Search Results

Search found 33297 results on 1332 pages for 'java java ee'.

Page 882/1332 | < Previous Page | 878 879 880 881 882 883 884 885 886 887 888 889  | Next Page >

  • Conceptual inheritance implementation

    - by TheSENDER
    Hi there, I'm writing a spatial data structure and I have a doubt about what's the best NODE implementation. According to my design I have an abstract node entity and three classes which inherit from it: EMPTYNODE, FULLNODE, INTERNALNODE. The first one has no particular data. The second one has 1 reference to a generic element. The third one has 2 references to other nodes. I have found several ways to implement this situation (that I have already coded) but I can't decide what's the best. The first solution that I have found is to use a single class Node that potentially performs all the operation in this way: private static class Node { private Elem elem = null; private Node left = null, right = null; public Elem getElem() { assert isFull(); return elem; } public boolean isEmpty() { return elem == null && left == null; } public boolean isFull() { return elem != null; } public boolean isInternal() { return elem == null && left != null; } } The second solution is to write an explicit division by classes where every class offers only its methods. Obviously in this way we are obliged to perform several casts to the node objects. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); } private static class FullNode extends Node{ private ITriangle elem; @Override public boolean isEmpty() { return false; } @Override public final boolean isFull() { return true; } @Override public final boolean isInternal() { return false; } public Elem getElem() { return elem; } } The third one solution is to use the inheritance allowing every classes to offer all the methods, but the object type should by check by "isEmpty()" and similar methods. In case of wrong call we'll throw an exception. private static abstract class Node { public abstract boolean isEmpty(); public abstract boolean isFull(); public abstract boolean isInternal(); public abstract Elem getElem(); } private static class Empty extends Node{ @Override public boolean isEmpty() { return true; } @Override public final boolean isFull() { return false; } @Override public final boolean isInternal() { return false; } @Override public Elem getElem() { throw new AssertionError(); } } What do you think about these three solutions? Which one would you use? Any other ideas? Thanks for your help. Every idea will be appreciated.

    Read the article

  • Making a FTP connection in Android

    - by Elisha Khan
    i am working to make a Android application that can upload and download data from android phone to server using this link. As i am new to connection Android with server. is my local host works as a server to download and upload. i am using Uri ftpUri = Uri.parse("ftp://10.0.2.2"); But its not working help me to get out of this problem. I need your help just to sucessfullt connect to server, As i already said i aam new to connect Android Application to server. I am learning Programing myself and Internet is my teacher. Thank You Very Much

    Read the article

  • Testing a quadratic equation

    - by user1201587
    I'm doing a code testing for a program that calculate the results for a quadratic equation I need to have test data for the following situation, when a is not zero and d positive there is two possibilities which are in the code below, I need to find an example for the first satiation when Math.abs(b / a - 200.0) < 1.0e-4 , all the values that I have tried, excute the second one caption= "Two roots"; if (Math.abs(b / a - 200.0) < 1.0e-4) { System.out.println("first one"); x1 = (-100.0 * (1.0 + Math.sqrt(1.0 - 1.0 / (10000.0 * a)))); x2 = (-100.0 * (1.0 - Math.sqrt(1.0 - 1.0 / (10000.0 * a)))); } else { System.out.println("secrst one"); x1 = (-b - Math.sqrt(d)) / (2.0 * a); x2 = (-b + Math.sqrt(d)) / (2.0 * a); } } }

    Read the article

  • RMI client tracking

    - by 0000
    I'm building a Client / Server app that has some very specific needs. There are 2 kinds of servers: the first kind provide most of the remote procedures and clients connect to these directly, while the second kind is a single server that should keep track of what users are active (clients) and how many servers of the first kind are active when a method is called. The main thing is that the monitor should ONLY connect to the servers and not the clients directly. My first idea was to implement a simple login/logout rmi method when a client connects/ disconnects and keep track of those in a list but the main problem is when a client or server end abnormally. For example, if a client goes offline abruptly the server should somehow be notified and update the list accordingly, while if a server goes out all of the clients connected to it should be marked as not active in the control server. Any ideas of how to implement this functionality would be appreciated.

