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- 1
  - Java compiler with inline bytecode?Does anyone know of a java compiler that allows inline "java assembly
    mnemonics" to be included in amongst the standard java code?
    
    Similar to the inline asm keyword in C/C++ compilers...
    
    Cheers :o)
    
    Will
- 1
  - Reflection with Java and Oracle 10gHi everyone,
    
    We have change oracle 8i to oracle 10g, now we have problems with the
    reflection in JAVA.
    I've got an IllegalAccessException:
    
    Object value;
    value = infoResultSetAndData.getResultSetMethodGet().invoke(rs, new
    Object[] {new Integer(infoResultSetAndData.getResultSetIndice())});
    
    thanks for suggestions,
    
    fourmi
- 5
  - java.security.NoSuchAlgorithmException: No such algorithm: RSAI have this code
    
    import java.io.*;
    import java.security.*;
    import javax.crypto.*;
    
    class Encrypt {
    private Cipher RSAtransform;
    
    public Encrypt()
    {
    
    Provider rsajca = new com.sun.rsajca.Provider();
    Security.addProvider(rsajca);
    try
    {
    RSAtransform = Cipher.getInstance("RSA",rsajca);
    }
    catch (NoSuchAlgorithmException e) {
    e.printStackTrace();
    }
    catch (NoSuchPaddingException e) {
    e.printStackTrace();
    }
    
    }
    ...
    ...
    
    But when I run it on winxp (using Java 1.4.2) I get:
    
    java.security.NoSuchAlgorithmException: No such algorithm: RSA
    at javax.crypto.SunJCE_b.c(DashoA6275)
    at javax.crypto.SunJCE_b.a(DashoA6275)
    at javax.crypto.Cipher.a(DashoA6275)
    at javax.crypto.Cipher.getInstance(DashoA6275)
    at keys.Encrypt.<init>(Encrypt.java:18)
    at keys.Encrypt.main(Encrypt.java:115)
    java.lang.NullPointerException
    at keys.Encrypt.encrypt(Encrypt.java:73)
    at keys.Encrypt.main(Encrypt.java:128)
    
    Why is it not possible to use the RSA algorithm?
    
    I would prefer to use an asymmetric algorithm instead of DES.
    
    Hope someone can help
    
    JOhs
- 6
  - modeling possible polymorphism?hi..
    
    i have entity called AssuredPerson and entity called PolicyOwner, both
    have similar attributes (meaning Abstract Person Class)
    
    however an AssuredPerson can be PolicyOwner (but not the way around).
    
    so i've added a property called isPolicyHolder (boolean) to
    AssuredPerson.
    
    is this correct way to go about it?
- 6
  - How to load INI file to JTree Nodes?Hi,
    
    I am new to JAVA SWING and would like someone to help me out here.
    I need to read the INI file to load out the structure and display them
    on the JTree.
    
    How can I go about doing that?
    
    The INI file format looks like following:
    
    [R]
    ChildsCount = 2
    C1 = Enclosure(s)
    C2 = JBOD(s)
    
    [R\C1]
    ChildsCount = 2
    C1 = EnclosureWWN A
    C2 = EnclosureWWN B
    
    [R\C1\C1]
    ChildsCount = 6
    C1 = Power Supply
    C2 = Fan
    C3 = Battery
    C4 = Numeric Sensor
    C5 = Controller
    C6 = Device Group(s)
    
    [R\C1\C1\C1]
    ChildsCount = 2
    C1 = PSU0
    C2 = PSU1
    
    [R\C1\C1\C2]
    ChildsCount = 2
    C1 = Fan0
    C2 = Fan1
    
    [R\C1\C1\C3]
    ChildsCount = 2
    C1 = UPS
    C2 = Motherboard
    
    [R\C1\C1\C4]
    ChildsCount = 3
    C1 = NS0
    C2 = NS1
    C3 = NS2
    
    [R\C1\C1\C5]
    ChildsCount = 2
    C1 = ControllerWWN A
    C2 = ControllerWWN B
    
    [R\C1\C1\C6]
    ChildsCount = 7
    C1 = Device Group A
    C2 = Device Group B
    C3 = Device Group C
    C4 = Device Group D
    C5 = Device Group E
    C6 = Device SubGroup A
    C7 = Device SubGroup B
    
