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  • What features EJB3 bring and also how does EJB3 stack up with Spring Framework ?

    - by Rachel
    I have never worked on ejb, when I started programming Spring was already arrived and all my projects have been with Spring only, recently I had one interview and they wanted knowledge of EJB3.0 and so I want to know how does EJB3.0 stack up with Spring Framework and why many projects now a day are with Spring Framework and not with EJB3.0, do not quote me here as I can be wrong I would really appreciate if difference and benefits of using one over another could be explained from practical perspective.

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  • How can I set the Jbuttons in a preferred order?

    - by Umzz Mo
    I have a grid of 30 buttons, and I want to have it from left to right then goes down, right to left, down again left to right. Basically the numbering would be as follow: 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28 29 30 So if I have a piece on the button 10 and I instruct it to move up 2 bits it would land on 12 not 19. Below is my Code: //Creates the button using the loop, adds it into the panel and frame. JPanel panel = new JPanel(); panel.setLayout(new GridLayout(3,10)); JButton [] buttons = new JButton[30]; for(int i=0;i<30;i++){ buttons[i] = new JButton("label" + i); buttons[i].setBackground(Color.white); //Puts the player 1 piece on button 1,3,5,7,9 and player 2 piece on button 2,4,6,8,10 if (i < 10) { if (i%2 == 0) { buttons[i].setIcon(piece1); } else { buttons[i].setIcon(piece2); } } panel.add(buttons[i]); } frame.add(panel, BorderLayout.CENTER);

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  • custom ListView --Null pointer exception

    - by raghs
    this code throws a Null pointer exception. It was thrown by getChildAt(i). The getCount() returns the number of items in listView. But getChildAt(i) returns only if item is present in current list view. For example in a scrollable list view assume that there are 20 items. The getCount() returns 20. But getChildAt(20) returns null. Because it doesnot fit in listview. How to solve this problem?? int i,j=object.getCount(); View v=getListView(); CheckBox chk=null; for(i=0;i<j;i++) { chk=((CheckBox)((ViewGroup) v).getChildAt(i).findViewById(R.id.checkBox1)); if(chk.isChecked()) { //download the contents to specific folder in sd card } }

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  • "Change" panel on jframe

    - by bog
    I have 2 panels, the first one is the menu, and the second is the application main panel. Firstly the menu panel shows up, than i need to switch to the other panel if a specific button is pressed on the menu (the menu is hidden but the app returns to it after running is completed). && i need to resize the frame too if it's possible. can i do this somehow?

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  • Should try...catch go inside or outside a loop?

    - by mmyers
    I have a loop that looks something like this: for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } This is the main content of a method whose sole purpose is to return the array of floats. I want this method to return null if there is an error, so I put the loop inside a try...catch block, like this: try { for(int i = 0; i < max; i++) { String myString = ...; float myNum = Float.parseFloat(myString); myFloats[i] = myNum; } } catch (NumberFormatException ex) { return null; } But then I also thought of putting the try...catch block inside the loop, like this: for(int i = 0; i < max; i++) { String myString = ...; try { float myNum = Float.parseFloat(myString); } catch (NumberFormatException ex) { return null; } myFloats[i] = myNum; } So my question is: is there any reason, performance or otherwise, to prefer one over the other? EDIT: The consensus seems to be that it is cleaner to put the loop inside the try/catch, possibly inside its own method. However, there is still debate on which is faster. Can someone test this and come back with a unified answer? (EDIT: did it myself, but voted up Jeffrey and Ray's answers)

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  • JButton and next/previous object of treemap

    - by supacat
    I have this problem: 1) There are objects placed in the TreeMap through the JTextField. (Phonebook-like program). 2)There are buttons that implement view of available records in TreeMap. When you click on these buttons next / previous available objects of TreeMap displaying in JTextField. (scroll through the available records). I tried this code, but I didn't work :/ btn[4].addActionListener(new ActionListener(){ Iterator iter = tree.keySet().iterator(); public void actionPerformed(ActionEvent e) { if (iter.hasNext()){ String str = iter.next().toString(); fldFio.setText(str); fldNumber.setText(tree.get(str)); } } });

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  • 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.

