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  • Pattern for database-wrapper in java

    - by Space_C0wb0y
    I am currently writing a java-class that wraps an SQLite database. This class has two ways to be instantiated: Open an existing database. Create a new database. This is what I cam up with: public class SQLiteDatabaseWrapper { public static SQLiteDatabaseWrapper openExisting(File PathToDB) { return new SQLiteDatabaseWrapper(PathToDB); } public static SQLiteDatabaseWrapper createNew(File PathToDB) { CreateAndInitializeNewDatabase(PathToDB); return new SQLiteDatabaseWrapper(PathToDB); } private SQLiteDatabaseWrapper(File PathToDB) { // Open connection and setup wrapper } } Is this the way to go in Java, or is there any other best practice for this situation?

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  • Using external SOAP service in Workflow service

    - by whirlwin
    I am using the .NET 4 framework and have made a WCF Workflow Service Application. I want to use a SOAP web service (.NET 3.5) I have running in another instance of VS. The only method that is exposed is the following: [WebMethod] public string Reverse(string input) { char[] chars = input.ToCharArray(); Array.Reverse(chars); return new string(chars); } I have used the following steps to add the service in my Workflow: Add Service Reference Provided the WSDL (the operation shows in the Operations box as expected) Clicked OK Build the solution to ensure that the service shows in my toolbox Drag the service from the toolbox into the workflow However, when I look at the properties of the service in the workflow, there is no way to specify the input argument or where to store the result of the invocation of the service. I only have the option of specifying some obscure parameters such as Body:InArgument<ReverseRequestBody and outBody:OutArgument<ReverseResponseBody (none of which are strings). Here is a screenshot depicting the properties of the service in the workflow: My question is therefore: Is it possible at all to use the SOAP service by specifying a string as the input argument (like it is meant to be used), and also assign the result to a workflow variable?

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  • google calendar api (java) authentication error in dynamic web project

    - by HazProblem
    org.springframework.web.util.NestedServletException: Handler processing failed; nested exception is java.lang.NoClassDefFoundError: com/google/gdata/util/AuthenticationException org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:823) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644) org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560) javax.servlet.http.HttpServlet.service(HttpServlet.java:641) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) The class i have written works fine as a normal java application, but when i try to use the code in an dynamic web project i get this authentication failure. Where´s the difference?

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  • class hierarchy design for small java project

    - by user523956
    I have written a java code which does following:- Main goal is to fetch emails from (inbox, spam) folders and store them in database. It fetches emails from gmail,gmx,web.de,yahoo and Hotmail. Following attributes are stored in mysql database. Slno, messagedigest, messageid, foldername, dateandtime, receiver, sender, subject, cc, size and emlfile. For gmail,gmy and web.de, I have used javamail API, because email form it can be fetched with IMAP. For yahoo and hotmail, I have used html parser and httpclient to fetch emails form spam folder and for inbox folder, I have used pop3 javamail API. I want to have proper class hierarchy which makes my code efficient and easily reusable. As of now I have designed class hierarchy as below: I am sure it can still be improved. So I would like to have different opinions on it. I have following classes and methods as of now. MainController:- Here I pass emailid, password and foldername from which emails have to be fetched. Abstract Class :-EmailProtocol Abstract Methods of it (All methods except executeParser contains method definition):- connectImap() // used by gmx,gmail and web.de email ids connectPop3() // used by hotmail and yahoo to fetch emails of inbox folder createMessageDigest // used by every email provider(gmx, gmail,web.de,yahoo,hotmail) establishDBConnection // used by every email emailAlreadyExists // used by every email which checks whether email already exists in db or not, if not then store it. storeemailproperties // used by every email to store emails properties to mysql database executeParser // nothing written in it. Overwridden and used by just hotmail and yahoo to fetch emails form spam folder. Imap extends EmailProtocol (nothing in it. But I have to have it to access methods of EmailProtocol. This is used to fetch emails from gmail,gmx and web.de) I know this is really a bad way but don't know how to do it other way. Hotmsil extends EmailProtocol Methods:- executeParser() :- This is used by just hotmail email id. fetchjunkemails() :- This is also very specific for only hotmail email id. Yahoo extends EmailProtocol Methods:- executeParser() storeEmailtotemptable() MoveEmailtoInbox() getFoldername() nullorEquals() All above methods are specific for yahoo email id. public DateTimeFormat(class) format() //this formats datetime of gmax,gmail and web.de emails. formatYahoodate //this formats datetime of yahoo email. formatHotmaildate // this formats datetime of hotmail email. public StringFormat ConvertStreamToString() // Accessed by every class except DateTimeFormat class. formatFromTo() // Accessed by every class except DateTimeFormat class. public Class CheckDatabaseExistance public static void checkForDatabaseTablesAvailability() (This method checks at the beginnning whether database and required tables exist in mysql or not. if not it creates them) Please see code of my MainController class so that You can have an idea about how I use different classes. public class MainController { public static void main(String[] args) throws Exception { ArrayList<String> web_de_folders = new ArrayList<String>(); web_de_folders.add("INBOX"); web_de_folders.add("Unbekannt"); web_de_folders.add("Spam"); web_de_folders.add("OUTBOX"); web_de_folders.add("SENT"); web_de_folders.add("DRAFTS"); web_de_folders.add("TRASH"); web_de_folders.add("Trash"); ArrayList<String> gmx_folders = new ArrayList<String>(); gmx_folders.add("INBOX"); gmx_folders.add("Archiv"); gmx_folders.add("Entwürfe"); gmx_folders.add("Gelöscht"); gmx_folders.add("Gesendet"); gmx_folders.add("Spamverdacht"); gmx_folders.add("Trash"); ArrayList<String> gmail_folders = new ArrayList<String>(); gmail_folders.add("Inbox"); gmail_folders.add("[Google Mail]/Spam"); gmail_folders.add("[Google Mail]/Trash"); gmail_folders.add("[Google Mail]/Sent Mail"); ArrayList<String> pop3_folders = new ArrayList<String>(); pop3_folders.add("INBOX"); CheckDatabaseExistance.checkForDatabaseTablesAvailability(); EmailProtocol imap = new Imap(); System.out.println("CHECKING FOR NEW EMAILS IN WEB.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", web_de_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMX.DE...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmx_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN GMAIL...(IMAP)"); System.out.println("*********************************************************************************"); imap.connectImap("[email protected]", "pwd", gmail_folders); EmailProtocol yahoo = new Yahoo(); Yahoo y=new Yahoo(); System.out.println("\nEXECUTING YAHOO PARSER"); System.out.println("*********************************************************************************"); y.executeParser("http://de.mc1321.mail.yahoo.com/mc/welcome?ymv=0","[email protected]","pwd"); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF YAHOO (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); System.out.println("\nCHECKING FOR NEW EMAILS IN INBOX OF HOTMAIL (POP3)"); System.out.println("*********************************************************************************"); yahoo.connectPop3("[email protected]","pwd",pop3_folders); EmailProtocol hotmail = new Hotmail(); Hotmail h=new Hotmail(); System.out.println("\nEXECUTING HOTMAIL PARSER"); System.out.println("*********************************************************************************"); h.executeParser("https://login.live.com/ppsecure/post.srf","[email protected]","pwd"); } } I have kept DatetimeFormat and StringFormat class public so that I can access its public methods by just (DatetimeFormat.formatYahoodate for e.g. from different methods). This is the first time I have developed something in java. It serves its purpose but of course code is still not so efficient I think. I need your suggestions on this project.

