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  • I'm a PeopleSoft Developer. Should I learn other languages (C# Java...)?

    - by PSDev
    I've been doing PeopleSoft development for 2 years. Recently, I want to relocate and find out there are not that many PeopleSoft development out there. 90% of the vacant positions are contract type of jobs. I'd rather get a full time permanent position. In PS, I do a lot of maintenance rather than new programming. It does get very boring. Also, I'm not sure if Oracle will one day pull off the plug for PS. What language is in most demand and also offers above average salary? Is it C#, Java, Python, Perl, ...? Thanks.

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  • How do i add a start menu page to my java game?

    - by user2149407
    I have a rather cool space invaders game that my friend and I have been working on for a while, and we have decided it needs an opening page, with "Start" options, "Quit" options and so forth. I have looked at several methods online, but cant seem to get any of them to work! Does anybody have any ideas? P.S Using JFrame to draw the main frame Im just looking to do this within Java, so just a panel that appears at a state change (GAME, MENU). Id like it to contain a few buttons to start the game, and quit. Later, I will add achievements, but im after something really basic for now. But thanks for the suggestions!

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  • How do I make a Java gave without a JFrame?

    - by kullalok
    I am working on an arcade-like game, and so far, I have been using JFrame. All the action occurs in the JFrame basically. However, I've noticed that a lot of games that you install on a computer don't have a frame. When you play them on Windows, the game covers the entire screen (the start bar disappears and you can't access any other application on your computer). I'd like to do that for my game. Is it possible to do so with Java? If so, how would I do this?

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  • what are best cities for a java developer to live and work in america? [closed]

    - by Shabangu
    hi everyone. I am doing research on the topic as per subject line. I am currently attending BSc Honours Studies in computer science at university of pretoria - south africa, and intend to do masters/PhD either in america or the uk. I am a java programmer, and currently hold a sun scjp certification (intend to study further). as per my findings so far, america seems to be a better option than uk. could you kindly comment on what good universities are there for computer science postgraduate studies in america, especially in california? and what about work thereafter? I also need to sort this out asap, as I need to decide if will doing toefl or ielts. please comment. shabangu

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  • What is the best way to work with large databases in Java depending on context?

    - by user19000
    We are trying to figure out the best practice for working with very large DBs in Java. What we do is a kind of BI (business Intelligence), i.e analyzing very large DBs, and using them to create intermediate DBs that represent intelligent knowledge of the DBs. We are currently using JDBC, and just preforming queries using a ResultSet. As more and more data is being created, we are wondering whether more appropriate ways exist for parsing and manipulating these large DBs: We need to support 'chunk' manipulation and not an entire DB at once(e.g. limit in JDBC, very poor performance) We do not need to be constantly connected since we are just pulling results and creating new tables of our own. We want to understand JDBC alternatives, with respect to advantages and disadvantages. Whether you think JDBC is the way to go or not, what are the best practices to go by depending on context (e.g. for large DBs queried in chunks)?

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  • How can I make my Java desktop application to run on different computers in a network locally and updating same mysql database?

    - by JaMpa
    I have developed Java desktop application for registration of students in the computer laboratories in our college, but what I need is to make this application whenever it runs on any computer (Windows XP machines) on the laboratory each and every data filled by the college students goes to the same MySql database (through WAMP server) running on the server machine (Win Server 2003). Also, I need this application to run during booting of windows computers in the laboratory for the purpose when any student tries to switch on any PC in the comp lab before interfacing the desktop icons should sign in through user name and password when he has already registered or signing up in order for getting the access.

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  • Webservice returns java.lang.reflect.InvocationTargetException

