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  • Encountering NullPointerException when trying to add polynoms

    - by Ayler Cruz
    I need to add two polynomials, which is composed of two ints. For example, the coefficient and the exponent 3x^2 would be constructed using 3 and 2 as parameters. I am getting a NullPointerException but I can't figure out why. Any help would be appreciated! public class Polynomial { private Node poly; public Polynomial() { } private Polynomial(Node p) { poly = p; } private class Term { int coefficient; int exponent; private Term(int coefficient, int exponent) { this.coefficient = coefficient; this.exponent = exponent; } } private class Node { private Term data; private Node next; private Node(Term data, Node next) { this.data = data; this.next = next; } } public void addTerm(int coeff, int exp) { Node pointer = poly; if (pointer.next == null) { poly.next = new Node(new Term(coeff, exp), null); } else { while (pointer.next != null) { if (pointer.next.data.exponent < exp) { Node temp = new Node(new Term(coeff, exp), pointer.next.next); pointer.next = temp; return; } pointer = pointer.next; } pointer.next = new Node(new Term(coeff, exp), null); } } public Polynomial polyAdd(Polynomial p) { return new Polynomial(polyAdd(this.poly, p.poly)); } private Node polyAdd(Node p1, Node p2) { if (p1 == p2) { Term adding = new Term(p1.data.coefficient + p2.data.coefficient, p1.data.exponent); p1 = p1.next; p2 = p2.next; return new Node(adding, null); } if (p1.data.exponent > p2.data.exponent) { p2 = p2.next; } if (p1.data.exponent < p2.data.exponent) { p1 = p1.next; } if (p1.next != null && p2.next != null) { return polyAdd(p1, p2); } return new Node(null, null); } }

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  • org.apache.commons.httpclient.NameValuePair in post method

    - by pushkins
    I'm writing some code like : PostMethod p = new PostMethod(someurl); ... NameValuePair[] data = { new NameValuePair("name1", "somevalue1"), new NameValuePair("var[3][1]", "10") }; try { hc.executeMethod(p); } ... And that's what I get, when I look at my post in Wireshark: POST /someurl HTTP/1.1 ... type=var&ship%5B3%5D%5B1%5D=10 %5B means [, %5D- ] So the problem is how I can get square brackets in my post?

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  • Collision problems with drag-n-drop puzzle game.