    [R\C1\C1\C6\C1]
    ChildsCount = 3
    C1 = Volume 1
    C2 = Volume 2
    C3 = Volume 3
    
    [R\C1\C1\C6\C1\C1]
    ChildsCount = 2
    C1 = LUN0
    C2 = LUN1
    
    [R\C1\C1\C6\C1\C1\C1]
    ChildsCount = 4
    C1 = Host A
    C2 = Host B
    C3 = Host C
    C4 = Host D
    
    [R\C1\C1\C6\C1\C1\C2]
    ChildsCount = 2
    C1 = Host A
    C2 = Host C
    
    In the JTree it should shows something like this:
    
    Enclosure(s)
    |__EnclosureWWN A
    |__Power Supply
    |__PSU0
    |__PSU1
    |__Fan
    |__Battery
    |__Numeric Sensor
    |__Controller
    |__Device Group(s)
    
    |__EnclosureWWN B
- 7
  - MyCalendar subclass and threadingI have an application that deals with alot of dates, I have classes that
    represent time & duration. I do not need to cart around the beast that is
    GregorianCalendar.
    However I do need to use it to convert data.
    
    eg:
    gregCal.setTime(myDate);
    gregCal.get(Calendar.DATE);
    gregCal.get(Calendar.MONTH_OF_YEAR); // etc
    
    Also I really need a different Calendar, something that I can do this with
    
    myCal.isSpecialDay();
    
    So I'm wondering whether I should subclass Calendar/Gregorian to add my
    special dates.
    
    Because I don't see the need to have an instance of this in my time/duration
    objects, I'm thinking, I could have a Singleton MyCalendar to use for look
    ups.
    
    At present there isn't a threading issue, just one thread. But I'd like to
    make it thread safe, none the less. Also if there are multiple threads
    eventually, I should convert my Singleton to an Object pool - right?
    
    Anyhow I'd need to synchronise over several calls within MyCalendar to make
    sure the date is setup and retrieved correctly:
    
    synchronized public boolean isSpecialDay(Date date) {
    setTime(date);
    return isSpecialDay();
    }
    Presumably I should make all methods that set the date synchronized also?
    
    I know there is probably some bad stuff above, how should I do this please?
    
    --
    Mike W
- 7
  - A java network sniffer for WindowsHi everybody,
    
    If you want to listen or publish Ethernet packet with Java, please try
    Jiffer.
    You can download Jiffer here : http://aroche.free.fr
    
    If you have any suggestion or experience problem to install Jiffer
    please contact.
    
    Have fun !!
    
    Arnaud ROCHE
- 8
  - java.lang.NullPointerException at com.sun.kvem.midp.MIDP.run(MIDP.java:651)Hi Friends,
    
    Does any one has any idea about the following StackTrace. I am using
    CLDC1.1 and MIDP2.0 with Sun Java Studio Mobility. Any help will be
    highly appreciated.
    
    java.lang.NullPointerException
    at com.sun.kvem.midp.MIDP.run(MIDP.java:651)
    at
    com.sun.kvem.environment.EmulatorInvoker.runEmulatorImpl(EmulatorInvoker.java:116)
    at
    com.sun.kvem.environment.EmulatorInvoker.runEmulatorSameVM(EmulatorInvoker.java:105)
    at
    com.sun.kvem.environment.EmulatorInvoker.runEmulator(EmulatorInvoker.java:63)
    at com.sun.kvem.environment.ProfileEnvironment$KVMThread.runEmulator
    (ProfileEnvironment.java:240)
    at
    com.sun.kvem.environment.ProfileEnvironment$KVMThread.run(ProfileEnvironment.java:262)
    
    Greetings,
- 8
  - Custom JComponent: add to contentPaneHello,
    
    I created a custom JComponent which consists of two JTables on a
    JScrollPane.
    My problem is when I add a JDividedTable instance to the content pain of a
    JFrame,
    I only see a grey frame with the preferredSize of the scrollpane of my
    custom component.
    When I pass the contentPane of the Frame to the constructor of
    JCustomComponent
    and contentPane.add(scrollPane) call at the end everything works fine.
    