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  • Velocity templates seem to fail with UTF-8

    - by steve
    Hi, i have been trying to use a velocity Template with the following content: Sübjäct $item everything works fine except the translation of the tow unicode characters. The result string printed on the commandline looks like: Sübjäct foo I searched the velocity website and the web an this issue, and came uo with differnt font encoding options, which i added to my code. But those won't help. This is the actuall code: velocity.setProperty("file.resource.loader.path", absPath); velocity.setProperty("input.encoding", "UTF-8"); velocity.setProperty("output.encoding", "UTF-8"); Template t = velocity.getTemplate("subject.vm"); t.setEncoding("UTF-8"); StringWriter sw = new StringWriter(); t.merge(null, sw); System.out.println(sw.getBuffer()); Can anyone give me some hints, how to fix this issue?

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  • Is it possible to establish default values for inherited fields in subclasses?

    - by Christian Mann
    I'm trying to establish a default value for inherited fields from superclasses. So, my class hierarchy is thus: Character - Enemy - Boss                 \                   - Hero Each Character has a public static char avatar to represent him on an ASCII playing field. How do I set a default value for the avatar of each class inherited from Character? Thank you!

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  • Get the screen height in Android

    - by Dan Bray
    How can I get the available height of the screen in Android? I need to the height minus the status bar / menu bar or any other decorations that might be on screen and I need it to work for all devices. Also, I need to know this in the onCreate function. I know this question has been asked before but I have already tried their solutions and none of them work. Here are some of the things I have tried: I have tested this code on API 7 - 17. Unfortunately, on API 13 there is extra space at bottom both horizontally and vertically and on API 10, 8, and 7 there is not enough space at the bottom both horizontally and vertically. (I have not tested on obsolete API's): Display display = getWindowManager().getDefaultDisplay(); DisplayMetrics metrics = new DisplayMetrics(); display.getMetrics(metrics); screenWidth = metrics.widthPixels; screenHeight = metrics.heightPixels; TypedValue tv = new TypedValue(); if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) { if (getTheme().resolveAttribute(android.R.attr.actionBarSize, tv, true)) screenHeight -= TypedValue.complexToDimensionPixelSize(tv.data,getResources().getDisplayMetrics()); } int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android"); if (resourceId > 0) screenHeight -= getResources().getDimensionPixelSize(resourceId); This does not take into account the status bar / menu bar: Display display = getWindowManager().getDefaultDisplay(); screenWidth = display.getWidth(); screenHeight = display.getHeight(); Neither does this: Point size = new Point(); getWindowManager().getDefaultDisplay().getSize(size); screenWidth = size.x; screenHeight = size.y; Nor this: Point size = new Point(); getWindowManager().getDefaultDisplay().getRealSize(size); screenWidth = size.x; screenHeight = size.y; This does not work: Display display = getWindowManager().getDefaultDisplay(); DisplayMetrics metrics = new DisplayMetrics(); display.getMetrics(metrics); // since SDK_INT = 1; screenWidth = metrics.widthPixels; screenHeight = metrics.heightPixels; try { // used when 17 > SDK_INT >= 14; includes window decorations (statusbar bar/menu bar) screenWidth = (Integer) Display.class.getMethod("getRawWidth").invoke(display); screenHeight = (Integer) Display.class.getMethod("getRawHeight").invoke(display); } catch (Exception ignored) { // Do nothing } try { // used when SDK_INT >= 17; includes window decorations (statusbar bar/menu bar) Point realSize = new Point(); Display.class.getMethod("getRealSize", Point.class).invoke(display, realSize); screenWidth = realSize.x; screenHeight = realSize.y; } catch (Exception ignored) { // Do nothing } I then used the following code to subtract the height of the status bar and menu bar from the screen height: int result = 0; int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android"); if (resourceId > 0) result = getResources().getDimensionPixelSize(resourceId); screenHeight -= result; result = 0; if (screenHeight >= screenWidth) resourceId = getResources().getIdentifier("navigation_bar_height", "dimen", "android"); else resourceId = getResources().getIdentifier("navigation_bar_height_landscape", "dimen", "android"); if (resourceId > 0) result = getResources().getDimensionPixelSize(resourceId); screenHeight -= result; On API 17 it correctly calculates the height of the status bar and menu bar in portrait but not in landscape. On API 10, it returns 0. I need it to work ideally on all devices or minimum API 7. Any help would be greatly appreciated.

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  • Question on XJB

    - by Hima
    I have two tables -- INSTALL_BUILD_RESULTS and BUILD_RESULTS. IBR has a primary key called Install_Build_Id and BR has a primary key called Build_Id. Both are numbers A third table, LINK_BUILD_TO_INSTALL_BUILD is a table simply consisting of the two columns mentioned above, used together as a composite key. How can I write an xjb for these 3 tables.

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  • What if I made an explicit reference to 'this' for use inside an inner class?