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  • Java collision detection and player movement: tips

    - by Loris
    I have read a short guide for game develompent (java, without external libraries). I'm facing with collision detection and player (and bullets) movements. Now i put the code. Most of it is taken from the guide (should i link this guide?). I'm just trying to expand and complete it. This is the class that take care of updates movements and firing mechanism (and collision detection): public class ArenaController { private Arena arena; /** selected cell for movement */ private float targetX, targetY; /** true if droid is moving */ private boolean moving = false; /** true if droid is shooting to enemy */ private boolean shooting = false; private DroidController droidController; public ArenaController(Arena arena) { this.arena = arena; this.droidController = new DroidController(arena); } public void update(float delta) { Droid droid = arena.getDroid(); //droid movements if (moving) { droidController.moveDroid(delta, targetX, targetY); //check if arrived if (droid.getX() == targetX && droid.getY() == targetY) moving = false; } //firing mechanism if(shooting) { //stop shot if there aren't bullets if(arena.getBullets().isEmpty()) { shooting = false; } for(int i = 0; i < arena.getBullets().size(); i++) { //current bullet Bullet bullet = arena.getBullets().get(i); System.out.println(bullet.getBounds()); //angle calculation double angle = Math.atan2(bullet.getEnemyY() - bullet.getY(), bullet.getEnemyX() - bullet.getX()); //increments x and y bullet.setX((float) (bullet.getX() + (Math.cos(angle) * bullet.getSpeed() * delta))); bullet.setY((float) (bullet.getY() + (Math.sin(angle) * bullet.getSpeed() * delta))); //collision with obstacles for(int j = 0; j < arena.getObstacles().size(); j++) { Obstacle obs = arena.getObstacles().get(j); if(bullet.getBounds().intersects(obs.getBounds())) { System.out.println("Collision detect!"); arena.removeBullet(bullet); } } //collisions with enemies for(int j = 0; j < arena.getEnemies().size(); j++) { Enemy ene = arena.getEnemies().get(j); if(bullet.getBounds().intersects(ene.getBounds())) { System.out.println("Collision detect!"); arena.removeBullet(bullet); } } } } } public boolean onClick(int x, int y) { //click on empty cell if(arena.getGrid()[(int)(y / Arena.TILE)][(int)(x / Arena.TILE)] == null) { //coordinates targetX = x / Arena.TILE; targetY = y / Arena.TILE; //enables movement moving = true; return true; } //click on enemy: fire if(arena.getGrid()[(int)(y / Arena.TILE)][(int)(x / Arena.TILE)] instanceof Enemy) { //coordinates float enemyX = x / Arena.TILE; float enemyY = y / Arena.TILE; //new bullet Bullet bullet = new Bullet(); //start coordinates bullet.setX(arena.getDroid().getX()); bullet.setY(arena.getDroid().getY()); //end coordinates (enemie) bullet.setEnemyX(enemyX); bullet.setEnemyY(enemyY); //adds bullet to arena arena.addBullet(bullet); //enables shooting shooting = true; return true; } return false; } As you can see for collision detection i'm trying to use Rectangle object. Droid example: import java.awt.geom.Rectangle2D; public class Droid { private float x; private float y; private float speed = 20f; private float rotation = 0f; private float damage = 2f; public static final int DIAMETER = 32; private Rectangle2D rectangle; public Droid() { rectangle = new Rectangle2D.Float(x, y, DIAMETER, DIAMETER); } public float getX() { return x; } public void setX(float x) { this.x = x; //rectangle update rectangle.setRect(x, y, DIAMETER, DIAMETER); } public float getY() { return y; } public void setY(float y) { this.y = y; //rectangle update rectangle.setRect(x, y, DIAMETER, DIAMETER); } public float getSpeed() { return speed; } public void setSpeed(float speed) { this.speed = speed; } public float getRotation() { return rotation; } public void setRotation(float rotation) { this.rotation = rotation; } public float getDamage() { return damage; } public void setDamage(float damage) { this.damage = damage; } public Rectangle2D getRectangle() { return rectangle; } } For now, if i start the application and i try to shot to an enemy, is immediately detected a collision and the bullet is removed! Can you help me with this? If the bullet hit an enemy or an obstacle in his way, it must disappear. Ps: i know that the movements of the bullets should be managed in another class. This code is temporary. update I realized what happens, but not why. With those for loops (which checks collisions) the movements of the bullets are instantaneous instead of gradual. In addition to this, if i add the collision detection to the Droid, the method intersects returns true ALWAYS while the droid is moving! public void moveDroid(float delta, float x, float y) { Droid droid = arena.getDroid(); int bearing = 1; if (droid.getX() > x) { bearing = -1; } if (droid.getX() != x) { droid.setX(droid.getX() + bearing * droid.getSpeed() * delta); //obstacles collision detection for(Obstacle obs : arena.getObstacles()) { if(obs.getRectangle().intersects(droid.getRectangle())) { System.out.println("Collision detected"); //ALWAYS HERE } } //controlla se è arrivato if ((droid.getX() < x && bearing == -1) || (droid.getX() > x && bearing == 1)) droid.setX(x); } bearing = 1; if (droid.getY() > y) { bearing = -1; } if (droid.getY() != y) { droid.setY(droid.getY() + bearing * droid.getSpeed() * delta); if ((droid.getY() < y && bearing == -1) || (droid.getY() > y && bearing == 1)) droid.setY(y); } }

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  • JMS MQ Connection closed in JSF 2 SessionBean