    The solution with the contentPane as parameter in the constructor is not
    desirable in thougths of
    reusability and flexibility.
    
    Can anybody tell me what is wrong?
    
    I want to use it like this from a JFrame, for example:
    
    public class MyApp extends JFrame {
    
    public MyApp() {
    Container cp = getContentPane();
    ....
    
    JDividedTable dividedTable = new JDividedTable(someModel,3);
    cp.add(dividedTable);
    ...
    }
    
    public static void main ....
    
    In JCustomComponent I override set getter and setter methods for the
    preferred, maximum and minimum
    size of JComponent.
    
    Here is the source of my Component:
    
    -------------------------------------------------------------------------
    import java.awt.Container;
    import java.awt.Dimension;
    import java.awt.event.MouseAdapter;
    import java.awt.event.MouseEvent;
    import java.awt.event.MouseListener;
    
    import javax.accessibility.AccessibleContext;
    import javax.swing.JComponent;
    import javax.swing.JScrollPane;
    import javax.swing.JTable;
    import javax.swing.event.ListSelectionEvent;
    import javax.swing.event.ListSelectionListener;
    import javax.swing.table.JTableHeader;
    import javax.swing.table.TableColumnModel;
    import javax.swing.table.TableModel;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    
    /**This swing UI class provides a
    * {@link javax.swing.JTable JTable} in a {@link javax.swing.JScrollPane
    * JScrollPane} with fixed columns on the left side and
    * horizontal scrollable columns on the right side. The number of fixed
    * columns is user defined within the constructor.<br><br>
    *
    * The divided table is constructed out of two JTable's with the same
    * TableModel. The fixed table is installed as RowHeaderView on the
    * JScrollPane. From the scrollable table's TableColumnModel the
    * first <code>fixedCols</code> are removed.
    *
    */
    public class JDividedTable extends JComponent {
    
    private static final Log log = LogFactory.getLog(JDividedTable.class);
    
    /* ==================================================================== */
    /**
    * Cronstructs a <code>JDividedTable</code> in a <code>JScrollPane</code>
    * with a number of <code>fixedCols</code> on the left.
    *
    * @param dm The underlying tableModel of this table.
    * @param fixedCols The number of fixed columns on the left side.
    * @param contentPane The container the table should be installed on.
    */
    public JDividedTable(TableModel dm, int fixedCols, Container contentPane)
    {
    fixedColumns = fixedCols;
    
    initDividedTable(dm, null);
    
    removeFixedColsFromScrollableTable();
    
    synchronizeSelection();
    
    putTablesOnContainer(contentPane);
    }
    
    /* ==================================================================== */
    /**
    * Cronstructs a <code>JDividedTable</code> in a <code>JScrollPane</code>
    * with a number of <code>fixedCols</code> on the left. The data are
    * arranged according to <code>sorter</code> if a sorter is provided.
    *
    * @param dm The underlying tableModel of this table.
    * @param fixedCols The number of fixed columns on the left side.
    * @param sorter A custom sorter (optional).
    * @param contentPane The container the table should be installed on.
    */
    public JDividedTable(TableModel dm, int fixedCols, AbstractSortDecorator
    sorter,
    Container contentPane) {
    fixedColumns = fixedCols;
    
    initDividedTable(dm, sorter);
    
    removeFixedColsFromScrollableTable();
    
    synchronizeSelection();
    
    putTablesOnContainer(contentPane);
    }
    
    /* ==================================================================== */
    /**Gets the actual sort decorator.
    * @return The sort decorator.
    */
    public AbstractSortDecorator getSortDecorator () {
    return customSorter;
    }
    
