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  • Null Pointer Exception

    - by user1507835
    I am getting a null pointer exception, but I dont know why. I checked to see if the cell was null before I read it to a string. So, why is that string null? private void fillArray() private void fillArray() { try { readBook = new HSSFWorkbook(readFile); } catch (IOException e) { System.out .println("If we know what we're doing, no one should ever see this line."); } if (readBook != null) {HSSFSheet infoSheet = readBook.getSheetAt(0); HSSFRow headingsRow = infoSheet.getRow(0); int i = 0; HSSFCell cell = headingsRow.getCell(i); String columnHeading = cell.toString(); while (cell != null && !(cell.toString().equals(""))) { cell = headingsRow.getCell(i); columnHeading = cell.toString(); columnHeadings.add(columnHeading); i++; } if(columnListIsSetup == false) { createList(); columnListIsSetup = true; } }

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  • Getting instance of a class in ArrayList

    - by user1499974
    I have a small problem with ArrayList. You see, I wish to get an instance of RenderNewHUD in my renderer class, which has a list of registered renderers. I did not want to create a variable for this due to limitations and awkwardness. Here is my code. RenderNewHUD hud = renderer.renderList.get(RenderNewHUD()); How exactly can I go along getting the instance of RenderNewHUD without creating a new instance? If you need any more of my code, just ask. Sorry if this is a very dumb question - I have looked EVERYWHERE for an answer.

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  • When i add a bitmap to an array list the last element is duplicated in previous indexes

    - by saxofone2
    I'm trying to implement a personal way of undo/redo in a finger paint-like app. I have in synthesis three objects: the Main class (named ScorePadActivity), the relative Main Layout (with buttons, menus, etc, as well as a View object where I create my drawings), and a third object named ArrayList where i'm writing the undo/redo code. The problem is, when I press the undo button nothing happens, but if I draw anything again "one-time" and press undo, the screen is updated. If I draw many times, to see any changes happen on screen I have to press the undo button the same number of times I have drawn. Seems like (as in title) when I add a bitmap to the array list the last element is duplicated in previous indexes, and for some strange reason, everytime I press the Undo Button, the system is ok for one time, but starts to duplicate until the next undo. The index increase is verified with a series of System.out.println inserted in code. Now when I draw something on screen, the array list is updated with the code inserted after the invocation of touchup(); method in motionEvent touch_up(); } this.arrayClass.incrementArray(mBitmap); mPath.rewind(); invalidate(); and in ArrayList activity; public void incrementArray(Bitmap mBitmap) { this._mBitmap=mBitmap; _size=undoArray.size(); undoArray.add(_size, _mBitmap); } (All Logs removed for clear reading) The undo button in ScorePadActivity calls the undo method in View activity: Button undobtn= (Button)findViewById(R.id.undo); undobtn.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { mView.undo(); } }); in View activity: public void undo() { this.mBitmap= arrayClass.undo(); mCanvas = new Canvas(mBitmap); mPath.rewind(); invalidate(); } that calls the relative undo method in ArrayList activity: public Bitmap undo() { // TODO Auto-generated method stub _size=undoArray.size(); if (_size>1) { undoArray.remove(_size-1); _size=undoArray.size(); _mBitmap = ((Bitmap) undoArray.get(_size-1)).copy(Bitmap.Config.ARGB_8888,true); } return _mBitmap; } return mBitmap and invalidate: Due to my bad English I have made a scheme to make the problem more clear: I have tried with HashMap, with a simple array, I have tried to change mPath.rewind(); with reset();, new Path(); etc but nothing. Why? Sorry for the complex answer, i want give you a great thanks in advance. Best regards

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  • How do I restrict accepting only one type in my generic method?

    - by kunjaan
    I have a generic function foo, which accepts any type and prints them out. public static <T> T foo(T... arg) { List<T> foo = Arrays.asList(arg); for (T t : foo) { System.out.println(t); } return null; } How do I make sure that the arguments received are of only 1 type. For example, {1,'a',3} should be invalid. It should either be all numbers or all characters.

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  • How to calculate the y-pixels of someones weight on a graph? (math+programming question)

    - by RexOnRoids
    I'm not that smart like some of you geniuses. I need some help from a math whiz. My app draws a graph of the users weight over time. I need a surefire way to always get the right pixel position to draw the weight point at for a given weight. For example, say I want to plot the weight 80.0(kg) on the graph when the range of weights is 80.0 to 40.0kg. I want to be able to plug in the weight (given I know the highest and lowest weights in the range also) and get the pixel result 400(y) (for the top of the graph). The graph is 300 pixels high (starts at 100 and ends at 400). The highest weight 80kg would be plot at 400 while the lowest weight 40kg would be plot at 100. And the intermediate weights should be plotted appropriately. I tried this but it does not work: -(float)weightToPixel:(float)theWeight { float graphMaxY = 400; //The TOP of the graph float graphMinY = 100; //The BOTTOM of the graph float yOffset = 100; //Graph itself is offset 100 pixels in the Y direction float coordDiff = graphMaxY-graphMinY; //The size in pixels of the graph float weightDiff = self.highestWeight-self.lowestWeight; //The weight gap float pixelIncrement = coordDiff/weightDiff; float weightY = (theWeight*pixelIncrement)-(coordDiff-yOffset); //The return value return weightYpixel; }