    - by veote
    I use Websphere Application Server 8 with MQ Series as Messaging Queue. When I open close the connection in sessionbean in a "postConstruct" method and I use it in another method then its closed. My Code is: import java.io.Serializable; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import javax.annotation.Resource; import javax.faces.application.FacesMessage; import javax.faces.bean.ManagedBean; import javax.faces.bean.SessionScoped; import javax.faces.context.FacesContext; import javax.jms.JMSException; import javax.jms.Queue; import javax.jms.QueueConnection; import javax.jms.QueueConnectionFactory; import javax.jms.QueueSender; import javax.jms.QueueSession; import javax.jms.Session; import javax.jms.TextMessage; @ManagedBean @SessionScoped public class MQRequest implements Serializable { private static final long serialVersionUID = 1L; @Resource(name = "jms/wasmqtest/wasmqtest_QCF") private QueueConnectionFactory connectionFactory; @Resource(name = "jms/wasmqtest/Request_Q") private Queue requestQueue; private QueueConnection connection; private String text = ""; public void sendMessage() { System.out.println("Connection in sendMessage: \n" + connection); TextMessage msg; try { QueueSession queueSession = connection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); QueueSender sender = queueSession.createSender(requestQueue); msg = queueSession.createTextMessage(text); sender.send(msg); queueSession.close(); sender.close(); } catch (JMSException e) { // TODO Auto-generated catch block e.printStackTrace(); } text = ""; } @PostConstruct public void openConenction() { System.out.println("Open Connection"); try { connection = connectionFactory.createQueueConnection(); connection.start(); System.out.println("Connection in OpenConnectioN: \n" + connection); } catch (JMSException e) { e.printStackTrace(); } } @PreDestroy public void closeConnection() { try { System.out.println("Closing Connection"); connection.close(); } catch (JMSException e) { e.printStackTrace(); } } public void setText(String text) { this.text = text; } public String getText() { return text; } } In PostConstruct method the connection is initialized: [21.10.13 07:36:05:574 CEST] 00000025 SystemOut O Connection in OpenConnectioN: com.ibm.ejs.jms.JMSQueueConnectionHandle@36c9b1a managed connection = com.ibm.ejs.jms.JMSManagedQueueConnection@3657e8b physical connection = com.ibm.mq.jms.MQXAQueueConnection@36618b6 closed = false invalid = false restricted methods enabled = false open session handles = [] temporary queues = [] But in sendMessage() method it isnt and I get a ConnectionClosed Problem: [21.10.13 07:36:12:493 CEST] 00000025 SystemOut O Connection in sendMessage: com.ibm.ejs.jms.JMSQueueConnectionHandle@36c9b1a managed connection = null physical connection = null closed = true invalid = false restricted methods enabled = false open session handles = [] temporary queues = [] 21.10.13 07:36:12:461 CEST] 00000025 SystemErr R 15 [WebContainer : 3] INFO org.apache.bval.jsr303.ConfigurationImpl - ignoreXmlConfiguration == true [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R javax.jms.IllegalStateException: Connection closed [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at com.ibm.ejs.jms.JMSConnectionHandle.checkOpen(JMSConnectionHandle.java:821) [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at com.ibm.ejs.jms.JMSQueueConnectionHandle.createQueueSession(JMSQueueConnectionHandle.java:206) [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at de.volkswagen.wasmqtest.queue.MQRequest.sendMessage(MQRequest.java:51) [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60) [21.10.13 07:36:12:601 CEST] 00000025 SystemErr R at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at java.lang.reflect.Method.invoke(Method.java:611) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at org.apache.el.parser.AstValue.invoke(AstValue.java:262) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at org.apache.myfaces.view.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:83) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component._MethodExpressionToMethodBinding.invoke(_MethodExpressionToMethodBinding.java:88) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:100) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component.UICommand.broadcast(UICommand.java:120) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component.UIViewRoot._broadcastAll(UIViewRoot.java:973) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:275) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component.UIViewRoot._process(UIViewRoot.java:1285) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:711) [21.10.13 07:36:12:602 CEST] 00000025 SystemErr R at org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:34) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java:171) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at javax.faces.webapp.FacesServlet.service(FacesServlet.java:189) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1147) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:722) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:449) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1020) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3703) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:304) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:953) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1655) [21.10.13 07:36:12:603 CEST] 00000025 SystemErr R at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:195) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:452) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:511) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:305) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:83) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775) [21.10.13 07:36:12:604 CEST] 00000025 SystemErr R at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905) [21.10.13 07:36:12:605 CEST] 00000025 SystemErr R at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1650) Do you have an idea why the connection is closed?

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  • Design pattern for window management in a Java Swing app

    - by Lord Torgamus
    I've just started creating my very first little Java Swing app. When the program opens, it brings up a single, simple window with a label and a couple buttons. Clicking one of those buttons is supposed to wipe out the welcome screen and replace it with a totally different panel. I'm not sure what the best way to create that functionality is. One method would be to pass my JFrame as an argument into... just about every other component, but that feels hacky to me. Or, there's making each panel double as an action listener, but that doesn't seem right, either. Is there a design pattern I should be applying here? "Replace the contents of the main — and only — window" must be a reasonably common operation. A name for the pattern would be enough; I can use Google on my own from there. (I wouldn't say no to a longer explanation, though.)

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  • Why do you hate Java? Is it the language or the framework? [closed]

    - by zneak
    According to you all, Java is the third most-hated language here. The two other most hated languages are PHP and VBScript. (It's quite funny how they stand together on the podium.) I'd like to make it known that the question mostly addresses people who don't like Java. I assume here a number of subjective opinions as facts because they're usually considered true among people who don't like Java, and I don't want to be convinced otherwise here. If you're a Java enthusiast, you might find this question frustrating. It's never been made clear if people hate Java itself, or if they hate it because of the framework, or if it's a mixture of the two. On a side you have the language, where you have: the "everything should be an object" philosophy, even in instances where it should obviously be something else (event handlers I'm pointing you); checked exceptions; the idea that all logic should be presented as methods and properties is a big no-no; the fact that "closures" created by anonymous types only include final variables and arguments, but will allow write access to any member of the parent class; a few more. On the other side, you have the JDK, with... its load of inconsistencies and overengineering; monolithic class hierarchies; meaningless base exceptions like IOException (though other frameworks have similar exception hierarchies); sluggish responsiveness even with Swing; a few more. My question is, do you think that, if either one (Java or the JDK) was taken alone, and the other was dropped in favor of something else, the new combination would be better? For instance, if you could use the C# syntax with the JDK (adapting get*/set* methods into properties, and interfaces with only one method into delegates), or the Java syntax with the .NET Framework (doing the inverse transformations), would things get better in your opinion?