    /* ==================================================================== */
    /**Adds a new <code>AbstractSortDecorator</code> to the divided table.
    * @param sorter The new sort decorator.
    * @throws IllegalArgumentException If sorter is null.
    */
    public void setSortDecorator(AbstractSortDecorator sorter)
    throws IllegalArgumentException{
    
    if (sorter == null) {
    log.error("AbstractSortDecorator can't be set to 'null'");
    throw new IllegalArgumentException("AbstractSortDecorator " +
    "can't be set to 'null'");
    } else {
    
    if (log.isInfoEnabled()) {
    log.info("Adding a sorter to the divided table: '" +
    sorter + "'");
    }
    
    customSorter = sorter;
    fixedTable.setModel(customSorter);
    scrollableTable.setModel(customSorter);
    
    removeFixedColsFromScrollableTable();
    
    setMouseListenerToHeader(false);
    }
    }
    
    /* ==================================================================== */
    /**Allows to reorder interactively the columns in the scrollable table
    * if <code>allowed</code> is true.
    * @param allowed Allow reordering of columns? Per default it is set to
    true.
    */
    public void setHeaderReorderingAllowed(boolean allowed) {
    scrollableTable.getTableHeader().setReorderingAllowed(allowed);
    }
    
    /* ==================================================================== */
    /**Sets the mouse listeners for the table headers of both tables for the
    * sorter and synchronizes both models. When the listener is set to true
    * the user can sort the table interactively by clicking on the table
    * headers. If it is set to false, the table is sorted according
    * to the fixed sort criteria defined in the sorter.<br>
    * The default for the divided table is 'listeners off'.<br>
    * After a mouseClicked event both tables needs to be repainted because
    * otherwise their were problems encountered with updating of the two
    * table components.
    *
    * @param mouseListenerOn Set or remove the listener to/from the headers,
    * per default it is set to false. It only adds a
    * listener if the divided table has a sorter.
    */
    public void setMouseListenerToHeader(boolean mouseListenerOn) {
    JTableHeader fixedHdr = (JTableHeader) fixedTable.getTableHeader();
    JTableHeader scrollableHdr = (JTableHeader)
    scrollableTable.getTableHeader();
    MouseListener fixedListener = null;
    MouseListener scrollableListener = null;
    
    if ((mouseListenerOn == true) && (customSorter != null)) {
    fixedListener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
    TableColumnModel tcm = fixedTable.getColumnModel();
    int vc = tcm.getColumnIndexAtX(e.getX());
    int mc = fixedTable.convertColumnIndexToModel(vc);
    customSorter.sort(mc);
    fixedTable.repaint();
    scrollableTable.repaint();
    }
    };
    fixedHdr.addMouseListener(fixedListener);
    
    scrollableListener = new MouseAdapter() {
    public void mouseClicked(MouseEvent e) {
    TableColumnModel tcm = scrollableTable
    .getColumnModel();
    int vc = tcm.getColumnIndexAtX(e.getX());
    int mc = scrollableTable
    .convertColumnIndexToModel(vc);
    customSorter.sort(mc);
    fixedTable.repaint();
    scrollableTable.repaint();
    }
    };
    scrollableHdr.addMouseListener(scrollableListener);
    } else if (customSorter != null) {
    // If the listener is null, no action is performed by
    removeMouseListener().
    fixedHdr.removeMouseListener(fixedListener);
    scrollableHdr.removeMouseListener(scrollableListener);
    customSorter.sort();
    }
    }
    
    /* ==================================================================== */
    /**Creates and initializes the divided table.
    *
    * @param dm The TableModel.
    * @param sorter The sort decorator for this table.
    */
    private void initDividedTable(TableModel dm, AbstractSortDecorator
    sorter) {
    
    // Try to set sorter between model and view.
    if (sorter != null) {
    
    if (log.isInfoEnabled()) {
    log.info("Creating a divided table with sorter '" +
    sorter.toString() + "'");
    }
    
    customSorter = sorter;
    fixedTable = new JTable(customSorter);
    scrollableTable = new JTable(customSorter);
    
    setMouseListenerToHeader(false);
    } else {
    
    if (log.isInfoEnabled()) {
    log.info("Creating a divided table without sorter");
    }
    fixedTable = new JTable(dm);
    scrollableTable = new JTable(dm);
    }
    
    // Reordering not allowed, because wanted columns can be substituted
    with
    // unwanted ones in the fixed table with this option set to true.
    fixedTable.getTableHeader().setReorderingAllowed(false);
    fixedTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    
    scrollableTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
    }
    