    - by Amplify91
    I am working on an Android game similar to the Rush Hour/Traffic Jam/Blocked puzzle games. The board is a square containing rectangular pieces. Long pieces may only move horizontally, and tall pieces may only move vertically. The object is to free the red piece and move it out of the board. This game is only my second ever programming project in any language, so any tips or best practices would be appreciated along with your answer. I have a class for the game pieces called Pieces that describes how they are sized and drawn to the screen, gives them drag-and-drop functionality, and detects and handles collisions. I then have an activity class called GameView which creates my layout and creates Pieces objects to add to a RelativeLayout called Board. I have considered making Board its own class, but haven't needed to yet. Here's what my work in progress looks like: My Question: Most of this works perfectly fine except for my collision handling. It seems to be detecting collisions well but instead of pushing the pieces outside of each other when there is a collision, it frantically snaps back and forth between (what seems to be) where the piece is being dragged to and where it should be. It looks something like this: Another oddity: when the dragged piece collides with a piece to its left, the collision handling seems to work perfectly. Only piece above, below, and to the right cause problems. Here's the collision code: @Override public boolean onTouchEvent(MotionEvent event){ float eventX = event.getX(); float eventY = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: //check if touch is on piece if (eventX > x && eventX < (x+width) && eventY > y && eventY < (y+height)){ initialX=x; initialY=y; break; }else{ return false; } case MotionEvent.ACTION_MOVE: //determine if piece should move horizontally or vertically if(width>height){ for (Pieces piece : aPieces) { //if object equals itself in array, skip to next object if(piece==this){ continue; } //if next to another piece, //do not allow to move any further towards said piece if(eventX<x&&(x==piece.right+1)){ return false; }else if(eventX>x&&(x==piece.x-width-1)){ return false; } //move normally if no collision //if collision, do not allow to move through other piece if(collides(this,piece)==false){ x = (eventX-(width/2)); }else if(collidesLeft(this,piece)){ x = piece.right+1; break; }else if(collidesRight(this,piece)){ x = piece.x-width-1; break; } } break; }else if(height>width){ for (Pieces piece : aPieces) { if(piece==this){ continue; }else if(collides(this,piece)==false){ y = (eventY-(height/2)); }else if(collidesUp(this,piece)){ y = piece.bottom+1; break; }else if(collidesDown(this,piece)){ y = piece.y-height-1; break; } } } invalidate(); break; case MotionEvent.ACTION_UP: // end move if(this.moves()){ GameView.counter++; } initialX=x; initialY=y; break; } // parse puzzle invalidate(); return true; } This takes place during onDraw: width = sizedBitmap.getWidth(); height = sizedBitmap.getHeight(); right = x+width; bottom = y+height; My collision-test methods look like this with different math for each: private boolean collidesDown(Pieces piece1, Pieces piece2){ float x1 = piece1.x; float y1 = piece1.y; float r1 = piece1.right; float b1 = piece1.bottom; float x2 = piece2.x; float y2 = piece2.y; float r2 = piece2.right; float b2 = piece2.bottom; if((y1<y2)&&(y1<b2)&&(b1>=y2)&&(b1<b2)&&((x1>=x2&&x1<=r2)||(r1>=x2&&x1<=r2))){ return true; }else{ return false; } } private boolean collides(Pieces piece1, Pieces piece2){ if(collidesLeft(piece1,piece2)){ return true; }else if(collidesRight(piece1,piece2)){ return true; }else if(collidesUp(piece1,piece2)){ return true; }else if(collidesDown(piece1,piece2)){ return true; }else{ return false; } } As a second question, should my x,y,right,bottom,width,height variables be ints instead of floats like they are now? Also, any suggestions on how to implement things better would be greatly appreciated, even if not relevant to the question! Thanks in advance for the help and for sitting through such a long question! Update: I have gotten it working almost perfectly with the following code (this doesn't include the code for vertical pieces): @Override public boolean onTouchEvent(MotionEvent event){ float eventX = event.getX(); float eventY = event.getY(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: //check if touch is on piece if (eventX > x && eventX < (x+width) && eventY > y && eventY < (y+height)){ initialX=x; initialY=y; break; }else{ return false; } case MotionEvent.ACTION_MOVE: //determine if piece should move horizontally or vertically if(width>height){ for (Pieces piece : aPieces) { //if object equals itself in array, skip to next object if(piece==this){ continue; } //check if there the possibility for a horizontal collision if(this.isAllignedHorizontallyWith(piece)){ //check for and handle collisions while moving left if(this.isRightOf(piece)){ if(eventX>piece.right+(width/2)){ x = (int)(eventX-(width/2)); //move normally }else{ x = piece.right+1; } } //check for and handle collisions while moving right if(this.isLeftOf(piece)){ if(eventX<piece.x-(width/2)){ x = (int)(eventX-(width/2)); }else{ x = piece.x-width-1; } } break; }else{ x = (int)(eventX-(width/2)); } The only problem with this code is that it only detects collisions between the moving piece and one other (with preference to one on the left). If there is a piece to collide with on the left and another on the right, it will only detect collisions with the one on the left. I think this is because once it finds a possible collision, it handles it without finishing looping through the array holding all the pieces. How do I get it to check for multiple possible collisions at the same time?

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  • Download dynaic file with GWT

    - by Maksim
    I have a GWT page where user enter data (start date, end date, etc.), then this data goes to the server via RPC call. On the server I want to generate Excel report with POI and let user save that file on their local machine. This is my test code to stream file back to the client but for some reason it does not know: public class ReportsServiceImpl extends RemoteServiceServlet implements ReportsService { public String myMethod(String s) { File f = new File("/excelTestFile.xls"); String filename = f.getName(); int length = 0; try { HttpServletResponse resp = getThreadLocalResponse(); ServletOutputStream op = resp.getOutputStream(); ServletContext context = getServletConfig().getServletContext(); resp.setContentType("application/octet-stream"); resp.setContentLength((int) f.length()); resp.setHeader("Content-Disposition", "attachment; filename*=\"utf-8''" + filename + ""); byte[] bbuf = new byte[1024]; DataInputStream in = new DataInputStream(new FileInputStream(f)); while ((in != null) && ((length = in.read(bbuf)) != -1)) { op.write(bbuf, 0, length); } in.close(); op.flush(); op.close(); } catch (Exception ex) { ex.printStackTrace(); } return "Server says: " + filename; } } I've red somewhere on internet that you can't do file stream with RPC and I have to use Servlet for that. Is there any example of how to use Servlet and how to call that servlet from ReportsServiceImpl

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  • Eclipse 3.5: Implementing my own context menu for a MultipageEditorPart --> no viewer involved

    - by Patrick
    Hello! :-) In my current RCP-project i use a MultipageEditorPart. It has various pages, with simple SWT composites on it. The composites contain some Text and Combo elements. When the user right clicks onto the editor page, I want a context menu to open. This menu holds a command for creating a new editor page, with a composite on it. The command is already working, but I'm quite clueless about how to implement the context menu for the editor. Can someone help with this?