    Read the article

  • Line by line image swing

    - by user1046017
    I want to show an image as it is downloading, I have the URL, and I am trying to get the image parts like this: InputStream openStream = url.openStream(); DataInputStream dis = new DataInputStream(new BufferedInputStream(openStream)); ByteArrayOutputStream os = new ByteArrayOutputStream(); while ((s = dis.read(b)) != -1) { os.write(b , 0, s); support.firePropertyChange("stream", null, os); } This way, any listener get the stream and creates an image, this way: if("stream".equals(evt.getPropertyName())){ try { ByteArrayOutputStream stream = (ByteArrayOutputStream) evt.getNewValue(); byte[] byteArray = stream.toByteArray(); stream.flush(); Image createImage = Toolkit.getDefaultToolkit().createImage(byteArray); this.getContentPane().add(new JLabel(new ImageIcon(createImage))); } catch (IOException ex) { Logger.getLogger(ImageTest.class.getName()).log(Level.SEVERE, null, ex); } } However, I am getting a "Premature end of JPEG file sun.awt.image.ImageFormatException: JPEG datastream contains no image" error, the image is a JPG image format, is there any library or method known to make something similar?

    Read the article

  • switch statemt functioning improperly and giving error when i put break;

    - by nav
    The following is the code i used in a program - over here the month variable is an integer switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; break; case 2: return 28; break; case 4: case 6: case 9: case 11: return 30; break; default: System.out.println("Invalid month."); return 0; } surprisingly, when i use the above switch construct.. it gives an error saying.. code unreachable for statements after each break statement Then i removed all the break statements, and the new code looks like this --- switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; case 2: return 28; case 4: case 6: case 9: case 11: return 30; default: System.out.println("Invalid month."); return 0; } Now.. after removing the break statements .. the code worked perfectly well.. My question is... in the switch construct.. it is mandatory to use break.. or else the control flow continued.. and all the conditions are tested and executed!! right??? So why in the world is the previous ** syntactically Right** version giving an error.. and the modified syntactically incorrect version running perfectly well.. Any explanation.. anyone!!

    Read the article

  • Can JAXB store the class name in the XML so that the the deserialize code doesn't need knowledge of the class?

    - by Andrew
    It seems the standard approach for deserializing JAXB XML is to specify the package name when creating the context. Then, JAXB looks up the class based on the root element: JAXBContext jc = JAXBContext.newInstance("com.foo"); Unmarshaller u = jc.createUnmarshaller(); Object o = u.unmarshal(new StringReader("...")); I'm looking for a more flexible approach where I don't have to specify the package name and could still deserialize any object. This would be as simple as JAXB storing the package in the XML, but I can't seem to find out how to do this. I can write the code to do it myself but that would be unpleasant. It would like JAXB to do it, if possible. BTW, I am not using schemas, just Annotations and marshal/unmarshal. Any ideas?

    Read the article

  • @ManyToMany Duplicate Entry Exception

    - by zp26
    I have mapped a bidirectional many-to-many exception between the entities Course and Trainee in the following manner: Course { ... private Collection<Trainee> students; ... @ManyToMany(targetEntity = lesson.domain.Trainee.class, cascade = {CascadeType.All}, fetch = {FetchType.EAGER}) @Jointable(name="COURSE_TRAINEE", joincolumns = @JoinColumn(name="COURSE_ID"), inverseJoinColumns = @JoinColumn(name = "TRAINEE_ID")) @CollectionOfElements public Collection<Trainee> getStudents() { return students; } ... } Trainee { ... private Collection<Course> authCourses; ... @ManyToMany(cascade = {CascadeType.All}, fetch = {FetchType.EAGER}, mappedBy = "students", targetEntity = lesson.domain.Course.class) @CollectionOfElements public Collection<Course> getAuthCourses() { return authCourses; } ... } Instead of creating a table where the Primary Key is made of the two foreign keys (imported from the table of the related two entities), the system generates the table "COURSE_TRAINEE" with the following schema: I am working on MySQL 5.1 and my App. Server is JBoss 5.1. Does anyone guess why?

