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• java+netbeans+mysql+ubuntu 64 bits LTS VS C#+MS SQL for fast develop trading system

  - by crunchor

  I am going to build a trading system and use with the broker "Interactive Broker" API. The API supports C++ Socket, Java Socket, DDE, Active X APIs in Windows. The API supports Java Socket API, Posix C++ Socket API in Unix kind like Ubuntu. My trading system has some real time long calculations to do and a lot of maths for backtest. I am using a retail trading program Amibroker which is written in C++ and I run it in windows xp 32 bits, it will take me days to do one serious backtest with my G620 Sandy Bridge CPU and 3GB of ram. So for my trading system, I need to have 1. speed, 2. stability, 3. fast development I have done some research, C++ is fastest but I am not good at it and it takes much longer time to develop. Other than C++, Java in linux has the best speed. I also did some research for database and look like mysql has the best speed. Mysql and PostgreSQL both are very popular open source sql db, which one should I choose? I see MySQL has Workbench now which looks like similar to MS SQL management studio so look like a good start. Netbeans should be the most popular Java IDE now and seem like its GUI design can be as easy as Virtual Studio now. I am not sure if made by Netbeans would affect the speed and if its GUI design is really that good and easy to use. Ubuntu 64 bits LTS has good long term support, good community support, and stable. I will buy a new computer if I can create a good trading system for live trading and backtest. Very likely I will buy a I7 or I5 depends on if I7 can really have better speed for my case. Actually I mainly deal with C# in my jobs and I just knew java but not good at java. What would you guys recommend? Any better solution? This will be a big project and very likely life long project for me so I seriously do research including asking you guys before I start and focus on what I should, thanks!

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• Fonts look horrible in any java application

  - by Eirik Berg

  All fonts in java applications look horrible. I have seen a few questions about this previously, but they are quite old now(11.04 was the most recent, but that didn't seem to be the same problem). For some reason java applications do not use the system font (Ubuntu 11), but rather some elongated font that doesn't seem to have any anti-aliasing. So what I'm asking is if this is an open bug(couldn't find any on launchpad), something the developers have done wrong, or if there is a way to configure the fonts used in java application. Perhaps this is just a shortcoming of openjdk and I should install the Sun version instead? Attached an image showing jitsi, but the problem is also present in minecraft, my internet-bank and anything else involving java. I'm on 12.04, but since I couldn't find anything on launchpad I'm assuming that isn't relevant. Edit: actually managed to forget the picture... Thanks!

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• Should Swing knowledge be required from Java programmers?

  - by Anto

  Swing is an integral part of the Java API. It is also the most popular GUI framework for Java. I still wonder, should every Java programmer still know, or at least be pretty familiar with, Swing (possibly excluding web developers)? There are alternatives (e.g. SWT), but they are not very widely used (compared to Swing). What do you think about requiring Swing knowledge from Java programmers? If such knowledge is important, to what degree? Are the basics enough or not? The reason I wonder is because I really don't like Swing but wonder if I still should brush up my skills in it. I'm able to create simple GUIs in it, but I would definitely not say that I know Swing well.

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• Java HttpURLConnection class Program

  - by pandu

  I am learning java. Here is the sample code of HttpURLConnection class usage in some text book import java.net.*; import java.io.*; import java.util.*; class HttpURLDemo { public static void main(String args[]) throws Exception { URL hp = new URL("http://www.google.com"); HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); // Display request method. System.out.println("Request method is " + hpCon.getRequestMethod()); // Display response code. System.out.println("Response code is " + hpCon.getResponseCode()); // Display response message. System.out.println("Response Message is " + hpCon.getResponseMessage()); // Get a list of the header fields and a set // of the header keys. Map<String, List<String>> hdrMap = hpCon.getHeaderFields(); Set<String> hdrField = hdrMap.keySet(); System.out.println("\nHere is the header:"); // Display all header keys and values. for(String k : hdrField) { System.out.println("Key: " + k + " Value: " + hdrMap.get(k)); } } } Question is Why hpCon Object is declared in the following way? HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); instead of declaring like this HttpURLConnection hpCon = new HttpURLConnection(); Author provided the following explanation. I cant understand Java provides a subclass of URLConnection that provides support for HTTP connections. This class is called HttpURLConnection. You obtain an HttpURLConnection in the same way just shown, by calling openConnection( ) on a URL object, but you must cast the result to HttpURLConnection. (Of course, you must make sure that you are actually opening an HTTP connection.) Once you have obtained a reference to an HttpURLConnection object, you can use any of the methods inherited from URLConnection

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• Should Swing knowledge be required from Java programmers?