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  • Representing element as boolean with JAXB?

    - by Marcus
    We have this XML: <Summary> <ValueA>xxx</ValueA> <ValueB/> </Summary> <ValueB/> will never have any attributes or inner elements. It's a boolean type element - it exists (true) or it doesn't (false). JAXB generated a Summary class with a String valueA member, which is good. But for ValueB, JAXB generated a ValueB inner class and a corresponding member: @XmlElement(name = "ValueB") protected Summary.ValueB valueB; But what I'd like is a boolean member and no inner class: @XmlElement(name = "ValueB") protected boolean valueB; How can you do this? I'm not looking to regenerate the classes, I'd like to just make the code change manually. Update: In line with the accepted answer, we created a new method returning the boolean value conditional on whether valueB == null. As we are using Hibernate, we annotated valueB with @Transient and annotated the boolean getter with Hibernate's @Column annotation.

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  • Get the ID of a Child in a cascade="all" relationship, while adding it to a collection, in Hibernate

    - by Marco
    Hi, i have two Entities, "Parent" and "Child", that are linked through a bidirectional one-to-many relationship with the cascade attribute set to "all". When adding a Child object to the Parent children collection using the code below, i can't get the ID of the persisted child until i commit the transaction: Parent p = (Parent) session.load(Parent.class, pid); Child c = new Child(); p.addChild(c); // "c" hasn't an ID (is always zero) However, when i persist a child entity by explicitly calling the session.save() method, the ID is created and set immediately, even if the transaction hasn't been committed: Child c = new Child(); session.save(c); // "c" has an ID Is there a way to get the ID of the child entity immediately without calling the session.save() method? Thanks

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  • What is the best way to manage application screens in SWT?

    - by parxier
    I'm creating a standalone SWT desktop application that has around 10 different screens (few wizards, help, forms, etc). Some elements on screen don't change at all (like header, background, etc) and there is a working area that changes depending on what is clicked, etc. What is the best way to manage application screens? Do I need to create all screen at startup and then show/hide them depending on what is clicked? Or do I need to create those screens dynamically? Also, I couldn't find any way to show/hide a Composite, do I need to dispose it and then create again? What is the best practice? I'm new to SWT developing outside of Eclipse so any help would be beneficial.

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  • Type-safe mapping from Class<T> to Thing<T>

    - by Joonas Pulakka
    I want to make a map-kind of container that has the following interface: public <T> Thing<T> get(Class<T> clazz); public <T> void put(Class<T> clazz, Thing<T> thing); The interesting point is that the Ts in each Class<T><- Thing<T> pair is the same T, but the container should be able to hold many different types of pairs. Initially I tried a (Hash)Map. But, for instance, Map<Class<T>, Thing<T>> is not right, because then T would be same T for all pairs in that map. Of course, Map<Class<?>, Thing<?>> works, but then I don't have type-safety guarantees so that when I get(String.class), I can't be sure that I get a Thing<String> instance back. Is there a way to accomplish the kind of type safety that I'm looking for?

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  • Print an array elements

    - by 1ace1
    Hello guys, this is my first post and im still a beginner in the programming world so bare with me. I just created an array with 100 initialized values and i want to print out 10 elements on each line so it would be somthing like this 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ...26 this is the code i used and i managed to do it for the first 10 elements but i couldnt figure out how to do it for the rest public static void main(String[] args) { int[] numbers = { 0,1,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17}; int i, count = 0; for (i = 0; i < numbers.length; i++) { System.out.print(numbers[i] + " "); count++; if (count == 9) for (i = 9; i < numbers.length; i++) System.out.println(numbers[i] + " "); } } thanks!

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  • I am faceing problem with this error

    - by Sanjeev
    I am using Struts application while running welcome page is run successfully after that the following error is appear org.apache.jasper.JasperException: Failed to load or instantiate TagLibraryValidator class: org.apache.taglibs.standard.tlv.JstlCoreTLV any idea whats the problem.