    Read the article

  • schedule task with spring mvc

    - by user3586352
    I want to run the following method every specific time in spring mvc project it works fine and print first output but it doesn't access the database so it doesn't display list the method public class ScheduleService { @Autowired private UserDetailService userDetailService; public void performService() throws IOException { System.out.println("first output"); List<UserDetail> list=userDetailService.getAll(); System.out.println(list); } config file <!-- Spring's scheduling support --> <task:scheduled-tasks scheduler="taskScheduler"> <task:scheduled ref="ScheduleService" method="performService" fixed-delay="2000"/> </task:scheduled-tasks> <!-- The bean that does the actual work --> <bean id="ScheduleService" class="com.ctbllc.ctb.scheduling.ScheduleService" /> <!-- Defines a ThreadPoolTaskScheduler instance with configurable pool size. --> <task:scheduler id="taskScheduler" pool-size="1"/>

    Read the article

  • Batch processing JDBC

    - by Wai Hein
    I am practicing JDBC batch processing and having errors: error 1: Unsupported feature error 2: Execute cannot be empty or null Property files include: itemsdao.updateBookName = Update Books set bookname = ? where books.id = ? itemsdao.updateAuthorName = Update books set authorname = ? where books.id = ? I know I can execute about DML statements in one update, but I am practicing batch processing in JDBC. Below is my method public void update(Item item) { String query = null; try { connection = DbConnector.getConnection(); property = SqlPropertiesLoader.getProperties("dml.properties"); connection.setAutoCommit(false); if ( property == null ) { Logging.log.debug("dml.properties does not exist. Check property loader or file name is spelled right"); return; } query = property.getProperty("itemsdao.updateBookName"); statement = connection.prepareStatement(query); statement.setString(1, item.getBookName()); statement.setInt(2, item.getId()); statement.addBatch(query); query = property.getProperty("itemsdao.updateAuthorName"); statement = connection.prepareStatement(query); statement.setString(1, item.getAuthorName()); statement.setInt(2, item.getId()); statement.addBatch(query); statement.executeBatch(); connection.commit(); }catch (ClassNotFoundException e) { Logging.log.error("Connection class does not exist", e); } catch (SQLException e) { Logging.log.error("Violating PK constraint",e); } //helper class th finally { DbUtil.close(connection); DbUtil.closePreparedStatement(statement); }