    /* ==================================================================== */
    /**Removes the columns said to be fix from the scrollableTable
    TableColumnModel,
    * sets the column width of fixedTable-columns to fixed size and
    * sets the viewport size of fixedTable to the width of the fixed columns.
    */
    private void removeFixedColsFromScrollableTable() {
    TableColumnModel tcm = scrollableTable.getColumnModel();
    // columnMargin necessary for displaying the grid line.
    Dimension dim = new
    Dimension(fixedTable.getColumnModel().getColumnMargin(),0);
    
    for(int i = 0;i < fixedColumns; i++) {
    dim.width += tcm.getColumn(i).getPreferredWidth();
    fixedTable.getColumnModel().getColumn(i).setResizable(false);
    
    // always delete the first column because columns in tcm are reordered
    // after deletion
    tcm.removeColumn(tcm.getColumn(0));
    }
    fixedTable.setPreferredScrollableViewportSize(dim);
    }
    
    /* ==================================================================== */
    /**Creates the scrollPane for scrollableTable and setting its upper
    * left corner view to fixedTable. Finally the scrollpane is installed
    * on the provided container.
    *
    * @param contentPane The container the tables should get installed on.
    */
    private void putTablesOnContainer(Container contentPane) {
    scrollPane = new JScrollPane(scrollableTable);
    
    scrollPane.setRowHeaderView(fixedTable);
    scrollPane.setCorner(JScrollPane.UPPER_LEFT_CORNER,
    fixedTable.getTableHeader());
    
    //with this line everything is ok:
    contentPane.add(scrollPane);
    }
    
    /* ==================================================================== */
    /**Allows only the selection of one row and synchronizes the selection
    * in both tables. Both tables should be represented to the user as one.
    * Therefore the selection model of the tables must be synchronized.
    */
    private void synchronizeSelection() {
    
    fixedTable
    .getSelectionModel()
    .addListSelectionListener(new ListSelectionListener() {
    public void valueChanged(ListSelectionEvent evt) {
    int selRowIndex;
    
    selRowIndex = fixedTable.getSelectedRow();
    // only one row can be selected
    scrollableTable.setRowSelectionInterval(selRowIndex, selRowIndex);
    fixedTable.setRowSelectionInterval(selRowIndex, selRowIndex);
    }
    });
    
    scrollableTable
    .getSelectionModel()
    .addListSelectionListener(new ListSelectionListener() {
    public void valueChanged(ListSelectionEvent evt) {
    int selRowIndex;
    
    selRowIndex = scrollableTable.getSelectedRow();
    // only one row can be selected
    fixedTable.setRowSelectionInterval(selRowIndex, selRowIndex);
    scrollableTable.setRowSelectionInterval(selRowIndex, selRowIndex);
    }
    });
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see java.awt.Component#getPreferredSize()
    */
    public Dimension getPreferredSize() {
    return scrollPane.getPreferredSize();
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see javax.swing.JComponent#getMaximumSize()
    */
    public Dimension getMaximumSize() {
    return scrollPane.getMaximumSize();
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see javax.swing.JComponent#getMinimumSize()
    */
    public Dimension getMinimumSize() {
    return scrollPane.getMinimumSize();
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see javax.swing.JComponent#setMaximumSize(java.awt.Dimension)
    */
    public void setMaximumSize(Dimension maximumSize) {
    scrollPane.setMaximumSize(maximumSize);
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see javax.swing.JComponent#setMinimumSize(java.awt.Dimension)
    */
    public void setMinimumSize(Dimension minimumSize) {
    scrollPane.setMinimumSize(minimumSize);
    }
    
    /* ==================================================================== */
    /* (non-Javadoc)
    * @see javax.swing.JComponent#setPreferredSize(java.awt.Dimension)
    */
    public void setPreferredSize(Dimension preferredSize) {
    scrollPane.setPreferredSize(preferredSize);
    }
    
    /* ==================================================================== */
    /** The JTable with fixed columns shown on the left. Not horizontally
    scrollable. */
    private JTable fixedTable;
    /** The JTable with horizontally scrollable columns. */
    private JTable scrollableTable;
    /** The JScrollPane the JTables are installed on. */
    private JScrollPane scrollPane;
    /** The sorter for this divided table. */
    private AbstractSortDecorator customSorter = null;
    /** Stores the number of fixed columns on the left. */
    private int fixedColumns;
    }
- 8
  - Back To College Is Here!Big, Big Savings!
    
