the requirement to produce fields in "natural order" is unnatural. In case of alarmclock or armchair, which are still chair and clock, you may need first develop the base (clock and chair) and then add extra. So, I can have examples where superfields must be initialized first and, oppositely, when they need to be initialized later. The order does not exist in advance. So, the compiler cannot be aware of the proper order. Only programmer/constructor knows is. Compiler should not take more responsibility and enforce the wrong order onto programmer. Saying that I cannot initialize some fields because I did not ininialized the others is like "you cannot initialize the thing because it is not initialized". This is a kind of argument we have. So, to conclude once more, the feature that "protects" me from doing things in simple and right way in order to enforce something that does not add noticeably to the bug elimination at that is a strongly negative thing and it pisses me off, altogether with the all the arguments to support it I've seen so far. It is "a conceptual question about software development" Should there be the requirement to call super() first or not. I do not know. If you do or have an idea, you have place to answer. I think that I have provided enough arguments against this feature. Lets appreciate the ones who benefit form it. Let it just be something more than simple abstract and stupid "write your own language" or "protection" kind of argument. Why do we need it in the language that I am going to develop?

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  • Java SE Embedded-Enabled Raspberry Pi Ice Bucket Challenge

    - by hinkmond
    Help fight ALS at: http://www.alsa.org/fight-als/ See: Java SE Embedded-Enabled Raspberry Pi Ice Bucket Challenge My Java SE Enabled Raspberry Pi accepts the nomination for the ALS Ice Bucket Challenge and I hereby nominate the Nest thermostat, the Fitbit fitness tracker, and Apple TV. Take the Ice Bucket Challenge. Help find the cure for ALS: http://www.alsa.org/fight-als/ice-bucket-challenge.html Hinkmond

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  • Need help drawings planets in Java.

    - by d33j
    I am looking for help/links/notes/agorithms/URLs/examples on drawing/rendering spheres in pure Java (so that I can hopefully, one day, generate/render planets with various surfaces & atmospheres) So for the moment, i'd be pretty happy to be able to start off with just drawing a wireframed sphere(s). ps: I don't want to use external libraries like Java3D, JOGL or aftermarket engines like JMonkeyEngine, Would rather keep it as straight Java.

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  • Java heap space

    - by java_mouse
    In Java/JVM, why do we call the memory place where Java creates objects as "Heap"? Does it use the Heap Data Structure to create/remove/maintain the objects? As I read in the documentation of Heap data structure, the algorithm compares the objects with existing nodes and places them in such a way that Parent object is "greater" than the children. ( Or "lesser" in case of min heap). So in JVM, how are the objects compared against each other before placing them in the heap?

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  • [JAVA]How to make my Oracle update/insert action through JAVA faster?

    - by gunbuster363
    [JAVA]How to make my Oracle update/insert action through JAVA faster? Hi everyone, I am facing a problem in my company that is - our program's speed is not fast enough. To be more specific, we are telecommunication company and this program handle call/internet serfing transaction made by every mobile phone users in our city. Because the amount of download content made by the iphone users is just too much, our program cannot handle them fast enough. The situation is, the amount of transaction made by users are double of the transaction processed by our program. Most of the running time of the program are dominated by DB transactions. I've search through the internet and browsed some sites ( for example: http://www.javaperformancetuning.com/tips/rawtips.shtml ) talking about java performace in DB, but I cannot find a suggestion suitable for us. these advices are not applicable/already used, for instance: 1)Use prepared statements. Use parametrized SQL Already used prepared statement. Each time will use different parameter by clear parameters and set parameters. 2)Tune the SQL to minimize the data returned (e.g. not 'SELECT *'). Sure, already used. 3)Use connection pooling. We hold a single connection during the program's execution. And I doubt that pooling cannot solve the problem because our program act as 1 user, so there are no problem for concurrent access to DB. If anyone of you think pooling is good, please tell me why. Thanks. 4)Try to combine queries and batch updates. Cannot do it. Every query/insert/update is depend on the database's information. For example, we look up the DB for the client's information, if we cannot find his usage, we insert the usage into DB, otherwise we do update. 5)Close resources (Connections, Statements, ResultSets) when finished Sure. 6)Select the fastest JDBC driver. I don't know. I've search on the internet about the type of driver available and I am very confused. We use oracle.jdbc.driver.OracleDriver and we use thin instead of oci, that's all I know. In addition, our program is a two-tier way ( java <- oracle ) 7)turn off auto-commit already done that. Looking forwards to any helps, thank you very much.

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  • Java GNOME bindings, are those a good idea?

    - by Phobia
    What do you think of Java's GNOME bindings and I was surprised to know that the latest version of the bindings was released this month and they're backed by a company that uses them, which means that there's a considerable amount of activity in the project, and that it's not going to be ditched anytime soon Is this going to be a second chance for Java on the desktop, since GTK+ is cross platform like swing, but less bloated and more responsive Should I be learning how to develop applications using it? or it's not worth the time?

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  • Instantiating objects in Java

    - by Davis Naglis
    I'm learning now Java from scratch and when I started to learn about instantiating objects, I don't understand - in which cases do I need to instantiate objects? For example I'm studying from TutsPlus course about it and there is example about "Rectangle" class. Instructor says that it needs to be instantiated. So I started to doubt about - when do I need to instantiate those objects when writing Java code?

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  • Why can't Java/C# implement RAII?

    - by mike30
    Question: Why can't Java/C# implement RAII? Clarification: I am aware the garbage collector is not deterministic. So with the current language features it is not possible for an object's Dispose() method to be called automatically on scope exit. But could such a deterministic feature be added? My understanding: I feel an implementation of RAII must satisfy two requirements: 1. The lifetime of a resource must be bound to a scope. 2. Implicit. The freeing of the resource must happen without an explicit statement by the programmer. Analogous to a garbage collector freeing memory without an explicit statement. The "implicitness" only needs to occur at point of use of the class. The class library creator must of course explicitly implement a destructor or Dispose() method. Java/C# satisfy point 1. In C# a resource implementing IDisposable can be bound to a "using" scope: void test() { using(Resource r = new Resource()) { r.foo(); }//resource released on scope exit } This does not satisfy point 2. The programmer must explicitly tie the object to a special "using" scope. Programmers can (and do) forget to explicitly tie the resource to a scope, creating a leak. In fact the "using" blocks are converted to try-finally-dispose() code by the compiler. It has the same explicit nature of the try-finally-dispose() pattern. Without an implicit release, the hook to a scope is syntactic sugar. void test() { //Programmer forgot (or was not aware of the need) to explicitly //bind Resource to a scope. Resource r = new Resource(); r.foo(); }//resource leaked!!! I think it is worth creating a language feature in Java/C# allowing special objects that are hooked to the stack via a smart-pointer. The feature would allow you to flag a class as scope-bound, so that it always is created with a hook to the stack. There could be a options for different for different types of smart pointers. class Resource - ScopeBound { /* class details */ void Dispose() { //free resource } } void test() { //class Resource was flagged as ScopeBound so the tie to the stack is implicit. Resource r = new Resource(); //r is a smart-pointer r.foo(); }//resource released on scope exit. I think implicitness is "worth it". Just as the implicitness of garbage collection is "worth it". Explicit using blocks are refreshing on the eyes, but offer no semantic advantage over try-finally-dispose(). Is it impractical to implement such a feature into the Java/C# languages? Could it be introduced without breaking old code?

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