  - by Anto

  Swing is an integral part of the Java API. It is also the most popular GUI framework for Java. I still wonder, should every Java programmer still know, or at least be pretty familiar with, Swing (possibly excluding web developers)? There are alternatives (e.g. SWT), but they are not very widely used (compared to Swing). What do you think about requiring Swing knowledge from Java programmers? If such knowledge is important, to what degree? Are the basics enough or not? The reason I wonder is because I really don't like Swing but wonder if I still should brush up my skills in it. I'm able to create simple GUIs in it, but I would definitely not say that I know Swing well.

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• What is the exception in java code? [closed]

  - by Karandeep Singh

  This java code is for reverse the string but it returning concat null with returned string. import java.util.*; import java.util.logging.Level; import java.util.logging.Logger; public class Practice { public static void main(String[] args) { String str = ""; try { str = reverse("Singh"); } catch (Exception ex) { Logger.getLogger(Practice.class.getName()).log(Level.SEVERE, null, ex); System.out.print(ex.getMessage()); }finally{ System.out.println(str); } } public static String reverse(String str) throws Exception{ String temp = null; if(str.length()<=0){ throw new Exception("empty"); }else{ for(int i=str.length()-1;i>=0;i--){ temp+=str.charAt(i); } } return temp.trim(); } } Output: nullhgniS

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• Opera Mini 7 launch to turn Java ME phones into smart browser phones

  - by hinkmond

  Here's a good way to smarten up your Java ME smart-challenged phone. Use the new Opera Mini 7 browser to view your personalized "Smart Page". See: Opera Mini 7 w/Java ME Here's a quote: The browser comes with a new feature called 'Smart Page'... a one-page summary of all the news from your Facebook and Twitter feeds. In addition to showing your friends' status updates and tweets, Smart Page will offer up suggestions for news sites to follow, and... save you the hassle of manually typing Web addresses into your mobile keyboard. ... Opera Mini 7 is available as a free download for Java-compatible (J2ME), Nokia S60, and Blackberry devices at m.opera.com That's smart! Using Java ME means you don't have to deal with those other platforms. Hinkmond

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• Jdk 6.0 update 6 installed sucessfully but java command not working

  - by Ravi.Kumar

  I switched to linux (Ubuntu 12.04) this morning and find it great but messed up while installing java. :-(. I have installed jdk6.0_6 successfully but when I run java command in terminal, I get this ravi@ravi-LIFEBOOK-AH531:~$ java The program 'java' can be found in the following packages: * default-jre * gcj-4.6-jre-headless * openjdk-6-jre-headless * gcj-4.5-jre-headless * openjdk-7-jre-headless Try: sudo apt-get install <selected package> Could someone help me with this? Below are the steps that I followed to install: copied file named jdk-6u6-linux-x64.bin to my documents from terminal executed chmod a+x jdk-6u6-linux-x64.bin and then executed sudo ./jdk-6u6-linux-x64.bin In terminal I accepted the license agreement and done.

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• UML Class diagrams with Java packages?

  - by loosebruce

  I am trying to model in UML 2.0 a Java servlet application that has three classes Servlet class; essentially a main class that acts as the controller DatabaseLogic; contains methods for database operations XMLBuilder; builds an XML from a query result string The classes use a variety of packages from the Java library. I am unsure how to model this in UML Do I have to create a package and show which libraries are used for each individual class or can I just have one large package in the diagram with all the libraries showing which classes have dependencies on which. As per this diagram This is my first time working with java properly (im a C++ guy) Apart from being a bit messy , is this a correct UML representation of the system I described? Does a Package in UML mean the same as a Package in Java?

