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  • using eclipse to connect to remote machine[linux server] using ssh

    - by lalit
    Hi, I am searching out for solution to use any of the IDE's such as Netbeans/ eclipse to run .jsp and .java files from a remote machine using linux as the OS. The .java and .jsp files are on the server . So, an IDE which would let me access the server and let me update the files directly on the server would be great. I use SSH terminal to connect to the server to update and get files. Now, if there was an easier way to just have an access using IDE to the linux remote machine. that would be great. Please let me know regarding the same. Thank you very much for your time. Regards.

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  • If statements Evaluations

    - by user2464795
    Using the code below I get this result even though I put in a number that is greater than 18. run: How old are you? 21 You have not reached the age of Majority yet! BUILD SUCCESSFUL (total time: 3 seconds) I am new to java and trying to self learn can anybody help? import java.util.Scanner; public class Chapter8 { /** * @param args the command line arguments */ public static void main(String[] args) { Scanner reader = new Scanner (System.in); // TODO code application logic here //Excercise 15 System.out.print("How old are you? "); int x = Integer.parseInt(reader.nextLine()); if (x > 18){ System.out.println("You have not reached the age of Majority yet!"); }else { System.out.println("You have reached the age of Majority!"); }

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  • Tied up with injection implemented with setter functions

    - by puudeli
    Hi, I'm trying to use Scala as part of an existing Java application and now I run into an issue with dependencies injected with a setter method (no DI frameworks in this part of code). How is this handled in a Scala way? In Scala both val and var require to be initialized when declared but I can't do that, since the Java setters inject objects that implement a certain interface and interfaces are abstract and can not be instantiated. class ScalaLogic { var service // How to initialize? def setService (srv: OutputService) = { service = srv } Is there a way to initialize the var service so that I can later assign a dependency into it? It should be lexically scoped to be visible in the whole class.

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  • Proper Form Application Design

    - by Soo
    I'm creating a WinForm application in C# and one of its functions is displaying text in text boxes. I'm coding the logic for querying a database in a separate class and am unable to access the text box element in the class I'm creating (I'm getting a "name" does not exist in the current context error). Do I put all of my form logic into my Form1.cs file?

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  • Team activity/game for illustrating design in a SCRUM environment

    - by njreed.myopenid.com
    I'm looking for a team building / training activity for some of my scrum teams. I want something that really illustrates the flexibility that the team has when implementing stories to define the scope and complexity of the feature themselves. Most of the teams have long-term waterfall experience and are used to having a well-defined specification. I'm looking for something that illustrates the need for the team to vary the scope of what they are building themselves, dependent on the time and resources available. I couldn't find anything at tastycupcakes.com and Google wasn't much help. Maybe someone has prepared something themselves they would care to share?

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  • I need something to automate web browser tasks in its own virtual enviorment (Chrome)

    - by user1745926
    Ever since i started learning java i wanted to create a way to automate a few actions on a couple websites, For example, topline is a website that replaces all your ads with its own ads and pays you a bit of money for it, i want to emulate the act of just surfing the web, then start emulating specific tasks like clicking certain buttons or playing flash games (Actually playing the game by using image recognition) and this has to be written in java as i want to run this on a raspberry pi. any help is appreciated, is there a class that i can use? any help is appreciated!

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  • Why hashCode() returns the same value for a object in all consecutive executions?

    - by Vijay Shanker
    Hi, I am trying some code around object equality in java. As I have read somewhere hashCode() is a number which is generated by applying the hash function. Hash Function can be different for each object but can also be same. At the object level, it returns the memory address of the object. Now, I have sample program, which I run 10 times, consecutively. Every time i run the program I get the same value as hash code. If hashCode() function returns the memory location for the object, how come the java(JVM) store the object at same memory address in the consecutive runs? Can you please give me some insight and your view over this issue?