    College '07. Live. Study. Save. Back To College is one of our largest
    campaigns of the year! Help our customers find the essentials they
    need for college living at unbeatable prices.
    Most See!
    Click: http://ashopper.net
    Donot miss out!
- 8
  - Servlet for Connection Pooling in NetBeans & builtin TomcatHi,
    
    I installed Netbeans 4.0 a few days ago and so far pretty impressed by
    it. Previously I was using Tomat 4.0, and I like the idea of embedded
    Tomcat 5 that can be managed via the IDE. To get things started, I
    followed the article here:
    
    http://www.netbeans.org/kb/using-netbeans/40/dbconn.html
    
    to get a connection pool configured in the included Tomcat 5 web
    server. Everything in the example works great. However, I don't want
    to use the taglibs, and would rather write servlets and beans to do
    the task. I tried following the example listed here:
    http://jakarta.apache.org/tomcat/tomcat-5.0-doc/jndi-datasource-examples-howto.html
    however that doesn't work for me (I get foo -1 or something; basically
    its not working).
    
    So I was wondering if someone could kindly provide me a simple servlet
    that works in the Netbeans IDE so I can simply extend on the tutorial
    here: http://www.netbeans.org/kb/using-netbeans/40/dbconn.html and and
    draw connection from the tomcat 5 connection pool having configured
    everything perfectly in this tutorial. Basically do the same thing as:
    
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
    
    <sql:query var="queryresults" dataSource="jdbc/poolDB">
    SELECT * FROM t_emp ORDER BY upper(f_name)
    </sql:query>
    
    <table border=1>
    <tr>
    <th>First</th><th>Last</th>
    </tr>
    <c:forEach var="row" items="${queryresults.rows}">
    <tr>
    <td><c:out value="${row.f_name}" /></td>
    <td><c:out value="${row.l_name}" /></td>
    </tr>
    </c:forEach>
    </table>
    
    but in a servlet rather than using the tag library.
    
    Very much appreciated!
- 13
  - Binary search Tree:HelpIs this implementation of a binary search tree correct ?
    
    numbers from 0 to 14 arranged in a binary tree (binary search tree). Is
    this correct ? (left node is less, right node is greater than the
    current node)
    
    7
    6 8
    5 9 2 12
    4 10 3 11 1 13 0 14
- 14
  - Anyone using Studio 4 with MSAccess as DBMS?Is anyone using the Studio4 (Community version, Windows NT) IDE for
    building forms using an MS Access database to supply a JTable via
    net.beans palette components (nBCachedRowSet or nJcdbRowSet)? (Using
    the JDBC-ODCB bridge). I can succesfully connect and initialize
    components--can see the tables and columns in the Runtime explorer
    connection--but when I execute the form, all columns are blank.
    
    Also, when GUI editing, if I try to set the TableModel using the
    TableEditor tab and select the nBCachedRowSet component, I get the
    following error: "Unable to fetch columns; SQL-server rejected
    establishment of SQL-connection. PointBase." Why is it still looking
    at Pointbase?
    
    Here's how components are set:
    connectionSource1
    Database URL = jdbc:odbc:IM_EDITOR (this works with MSQuery, so ODBC
    is good)
    Driver = sun.jdbc.odbc.JdbcOdbcDriver (ok here)
    nBCachedRowSet1
    command = select * from IM (this also works in MSQuery)
    Database URL = jdbc:odbc:IM_EDITOR
    jTable1
    selection Model = nBCachedRowSet1
    
    Need more code?
    
    I give up! I really want to use Access for the DBM due to other
    issues, but I am running out of patience!
    TIA
    Frustrated...
    Mark
- 16
  - Resize JSplitPane ContanierHi all,
    
    I want to resize the container which holds JSplitPane. The situation
    is with right button pressed the container should be resized to the
    size of left component of JSplitpane and with left button pressed
    container should be expanded to the size of left component +
    Jsplitpane + right component, unlike the default behaviour of
    JSplitpane. How can i acheive this?
    
