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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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  • JPanels, JFrames, and Windows, Oh my!

    - by Jonathan
    Simply stated, I am trying to make a game I am working on full-screen. I have the following code I am trying to use: GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); GraphicsDevice gs = ge.getDefaultScreenDevice(); if(!gs.isFullScreenSupported()) { System.out.println("full-screen not supported"); } Frame frame = new Frame(gs.getDefaultConfiguration()); Window win = new Window(frame); try { // Enter full-screen mode gs.setFullScreenWindow(win); win.validate(); } Problem with this is that I am working within a class that extends JPanel, and while I have a variable of type Frame, I have none of type Window within the class. My understanding of JPanel is that it is a Window of sorts, but I cannot pass 'this' into gs.setFullScreenWindow(Window win)... How should I go about doing this? Is there any easy way of calling that, or a similar method, using a JPanel? Is there a way I can get something of type Window from my JPanel? - EDIT: The following method changes the state of JFrame and is called every 10ms: public void paintScreen() { Graphics g; try{ g = this.getGraphics(); //get Panel's graphic context if(g == null) { frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setExtendedState(frame.getExtendedState()|JFrame.MAXIMIZED_BOTH); frame.add(this); frame.pack(); frame.setResizable(false); frame.setTitle("Game Window"); frame.setVisible(true); } if((g != null) && (dbImage != null)) { g.drawImage(dbImage, 0, 0, null); } Toolkit.getDefaultToolkit().sync(); //sync the display on some systems g.dispose(); } catch (Exception e) { if(blockError) { blockError = false; } else { System.out.println("Graphics context error: " + e); } } } I anticipate that there may be a few redundancies or unnecessary calls after the if(g==null) statement (all the frame.somethingOrOther()s), any cleanup advice would be appreciated... Also, the block error is what it seems. I am ignoring an error. The error only occurs once, and this works fine when setup to ignore the first instance of the error... For anyone interested I can post additional info there if anyone wants to see if that block can be removed, but i'm not concerned... I might look into it later.

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  • 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?

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  • Is it OK to write a constructor which does nothing?

    - by Roman
    To use methods of a class I need to instantiate a class. At the moment the class has not constructor (so I want to write it). But than I have realized that the constructor should do nothing (I do need to specify values of fields). In this context I have a question if it is OK to write constructor which does nothing. For example: public Point() { }

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  • What is the fastest findByName query with hibernate?

    - by Karussell
    I am sure I can improve the performance of the following findByName query of hibernate: public List<User> findByName(String name) { session.createCriteria(User.class).add(Restrictions.eq("name", name)).list(); } In which way should I improve it or even more important: in which ways should I improve it first? I will need the full object with all the collections (layz or not) and deps of this class.

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  • Passing information between test methods in a junit testcase

    - by Jijoy
    Hi, Currently I am creating a TestCase for one work flow and a workflow have different steps. The results of one step is important since , second step needs to know value of step1's execution. class TestCaseWorkFlow1 extends TestCase { private static String resultOfStep1 = null; public void testStep1(){ if(failed){ resultOfStep1 = "failed"; } } public void testStep2(){ if(resultOfStep1 != null ) { //First test failed. }else { } } } Currently we are using static variable to pass information between testmethods . What is the best solution for this scenario ? Please help. Thanks J

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  • Generating different randoms valid for a day on different independent devices?

    - by Pentium10
    Let me describe the system. There are several mobile devices, each independent from each other, and they are generating content for the same record id. I want to avoid generating the same content for the same record on different devices, for this I though I would use a random and make it so too cluster the content pool based on these randoms. Suppose you have choices from 1 to 100. Day 1 Device#1 will choose for the record#33 between 1-10 Device#2 will choose for the record#33 between 40-50 Device#3 will choose for the record#33 between 50-60 Device#1 will choose for the record#55 between 40-50 Device#2 will choose for the record#55 between 1-10 Device#3 will choose for the record#55 between 10-20 Device#1 will choose for the record#11 between 1-10 Device#2 will choose for the record#22 between 1-10 Device#3 will choose for the record#99 between 1-10 Day 2 Device#1 will choose for the record#33 between 90-100 Device#2 will choose for the record#33 between 1-10 Device#3 will choose for the record#33 between 50-60 They don't have access to a central server. Data available for each of them: IMEI (unique per mobile) Date of today (same on all devices) Record id (same on all devices) What do you think, how is it possible? ps. tags can be edited

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  • 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()?