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  • WebService Loggins

    - by KItis
    Hi, I have my webservice deployed on Apache tomcat 5.5. When I run my webservice using eclipse IDE, it prints logs to the location I have specified . I have put log4j property file for my webservice in the apache-tomcat-5.5.28/common/classes folder. Problem is , when i run this using webservice .aar file which is put in to apache-tomcat-5.5.28/webapps/axis2/WEB-INF/classes folder in the webservice ,it does not print logs. Could anyone tell me what is going wrong here. why does it print logs when running from eclipse ide and, why is it not printing logs when it is started

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  • Thread runs only once

    - by folone
    When a Thread is finished, you cannot run it once more, using start() method: it throws an Exception. Could anyone explain, why? What stands behind such an architectural decision?

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  • Create custom component based on LinearLayout, declaring layout in XML

    - by pheelicks
    I've been trying to create a Compound Control in Android 1.5 (as described here) but havn't been able to find any good examples on how to do this using an XML file to specify a layout. I'm fine with creating an Activity and then loading an xml file using the following in the constructor: setContentView(R.layout.main); However, I want to do this in subclass of LinearLayout - so I can use this compound component in other XML layouts. Something along the lines of: public class CustomView extends LinearLayout { public CustomView(Context context) { super(context); setupView(); } public CustomView(Context context, AttributeSet attrs) { super(context, attrs); setupView(); } public void setupView() { setContentView(R.layout.custom); // Not possible } } What is the correct way of going about doing this?

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  • looping problem while appending data to existing text file

    - by Manu
    try { stmt = conn.createStatement(); stmt1 = conn.createStatement(); stmt2 = conn.createStatement(); rs = stmt.executeQuery("select cust from trip1"); rs1 = stmt1.executeQuery("select cust from trip2"); rs2 = stmt2.executeQuery("select cust from trip3"); File f = new File(strFileGenLoc); OutputStream os = (OutputStream)new FileOutputStream(f,true); String encoding = "UTF8"; OutputStreamWriter osw = new OutputStreamWriter(os, encoding); BufferedWriter bw = new BufferedWriter(osw); } while ( rs.next() ) { while(rs1.next()){ while(rs2.next()){ bw.write(rs.getString(1)==null? "":rs.getString(1)); bw.write("\t"); bw.write(rs1.getString(1)==null? "":rs1.getString(1)); bw.write("\t"); bw.write(rs2.getString(1)==null? "":rs2.getString(1)); bw.write("\t"); bw.newLine(); } } } Above code working fine. My problem is 1. "rs" resultset contains one record in the table 2. "rs1" resultset contains 5 record in the table 3. "rs2" resultset contains 5 record in the table "rs" data is getting recursive. while writing to the same text file , the output i am getting like 1 2 3 1 12 21 1 23 25 1 10 5 1 8 54 but i need output like below 1 2 3 12 21 23 25 10 5 8 54 What things i need to change in my code.. Please advice

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  • Return parent of node in Binary Tree

    - by user188995
    I'm writing a code to return the parent of any node, but I'm getting stuck. I don't want to use any predefined ADTs. //Assume that nodes are represented by numbers from 1...n where 1=root and even //nos.=left child and odd nos=right child. public int parent(Node node){ if (node % 2 == 0){ if (root.left==node) return root; else return parent(root.left); } //same case for right } But this program is not working and giving wrong results. My basic algorithm is that the program starts from the root checks if it is on left or on the right. If it's the child or if the node that was queried else, recurses it with the child.

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  • Source Lookup Path is correct but debugger can't find file (Eclipse EE IDE)?

    - by Greg McNulty
    When debugging stepping over each line does work. Stepping into a function located in another file debugger displays: Source not found. Also displays option for Edit Source Lookup Path... but the correct package is listed there. (Also tried pointing with the directory path.) No other breakpoints set, as is a common solution. Any point in the right direction is helpful. Thank You. Thread[main] in the debugger window: Thread [main] (Suspended) ClassNotFoundException(Throwable).<init>(String, Throwable) line: 217 ClassNotFoundException(Exception).<init>(String, Throwable) line: not available ClassNotFoundException.<init>(String) line: not available URLClassLoader$1.run() line: not available AccessController.doPrivileged(PrivilegedExceptionAction<T>, AccessControlContext) line: not available [native method] Launcher$ExtClassLoader(URLClassLoader).findClass(String) line: not available Launcher$ExtClassLoader.findClass(String) line: not available Launcher$ExtClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader.loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String) line: not available MyMain.<init>() line: 24 MyMain.main(String[]) line: 36

