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  • Designing a class in such a way that it doesn't become a "God object"

    - by devoured elysium
    I'm designing an application that will allow me to draw some functions on a graphic. Each function will be drawn from a set of points that I will pass to this graphic class. There are different kinds of points, all inheriting from a MyPoint class. For some kind of points it will be just printing them on the screen as they are, others can be ignored, others added, so there is some kind of logic associated to them that can get complex. How to actually draw the graphic is not the main issue here. What bothers me is how to make the code logic such that this GraphicMaker class doesn't become the so called God-Object. It would be easy to make something like this: class GraphicMaker { ArrayList<Point> points = new ArrayList<Point>(); public void AddPoint(Point point) { points.add(point); } public void DoDrawing() { foreach (Point point in points) { if (point is PointA) { //some logic here else if (point is PointXYZ) { //...etc } } } } How would you do something like this? I have a feeling the correct way would be to put the drawing logic on each Point object (so each child class from Point would know how to draw itself) but two problems arise: There will be kinds of points that need to know all the other points that exist in the GraphicObject class to know how to draw themselves. I can make a lot of the methods/properties from the Graphic class public, so that all the points have a reference to the Graphic class and can make all their logic as they want, but isn't that a big price to pay for not wanting to have a God class?

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  • Counting down to zero in contrast to counting up to length - 1

    - by Helper Method
    Is it recommended to count in small loops (where possible) down from length - 1 to zero instead of counting up to length - 1? 1.) Counting down for (int i = a.length - 1; i >= 0; i--) { if (a[i] == key) return i; } 2.) Counting up for (int i = 0; i < a.length; i++) { if (a[i] == key) return i; } The first one is slightly faster that the second one (because comparing to zero is faster) but is a little more error-prone in my opinion. Besides, the first one could maybe not be optimized by future improvements of the JVM. Any ideas on that?

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  • Is it bad to have multiple return statements?

    - by scot
    Hi, I have a code somethg like below: int method(string a ,int b , int c){ if(cond1) return -1; if(cond2 || cond3) return 3; if(cond1 && cond2) return 0; else return -999; } Does it perform badly when compared to having multiple if else and have single return?

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  • hibernate for dynamic table creation

    - by user369316
    i AM A HIBERNATE BEGINNER ,Since i need to create dynamic tables with dynamic fields in them i chose to use hibernate . As far as my understanding , creating tables requires a class with the fields defined in the class . How do i generate the classes dynamically based on the table with the required fields ?

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  • 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?

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  • 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

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  • Hibernate: Querying objects by attributes of inherited classes

    - by MichaelD
    Hi all, I ran into a problem with Hibernate concerning queries on classes which use inheritance. Basically I've the following class hierarchy: @Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } The hierarchy is already given like this and I cannot change it easily. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes which sometimes even have the same names (but I can't move them to ClassA since there are possible more sub-classes which do not use them). The Recording class references one instance of one of this classes. Now my question: What I want to do is selecting all Recording objects in my database which refer to an instance of either ClassB1 or ClassB2 with e.g. the field P1300 == 15.5 (so this could be ClassB1 or ClassB2 instances since the P1300 attribute is declared in both classes). What I tried is something like this: Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); But since P1300 is not an attribute of ClassA hibernate throws an exception telling me: could not resolve property: P1300 of: ClassA How can I tell hibernate that it should search in all subclasses to find the attribute I want to filter? Thanks MichaelD

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  • Best way to implement refusing a value change by the user in Swing?

    - by Michael Borgwardt
    I have a JCheckBox that should not be checked by the user when a certain other field is empty. So now I want to have an error popup and then reset the checkbox (I've considered disabling the checkbox, but the connection to the other field is non-obvious, and a tooltip text IMO not visible enough). What's the correct way to do that in Swing? Through a PropertyVetoException? Where do I throw it and where do I catch it? My first (probably ugly) idea would be to add a ChangeListener that itself shows the popup and resets the value.

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  • Meta Search Engine Architecture

    - by Loki
    The question wasn't clear enough, I think; here's an updated straight to the point question: What are the common architectures used in building a meta search engine and is there any libraries available to build that type of search engine? I'm looking at building an "enterprise" type of search engine where the indexed data could be coming from proprietary (like Autonomy or a Google Box) or public search engines (like Google Web or Yahoo Web).