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• No Android SDK, neither Java found

  - by Alex

  I have Java installed correctly, I did it by the manual http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux I also installed Android SDK. However when I try to create a new Project IntelliJ Idea 12 and specify Project SDk choosing New - /home/alex/android-sdk-linux , it says me No Java SDK of appropriate version found. In addition to the Android SDK, you need to define a JSDK 1.5, 1.6 or 1.7 What did I miss?

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• Do you need to know Java before trying Scala

  - by gizgok

  I'm interested in learning Scala. I've been reading a lot about it, but a lot of people value it because it has an actor model which is better for concurrency, it handles xml in a much better way, solves the problem of first class functions. My question is do you need to know Java to understand/appreciate the way things work in Scala? Is it better to first take a stab at Java and then try Scala or you can start Scala with absolutely no java backround?

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• Need suggestion for Mutiple Windows application design

  - by King Chan

  This was previously posted in StackOverflow, I just moved to here... I am using VS2008, MVVM, WPF, Prism to make a mutiple window CRM Application. I am using MidWinow in my MainWindow, I want Any ViewModel would able to make request to MainWindow to create/add/close MidChildWindow, ChildWindow(from WPF Toolkit), Window (the Window type). ViewModel can get the DialogResult from the ChildWindow its excutes. MainWindow have control on all opened window types. Here is my current approach: I made Dictionary of each of the windows type and stores them into MainWindow class. For 1, i.e in a CustomerInformationView, its CustomerInformationViewModel can execute EditCommand and use EventAggregator to tell MainWindow to open a new ChildWindow. CustomerInformationViewModel: CustomerEditView ceView = new CustomerEditView (); CustomerEditViewModel ceViewModel = CustomerEditViewModel (); ceView.DataContext = ceViewModel; ChildWindow cWindow = new ChildWindow(); cWindow.Content = ceView; MainWindow.EvntAggregator.GetEvent<NewWindowEvent>().Publish(new WindowEventArgs(ceViewModel.ViewModeGUID, cWindow )); cWindow.Show(); Notice that all my ViewModel will generates a Guid for help identifies the ChildWindow from MainWindow's dictionary. Since I will only be using 1 View 1 ViewModel for every Window. For 2. In CustomerInformationViewModel I can get DialogResult by OnClosing event from ChildWindow, in CustomerEditViewModel can use Guid to tell MainWindow to close the ChildWindow. Here is little question and problems: Is it good idea to use Guid here? Or should I use HashKey from ChildWindow? My MainWindows contains windows reference collections. So whenever window close, it will get notifies to remove from the collection by OnClosing event. But all the Windows itself doesn't know about its associated Guid, so when I remove it, I have to search for every KeyValuePair to compares... I still kind of feel wrong associate ViewModel's Guid for ChildWindow, it would make more sense if ChildWindow has it own ID then ViewModel associate with it... But most important, is there any better approach on this design? How can I improve this better?

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• Hot-hot-hot for jobs in Java and mobile software

  - by hinkmond

  It's hot-hot-hot! The market for Java and mobile developers keeps growing hotter, and hotter--so says the latest Dice survey. See: Dice survey says Java & Mobile are tops Here's a quote: The market for mobile developers is expanding faster than the talent pool can adapt, a Dice survey indicates. Software developers in general—as well as Java, mobile software and Microsoft .Net developers in particular—are in short supply today. Those fields represent four of the top five most difficult positions IT managers are looking to fill... ... The New York/New Jersey metro area led the country with 8,871 positions listed... So, if you are looking to get into software development get crackin' in learning Java mobile programming and move to NY or NJ. Let's go Mets! Hinkmond

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• Using XSLT for messaging instead of marshalling/unmarshalling Java message objects

  - by Joost van Stuijvenberg

  So far I have been using either handmade or generated (e.g. JAXB) Java objects as 'carriers' for messages in message processing software such as protocol converters. This often leads to tedious programming, such as copying/converting data from one system's message object to an instance of another's system message object. And it sure brings in lots of Java code with getters and setters for each message attribute, validation code, etc. I was wondering whether it would be a good idea to convert one system's XML message into another system's format - or even convert requests into responses from the same system - using XSLT. This would mean I would no longer have to unmarshall XML streams to Java objects, copy/convert data using Java and marshall the resulting message object to another XML stream. Since each message may actually have a purpose I would 'link' the message (and the payload it contains in its properties or XML elements/attributes) to EXSLT functions. This would change my design approach from an imperative to a declarative style. Has anyone done this before and, if so, what are your experiences? Does the reduced amount of Java 'boiler plate' code weigh up to the increased complexity of (E)XSLT?