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  • how to think like a computer scientist java edition exercise 7.2 [on hold]

    - by James Canfield
    I cannot figure out how to write this program, can someone please help me?! The purpose of this method is to practice manipulating St rings. Create a new program called Name.java. This program will take a name string consisting of EITHER a first name followed by a last name (nonstandar d format) or a last name followed by a comma then a first name (standard format). Ie . “Joe Smith” vs. “Smith, Joe”. This program will convert the string to standard format if it is not already in standard format. Write a method called hasComma that takes a name as an argument and that returns a boolean indicating whether it contains a comma. If i t does, you can assume that it is in last name first format. You can use the indexOf String m ethod to help you. Write a method called convertName that takes a name as an argument. It should check whether it contains a comma by calling your hasComma method. If it does, it should just return the string. If not, then it should assume th at the name is in first name first format, and it should return a new string that contains the name converted to last name comma first format. Uses charAt, length, substring, and indexOf methods. In your main program, loop, asking the user for a n ame string. If the string is not blank, call convertName and print the results. The loop terminat es when the string is blank. HINTS/SUGGESTIONS: Use the charAt, length, substring, and indexOf Str ing methods. Use scanner for your input. To get the full line, complete with spaces, use reader.nextLine()

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  • unexpected EOF and end of document

    - by WASasquatch
    I have been fiddling with this code for a few days. Mind you I am a beginner. I just want to get my script to be able to download a remote file, and scan MineCraft plugins. I got the scan plugins to work, but I'm having two other issues. One, I can't get the mc_addplugin to work correctly, and I get a Unexpected EOF and unexpected end of document when running any other command besides mc_scanplugins or mc_start bash: -c: line 0: unexpected EOF while looking for matching `"' bash: -c: line 1: syntax error: unexpected end of file Help would be so much appreciated! Thanks in advance. #!/bin/bash # /etc/init.d/craftbukkit # version 0.9.1 2012-07-06 (YYYY-MM-DD) ### BEGIN INIT INFO # Provides: craftbukkit # Required-Start: $local_fs $remote_fs # Required-Stop: $local_fs $remote_fs # Should-Start: $network # Should-Stop: $network # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: Starts craftbukkit server # Description: Starts and controls the craftbukkit server ### END INIT INFO # SETTINGS SERVICE='craftbukkit-1.2.5-R1.0.jar' OPTIONS='nogui' USERNAME='smith' # LIST ALL THE WORLDS IN YOUR CRAFTBUKKIT SERVER FOLDER WORLDS[1]='world' WORLDS[2]='world_nether' WORLDS[3]='world_the_end' WORLDS[4]='flat_world' MCPATH='/var/www/servers/Foundation' PLUGINSPATH='/var/www/servers/Foundation/plugins' TEMPPLUGINS='/var/www/servers/Foundationplugins/temp_plugins' BACKUPPATH='/var/www/servers/Foundation/backup' CPU_COUNT=2 INVOCATION="java -Xmx2024M -Xms2024M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=$CPU_COUNT -XX:+AggressiveOpts -jar $SERVICE $OPTIONS" ME=`whoami` as_user() { if [ $ME == $USERNAME ] ; then bash -c "$1" else su - $USERNAME -c "$1" fi } mc_start() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is already running!" else echo "Starting $SERVICE..." cd $MCPATH as_user "cd $MCPATH && screen -dmS craftbukkit $INVOCATION" sleep 7 if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is now running." else echo "Error! Could not start $SERVICE!" fi fi } mc_saveoff() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running... suspending saves" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"say The server is preforming a backup. Server going to read-only mode. Do not build...\"\015'" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"save-off\"\015'" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"save-all\"\015'" sync sleep 10 else echo "$SERVICE is not running. Not suspending saves." fi } mc_save() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running... Saving worlds..." as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"save-all\"\015'" sync sleep 10 echo "Save complete!" else echo "$SERVICE is not running. Cannot save!" fi } mc_saveon() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running... re-enabling saves" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"save-on\"\015'" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"say Server backup has completed. Server going to read-write mode. You can now continue building...\"\015'" else echo "$SERVICE is not running. Not resuming saves." fi } mc_stop() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "Stopping $SERVICE" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"say $SERVERNAME is shutting down in 30 seconds! Please stop what you are doing. Check back later, we'll be back!