    Thanks in advance.
    
    Naveen.
- 16
  - simple STRUTS appi want to realize a simple struts app for creation of polls, can you
    help me with ideas or examples?
    a very very simple app but with "area" containers...and a simple
    graphical representetion of the results...
    
    tnx

Author

Message

Posted: 2005-11-1 21:15:00

Top

java-programmer, servlet and thread i am connecting to a servlet. i am passing some values from JSP to
servlet. the servlet gets those values from JSP by
request.getParameter(). then the servlet creates Threads as much as
values gives to it.

if the servlet is given 3 values from the JSP, then it would create 3
threads to calculate.

if the servlet is given 10 values from the JSP, then it would create 10
threads to calculate.

each Thread would return results to the JSP.

PROBLEM :
=========

how does my JSP would get the results from the threads. JSP would
refresh in 5 secs interval and would display the latest threads result.

Posted: 2005-11-1 21:27:00

Top

java-programmer >> servlet and thread i tried to put a bean in the server-side so that each thread would pour
data into it. but how does JSP would access that bean ? i am
refreshing the JSP in every 5 seconds interval.

i tried bean with static methods. and accessed the bean in my JSP. but
that is producing concurrency problems. (Not all the results are
coming out).

i also tried to put the threads results into session . but that too
also not producing result.

how does my JSP would get the results from the threads ?
please suggest example code.
regards

dnasmars

Posted: 2005-11-3 22:19:00

Top

java-programmer >> servlet and thread gk wrote:
> i tried to put a bean in the server-side so that each thread would pour
> data into it. but how does JSP would access that bean ? i am
> refreshing the JSP in every 5 seconds interval.
>
> i tried bean with static methods. and accessed the bean in my JSP. but
> that is producing concurrency problems. (Not all the results are
> coming out).
>
> i also tried to put the threads results into session . but that too
> also not producing result.
>
>
>
> how does my JSP would get the results from the threads ?
> please suggest example code.
> regards
>
hello,

how about trying to create an instance in the servlet
a sort of threadmanager this instance gets the parameters from
the jsp on one hand create thread instances that do the calculation.
when the thread finishes it returns the result to the threadmanager.
The instance of the threadmanager has to be session scope so that
the jsp each 5 sec can see the results in the threadmanager.

I hope this helps

Index ‹ java-programmer

Next
- 1
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- 4
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- 9
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    the row is deleted in the table "project"
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    Source)
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    Source)
    [java] at sun.java2d.pipe.SpanShapeRenderer
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    Source)
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    [java] at java.awt.event.InvocationEvent.dispatch(Unknown Source)
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- 14
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    public class Axis2420
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    private HttpURLConnection hurlconnection = null;
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    {
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    long before,after;
    
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    i =
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    image = i;
    i = null;
    
    fireChange(); //calls the stateChanged() method in
    the class 'MainProgram' below
    
    image = null;
    i = null;
    
    Thread.currentThread().sleep(10);
    }
    }
    }
    catch(Exception ex)
    {
    ex.printStackTrace();
    }
    finally
    {
    
    try {
    datainstream.close();
    } catch(Exception ex)
    {
    ex.printStackTrace();
    }
    }
    }
    
    //for the listening objects so they can fetch the latest image
    public Image getLatestImage()
    {
    return image;
    }
    
    <....>
    
    }
    
    Once a new image has arrived, the fireChange() method calls this method
    on the MainProgram class:
    
    class MainProgram
    extends JFrame
    implements Runnable,ChangeListener
    {
    public static String WINDOW_TITLE = "BINO GESTENERKENNUNG";
    public static int WINDOW_WIDTH = 640;
    public static int WINDOW_HEIGHT = 480;
    
    public static final int CAMERA_LEFT = 0;
    public static final int CAMERA_RIGHT = 1;
    
    //public static final String leftCameraURL =
    "http://192.168.1.51/axis-cgi/mjpg/video.cgi?resolution=704x576&compression=25&clock=0&date=1&fps=10";
    