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  • ArrayBlockingQueue - How to "interrupt" a thread that is wating on .take() method

    - by bernhard
    I use an ArrayBlockingQueue in my code. Clients will wait untill an element becomes available: myBlockingQueue.take(); How can I "shutdown" my service in case no elements are present in the queue and the take() ist wating indefenitely for an element to become available? This method throws an InterruptedException. My question is, how can I "evoke" an Interrupted Exception so that take() will quit? (I also tought about notify(), but it seems I doesnt help here..) I know I could insert an special "EOF/QUIT" marker Element but is this really the only solution? UPDATE (regarding the comment, that points to another question with two solutions: one mentioned above using a "Poisoning Pill Object" and the second one is Thread.interrupt(): The myBlockingQueue.take() is used NOT in a Thread (extending Thread) but rather implements Runnable. It seems a Runnable does not provide the .interrupt() method? How could I interrupt the Runnable? Million Thanks Bernhard

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  • How to use LocalValueBean in jsp page.

    - by Himanshu
    I have set certain bean label and bean value in one of my dao class.. I have created a list of LocalValueBean objects and passed it as a list to jsp.. now here at jsp i need to print the label seperately and on hover to the label i need to show the value.. i need to exttract or to say get those values in jsp directly... i have also imported the org.apache.struts.util.LabelValueBean in my jsp but still its not working.. please let me know if you any ideas...

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  • Getting a variable out of a Public Void (Android)

    - by James Rattray
    I have this code: hubSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { final MediaPlayer mp2 = MediaPlayer.create(Textbox.this, R.raw.hero); mp2.start(); } public void onNothingSelected(AdapterView<?> parentView) { } }); (The code basically runs when a new item is selected of a spinner and then plays a song, -which later will be a variable based on what was picked, but i'm fine as it is for now) Problem: And I want to be able to use 'mp2' out of this public void, (I want a button which pauses it) How can I do this? Please explain/show... Thanks alot James

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  • how to know which special character is there in a file?

    - by Pangea
    My app needs to process text files during a batch process. Occassionally I receive a file with some special character at the end of the file. I am not sure what that special character is. Is there anyway I can find what that character is so that I can tell the other team which is producing that file. I have used mozilla's library to guess the file encoding and it says UTF-8.

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  • How to access a variable in other class?

    - by Christine
    Hi! I've problem regarding GUI with one Menu and one Order Class. I've created a variable to store how many items have been selected in the Menu Class. private int totalSelected; The var totalSelected is live updated. It can be changed anytime depending on actionPerformed() function.(Exp: totalSelected will add up all the selected items) In the Order Class, how can I access to the live update variable totalSelected in order to retrieve the live update value? When I invoke getTotalSelected() function inside the Menu Class, I will only obtain a 0 value. Thanks for your help ^^! Please allow me to specify my question clearer. public class MenuTab extends JPanel { private JLabel display; private int totalSelected; public MenuTab() { .... } } public getTotalSelected(){ return totalSelected; } private class SelectedListener implements ActionListener { public void actionPerformed() { ....... //Assume that totalSelected has been updated! display = new JLabel("Total: " + totalSelected); // OK to display totalSelected live value here. } } // A new class is the confirmation of order public class OrderConfirmedTab extends JPanel{ private JLabel displayTotal; private MenuTab order = new MenuTab(); public OrderConfirmedTab() { ...... int totalSelected = order.getTotalSelected(); displayTotal = new JLabel("Total: " + totalSelected); // Problem to display totalSelected live value here. // Will obtain 0; // How can I obtain the live updated value from class MenuTab? Thanks! } }

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  • How to move point on arc?

    - by bbZ
    I am writing an app that is simulating RobotArm movement. What I want to achieve, and where I have couple of problems is moving a Point on arc (180degree) that is arm range of movement. I am moving an arm by grabbing with mouse end of arm (Elbow, the Point I was talking about), robot can have multiple arms with diffrent arm lenghts. If u can help me with this part, I'd be grateful. This is what I have so far, drawing function: public void draw(Graphics graph) { Graphics2D g2d = (Graphics2D) graph.create(); graph.setColor(color); graph.fillOval(location.x - 4, location.y - 4, point.width, point.height); //Draws elbow if (parentLocation != null) { graph.setColor(Color.black); graph.drawLine(location.x, location.y, parentLocation.x, parentLocation.y); //Connects to parent if (arc == null) { angle = new Double(90 - getAngle(parentInitLocation)); arc = new Arc2D.Double(parentLocation.x - (parentDistance * 2 / 2), parentLocation.y - (parentDistance * 2 / 2), parentDistance * 2, parentDistance * 2, 90 - getAngle(parentInitLocation), 180, Arc2D.OPEN); //Draws an arc if not drawed yet. } else if (angle != null) //if parent is moved, angle is moved also { arc = new Arc2D.Double(parentLocation.x - (parentDistance * 2 / 2), parentLocation.y - (parentDistance * 2 / 2), parentDistance * 2, parentDistance * 2, angle, 180, Arc2D.OPEN); } g2d.draw(arc); } if (spacePanel.getElbows().size() > level + 1) {//updates all childElbows position updateChild(graph); } } I just do not know how to prevent moving Point moving outside of arc line. It can not be inside or outside arc, just on it. Here I wanted to put a screenshot, sadly I don't have enough rep. Am I allowed to put link to this? Maybe you got other ways how to achieve this kind of thing. Here is the image: Red circle is actual state, and green one is what I want to do. EDIT2: As requested, repo link: https://github.com/dspoko/RobotArm

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  • JVMTI: FollowReferences : how to skip Soft/Weak/Phantom references?