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  • Ensure that all getter methods were called in a JUnit test

    - by Freiheit
    I have a class that uses XStream and is used as a transfer format for my application. I am writing tests for other classes that map this transfer format to and from a different messaging standard. I would like to ensure that all getters on my class are called within a test to ensure that if a new field is added, my test properly checks for it. A rough outline of the XStream class @XStreamAlias("thing") public class Thing implements Serializable { private int id; private int someField; public int getId(){ ... } public int someField() { ... } } So now if I update that class to be: @XStreamAlias("thing") public class Thing implements Serializable { private int id; private int someField; private String newField; public int getId(){ ... } public int getSomeField() { ... } public String getNewField(){ ... } } I would want my test to fail because the old tests are not calling getNewField(). The goal is to ensure that if new getters are added, that we have some way of ensuring that the tests check them. Ideally, this would be contained entirely in the test and not require modifying the underlying Thing class. Any ideas? Thanks for looking!

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  • Simple servlet or filter to process form

    - by David
    Is there a simple framework for processing form submissions via a servlet? For my needs, a framework like STRUTS seems like over kill. My ideal processor would be a servlet that converts form elements into a bean object, possibly using typing information in the form to help with the conversion. Does something like this exist or is there another solution out there geared toward simpler needs? Thanks!

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  • Unable to establish the connection to the file in BlackBerry

    - by Vikas
    I have tried the example code on SO to read the contents from the file in the resource directory in BlackBerry. But I am having an issue with the FileConnection. I get the following error: File system error (1003) I tried the example from here. I want only the read functionality, the file I want to read is in CSV format as a .txt file placed in the /res/test.txt. public class FileDemo extends MainScreen { public FileDemo() { setTitle("My Page"); String str = readTextFile("file:///test.txt"); System.out.println("Contents of the file::::::: " + str); } public String readTextFile(String fName) { String result = null; FileConnection fconn = null; DataInputStream is = null; try { fconn = (FileConnection) Connector.openInputStream(fName); is = fconn.openDataInputStream(); byte[] data = IOUtilities.streamToBytes(is); result = new String(data); } catch (IOException e) { System.out.println(e.getMessage()); } finally { try { if (null != is) is.close(); if (null != fconn) fconn.close(); } catch (IOException e) { System.out.println(e.getMessage()); } } return result; } } Any suggestions/advice on a better approach or as to how I can get this working??

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  • How can I filter out the "My Computer"-option in a SWT DirectoryDialog?

    - by Superfisi
    Hello *, in our Eclipse RCP application running on Windows XP we use a DirectoryDialog, in which the user should... ahmm... choose a directory! :D The problem is: If the user selects the "My Computer"-option (in German Windows "Arbeitsplatz") the Dialog returns null. The DirectoryDialog provides a method setFilterPath(String path) in which I put the File.pathSeparatorChar (to remain OS-independant). My suggestion was that if there has to be a file separator in the directory the "My Computer"-option would be ignored cause it is null - for example the "OK"-button would be greyed out or sth. like that... but it is also valid to klick "OK". Any suggestions from your side? :D Thanks in advance! Alex

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  • How to persist in order

    - by parhs
    I have two entities: EXAM and EXAM_NORMAL. EXAM @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; private String name; private String codeName; @Enumerated(EnumType.STRING) private ExamType examType; @ManyToOne private Category category; @OneToMany(mappedBy="id",cascade=CascadeType.PERSIST) @OrderBy("id") private List<Exam_Normal> exam_Normal; EXAM_NORMAL @Id private Long item; @Id @ManyToOne private Exam id; @Enumerated(EnumType.STRING) private Gender gender; private Integer age_month_from; private Integer age_month_to; The problem is that if I put a list of EXAM_NORMAL at an EXAM class if I try to persist(EXAM) I get an error because it tries to persist EXAM_NORMAL first but it cant because the primary key of EXAM is missing because it isn't persisted... Is there any way to define the order? Or should I set null the list, persist and then set the list again? thanks:)

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  • Hibernate entities: columns without entity properties

    - by lewap
    Is there a way to "magically" persist a column which is not represented as a property in an entity? Concretely I want to add audit info to an entity without having the audit info on the entity. The audit values are not stored in the entity, but are retrieved from the environment at the time of persisting the entity. This happens in a AuditInfoUserType. The nullSafeSet gets the info from the SecurityContext, instead of reading from the entity. In the hibernate mapping, however, the audit info properties have to be defined. Is there a way in hibernate to define columns without properties?