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  • Sending JSON(jQuery) to PHP and decoding it

    - by dscher
    I can't for the life of me figure out what I'm doing wrong. It seems like it should be simple because I can't find anyone else with this issue but I can't figure out to send basic data via javascript(jQuery) to PHP and decode it. For the sake of simplicity, this is what I have: JAVASCRIPT var json_data = { "name" : "john doe" }; $.ajax({ type: "POST", url: "../bin/process.php", dataType: "json", data: json_data }); and my PHP FILE $arr = json_decode("json_data", true); $fp = fopen('data.txt', "w"); fwrite($fp, $arr['name']); fclose($fp); The file I'm writing ends up with nothing in it. If I do an: fwrite($fp, 'test'); I get a file with the word test in it but no matter what I do I don't get the json data I sent. Can someone please share a thorough example of A to Z. Thanks for any help.

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  • How to figure out which key was pressed on a BlackBerry

    - by Skrud
    What I want: To know when the user has pressed the button that has the number '2' on it, for example. I don't care whether "Alt" or "Shift" has been pressed. The user has pressed a button, and I want to evaluate whether this button has '2' printed on it. Naturally, if I switch devices this key will change. On a Bold 9700/9500 this is the 'E' key. On a Pearl, this is the 'T'/'Y' key. I've managed to get this working in what appears to be a roundabout way, by looking up the keycode of the '2' character with the ALT button enabled and using Keypad.key() to get the actual button: // figure out which key the '2' is on: final int BUTTON_2_KEY = Keypad.key(KeypadUtil.getKeyCode('2', KeypadListener.STATUS_ALT, KeypadUtil.MODE_EN_LOCALE)); protected boolean keyDown(int keycode, int time) { int key = Keypad.key(keycode); if ( key == BUTTON_2_KEY ) { // do something return true; } return super.keyDown(keycode,time); } I can't help but wonder if there is a better way to do this. I've looked at the constants defined in KeypadListener and Keypad but I can't find any constants mapped to the actual buttons on the device. Would any more experienced BlackBerry devs care to lend a helping hand? Thanks!

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  • How can I retrieve the value of a PASTE (copy-pasta) event in a GWT TextBox?

    - by dominicbri7
    Hello fellow SO members, I want to prevent the user from copy-pasting values in my TextBox IF AND ONLY IF the values do not respect a certain condition. For instance, I created a DigitsOnlyTextBox which will be used for phone numbers. I already made it so only Character.isDigit characters can be typed into the box, and the user cannot copy-paste values into it, using : this.sinkEvents(Event.ONPASTE); and public void onBrowserEvent(Event event) { super.onBrowserEvent(event); // Permet d'empêcher le copier-coller, donc d'entrer des caractères non-numériques if (event.getTypeInt() == Event.ONPASTE) { event.stopPropagation(); event.preventDefault(); } } But I'd like to verify if the copy-pasted String is "digits only" and if so, let the event happen (therefore the text added). tl;dr : see title Thank you for your time. Sincerely.

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  • Combobox having values but not showing text

    - by ras
    hi, I'm using GWT-EXT combobox. My problem is when I render the combobox, it's having as many rows as it has values but all the rows are empty means text is not shown. Here's my code. Combobox cb = new Combobox(); cb.setForceSelection(true); cb.setMinChars(1); cb.setWidth(200); cb.setStore(store); // Store is perfectly loaded in combobox cb.setDisplayField("ReportName"); cb.setMode(ComboBox.LOCAL); cb.setTriggerAction(ALL); cb.setEmptyText("--Select--"); cb.setLoadingText("Searching..."); cb.setTypeAhead(true); cb.setSelectOnFocus(true); All other code is working fine. I'm sure for one thing that this problem is related to one of the functions of Combobox. Thanks in advance.

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  • Struts 2 Select tag

    - by nathj07
    I'm pretty new to the jsp and struts way of doing things and so far I like what I see. My current question is with the use of the struts select tag. I have a page that displays a number of dropdown boxes using struts select currently the options are hard coded in the jsp. I would like to populate them based on a properties file. However I have no idea where to start. I assume I need to take the contents of a properties file into an Array (of some sort) and assign that to the select tag. My questions are: Where does the code t build the array go? How do I connect that array to the select tag?

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