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  • convert char[] to String in btrace

    - by usovmv
    Hi folks! I'm profiling application with btrace (https://btrace.dev.java.net) and faced with limitation. I try to get a name of current java.lang.Thread. Normaly you can call getName() but it's forbidden in btrace-scripts (any calls exception BTraceUtils). Is there any idea how to get String from char[]. The original task is check if name of thread contains sub-string and only then log out tracing info (reducing output). thanks, Max.

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  • How to properly test for constraint violation in hibernate?

    - by Cesar
    I'm trying to test Hibernate mappings, specifically a unique constraint. My POJO is mapped as follows: <property name="name" type="string" unique="true" not-null="true" /> What I want to do is to test that I can't persist two entities with the same name: @Test(expected=ConstraintViolationException.class) public void testPersistTwoExpertiseAreasWithTheSameNameIsNotAllowed(){ ExpertiseArea ea = new ExpertiseArea("Design"); ExpertiseArea otherEA = new ExpertiseArea("Design"); ead.setSession(getSessionFactory().getCurrentSession()); ead.getSession().beginTransaction(); ead.makePersistent(ea); ead.makePersistent(otherEA); ead.getSession().getTransaction().commit(); } On commiting the current transaction, I can see in the logs that a ConstraintViolationException is thrown: 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,571 DEBUG SQL:111 - insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) Hibernate: insert into ExpertiseArea (VERSION, name, id) values (?, ?, ?) 16:08:47,572 WARN JDBCExceptionReporter:100 - SQL Error: -104, SQLState: 23505 16:08:47,572 ERROR JDBCExceptionReporter:101 - integrity constraint violation: unique constraint or index violation; SYS_CT_10036 table: EXPERTISEAREA 16:08:47,573 ERROR AbstractFlushingEventListener:324 - Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update So I would expect the test to pass, since the expected ConstraintViolationException is thrown. However, the test never completes (neither pass nor fails) and I have to manually kill the test runner. What's the correct way to test this?

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  • Creating a Custom EventAggregator Class

    - by Phil
    One thing I noticed about Microsoft's Composite Application Guidance is that the EventAggregator class is a little inflexible. I say that because getting a particular event from the EventAggregator involves identifying the event by its type like so: _eventAggregator.GetEvent<MyEventType>(); But what if you want different events of the same type? For example, if a developer wants to add a new event to his application of type CompositePresentationEvent<int>, he would have to create a new class that derives from CompositePresentationEvent<int> in a shared library somewhere just to keep it separate from any other events of the same type. In a large application, that's a lot of little two-line classes like the following: public class StuffHappenedEvent : CompositePresentationEvent<int> {} public class OtherStuffHappenedEvent : CompositePresentationEvent<int> {} I don't really like that approach. It almost feels dirty to me, partially because I don't want a million two-line event classes sitting around in my infrastructure dll. What if I designed my own simple event aggregator that identified events by an event ID rather than the event type? For example, I could have an enum such as the following: public enum EventId { StuffHappened, OtherStuffHappened, YetMoreStuffHappened } And my new event aggregator class could use the EventId enum (or a more general object) as a key to identify events in the following way: _eventAggregator.GetEvent<CompositePresentationEvent<int>>(EventId.StuffHappened); _eventAggregator.GetEvent<CompositePresentationEvent<int>>(EventId.OtherStuffHappened); Is this good design for the long run? One thing I noticed is that this reduces type safety. In a large application, is this really as important of a concern as I think it is? Do you think there could be a better alternative design?