    - by badp
    So far, I've used this approach to access this from the scope of an inner class: class FooManagementWindow extends JFrame { JButton rejectFoo; //... void getFooAcceptingPanel(){ //... final FooManagementWindow referenceToThis = this; rejectFoo = new JButton("Reject"); rejectFoo.addEventListener(new EventListener() { @Override public void actionPerformed(ActionEvent arg) { referenceToThis.setEnabled(false); //this requires a network call //... referenceToThis.setEnabled(true); //the user may resume his work } }); //... } } However, I just learned that instead of declaring referenceToThis, a direct reference is kept for me as: FooManagementWindow.this I have no reason to think my less standard approach may lead to errors or weird corner cases. Or are there?

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  • Beautify Integer values for comparing as strings

    - by Zahra
    Hi. For some reason I need to enter my integer values to database as string, then I want to run a query on them and compare those integers as strings. Is there any way to beautify integer numbers (between 1 and 1 US billion as an example) so I can compare them as strings? Thanks in advance.

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  • Using an empty column as a divider in a JTable.

    - by Catalina Island
    I'm trying to use an empty column as a divider between pairs of columns in a JTable. Here's a picture and code for what I have so far. I know I can change the look using a custom TableCellRenderer. Before I go down that road, is there a better way to do this? Any ideas appreciated. import javax.swing.*; import javax.swing.table.*; public class TablePanel extends JPanel { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { JFrame f = new JFrame("TablePanel"); f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); f.add(new TablePanel()); f.pack(); f.setVisible(true); } }); } public TablePanel() { TableModel dataModel = new MyModel(); JTable table = new JTable(dataModel); table.getColumnModel().getColumn(MyModel.DIVIDER).setMaxWidth(0); JScrollPane jsp = new JScrollPane(table); jsp.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); this.add(jsp); } private static class MyModel extends AbstractTableModel { private static final int DIVIDER = 2; private final String[] names = { "A1", "A2", "", "B1", "B2" }; @Override public int getRowCount() { return 32; } @Override public int getColumnCount() { return names.length; } @Override public String getColumnName(int col) { if (col == DIVIDER) return ""; return names[col]; } @Override public Object getValueAt(int row, int col) { if (col == DIVIDER) return ""; return (row + 1) / 10.0; } @Override public Class<?> getColumnClass(int col) { if (col == DIVIDER) return String.class; return Number.class; } } }

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  • Error when running a basic Hadoop code

    - by Abhishek Shivkumar
    I am running a hadoop code that has a partitioner class inside the job. But, when I run the command hadoop jar Sort.jar SecondarySort inputdir outputdir I am getting a runtime error that says class KeyPartitioner not org.apache.hadoop.mapred.Partitioner. I have ensured that the KeyPartitioner class has extended the Partitioner class, but why am I getting this error? Here is the driver code: JobConf conf = new JobConf(getConf(), SecondarySort.class); conf.setJobName(SecondarySort.class.getName()); conf.setJarByClass(SecondarySort.class); conf.setInputFormat(TextInputFormat.class); conf.setOutputFormat(TextOutputFormat.class); conf.setMapOutputKeyClass(StockKey.class); conf.setMapOutputValueClass(Text.class); conf.setPartitionerClass((Class<? extends Partitioner<StockKey, DoubleWritable>>) KeyPartitioner.class); conf.setMapperClass((Class<? extends Mapper<LongWritable, Text, StockKey, DoubleWritable>>) StockMapper.class); conf.setReducerClass((Class<? extends Reducer<StockKey, DoubleWritable, Text, Text>>) StockReducer.class); and here is the code of the partitioner class: public class KeyPartitioner extends Partitioner<StockKey, Text> { @Override public int getPartition(StockKey arg0, Text arg1, int arg2) { int partition = arg0.name.hashCode() % arg2; return partition; } }

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  • Loading GWT Messages from a Database

    - by Lars Tackmann
    In GWT one typically loads i18n strings using a interface like this: public interface StatusMessage extends Messages { String error(String username); : } which then loads the actual strings from a StatusMessage.property file: error=User: {0} does not have access to resource This is a great solution, however my client is unbendable in his demand for putting the i18n strings in a database so they can be changed at runtime (though its not a requirement that they be changed realtime). One solution is to create a async service which takes a message ID and user locale and returns a string. I have implemented this and find it terribly ugly (and it introduces a huge amount of extra communication with the server, plus it makes property placeholder replacement rather complicated). So my question is this, can I in some nice way implement a custom message provider that loads the messages from the backend in one big swoop (for the current user session). If it can also hook into the default GWT message mechanism, then I would be completely happy (i.e. so I can create a interface like above and keep using the the nice {0}, {1}... property replacement format). Other suggestions for clean database driven messages in GWT are also welcome.