    Read the article

  • Android Sqlite - obtaining the correct database row id

    - by Dan_Dan_Man
    I'm working on an app that allows the user to create notes while rehearsing a play. The user can view the notes they have created in a listview, and edit and delete them if they wish. Take for example the user creates 3 notes. In the database, the row_id's will be 1, 2 and 3. So when the user views the notes in the listview, they will also be in the order 1, 2, 3 (intially 0, 1, 2 before I increment the values). So the user can view and delete the correct row from the database. The problem arises when the user decides to delete a note. Say the user deletes the note in position 2. Thus our database will have row_id's 1 and 3. But in the listview, they will be in the position 1 and 2. So if the user clicks on the note in position 2 in the listview it should return the row in the database with row_id 3. However it tries to look for the row_id 2 which doesn't exist, and hence crashes. I need to know how to obtain the corresponding row_id, given the user's selection in the listview. Here is the code below that does this: // When the user selects "Delete" in context menu public boolean onContextItemSelected(MenuItem item) { AdapterContextMenuInfo info = (AdapterContextMenuInfo) item .getMenuInfo(); switch (item.getItemId()) { case DELETE_ID: deleteNote(info.id + 1); return true; } return super.onContextItemSelected(item); } // This method actually deletes the selected note private void deleteNote(long id) { Log.d(TAG, "Deleting row: " + id); mNDbAdapter.deleteNote(id); mCursor = mNDbAdapter.fetchAllNotes(); startManagingCursor(mCursor); fillData(); // TODO: Update play database if there are no notes left for a line. } // When the user clicks on an item, display the selected note protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); viewNote(id, "", "", true); } // This is where we display the note in a custom alert dialog. I've ommited // the rest of the code in this method because the problem lies in this line: // "mCursor = mNDbAdapter.fetchNote(newId);" // I need to replace "newId" with the row_id in the database. private void viewNote(long id, String defaultTitle, String defaultNote, boolean fresh) { final int lineNumber; String title; String note; id++; final long newId = id; Log.d(TAG, "Returning row: " + newId); mCursor = mNDbAdapter.fetchNote(newId); lineNumber = (mCursor.getInt(mCursor.getColumnIndex("number"))); title = (mCursor.getString(mCursor.getColumnIndex("title"))); note = (mCursor.getString(mCursor.getColumnIndex("note"))); . . . } Let me know if you would like me to show anymore code. It seems like something so simple but I just can't find a solution. Thanks!

    Read the article

  • OpenGL gluLookAt issues

    - by Chris D
    I am trying to switch my space invaders game to a first person view, i.e. a view of the world from the ship. I am getting a bit confused about what point I should be looking at. I am currently using these parameters in gluLookAt: GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glLoadIdentity(); GLU.gluLookAt(ship3dPos.x, ship3dPos.y, ship3dPos.z,400.0f, 600.0f,-50.0f, 0.0f, 1.0f,-0.0f); Where ship3dPos is a Vector3f. I'm not sure what I'm supposed to set parameters 4,5 and 6 to, to get a view of the whole world(window is 800/600). I want to have a view of say 100.0 wide from the ships perspective, with this view moving along the x-axis as the player moves the ship. Thanks

    Read the article

  • db2 jdbc driver does not release table locks

    - by as
    situation: We have a web service running on tomcat accessing DB2 database on AS400, we are using JTOPEN drivers for JNDI connections handled by tomcat. For handling transactions and access to database we are using Spring. For each select system takes JDBC connection from JNDI (i.e. from connection pool), does selection, and in the end it closes ResultSet, Statement and releases Connection in that order. That passes fine, shared lock on table dissappears. When we want to do update the same way as we did with select (exception on ResultSet object, we don't have one in such situation), after releasing Connection to JNDI lock on table stays. If we put maxIdle=0 for number of connections in JNDI configuration, this problem disappears, but this degrades performances, we have cca 100 users online on that service, we need few connections to be alive in pool. What do you suggest?

    Read the article

  • How often should we write unit tests?

    - by Midnight Blue
    Hi, I am recently introduced to the test-driven approach to development by my mentor at work, and he encourages me to write an unit-test whenenver "it makes sense." I understand some benefits of having a throughout unit-test suite for both regression testing and refractoring, but I do wonder how often and how throughout we should write unit-test. My mentor/development lead asks me to write a new unit test-case for a newly written control flow in a method that is already being tested by the exsisting test class, and I think it is an overkill. How often do you write your unit tests, and how detailed do you think your unit tests should be? Thanks!

    Read the article

  • how to differentiate between two threads

    - by mithun1538
    Hello everyone, I have the following code in my program: Thread getUsersist, getChatUsers; getUsersList = new Thread(this, "getOnlineUsers"); getUsersList.start(); getChatUsers = new Thread(this, "getChatUsers"); getChatUsers.start(); In run(), I wish to know which thread is using run(). If its "getOnlineUsers" i will do something, If it is "getChatUsers" I will do something else. So how do I know which thread is using run()?