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  • Static factory pattern with EJB3/JBoss

    - by purecharger
    I'm fairly new to EJBs and full blown application servers like JBoss, having written and worked with special purpose standalone Java applications for most of my career, with limited use of JEE. I'm wondering about the best way to adapt a commonly used design pattern to EJB3 and JBoss: the static factory pattern. In fact this is Item #1 in Joshua Bloch's Effective Java book (2nd edition) I'm currently working with the following factory: public class CredentialsProcessorFactory { private static final Log log = LogFactory.getLog(CredentialsProcessorFactory.class); private static Map<CredentialsType, CredentialsProcessor> PROCESSORS = new HashMap<CredentialsType, CredentialsProcessor>(); static { PROCESSORS.put(CredentialsType.CSV, new CSVCredentialsProcessor()); } private CredentialsProcessorFactory() {} public static CredentialsProcessor getProcessor(CredentialsType type) { CredentialsProcessor p = PROCESSORS.get(type); if(p == null) throw new IllegalArgumentException("No CredentialsProcessor registered for type " + type.toString()); return p; } However, in the implementation classes of CredentialsProcessor, I require injected resources such as a PersistenceContext, so I have made the CredentialsProcessor interface a @Local interface, and each of the impl's marked with @Stateless. Now I can look them up in JNDI and use the injected resources. But now I have a disconnect because I am not using the factory anymore. My first thought was to change the getProcessor(CredentialsType) method to do a JNDI lookup and return the SLSB instance that is required, but then I need to configure and pass the proper qualified JNDI name. Before I go down that path, I wanted to do more research on accepted practices. How is this design pattern treated in EJB3 / JEE?

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  • Looking for a lock-free RT-safe single-reader single-writer structure

    - by moala
    Hi, I'm looking for a lock-free design conforming to these requisites: a single writer writes into a structure and a single reader reads from this structure (this structure exists already and is safe for simultaneous read/write) but at some time, the structure needs to be changed by the writer, which then initialises, switches and writes into a new structure (of the same type but with new content) and at the next time the reader reads, it switches to this new structure (if the writer multiply switches to a new lock-free structure, the reader discards these structures, ignoring their data). The structures must be reused, i.e. no heap memory allocation/free is allowed during write/read/switch operation, for RT purposes. I have currently implemented a ringbuffer containing multiple instances of these structures; but this implementation suffers from the fact that when the writer has used all the structures present in the ringbuffer, there is no more place to change from structure... But the rest of the ringbuffer contains some data which don't have to be read by the reader but can't be re-used by the writer. As a consequence, the ringbuffer does not fit this purpose. Any idea (name or pseudo-implementation) of a lock-free design? Thanks for having considered this problem.

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  • How can I write good "research code"?

    - by John
    "Research code" is often held up as a paragon of what not to do when writing software. Certainly, the kind of code that often results from trying to solve a research problem can end up being poorly-designed, difficult to debug, etc. But my question is this: does research code have to be this way? Is it possible to write good research code? Is the only approach to consider the first version a poorly-written prototype to be discarded in favour of the better-designed second version? Software engineering has all sorts of best practices about how to design and write good code, but I don't usually find this relevant when you don't have a good idea ahead of time what the final system will look like. The final system is likely to be a result of what did or didn't work along the way, and the only way to determine what does or doesn't work is to write the code first. As you find things that don't work, you change what the final system looks like, moving further away from your original design (assuming you had one). I'd be interested in any personal experience with these issues, as well as any books or other resources anyone can point me to.

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  • Correctly use dependency injection

    - by Rune
    Me and two other colleagues are trying to understand how to best design a program. For example, I have an interface ISoda and multiple classes that implement that interface like Coke, Pepsi, DrPepper, etc.... My colleague is saying that it's best to put these items into a database like a key/value pair. For example: Key | Name -------------------------------------- Coke | my.namespace.Coke, MyAssembly Pepsi | my.namespace.Pepsi, MyAssembly DrPepper | my.namespace.DrPepper, MyAssembly ... then have XML configuration files that map the input to the correct key, query the database for the key, then create the object. I don't have any specific reasons, but I just feel that this is a bad design, but I don't know what to say or how to correctly argue against it. My second colleague is suggesting that we micro-manage each of these classes. So basically the input would go through a switch statement, something similiar to this: ISoda soda; switch (input) { case "Coke": soda = new Coke(); break; case "Pepsi": soda = new Pepsi(); break; case "DrPepper": soda = new DrPepper(); break; } This seems a little better to me, but I still think there is a better way to do it. I've been reading up on IoC containers the last few days and it seems like a good solution. However, I'm still very new to dependency injection and IoC containers, so I don't know how to correctly argue for it. Or maybe I'm the wrong one and there's a better way to do it? If so, can someone suggest a better method? What kind of arguments can I bring to the table to convince my colleagues to try another method? What are the pros/cons? Why should we do it one way? Unfortunately, my colleagues are very resistant to change so I'm trying to figure out how I can convince them.