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  • [Android] XML Parser

    - by lemon
    I'm trying to extract n0Y7ezLlIYA8R0K54rEmHaTOraBQVSPDjQaGlQxlGso4jdVN1kRxtcfskEs= using w3c dom <html> <div id='token' style='display:none;'> n0Y7ezLlIYA8R0K54rEmHaTOraBQVSPDjQaGlQxlGso4jdVN1kRxtcfskEs= </div> </html> but I seem to be stuck DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(con.getInputStream()); NodeList list = doc.getElementsByTagName("div"); Can someone please point me to some basic tutorials that would help me solve my dilemma. Thanks.

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  • MD5 and Hibernate Query

    - by theJava
    public Login authenticate(Login login) { String query = "SELECT L FROM Login AS L WHERE L.email=? AND L.password=?"; Object[] parameters = { login.getEmail(), login.getPassword() }; List<Login> resultsList = (getHibernateTemplate().find(query,parameters)); if (resultsList.isEmpty()) { //error dude } else if (resultsList.size() > 1) { //throw expections } else { Login login1 = (Login) resultsList.get(0); return login1; } return null; } I have my DB tables password col set as MD5, now how to retrieve it back here.

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  • OSGi bundle imports packages from non-bundle jars: create bundles for them?

    - by John Simmons
    I am new to OSGi, and am using Equinox. I have done several searches and can find no answer to this. The discussion at OSGI - handling 3rd party JARs required by a bundle helps somewhat, but does not fully answer my question. I have obtained a jar file, rabbitmq-client.jar, that is already packaged as an OSGi bundle (with Bundle-Name and other such properties in its MANIFEST.MF), that I would like to install as a bundle. This jar imports packages org.apache.commons.io and org.apache.commons.io.input from commons-io-1.2.jar. The RabbitMQ client 2.7.1 distribution also includes commons-cli-1.1.jar, so I presume that it is required as well. I examined the manifests of these commons jars and found that they do not appear to be packaged as bundles. That is, their manifests have none of the standard bundle properties. My specific question is: if I install rabbitmq-client.jar as a bundle, what is the proper way to get access to the packages that it needs to import from the commons jars? There are only three alternatives that I can think of, without rebuilding rabbitmq-client.jar. The packages from the commons jars are already included in the Equinox global classpath, and rabbitmq-client.jar will get them automatically from there. I must make another bundle with the two commons jars, export the needed packages, and install that bundle in Equinox. I must put these two commons jars in the global classpath when I start Equinox, and they will be available to rabbitmq-client.jar from there. I have read that one normally does not use the global classpath in an OSGi container. I am not clear on whether items from the global classpath are even available when building individual bundle classpaths. However, I note that rabbitmq-client.jar also imports other packages such as javax.net, which I presume come from the global classpath. Or is there some other bundle that exports them? Thanks for any assistance!

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  • How can I force the server socket to re-accept a request from a client?