\"\015'" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"save-all\"\015'" sleep 30 as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"stop\"\015'" sleep 7 else echo "$SERVICE was not running." fi if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "Error! $SERVICE could not be stopped." else echo "$SERVICE is stopped." fi } mc_update() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running! Will not start update." else MC_SERVER_URL=http://dl.bukkit.org/latest-rb/craftbukkit.jar as_user "cd $MCPATH && wget -q -O $MCPATH/craftbukkit_server.jar.update $MC_SERVER_URL" if [ -f $MCPATH/craftbukkit_server.jar.update ] then if `diff $MCPATH/$SERVICE $MCPATH/craftbukkit_server.jar.update >/dev/null` then echo "You are already running the latest version of $SERVICE. Update anyway? [Y/n]" select yn in "Yes" "No"; do case $yn in Yes ) as_user "mv $MCPATH/$SERVICE $MCPATH/${SERVICE}_old.jar" as_user "mv $MCPATH/craftbukkit_server.jar.update $MCPATH/$SERVICE" echo "$SERVICE updated successfully!"; break;; No ) echo "The update was not installed! Removing temporary files and exiting..." as_user "rm $MCPATH/craftbukkit_server.jar.update" exit;; esac done else as_user "mv $MCPATH/$SERVICE $MCPATH/${SERVICE}_old.jar" as_user "mv $MCPATH/craftbukkit_server.jar.update $MCPATH/$SERVICE" echo "$SERVICE updated successfully!" fi else echo "$SERVICE update could not be downloaded." fi fi } mc_addplugin() { if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running! Please stop the service before adding a plugin." else echo "Paste the URL to the .JAR Plugin..." read JARURL JARNAME=$(basename "$JARURL") if [ -d "$TEMPPLUGINS" ] then as_user "cd $PLUGINSPATH && wget -r -A.jar $JARURL -o temp_plugins/$JARNAME" else as_user "cd $PLUGINSPATH && mkdir $TEMPPLUGINS && wget -r -A.jar $JARURL -o temp_plugins/$JARNAME" fi if [ -f "$TMPDIR/$JARNAME" ] then if [ -f "$PLUGINSPATH/$JARNAME" ] then if `diff $PLUGINSPATH/$JARNAME $TMPDIR/$JARNAME >/dev/null` then echo "You are already running the latest version of $JARNAME." else NOW=`date "+%Y-%m-%d_%Hh%M"` echo "Are you sure you want to overwrite this plugin? [Y/n]" echo "Note: Your old plugin will be moved to the "$TEMPPLUGINS" folder with todays date." select yn in "Yes" "No"; do case $yn in Yes ) as_user "mv $PLUGINSPATH/$JARNAME $TEMPPLUGINS/${JARNAME}_${NOW} && mv $TEMPPLUGINS/$JARNAME $PLUGINSPATH/$JARNAME"; break;; No ) echo "The plugin has not been installed! Removing temporary plugin and exiting..." as_user "rm $TEMPPLUGINS/$JARNAME"; exit;; esac done echo "Would you like to start the $SERVICE now? [Y/n]" select yn in "Yes" "No"; do case $yn in Yes ) mc_start; break;; No ) "$SERVICE not running! To start the service run: /etc/init.d/craftbukkit start"; exit;; esac done fi else echo "Are you sure you want to add this new plugin? [Y/n]" select yn in "Yes" "No"; do case $yn in Yes ) as_user "mv $PLUGINSPATH/$JARNAME $TEMPPLUGINS/${JARNAME}_${NOW} && mv $TEMPPLUGINS/$JARNAME $PLUGINSPATH/$JARNAME"; break;; No ) echo "The plugin has not been installed! Removing temporary plugin and exiting..." as_user "rm $TEMPPLUGINS/$JARNAME"; exit;; esac done echo "Would you like to start the $SERVICE now? [Y/n]?" select yn in "Yes" "No"; do case $yn in Yes ) mc_start; break;; No ) "$SERVICE not running! To start the service run: /etc/init.d/craftbukkit start"; exit;; esac done fi else echo "Failed to download the plugin from the URL you specified!" exit; fi fi } mc_scanplugins() { if [ "$(ls -A $PLUGINSPATH)" ] then shopt -s nullglob PLUGINS=($PLUGINSPATH/*.jar) i=1 for f in "${PLUGINS[@]}" do echo "${i}: $f" PLUGIN[$i]=$f i=$(( $i + 1 )) done echo "Enter the ID of a plugin you want removed, or any other key to cancel." read INPUT if [ ! -z "${INPUT##*[!0-9]*}" ] then if [ -f "${PLUGIN[INPUT]}" ] then echo "Removing plugin..." JAR=$(basename ${PLUGIN[INPUT]}) JARNAME=${JAR%.jar} as_user "rm -f ${PLUGIN[INPUT]}" sleep 2 as_user "cd $PLUGINSPATH && rm -rf ./${JARNAME}" if [ -f "${PLUGINSPATH}/${JARNAME}" ] then echo "Plugin folder could not be removed..." fi echo "Plugin removed." else echo "${PLUGIN[INPUT]}" echo "Invalid plugin! Does not exist! Canceling..." exit; fi else echo "Canceling..." exit; fi else echo "You have no plugins installed." exit; fi } mc_backup() { mc_saveoff for i in "${WORLDS[@]}"; do NOW=`date "+%Y-%m-%d_%Hh%M"` BACKUP_FILE="$BACKUPPATH/${i}_${NOW}.tar" echo "Backing up world: $i..." #as_user "cd $MCPATH && cp -r $i $BACKUPPATH/${i}_`date "+%Y.%m.%d_%H.%M""` as_user "tar -C \"$MCPATH\" -cf \"$BACKUP_FILE\" $i" done echo "Backing up $SERVICE" as_user "tar -C \"$MCPATH\" -rf \"$BACKUP_FILE\" $SERVICE" #as_user "cp \"$MCPATH/$SERVICE\" \"$BACKUPPATH/craftbukkit_server_${NOW}.jar\"" mc_saveon echo "Compressing backup..." as_user "tar -cvzf $BACKUPPATH/server_backup_${NOW}.tar.gz $MCPATH" echo "Backup has completed successfully." } mc_command() { command="$1"; if pgrep -u $USERNAME -f $SERVICE > /dev/null then pre_log_len=`wc -l "$MCPATH/server.log" | awk '{print $1}'` echo "$SERVICE is running... executing command" as_user "screen -p 0 -S craftbukkit -X eval 'stuff \"$command\"\015'" sleep .1 # assumes that the command will run and print to the log file in less than .1 seconds # print output tail -n $[`wc -l "$MCPATH/server.log" | awk '{print $1}'`-$pre_log_len] "$MCPATH/server.log" fi } #Start-Stop here case "$1" in start) mc_start ;; stop) mc_stop ;; restart) mc_stop mc_start ;; save) mc_save ;; update) mc_stop mc_backup mc_update mc_start ;; scanplugins) mc_scanplugins ;; addplugin) mc_addplugin ;; backup) mc_backup ;; status) if pgrep -u $USERNAME -f $SERVICE > /dev/null then echo "$SERVICE is running." else echo "$SERVICE is not running." fi ;; command) if [ $# -gt 1 ]; then shift mc_command "$*" else echo "Must specify server command (try 'help'?)" fi ;; *) echo "Usage: $0 {start|stop|update|backup|status|restart|command \"server command\"}" exit 1 ;; esac exit 0