    - by Jayan
    I am writing a small code to detect number of objects left behind after certain actions in our tool. This uses FollowReferences() JVMTI-API. This counts instances reachable by all paths. How can I skip paths that included weak/soft/phantom reference? (IterateThroughHeap counts all objects at the moment, so the number is not fully reliable) Thanks, Jayan

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  • JAXB appending unneeded namespace declarations to tags

    - by jb
    I'm implementing a homebrew subprotocol of XMPP, and i'm using combination of StAX and JAXB for parsing/marshalling mesages. And when I marshall a message I end up with loads of unneded namespace declarations: <ns2:auth xmlns:ns2="urn:ietf:params:xml:ns:ilf-auth" xmlns:ns4="ilf:iq:experiment:power" xmlns:ns3="ilf:iq:experiment:init" xmlns:ns5="ilf:iq:experiment:values" xmlns:ns6="ilf:iq:experiment:result" xmlns:ns7="ilf:iq:experiment:stop" xmlns:ns8="ilf:iq:experiment:end"> compton@ilf</ns2:auth> instead of: <ns:auth xmlns:ns="urn:ietf:params:xml:ns:ilf-auth>compton@ilf</ns:auth> Is there any way to turn that of? All these namespaces are used in different messages that get marshalled/unmarshalled by JAXB, but every message uses one namespace. PS. I am not an XML expert please dont rant me if I did some stupid mistake ;)

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  • 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.

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  • 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

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  • ArrayList<Int> Collections.Sort and LineNumberReader Help How to

    - by user1819551
    I have a issue i can't get it to work now let going to the point a explain in the code thanks. This is my class: what I want to do is insert the Integers sort the list and buffer writer in a column with out coma. Now I getting this: [1110018, 1110032, 1110056, 1110059, 1110063, 1110085, 1110096, 1110123, 1110125, 1110185, 1110456, 1110459] I want like this: 111xxxxx 111xxxx xxxx....... I can't do it in single array, have to be in ArrayList. This is my collecting: list.addNumbers(numbers); list.display(); This is my writer: Is buffered coma.write("\n"+list.display()); coma.flush();<br/> Here is my class: public class IdCount {<br/> private ArrayList<Integer> properNumber = new ArrayList<>(); public void addNumbers(Integer numbers) { properNumber.add(numbers); Collections.sort(properNumber); } public String display() { //(I try .toString() Not work) return properNumber.toString(); } My second issue is LineNumberReader: This is my collecting and my writing: try { Reader input = new BufferedReader( new FileReader(inputFile)); try (Scanner in = new Scanner(input)) { while (in.hasNext()) { //(More Code) asp = new LineNumberReader(input); int rom = 0; while (asp.readLine()!=null){ rom++; } System.out.println(rom); coma.write(rom); This one will not write anything an my System Print give me only 12 0 in column.

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  • JTextField that has inner fields or preformated format, something like the ip field in windows

    - by dimitar
    Hello guys, i want to create a text field that will be for date and will have dd.mm.YYYY format. Now what i want to do is the user to type only the numbers, not the dots to. So the field would be like: _ _. _ _ . _ _ _ _ So when the user wants to type the date: 15.05.2010 for example, he will only type the numbers in the sequence 15052010. Also i would like, when he preses on left or right arrow, the cursor to go from one field(not JTextField, but field in the JTextField). So lets say i have JTextField with text in it: 15.05.2010, so if user is on the beginning and he preses right arrow, the cursor to go to the .05 field. I hope you understand me 'cos right now i don't any idea how to make this, or at least how to look for it on google. Thank you.

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  • How do you refactor a large messy codebase?

    - by Ricket
    I have a big mess of code. Admittedly, I wrote it myself - a year ago. It's not well commented but it's not very complicated either, so I can understand it -- just not well enough to know where to start as far as refactoring it. I violated every rule that I have read about over the past year. There are classes with multiple responsibilities, there are indirect accesses (I forget the technical term - something like foo.bar.doSomething()), and like I said it is not well commented. On top of that, it's the beginnings of a game, so the graphics is coupled with the data, or the places where I tried to decouple graphics and data, I made the data public in order for the graphics to be able to access the data it needs... It's a huge mess! Where do I start? How would you start on something like this? My current approach is to take variables and switch them to private and then refactor the pieces that break, but that doesn't seem to be enough. Please suggest other strategies for wading through this mess and turning it into something clean so that I can continue where I left off!

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