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  • Building a custom iterator.

    - by Isai
    I am making this class which is a custom Map based off a hash map. I have an add method where if you add an object the object will be the key, and its value will be 1 if the object is not currently in the list. However if you add object that is currently in the list its value will be bumped up by 1. So if I added 10 strings which were all the same, the key would be that string and the value will be 10. I understand in practice when I iterate through the map, there is actually only one object to iterate, however, I am trying to create a inner class that will define an iterator that will iterate the same object however many times its value is. I can do this by simply using for loops to construct an appropriate ArrayList and just create an iterator for that, but that is too inefficient. Is there an easy or more efficient way of doing this?

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  • Redirect from docroot to an external url in glassfish

    - by tim_wonil
    I've googled around and only found solution where they suggest putting an apache httpd in front of glassfish. Sure, that works. But what if I do not wish to/cannot put any thing in front of glassfish? Without using the index.jsp in the docroot of the domain to have something like: <% String redirectURL = "http://stackoverflow.com/"; response.sendRedirect(redirectURL); %> Can I make browser to be redirected when I point it to: http://my.glassfish.domain/ ?

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  • Why doesn't list.get(0).equals(null) work?

    - by Jessy
    The first index is set to null (empty), but it doesn't print the right output, why? //set the first index as null and the rest as "High" String a []= {null,"High","High","High","High","High"}; //add array to arraylist ArrayList<Object> choice = new ArrayList<Object>(Arrays.asList(a)); for(int i=0; i<choice.size(); i++){ if(i==0){ if(choice.get(0).equals(null)) System.out.println("I am empty"); //it doesn't print this output } }

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  • Best way of invoking getter by reflection

    - by Javi
    Hello, I need to get the value of a field with a specific annotation, So with reflection I am able to get this Field Object. The problem is that this field will be always private though I know in advance it will always have a getter method. I know that I can use setAccesible(true) and get its value (when there is no PermissionManager), though I prefer to invoke its getter method. I know that I could look for the method by looking for "get+fieldName" (though I know for example for boolean fields are sometimes named as "is+fieldName"). I wonder if there is a better way to invoke this getter (many frameworks use getters/setters to access the attributes so maybe they do in another way). Thanks

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  • Recursively determine average value

    - by theva
    I have to calculate an average value of my simulation. The simulation is ongoing and I want (for each iteration) to print the current average value. How do I do that? I tried the code below (in the loop), but I do not think that the right value is calculated... int average = 0; int newValue; // Continuously updated value. if(average == 0) { average = newValue; } average = (average + newValue)/2; I also taught about store each newValue in an array and for each iteration summarize the whole array and do the calculation. However, I don't think that's a good solution, because the loop is an infinity loop so I can't really determine the size of the array. There is also a possibility that I am thinking too much and that the code above is actually correct, but I don't think so...

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  • How can I implement log4j logging to an existing J2EE Struts web application?

    - by Ruepen
    I have recently inherited a J2EE Struts web app that was written back in 2002. There is no logging in the application other than the odd System.out.println(). I have added log4j logging so that I can write out some info to the console, but I'm concerned on how best to approach this. Any suggestions, tips, best practices would be welcome as I don't want to spend too much time adding logging to every method or class (or trying to find what places where logging would be best - ie. bad code blocks/defects). My current approach is to just add some logging to the few classes that I have been looking at to understand the code, but are there a few key places where I can add logging to maximize my use of adding log4j?

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  • IS ResultSet thread safe

    - by javatraniee
    Is ResultSet Thread safe? My question arises because in this i have used a different statement for each query i have delsared a ResultSet as an local variable but it gives me a error of Operation not allowed after ResultSet is closed. But my statements are working as i'm using the statements in insert and delete query.I have commented the ResultSet part and have not got the error !! The source code of my program can be referd to , in my earlier Question .

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  • How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way?

    - by EugeneP
    How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way? As I see it returns a list of Objects. yes, it is tricky and only you who write the query know what should the query return (what objects). But are there ways to simplify things, so that it returned specific objects with no need in casting Object to a specific class according to its position in the query ? Maybe Spring can simplify things here? It has the similar functionality for JDBC, but I don't see if it can help in a similar way with Hibernate.

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  • Reading http file on url

    - by Nkunzis
    I am trying to read an xml file on an http url. "Unexpected end of file from server" keeps on coming . the page is password protected, I would like to know if I am properly giving in my url authentication details. I tried with non protected pages and I can read them properly. Here is my code: URL url = new URL("http://username:[email protected]:0000/test.xml"); URLConnection yc = url.openConnection(); BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream())); String inputLine; while ((inputLine = in.readLine()) != null) System.out.println(inputLine); in.close();

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