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  • swing layout: vertical flow

    - by pstanton
    Hi All, What LayoutManager should I use to achieve a transposed version of FlowLayout? Essentially, I want a vertical list which occupies multiple columns if it can't fit all of it's components within one column. +------------------------+ | item 1 | | item 2 | | item 3 | | item 4 | | item 5 | | item 6 | | item 7 | | item 8 | +------------------------+ or +------------------------+ | item 1 item 7 | | item 2 item 8 | | item 3 | | item 4 | | item 5 | | item 6 | +------------------------+

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  • Trying to packetize TCP with non-blocking IO is hard! Am I doing something wrong?

    - by Ricket
    Oh how I wish TCP was packet-based like UDP is! But alas, that's not the case, so I'm trying to implement my own packet layer. Here's the chain of events so far (ignoring writing packets) Oh, and my Packets are very simply structured: two unsigned bytes for length, and then byte[length] data. (I can't imagine if they were any more complex, I'd be up to my ears in if statements!) Server is in an infinite loop, accepting connections and adding them to a list of Connections. PacketGatherer (another thread) uses a Selector to figure out which Connection.SocketChannels are ready for reading. It loops over the results and tells each Connection to read(). Each Connection has a partial IncomingPacket and a list of Packets which have been fully read and are waiting to be processed. On read(): Tell the partial IncomingPacket to read more data. (IncomingPacket.readData below) If it's done reading (IncomingPacket.complete()), make a Packet from it and stick the Packet into the list waiting to be processed and then replace it with a new IncomingPacket. There are a couple problems with this. First, only one packet is being read at a time. If the IncomingPacket needs only one more byte, then only one byte is read this pass. This can of course be fixed with a loop but it starts to get sorta complicated and I wonder if there is a better overall way. Second, the logic in IncomingPacket is a little bit crazy, to be able to read the two bytes for the length and then read the actual data. Here is the code, boiled down for quick & easy reading: int readBytes; // number of total bytes read so far byte length1, length2; // each byte in an unsigned short int (see getLength()) public int getLength() { // will be inaccurate if readBytes < 2 return (int)(length1 << 8 | length2); } public void readData(SocketChannel c) { if (readBytes < 2) { // we don't yet know the length of the actual data ByteBuffer lengthBuffer = ByteBuffer.allocate(2 - readBytes); numBytesRead = c.read(lengthBuffer); if(readBytes == 0) { if(numBytesRead >= 1) length1 = lengthBuffer.get(); if(numBytesRead == 2) length2 = lengthBuffer.get(); } else if(readBytes == 1) { if(numBytesRead == 1) length2 = lengthBuffer.get(); } readBytes += numBytesRead; } if(readBytes >= 2) { // then we know we have the entire length variable // lazily-instantiate data buffers based on getLength() // read into data buffers, increment readBytes // (does not read more than the amount of this packet, so it does not // need to handle overflow into the next packet's data) } } public boolean complete() { return (readBytes > 2 && readBytes == getLength()+2); } Basically I need feedback on my code. Please suggest any improvements. Even overhauling my entire system would be okay, if you have suggestions for how better to implement the whole thing. Book recommendations are welcome too; I love books. I just get the feeling that something isn't quite right.

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  • Wait between tasks with SingleThreadExecutor

    - by Lord.Quackstar
    I am trying to (simply) make a blocking thread queue, where when a task is submitted the method waits until its finished executing. The hard part though is the wait. Here's my 12:30 AM code that I think is overkill: public void sendMsg(final BotMessage msg) { try { Future task; synchronized(msgQueue) { task = msgQueue.submit(new Runnable() { public void run() { sendRawLine("PRIVMSG " + msg.channel + " :" + msg.message); } }); //Add a seperate wait so next runnable doesn't get executed yet but //above one unblocks msgQueue.submit(new Runnable() { public void run() { try { Thread.sleep(Controller.msgWait); } catch (InterruptedException e) { log.error("Wait to send message interupted", e); } } }); } //Block until done task.get(); } catch (ExecutionException e) { log.error("Couldn't schedule send message to be executed", e); } catch (InterruptedException e) { log.error("Wait to send message interupted", e); } } As you can see, there's alot of extra code there just to make it wait 1.7 seconds between tasks. Is there an easier and cleaner solution out there or is this it?

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