    - by Roman
    For those who does not want to read a long question here is a short version: A server has an opened socket for a client. The server gets a request to open a socket from the same client-IP and client-port. I want to fore the server not to refuse such a request but to close the old socket and open a new one. How can I do ti? And here is a long (original) question: I have the following situation. There is an established connection between a server and client. Then an external software (Bonjour) says to my client the it does not see the server in the local network. Well, client does nothing about that because of the following reasons: If Bonjour does not see the server it does not necessarily means that client cannot see the server. Even if the client trusts the Bonjour and close the socket it does not improve the situation ("to have no open socket" is worser that "to have a potentially bad socket"). So, client do nothing if server becomes invisible to Bonjour. But than the server re-appears in the Bonjour and Bonjour notify the client about that. In this situation the following situations are possible: The server reappears on a new IP address. So, the client needs to open a new socket to be able to communicate with the server. The server reappears on the old IP address. In this case we have two subcases: 2.1. The server was restarted (switched off and then switched on). So, it does not remember the old socket (which is still used by the client). So, client needs to close the old socket and open a new one (on the same server-IP address and the same server-port). 2.2. We had a temporal network problem and the server was running the whole time. So, the old socket is still available for the use. In this case the client does not really need to close the old socket and reopen a new one. But to simplify my life I decide to close and reopen the socket on the client side in any case (in spite on the fact that it is not really needed in the last described situation). But I can have problems with that solution. If I close the socket on the client side and than try to reopen a socket from the same client-IP and client-port, server will not accept the call for a new socket. The server will think that such a socket already exists. Can I write the server in such a way, that it does not refuse such calls. For example, if it (the server) sees that a client send a request for a socket from the same client-IP and client-port, it (server) close the available socket, associated with this client-IP and client-port and than it reopens a new socket.

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  • Does <T> need to be imported as a class for this to work?

    - by zxc
    In order for this to work, do you have to have an import statement for the T class? private static <T> void invertOrdering(List<T> list) { for (int i = 0; i < list.size() / 2; i++) { int j = list.size() - 1 - i; T item1 = list.get(i); T item2 = list.get(j); list.set(i, item2); list.set(j, item1); } }

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  • need an empty XML while unmarshalling a JAXB annotated class

    - by sswdeveloper
    I have a JAXB annotated class Customer as follows @XmlRootElement(namespace = "http://www.abc.com/customer") public class Customer{ private String name; private Address address; @XmlTransient private HashSet set = new HashSet<String>(); public String getName(){ return name; } @XmlElement(name = "Name", namespace = "http://www.abc.com/customer" ) public void setName(String name){ this.name = name; set.add("name"); } public String getAddress(){ return address; } @XmlElement(name = "Address", namespace = "http://www.abc.com/customer") public void setAddress(Address address){ this.address = address; set.add("address"); } public HashSet getSet(){ return set; } } I need to return an empty XML representing this to the user, so that he may fill the necesary values in the XML and send a request So what I require is : <Customer> <Name></Name> <Address></Address> </Customer> If i simply create an empty object Customer cust = new Customer() ; marshaller.marshall(cust,sw); all I get is the toplevel element since the other fields of the class are unset. What can I do to get such an empty XML? I tried adding the nillable=true annotation to the elements however, this returns me an XML with the xsi:nil="true" which then causes my unmarshaller to ignore this. How do I achieve this?

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  • FileConnection Blackberry memory usage

    - by Dean
    Hello, I'm writing a blackberry application that reads ints and strings out of a database. This is my first time dealing with reading/writing on the blackberry, so forgive me if this is a dumb question. The database file I'm reading is only about 4kB I open the file with the following code fconn = (FileConnection) Connector.open("file_path_here", Connector.READ); if(fconn.exists()==false){fconn.close();return;} is = fconn.openDataInputStream(); while(!eof){ //etc... } is.close(); fconn.close(); The problem is, this code appears to be eating a LOT of memory. Using breakpoints and the "Memory Statistics" view, I determined the following: calling "Connector.open" creates 71 objects and changes "RAM Bytes in use" by 5376 calling "fconn.openDataInputStream();" increases RAM usage by a whopping 75920 Is this normal? Or am I doing something wrong? And how can I fix this? 75MB of RAM is a LOT of memory to waste on a handheld device, especially when the file I'm reading is only 4kB and I haven't even begun reading any data! How is this even possible?