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• Can't copy from clipboard to any Java applet

  - by Thomas O

  The clipboard does not work with any Java applet on my install of Ubuntu 10.04. I am using the IcedTea plugin. I cannot copy/paste from Ubuntu to Java in either direction. However, IcedTea can copy to itself - that is, I can cut text from a Java applet and paste it into another part of that same applet. Other than this, clipboard support is fine across the rest of Ubuntu. Is there anything I can do to fix this?

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• Android Java rectangle collision detection not working

  - by Charlton Santana

  I had been hard coding a collision detection system which was buggy. Then I came across using rectangles for collsion detection. So I put it all in and it does not work, I put a log in and it never logged. Note to Java programmers who are not Android programers: Android uses the word Rect instead of Rectangle. Code for Block.java: public Rect getBounds(){ return new Rect (this.x, this.y, 10, 20); } Code for Sprite.java: public Rect getBounds(){ return new Rect (this.x, this.y, 20, 20); } Code for MainGame.java: for(Block block : BLOCKS) { block.draw(canvas); block.rigidbody(); Rect spriter = sprite.getBounds(); Rect blockr = block.getBounds(); if(spriter.intersect(blockr)){ showgameover = 1; Log.d(TAG, "Game Over"); } } Is anyone able to help?

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• Forbes Article on Big Data and Java Embedded Technology

  - by hinkmond

  Whoa, cool! Forbes magazine has an online article about what I've been blogging about all this time: Big Data and Java Embedded Technology, tying it all together with a big bow, connecting small devices to the data center. See: Billions of Java Embedded Devices Here's a quote: By the end of the decade we could see tens of billions of new Internet-connected devices... with billions of Internet- connected devices generating Big Data, are the next big thing. ... That’s why Oracle has put together an ecosystem of solutions for this new, Big Data-oriented device-to-data center world: secure, powerful, and adaptable embedded Java for intelligent devices, integrated middleware... This is the next big thing. Java SE Embedded Technology is something to watch for in the new year. Start developing for it now to get a head-start... Hinkmond

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• Analyzing Memory Usage: Java vs C++ Negligible?

  - by Anthony

  How does the memory usage of an integer object written in Java compare\contrast with the memory usage of a integer object written in C++? Is the difference negligible? No difference? A big difference? I'm guessing it's the same because an int is an int regardless of the language (?) The reason why I asked this is because I was reading about the importance of knowing when a program's memory requirements will prevent the programmer from solving a given problem. What fascinated me is the amount of memory required for creating a single Java object. Take for example, an integer object. Correct me if I'm wrong but a Java integer object requires 24 bytes of memory: 4 bytes for its int instance variable 16 bytes of overhead (reference to the object's class, garbage collection info & synchronization info) 4 bytes of padding As another example, a Java array (which is implemented as an object) requires 48+bytes: 24 bytes of header info 16 bytes of object overhead 4 bytes for length 4 bytes for padding plus the memory needed to store the values How do these memory usages compare with the same code written in C++? I used to be oblivious about the memory usage of the C++ and Java programs I wrote, but now that I'm beginning to learn about algorithms, I'm having a greater appreciation for the computer's resources.

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• Free Online Translation Tool Hosting for Java Open Source Project [closed]

  - by Yan Cheng CHEOK

  I'm looking for a free online translation tool hosting. I wish to leverage help from open source community, to keep the language files for an open source project (Java) up to date. http://jstock.hg.sourceforge.net/hgweb/jstock/jstock/file/7871125356f7/src/org/yccheok/jstock/data Pootle seems good, as it supports Java language properties files as well. However, their official hosting site, is not opened for public registration. I was wondering, is there any free online translation tool hosting for Java open source project (Or similar) ?