    //public static final String rightCameraURL =
    "http://192.168.1.51/axis-cgi/mjpg/video.cgi?resolution=704x576&compression=25&clock=0&date=1&fps=10";
    
    public static final String leftCameraURL =
    "http://192.168.1.51/axis-cgi/mjpg/video.cgi?resolution=352x288&compression=70&date=1&fps=5";
    
    public static final String rightCameraURL =
    "http://192.168.1.51/axis-cgi/mjpg/video.cgi?resolution=352x288&compression=100&date=1&fps=5";
    
    Image currentLeftImage;
    Image currentRightImage;
    
    Graphics leftImageGraphics;
    Graphics rightImageGraphics;
    Graphics leftCameraGraphics;
    Graphics rightCameraGraphics;
    byte[] currentLeftImageJPG;
    byte[] currentRightImageJPG;
    
    BufferedImage testImage;
    
    Axis2420 leftCamera = null;
    Axis2420 rightCamera = null;
    
    CameraCanvas leftCameraCanvas = null;
    CameraCanvas rightCameraCanvas = null;
    
    Runnable drawThread = null;
    boolean readyToDraw = false;
    boolean newImage = false;
    
    long frameRateLeft = 0,frameRateRight = 0;
    long frameTimesLeft[],frameTimesRight[];
    
    //vPointerDetector leftImagePointer;
    //vPointerDetector rightImagePointer;
    vPointerDetector imagePointer;
    
    boolean updateLeftImage,updateRightImage;
    
    <.....lots of meaningless stuff.......>
    
    public void stateChanged(ChangeEvent e)
    {
    
    currentRightImage = rightCamera.getLatestImage();
    
    rightCameraCanvas.SetUpdate(true); //otherwise paintComponent()
    of the JCanvas won't draw the image
    rightCameraCanvas.SetImage(currentRightImage);
    rightCameraCanvas.repaint();
    currentRightImage = null;
    currentRightImageJPG = null;
    }
    }
    
    }
    
    } //end of MainProgram class
    
    Basically, all the stateChange method does is getting the image from the
    image-reading thread ('rightCamera' of type Axis2420) after
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    class CameraCanvas which derieves from JCanvas. After that, we cast
    repaint() on the CameraCanvas (rightCameraCanvas.repaint() ).
    
    This is the CameraCanvas that is responsible for drawing:
    
    public class CameraCanvas extends JPanel
    {
    
    private Image image = null;
    boolean drawNext = false;
    boolean readyForNext;
    
    public void paintComponent(Graphics g)
    {
    if(drawNext == true)
    {
    
    readyForNext =
    g.drawImage(image,0,0,getSize().width,getSize().height,this);
    //image.flush();
    image = null;
    //g.dispose();
    
    //imageBuffered.flush();
    drawNext = false;
    }
    
    }
    
    //indicates that there is a new image
    public void SetUpdate(boolean up)
    {
    drawNext = up;
    }
    
    //passes a new image to the Canvas
    public void SetImage(Image i)
    {
    image = i;
    }
    }
    
    The program draws the stream correctly and is smooth like butter.
    However, there is a HUGE memory leak somewhere that raises the memory
    usage by about 40MBytes per second. If I remove the call to
    
    readyForNext = g.drawImage(image,0,0,getSize().width,getSize().height,this);
    
    in the CameraCanvas thread, the leak will go down to about 40 kbyte /
    second. If I leave it in and post a System.gc() call afterwards, the
    leak will also go down.
    
    I think that I'm somewhat polling the AWTEvent thread which lots of
    copies of images waiting to be drawn. Also using
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    spawns abouth 4 ImageFetcher threads which I think are the reason for
    the small memory leak.
    
    Now the question: What can I do about it?
    
    It seems that the garbage collection isn't called after drawing an image
    and casting it manually via System.gc() slows everything down a lot.
    Using ImageIO.read)() instead of the Toolkit seems to remove the small
    leak, but not the big one for drawing. And it tends to be slower since
    it's blocking and keeping the Axis2420 thread from reading from the stream.
    
    My thesis is due soon, so pleease have a look at it again.!!
    Thanks in advance!!!
- 15
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