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  • Creating a fancy search bar with Swing components

    - by Kavon Farvardin
    I'm trying to come up with an elegant recreation of the search bar component in Thunderbird. The clear button doesn't appear until there is text in the box, so that screen-shot is a bit inaccurate. Should I use a layered pane and get some buttons to float above the box? (but then getting the text to not appear below the buttons would be hacky) Maybe just put buttons at the ends of the search bar and have it somehow blend in? Any ideas or maybe a style reconsideration is welcome, thank you.

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  • Draw Circle on the Map once the application gets loaded

    - by TechGeeky
    Background:- In my application what is happening currently- Whenever I am opening the application, In the top half of the android screen, it draws a Map and in the bottom half of the android screen it show's a list view. And then as soon as the location gets changed, it draw's a Circle with the current location as the center of the circle and show's an image at the current location(center of circle). Everything is working fine till here- Problem Statement:- What I want is when the user opens my application, circle should get draw immediately on the Google Map (this is currently not happening, it draw's circle only on the location changed), without waiting for the location to get changed and without any image on the center of circle and then if the location get's changed, take the current location as the center of circle and draw the circle with an image at the center of circle. And this is my below code which fulfills the scenario that I mentioned in my Background- How can I make this code to work the way I wanted to? hope I am clear enough in my question. Any suggestions will be appreciated. @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mapView = (MapView) findViewById(R.id.mapView); listView = (ListView) findViewById(R.id.mylist); locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); locationListener = new GPSLocationListener(mapView); locationManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 35000, 10, locationListener); mapView.setStreetView(true); mapView.setBuiltInZoomControls(true); mapController = mapView.getController(); mapController.setZoom(14); } Location Update class where I am sending the request to Overlay to draw the circle private class GPSLocationListener implements LocationListener { MapOverlay mapOverlay; public GPSLocationListener(MapView mapView) { } @Override public void onLocationChanged(Location location) { if (location != null) { GeoPoint point = new GeoPoint( (int) (location.getLatitude() * 1E6), (int) (location.getLongitude() * 1E6)); mapController.animateTo(point); mapController.setZoom(15); if (mapOverlay == null) { mapOverlay = new MapOverlay(this,android.R.drawable.star_on); List<Overlay> listOfOverlays = mapView.getOverlays(); listOfOverlays.add(mapOverlay); } mapOverlay.setPointToDraw(point); mapView.invalidate(); } } @Override public void onProviderDisabled(String provider) { } @Override public void onProviderEnabled(String provider) { } @Override public void onStatusChanged(String provider, int status, Bundle extras) { } } Class in which circle is getting drawn. class MapOverlay extends Overlay { private GeoPoint pointToDraw; int[] imageNames=new int[6]; private Point mScreenPoints; private Bitmap mBitmap; private Paint mCirclePaint; public MapOverlay(GPSLocationListener gpsLocationListener, int currentUser) { imageNames[0]=currentUser; mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG); mCirclePaint.setColor(0x30000000); mCirclePaint.setStyle(Style.FILL_AND_STROKE); mBitmap = BitmapFactory.decodeResource(getResources(),imageNames[0]); mScreenPoints = new Point(); } public void setPointToDraw(GeoPoint point) { pointToDraw = point; } public GeoPoint getPointToDraw() { return pointToDraw; } @Override public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) { super.draw(canvas, mapView, shadow); if (pointToDraw == null) { return true; } mScreenPoints = mapView.getProjection().toPixels(pointToDraw, mScreenPoints); int totalCircle=5; int radius=40; int centerimagesize=35; for (int i = 1; i <= totalCircle; i ++) { canvas.drawCircle(mScreenPoints.x,mScreenPoints.y, i*radius, mCirclePaint); } canvas.drawBitmap(mBitmap, (mScreenPoints.x-(centerimagesize/2)),(mScreenPoints.y-(centerimagesize/2)), null); super.draw(canvas,mapView,shadow); return true; } }

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