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• Constraints while designing the Java generics

  - by Andrea

  Java generics look quite different from those available in Scala, although both were designed by Martin Odersky. From my point of view, the design of generics in Java is worse, for instance: there is no possibility to specify variance one can get around the previous limitation by using wildcards, but this means the burden of specifying variance goes on the caller instead of the library designer one cannot use a type constructor in generics What were the constraints in Java that forced Odersky to design this mechanism for generics instead of the more flexible one he devised for Scala? Was he just savvier a few years later or there were actual limitations due to Java?

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• What are some Java patterns well-suited for fast, algorithmic coding?

  - by Casey Chu

  I'm in college, and I've recently started competing in programming competitions with my friends. These competitions involve solving algorithmic problems quickly. It's a lot of fun, but there's one problem: I'm forced to use Java. (My teammates use Java.) Background: I'm a self-taught JavaScript programmer, and it hurts to write Java code. I find it very verbose and inflexible, and I feel slowed down when having to declare types and decide which of the eighty list data structure to use. I'm also frustrated about the lack of functional programming features and how verbose using regular expressions, arrays, and dictionaries are. As an example, consider the problem of finding the length of the longest string of consecutive characters in a given string. So the string XX22BBBBccXX222 would give 4, for the string of four Bs. In Java, I'd have to loop through and manually count characters and manually keep track of the maximum. (That's at least as far as I'm aware -- I'm not as familiar with Java as I am with JavaScript.) In JavaScript, I'd find it like this: var max = Math.max.apply(Math, str.match(/(.)\1*/g).map(function (s) { return s.length; })); Much quicker and simpler, in my book. The question: what are some Java features, techniques, or patterns well-suited for fast, algorithmic coding?

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• Java Terms that are Plagued with Vaguery

  - by Adam Tannon

  What's the difference between a Java Process (what your OS sees) and a JVM? Are they one in the same or are they actually different? How are the JRE and JDK different (in purpose and file content), and which one contains the libraries for Java SE? What's the difference between the Java "Runtime" and a JVM? These are questions I've been asking myself (and colleagues) for years and everybody seems to have very different answers.

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• How quickly does the Java language get outdated?

  - by Dummy Derp

  I started learning Java recently. I started learning it using books that I picked up from the library, some that I bought, and here and there from Java documentation. The book that I use for Java was published in the year 2011. In 2012, Java8 will be released followed by Java9 in the year 2013. The questions are: How do I keep myself updated about developments in Java without having to buy a tome for Java8 and/or Java9 Is a book published in 2008 an outdated book for studying JSP and Servelets? I'm talking about Head First Servlets and JSP

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• Java is very slow on my laptop

  - by Ryan McClure

  I have 1.6.0_30 JRE on my 11.10 install. I have 3 GB of RAM and an Intel Core2 Duo CPU T6600 @ 2.20GHz × 2. Whenever I use my Java to play a game, the Java runs at about 4-5 FPS. When I used Windows, I found that I could get around 40 FPS. I'm not too terribly worried about this, but are there settings that I can tweak that I don't know about? If not, why is it that JRE Java can't do as much on Ubuntu as it can on Windows? Also, this may be related but I'm not too sure--My fan runs very fast when running a Java application. Is there a correlation?

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• How do I install Java?

  - by Jay

  I am using Ubuntu 11.04 Natty Narwhal. I recently installed openjdk-jre6 because one of the websites I use requires java for me to log in. Unfortunately, even after installing openjdk-jre6, I am not able to use the website. In place of 2 text boxes where I am supposed to enter my username and password, it simply shows a message "click here to download plugin". I am using Firefox by the way. I even tried to install java by clicking on that message. But it says "Java Runtime Environment not available". And then gives me a button to install java manually. But I would rather install it from the repo's. Could someone please tell me, what I should do to get Firefox to take note of the openjdk-jre6 that I have already installed?

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