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  • Database-as-a-Service on Exadata Cloud

    - by Gagan Chawla
    Note – Oracle Enterprise Manager 12c DBaaS is platform agnostic and is designed to work on Exadata/non-Exadata, physical/virtual, Oracle/non Oracle platforms and it’s not a mandatory requirement to use Exadata as the base platform. Database-as-a-Service (DBaaS) is an important trend these days and the top business drivers motivating customers towards private database cloud model include constant pressure to reduce IT Costs and Complexity, and also to be able to improve Agility and Quality of Service. The first step many enterprises take in their journey towards cloud computing is to move to a consolidated and standardized environment and Exadata being already a proven best-in-class popular consolidation platform, we are seeing now more and more customers starting to evolve from Exadata based platform into an agile self service driven private database cloud using Oracle Enterprise Manager 12c. Together Exadata Database Machine and Enterprise Manager 12c provides industry’s most comprehensive and integrated solution to transform from a typical silo’ed environment into enterprise class database cloud with self service, rapid elasticity and pay-per-use capabilities.   In today’s post, I’ll list down the important steps to enable DBaaS on Exadata using Enterprise Manager 12c. These steps are chalked down based on a recent DBaaS implementation from a real customer engagement - Project Planning - First step involves defining the scope of implementation, mapping functional requirements and objectives to use cases, defining high availability, network, security requirements, and delivering the project plan. In a Cloud project you plan around technology, business and processes all together so ensure you engage your actual end users and stakeholders early on in the project right from the scoping and planning stage. Setup your EM 12c Cloud Control Site – Once the project plan approval and sign off from stakeholders is achieved, refer to EM 12c Install guide and these are some important tips to follow during the site setup phase - Review the new EM 12c Sizing paper before you get started with install Cloud, Chargeback and Trending, Exadata plug ins should be selected to deploy during install Refer to EM 12c Administrator’s guide for High Availability, Security, Network/Firewall best practices and options Your management and managed infrastructure should not be combined i.e. EM 12c repository should not be hosted on same Exadata where target Database Cloud is to be setup Setup Roles and Users – Cloud Administrator (EM_CLOUD_ADMINISTRATOR), Self Service Administrator (EM_SSA_ADMINISTRATOR), Self Service User (EM_SSA_USER) are the important roles required for cloud lifecycle management. Roles and users are managed by Super Administrator via Setup menu –> Security option. For Self Service/SSA users custom role(s) based on EM_SSA_USER should be created and EM_USER, PUBLIC roles should be revoked during SSA user account creation. Configure Software Library – Cloud Administrator logs in and in this step configures software library via Enterprise menu –> provisioning and patching option and the storage location is OMS shared filesystem. Software Library is the centralized repository that stores all software entities and is often termed as ‘local store’. Setup Self Update – Self Update is one of the most innovative and cool new features in EM 12c framework. Self update can be accessed via Setup -> Extensibility option by Super Administrator and is the unified delivery mechanism to get all new and updated entities (Agent software, plug ins, connectors, gold images, provisioning bundles etc) in EM 12c. Deploy Agents on all Compute nodes, and discover Exadata targets – Refer to Exadata discovery cookbook for detailed walkthrough to ensure successful discovery of Exadata targets. Configure Privilege Delegation Settings – This step involves deployment of privilege setting template on all the nodes by Super Administrator via Setup menu -> Security option with the option to define whether to use sudo or powerbroker for all provisioning and patching operations. Provision Grid Infrastructure with RAC Database on Compute Nodes – Software is provisioned in this step via a provisioning profile using EM 12c database provisioning. In case of Exadata, Grid Infrastructure and RAC Database software is already deployed on compute nodes via OneCommand from Oracle, so SSA Administrator just needs to discover Oracle Homes and Listener as EM targets. Databases will be created as and when users request for databases from cloud. Customize Create Database Deployment Procedure – the actual database creation steps are "templatized" in this step by Self Service Administrator and the newly saved deployment procedure will be used during service template creation in next step. This is an important step and make sure you have locked all the required variables marked as locked as ‘Y’ in this table. Setup Self Service Portal – This step involves setting up of zones, user quotas, service templates, chargeback plan. The SSA portal is setup by Self Service Administrator via Setup menu -> Cloud -> Database option and following guided workflow. Refer to DBaaS cookbook for details. You also have an option to customize SSA login page via steps documented in EM 12c Cloud Administrator’s guide Final Checks – Define and document process guidelines for SSA users and administrators. Get your SSA users trained on Self Service Portal features and overall DBaaS model and SSA administrators should be familiar with Self Service Portal setup pieces, EM 12c database lifecycle management capabilities and overall EM 12c monitoring framework. GO LIVE – Announce rollout of Database-as-a-Service to your SSA users. Users can login to the Self Service Portal and request/monitor/view their databases in Exadata based database cloud. Congratulations! You just delivered a successful database cloud implementation project! In future posts, we will cover these additional useful topics around database cloud – DBaaS Implementation tips and tricks – right from setup to self service to managing the cloud lifecycle ‘How to’ enable real production databases copies in DBaaS with rapid provisioning in database cloud Case study of a customer who recently achieved success with their transformational journey from traditional silo’ed environment on to Exadata based database cloud using Enterprise Manager 12c. More Information – Podcast on Database as a Service using Oracle Enterprise Manager 12c Oracle Enterprise Manager 12c Installation and Administration guide, Cloud Administration guide DBaaS Cookbook Exadata Discovery Cookbook Screenwatch: Private Database Cloud: Set Up the Cloud Self-Service Portal Screenwatch: Private Database Cloud: Use the Cloud Self-Service Portal Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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  • Is there a canonical book for learning Java as an experienced developer?

    - by Steven Elliott Jr
    I have been a .NET developer now for about the past 5/6 years give or take. I have never done any professional Java development and the last time I really touched it was probably back in college. I have been toying with the Scala language a little bit but nothing serious. Recently, I've been offered an opportunity to do some pretty cool work, but using Java instead of .NET. I think I can get by alright with my current skill set, meaning I already know how to program well and am familiar with languages such as C# and C++, etc. So, the syntax and all that language stuff are really not a problem. What I need is a really good reference book and a book about how to think in Java. Each language/Framework/Stack tries to address things a certain way and I'm sure Java is no different. What are some great Java books that you simply can't live without? Are there any books that talk about the most important parts of Java that must be understood before all else? As a side note, I will be doing mostly Java web development. Not really 100% on what types of stuff they are using for persistence, framework, server, etc.

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  • Top Questions and Answers for Pluging into Oracle Database as a Service

    - by David Swanger
    Yesterday we hosted a comprehensive online forum that shared a comprehensive path to help your organization design, deploy, and deliver a Database as a Service cloud. If you missed the online forum, you can watch it on demand by registering here. We received numerous questions.  Below are highlights of the most informative: DBaaS requires a lengthy and careful design efforts. What is the minimum requirements of setting up a scaled-down environment and test it out? You should have an OEM 12c environment for DBaaS administration and then a target database deployment platform that has the key characteristics of what your production environment will look like. This could be a single server or it could be a small pool of hosts if your production DBaaS will be larger and you want to test a more robust / real world configuration with Zones and Pools or DR capabilities for example. How does this benefit companies having their own data center? This allows companies to transform their internal IT to a service delivery model for the database. The benefits to the company are significant cost savings, improved business agility and reduced risk. The benefits to the consumers (internal) of services if much fast provisioning, and response to change in business requirements. From a deployment perspective, is DBaaS's job solely DBA's job? The best deployment model enables the DBA (or end-user) to control the entire process. All resources required to deploy the service are pre-provisioned, and there are no external dependencies (on network, storage, sysadmins teams). The service is created either via a self-service portal or by the DBA. The purpose of self service seems to be that the end user does not rely on the DBA. I just need to give him a template. He decides how much AMM he needs. Why shall I set it one by one. That doesn't seem to be the purpose of self service. Most customers we have worked with define a standardized service catalog, with a few (2 to 5) different classes of service. For each of these classes, there is a pre-defined deployment template, and the user has the ability to select from some pre-defined service sizes. The administrator only has to create this catalog once. Each user then simply selects from the options offered in the catalog.  Looking at DBaaS service definition, it seems to be no different from a service definition provided by a well defined DBA team. Why do you attribute it to DBaaS? There are a couple of perspectives. First, some organizations might already be operating with a high level of standardization and a higher level of maturity from an ITIL or Service Management perspective. Their journey to DBaaS could be shorter and their Service Definition will evolve less but they still might need to add capabilities such as Self Service and Metering/Chargeback. Other organizations are still operating in highly siloed environments with little automation and their formal Service Definition (if they have one) will be a lot less mature today. Therefore their future state DBaaS will look a lot different from their current state, as will their Service Definition. How database as a service impact or help with "Click to Compute" or deploying "Database in cloud infrastructure" DBaaS enables Click to Compute. Oracle DBaaS can be implemented using three architecture models: Oracle Multitenant 12c, native consolidation using Oracle Database and consolidation using virtualization in infrastructure cloud. As Deploy session showed, you get higher consolidating density and efficiency using Multitenant and higher isolation using infrastructure cloud. Depending upon your business needs, DBaaS can be implemented using any of these models. How exactly is the DBaaS different from the traditional db? Storage/OS/DB all together to 'transparently' provide service to applications? Will there be across-databases access by application/user. Some key differences are: 1) The services run on a shared platform. 2) The services can be rapidly provisioned (< 15 minutes). 3) The services are dynamic and can be relocated, grown, shrunk as needed to meet business needs without disruption and rapidly. 4) The user is able to provision the services directly from a standardized service catalog.. With 24x7x365 databases its difficult to find off peak hrs to do basic admin tasks such as gathering stats, running backups, batch jobs. How does pluggable database handle this and different needs/patching downtime of apps databases might be serving? You can gather stats in Oracle Multitenant the same way you had been in regular databases. Regarding patching/upgrading, Oracle Multitenant makes patch/upgrade very efficient in that you can pre-provision a new version/patched multitenant db in a different ORACLE_HOME and then unplug a PDB from its CDB and plug it into the newer/patched CDB in seconds.  Thanks for all the great questions!  If you'd like to learn more and missed the online forum, you can watch it on demand here.