    Read the article

  • Getting the right result of mouse click event

    - by Jessy
    Hello, I'm curious why I got the "right" BUT "wrong"number of result when I click the mouse. I supposed to print on the console mouseClicked once everytimes the mouse is clicked. However I got many of them printed out everytimes I clicked the mouse ...sometimes 5 e.g. mouseClicked mouseClicked mouseClicked mouseClicked mouseClicked Instead of just mouseClicked Why? public void mouseClicked(MouseEvent arg0) { System.out.println("mouseClicked"); }

    Read the article

  • Trouble parsing self closing XML tags using SAX parser

    - by sandesh
    Hi, I am having trouble parsing self closing XML tags using SAX. I am trying to extract the link tag from the Google Base API.I am having reasonable success in parsing regular tags. Here is a snippet of the xml <entry> <id>http://www.google.com/base/feeds/snippets/15802191394735287303</id> <published>2010-04-05T11:00:00.000Z</published> <updated>2010-04-24T19:00:07.000Z</updated> <category scheme='http://base.google.com/categories/itemtypes' term='Products'/> <title type='text'>En-el1 Li-ion Battery+charger For Nikon Digital Camera</title> <link rel='alternate' type='text/html' href='http://rover.ebay.com/rover/1/711-67261-24966-0/2?ipn=psmain&amp;icep_vectorid=263602&amp;kwid=1&amp;mtid=691&amp;crlp=1_263602&amp;icep_item_id=170468125748&amp;itemid=170468125748'/> . . and so on I can parse the updates and published tags, but not the link and category tag. Here is my startElement and endElement overrides public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equals("title") && xmlTags.peek().equals("entry")) { insideEntryTitle = true; } xmlTags.push(qName); } public void endElement(String uri, String localName, String qName) throws SAXException { // If a "title" element is closed, we start a new line, to prepare // printing the new title. xmlTags.pop(); if (insideEntryTitle) { insideEntryTitle = false; System.out.println(); } } declaration for xmltags.. private Stack<String> xmlTags = new Stack<String>(); Any help guys? this is my first post here.. I hope I have followed posting rules! thanks a ton guys..

    Read the article

  • Tomcat does not persist Session during restart

    - by mabuzer
    How to force Tomcat to serialize Session so that the user is kept logged in when Tomcat has restarted? Right now the user has to login again everytime. Added the following lines into web-app context.xml: <Manager className="org.apache.catalina.session.PersistentManager"> <Store className="org.apache.catalina.session.FileStore"/> </Manager> but still I see login page after Tomcat restart, I use Tomcat 6.0.24

    Read the article

  • Annotations: methods vs variables

    - by Zenzen
    I was always sure (don't know why) that it's better to add annotations to variables, but while browsing the Hibernate doc http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-hibspec-collection I noticed they tend to annotate the methods. So should I put my annotations before methods, like this: @Entity public class Flight implements Serializable { private long id; @Id @GeneratedValue public long getId() { return id; } public void setId(long id) { this.id = id; } } Or is it better to do it like this: @Entity public class Flight implements Serializable { @Id @GeneratedValue private long id; public long getId() { return id; } public void setId(long id) { this.id = id; } } Or maybe there's no difference?

    Read the article

  • response.sendRedirect - check redirect is up

    - by Trick
    From JSP I just want a redirect to another page... <% response.sendRedirect("http://www.google.com/"); %> Can I check if google.com is up and then redirect (or write a msg else)... Something like that: <% if(ping("www.google.com")) { response.sendRedirect("http://www.google.com/"); } else { // write a message }%> Or <% try { response.sendRedirect("http://www.google.com/"); } catch(SomeException e) { // write a message }%> It is just an JSP page, I don't have any libraires available (like ApacheCommons for http GET methods).

    Read the article

< Previous Page | 878 879 880 881 882 883 884 885 886 887 888 889  | Next Page >