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  • Programming tips for writing document editors?

    - by Tesserex
    I'm asking this because I'm in the process of writing two such editors for my Mega Man engine, one a tileset editor, and another a level editor. When I say document editor, I mean the superset application type for things like image editors and text editors. All of these share things like toolbars, menu options, and in the case of image editors, and my apps, tool panes. We all know there's tons of advice out there for interface design in these apps, but I'm wondering about programming advice. Specifically, I'm doubting my code designs with the following things: Many menu options toggle various behaviors. What's the proper way to reliably tie the checked state of the option with the status of the behavior? Sometimes it's more complicated, like options being disabled when there's no document loaded. More and more consensus seems to be against using MDI, but how should I control tool panes? For example, I can't figure out how to get the panels to minimize and maximize along with the main window, like Photoshop does. When tool panels are responsible for a particular part of the document, who actually owns that thing? The main window, or the panel class? How do you do communication between the tool panels and the main window? Currently mine is all event based but it seems like there could be a better way. This seems to be a common class of gui application, but I've never seen specific pointers on code design for them. Could you please offer whatever advice or experience you have for writing them?

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  • What should every developer know about databases?

    - by Aaronaught
    Whether we like it or not, many if not most of us developers either regularly work with databases or may have to work with one someday. And considering the amount of misuse and abuse in the wild, and the volume of database-related questions that come up every day, it's fair to say that there are certain concepts that developers should know - even if they don't design or work with databases today. So: What are the important concepts that developers and other software professionals ought to know about databases? Guidelines for Responses: Keep your list short. One concept per answer is best. Be specific. "Data modelling" may be an important skill, but what does that mean precisely? Explain your rationale. Why is your concept important? Don't just say "use indexes." Don't fall into "best practices." Convince your audience to go learn more. Upvote answers you agree with. Read other people's answers first. One high-ranked answer is a more effective statement than two low-ranked ones. If you have more to add, either add a comment or reference the original. Don't downvote something just because it doesn't apply to you personally. We all work in different domains. The objective here is to provide direction for database novices to gain a well-founded, well-rounded understanding of database design and database-driven development, not to compete for the title of most-important.

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  • List of objects or parallel arrays of properties?

    - by Headcrab
    The question is, basically: what would be more preferable, both performance-wise and design-wise - to have a list of objects of a Python class or to have several lists of numerical properties? I am writing some sort of a scientific simulation which involves a rather large system of interacting particles. For simplicity, let's say we have a set of balls bouncing inside a box so each ball has a number of numerical properties, like x-y-z-coordinates, diameter, mass, velocity vector and so on. How to store the system better? Two major options I can think of are: to make a class "Ball" with those properties and some methods, then store a list of objects of the class, e. g. [b1, b2, b3, ...bn, ...], where for each bn we can access bn.x, bn.y, bn.mass and so on; to make an array of numbers for each property, then for each i-th "ball" we can access it's 'x' coordinate as xs[i], 'y' coordinate as ys[i], 'mass' as masses[i] and so on; To me it seems that the first option represents a better design. The second option looks somewhat uglier, but might be better in terms of performance, and it could be easier to use it with numpy and scipy, which I try to use as much as I can. I am still not sure if Python will be fast enough, so it may be necessary to rewrite it in C++ or something, after initial prototyping in Python. Would the choice of data representation be different for C/C++? What about a hybrid approach, e.g. Python with C++ extension?

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