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  • Java keyboard input [on hold]

    - by dØd
    I'm trying to implement a input system that can detect whether a certain key was held or was only pressed briefly. So far I have this: KEY_INTERACTION_TRESHOLD = 400ms //inside a constructor shouldMeasure = true; @Override public void keyPressed(KeyEvent e) { if (shouldMeasure) { startTime = System.currentTimeMillis(); shouldMeasure = false; return; } System.out.println("Button is held down"); e.consume(); } @Override public void keyReleased(KeyEvent e) { if (System.currentTimeMillis() - startTime < KEY_INTERACTION_TRESHOLD) { System.out.println("Button was only pressed briefly"); } startTime = 0; shouldMeasure = true; e.consume(); } Now this works, but the problem is that there is this delay between when I press a key to hold and when the message 'Button is held down' gets displayed. I understand why this delay occurs (for example when you press and hold a letter there will be a similar delay between the first and the second letter printed out), but I would like to somehow avoid it. I'm using only the Java API.

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  • Implementing Circle Physics in Java

    - by Shijima
    I am working on a simple physics based game where 2 balls bounce off each other. I am following a tutorial, 2-Dimensional Elastic Collisions Without Trigonometry, for the collision reactions. I am using Vector2 from the LIBGDX library to handle vectors. I am a bit confused on how to implement step 6 in Java from the tutorial. Below is my current code, please note that the code strictly follows the tutorial and there are redundant pieces of code which I plan to refactor later. Note: refrences to this refer to ball 1, and ball refers to ball 2. /* * Step 1 * * Find the Normal, Unit Normal and Unit Tangential vectors */ Vector2 n = new Vector2(this.position[0] - ball.position[0], this.position[1] - ball.position[1]); Vector2 un = n.normalize(); Vector2 ut = new Vector2(-un.y, un.x); /* * Step 2 * * Create the initial (before collision) velocity vectors */ Vector2 v1 = this.velocity; Vector2 v2 = ball.velocity; /* * Step 3 * * Resolve the velocity vectors into normal and tangential components */ float v1n = un.dot(v1); float v1t = ut.dot(v1); float v2n = un.dot(v2); float v2t = ut.dot(v2); /* * Step 4 * * Find the new tangential Velocities after collision */ float v1tPrime = v1t; float v2tPrime = v2t; /* * Step 5 * * Find the new normal velocities */ float v1nPrime = v1n * (this.mass - ball.mass) + (2 * ball.mass * v2n) / (this.mass + ball.mass); float v2nPrime = v2n * (ball.mass - this.mass) + (2 * this.mass * v1n) / (this.mass + ball.mass); /* * Step 6 * * Convert the scalar normal and tangential velocities into vectors??? */

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  • Would a typical corporate firewall block a Java applet having the following behaviour

    - by auser
    I'm thinking of developing a proxy-like program to forward ports on a remote PC to a local PC (for example SSH). Assume that both local and remote PCs are running behind typical firewalls (i.e. consumer broadband router firewall, Windows firewall or corporate firewalls). The program will be a Java program which the user will run on both the remote and local PC. The remote client will periodically poll a central server to determine whether there are pending client connections. A session could be initiated as follows: The local client contacts the central server and request the current connection details for a specific remote client. The central server responds with the remote server's last received IP address and port. The next time the remote server polls the central server, the client's IP address and port are returned. The remote server initiates a connection to the local client using the IP address and port returned by the central server and listens for a response on a random port. The remote server will pass the value of the port it's listening on to central server. Goto 1, if client fails to connect to server. Would this work or will a typical firewall block the interactions.

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  • Skynet Big Data Demo Using Hexbug Spider Robot, Raspberry Pi, and Java SE Embedded (Part 3)

    - by hinkmond
    In Part 2, I described what connections you need to make for this demo using a Hexbug Spider Robot, a Raspberry Pi, and Java SE Embedded for programming. Here are some photos of me doing the soldering. Software engineers should not be afraid of a little soldering work. It's all good. See: Skynet Big Data Demo (Part 2) One thing to watch out for when you open the remote is that there may be some glue covering the contact points. Make sure to use an Exacto knife or small screwdriver to scrape away any glue or non-conductive material covering each place where you need to solder. And after you are done with your soldering and you gave the solder enough time to cool, make sure all your connections are marked so that you know which wire goes where. Give each wire a very light tug to make sure it is soldered correctly and is making good contact. There are lots of videos on the Web to help you if this is your first time soldering. Check out Laday Ada's (from adafruit.com) links on how to solder if you need some additional help: http://www.ladyada.net/learn/soldering/thm.html If everything looks good, zip everything back up and meet back here for how to connect these wires to your Raspberry Pi. That will be it for the hardware part of this project. See, that wasn't so bad. Hinkmond

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  • Java: How to Make a Player Class in a Tile-Based RPG

    - by A.K.
    So I've been following a JavaHub tutorial that basically uses a pixel engine similar to MiniCraft. I've attempted to make a Player Class as such, and I'm basically making a mock Pokemon game for learning's sake: package pokemon.entity; import java.awt.Rectangle; import pokemon.gfx.Screen; import pokemon.levelgen.Tile; import pokemon.entity.SpritesManage;; public class Player { int x, y; int vx, vy; public Rectangle AshRec; public Sprite AshSprite; Screen screen; Sprite[][] AshSheet; public Player() { AshSprite = SpritesManage.AshSheet[1][0]; AshRec = new Rectangle(0, 0, 16, 16); x = 0; y = 0; vx = 1; vy = 1; screen.renderSprite(0, 0, AshSprite); } public void update() { move(); checkCollision(); } private void checkCollision() { } private void move() { AshRec.x += vx; AshRec.y += vy; } public void render(Screen screen, int x, int y) { screen.renderSprite(x, y, AshSprite); } } I guess what I really want to do is have the Player centered in the screen and have the sprite drawn based on an Input Handler. I'm just stumped as to how to sync these together.

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  • help with migrating from Widows, x64 FGLRX, CPU load, Java and Minecraft

    - by joxer
    Im new to ubuntu, it is the second time i have installed it. This comp is Dell studio 1558. some specs: CPU- intel core i7 Q720 1.6GHz, GPU- ATI Mobility Radeon HD 5400 FGLRX- i've fallowed these instructions among inspecting many others, i have tried all of the variants mentioned in that tread before reverting back to the drivers supplied with Ubuntu ( through additional drivers ) which apparently seem to work best. i am testing them with minecraft as silly as it may sound. in 2 to 60 minutes the FPS drop from 70+ to somewhere between 0 and 5. while "fgl_glxgears" runs at between 400 and 800 FPS smoothly.. I am using oracle ( sun ) JRE6 to run minecraft, i have gotten it through a tutorial linked on oracle's website, i currently have no other version of java installed ( was worse when i had a few others here ). after closing the game Ubuntu is similarly slow, i've checked the CPU load using System Monitor and it shows one of the CPU's jumping to 80%~100% load at a time.. a reboot solves it. i realize my mess is up to me to solve but a hand is always appreciated. tyvm in advance.

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  • JAVA Gui on Hello World [closed]

    - by user58892
    I am designing, implementing, testing, and debuging a GUI-based version of a “Hello, World!” program in a JFrame that includes a JLabel that reads “Hello, World!” and I am trying to use a layout manager, and an Exit button to close the program. Here's what I have so far, I would really apreciate if you could help on it syntax. I am 90% done but tried hard and it couldn't run. import java.awt.*; // Needed for flow layout manager import javax.swing.*; //All swing components live in the javax.swing package import javax.swing.JButton; //to recognize buttons import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JTextField; public class HelloWorld { public static void main(String[] args) { //creates the label. The JLabel constructor //takes an optional argument which set the text of the label /* The text will be aligned with the center of the frame * otherwise it will align on the left. */ JLabel label= new JLabel("Hello World!"); new FlowWindow(); label.setHorizontalAlignment (SwingConstants.CENTER); JFrame frame = new JFrame("Hello"); //create exit button JButton button1 = new JButton("Exit"); //Add exit button to the content pane. add(button1); frame.add(label); frame.setSize(300, 300); frame.setVisible(true); frame.setLocationRelativeTo(null); frame.toFront(); } public static void FlowWindow() { //Add a new FlowLayout()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } }

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  • Java game design question (graphical objects)

    - by vemalsar
    Hello Guys, I'm beginner in game development, in Java and here on this site too and I have a game design question. Please comment my idea: I have a main loop which call update and draw method. I want to use an ArrayList which store graphical objects, they have coordinate and image or text to draw and my game objects extends this class. In update, I can choose which objects should be put in the array and in draw method I'll display the elements of array on the screen. I'm using a buffer and draw first there, but it is not important now I guess...Here is a simple (not full) code, only the logic: public class GamePanel extends JPanel implements KeyListener { ArrayList<graphicalObjects> graphArray = new ArrayList<graphicalObjects>(); public void update() { //change the game scene, update the graphArray, process input etc. } public void draw() { //draws every element of graphArray to a JPanel } public static main(String[] args) { while(true) { update(); draw(); } } } My questions: Should have I use interface or abstract class for graphicalObjects? graphicalObjects class and the ArrayList really needs or there is some better solution? How to draw objects? They draw themself with their own method or in the draw method I have to draw manually based on graphicalObjects variables (x,y coordinates, image etc.)? If this conception is wrong, please suggest another one! All comments are welcome and sorry if this is dumb question, thanks!

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  • Add & Show data in Java ArrayList [closed]

    - by Kaidul Islam Sazal
    I have a class inside a main class : static class Graph{ static int u, v, cost; } I have instantiated an arraylist of the class: static List<Graph> g = new ArrayList<Graph>(); And I insert several values into the arraylist like this: Scanner input = new Scanner(System.in); for (int i = 0; i < edge_no; i++) { Graph e = new Graph(); e.u = input.nextInt(); e.v = input.nextInt(); e.cost = input.nextInt(); g.add(e); } And I print it like this: for (int i = 0; i < edge_no; i++) { System.out.println(g.get(i).u + " " + g.get(i).v + " " + g.get(i).cost); } But the problem is that, when I print it, only the last value is shown all the time.It seems that, all the previous values are over-written with it. Input : 1 2 5 1 3 8 2 3 9 Output: 2 3 9 2 3 9 2 3 9 Expected output is just like the input.But I can't fix the problem as I am novice in java.

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  • Checking validation of entries in a Sudoku game written in Java

    - by Mico0
    I'm building a simple Sudoku game in Java which is based on a matrix (an array[9][9]) and I need to validate my board state according to these rules: all rows have 1-9 digits all columns have 1-9 digits. each 3x3 grid has 1-9 digits. This function should be efficient as possible for example if first case is not valid I believe there's no need to check other cases and so on (correct me if I'm wrong). When I tried doing this I had a conflict. Should I do one large for loop and inside check columns and row (in two other loops) or should I do each test separately and verify every case by it's own? (Please don't suggest too advanced solutions with other class/object helpers.) This is what I thought about: Main validating function (which I want pretty clean): public boolean testBoard() { boolean isBoardValid = false; if (validRows()) { if (validColumns()) { if (validCube()) { isBoardValid = true; } } } return isBoardValid; } Different methods to do the specific test such as: private boolean validRows() { int rowsDigitsCount = 0; for (int num = 1; num <= 9; num++) { boolean foundDigit = false; for (int row = 0; (row < board.length) && (!foundDigit); row++) { for (int col = 0; col < board[row].length; col++) { if (board[row][col] == num) { rowsDigitsCount++; foundDigit = true; break; } } } } return rowsDigitsCount == 9 ? true : false; } I don't know if I should keep doing tests separately because it looks like I'm duplicating my code.

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