    - by Damian
    Hi, I am receiving the above message when making a request to a java webservice. We originally created a Java Console application and manually submitted an xml file. When running this as a Java Application the response is successfully created and displayed by using System.out.println. We are creating the web service by selecting the java file that contains the methods and choosing "create webservice" specifying the dynamic project that the webservice is to be created in and the methods to be exposed. What the application is doing is taking an xml file and unmarshalling this to an object using: public static Object unmarshalToObject(Class classToBeBound, String xmlRequest) { Object obj = new Object(); try { JAXBContext jc = JAXBContext.newInstance(classToBeBound); Unmarshaller um = jc.createUnmarshaller(); obj = um.unmarshal(new StringReader(xmlRequest)); } catch (Exception e) { e.printStackTrace() } return obj; } Some processing is carried out on the file and then an object is marshalled to xml as follows: public static String marshalToXML(Object data) { StringWriter sw = new StringWriter(); try { logger.info("Create new Marshall"); JAXBContext jc = JAXBContext.newInstance("ContextPathName"); logger.info("Marshalled to xmlObjects"); Marshaller marshaller = jc.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true); marshaller.marshal(data, sw); } catch (Exception e) { logException(logger, e); } return sw.toString(); } The following is the line of code that seems to be causing an issue as the logger displays the message prior to this: JAXBContext jc = JAXBContext.newInstance("ContextPathName"); The webservice never gets to the next line - the following is the body of the SOAP message: <soapenv:Fault> <faultcode>soapenv:Server.userException</faultcode> <faultstring>java.lang.reflect.InvocationTargetException</faultstring> <detail> <ns1:hostname xmlns:ns1="http://xml.apache.org/axis/">servername</ns1:hostname> </detail> </soapenv:Fault> I have added Try/Catch around this section of code even as far as looking for JAXBExceptions but this does not seem to catch anything - nor does the general exception. This issue does not occur when running the console application. The build path for this includes the following contents of sun\jwsdp-2.0\jaxb\lib: jaxb-api.jar jsr173_1.0_api.jar jaxb-impl.jar I have added these to the lib folder in the WEB-INF file of the dynamic project. I am running the webservice in JBuilder 2008 R2 and using SOAPUI to submit the request - this points to the wsdl generated when creating the webservice. If anyone has any help or ideas on how to solve this could they please reply - thanks for taking the time to read this post!

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  • Crawling engine architecture - Java/ Perl integration

    - by Bigtwinz
    Hi all, I am looking to develop a management and administration solution around our webcrawling perl scripts. Basically, right now our scripts are saved in SVN and are manually kicked off by SysAdmin/devs etc. Everytime we need to retrieve data from new sources we have to create a ticket with business instructions and goals. As you can imagine, not an optimal solution. There are 3 consistent themes with this system: the retrieval of data has a "conceptual structure" for lack of a better phrase i.e. the retrieval of information follows a particular path we are only looking for very specific information so we dont have to really worry about extensive crawling for awhile (think thousands-tens of thousands of pages vs millions) crawls are url-based instead of site-based. As I enhance this alpha version to a more production-level beta I am looking to add automation and management of the retrieval of data. Additionally our other systems are Java (which I'm more proficient in) and I'd like to compartmentalize the perl aspects so we dont have to lean heavily on outside help. I've evaluated the usual suspects Nutch, Droid etc but the time spent on modifying those frameworks to suit our specific information retrieval cant be justified. So I'd like your thoughts regarding the following architecture. I want to create a solution which use Java as the interface for managing and execution of the perl scripts use Java for configuration and data access stick with perl for retrieval An example use case would be a data analyst delivers us a requirement for crawling perl developer creates the required script and uses this webapp to submit the script (which gets saved to the filesystem) the script gets kicked off from the webapp with specific parameters .... Webapp should be able to create multiple threads of the perl script to initiate multiple crawlers. So questions are what do you think how solid is integration between Java and Perl specifically from calling perl from java has someone used such a system which actually is part perl repository The goal really is to not have a whole bunch of unorganized perl scripts and put some management and organization on our information retrieval. Also, I know I can use perl do do the web part of what we want - but as I mentioned before - trying to keep perl focused. But it seems assbackwards I'm not adverse to making it an all perl solution. Open to any all suggestions and opinions. Thanks

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  • Java web-app debugging not possible due to direct undeploy on debug

    - by Hendrik
    When i try to debug my webapp it starts up the tomcat server and the application, but shuts down the debugger shortly before the app gets usable. I see the debugging toolbar for a second before it vanishes again, though the app keeps running. Tomcat-log: Listening for transport dt_socket at address: 11555 23.03.2010 01:24:35 org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: .:/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java 23.03.2010 01:24:35 org.apache.coyote.http11.Http11Protocol init INFO: Initializing Coyote HTTP/1.1 on http-8084 23.03.2010 01:24:35 org.apache.catalina.startup.Catalina load INFO: Initialization processed in 847 ms 23.03.2010 01:24:35 org.apache.catalina.core.StandardService start INFO: Starting service Catalina 23.03.2010 01:24:35 org.apache.catalina.core.StandardEngine start INFO: Starting Servlet Engine: Apache Tomcat/6.0.20 log4j:WARN No appenders could be found for logger (org.springframework.web.context.ContextLoader). log4j:WARN Please initialize the log4j system properly. 23.03.2010 01:24:41 org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8084 23.03.2010 01:24:41 org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 23.03.2010 01:24:41 org.apache.jk.server.JkMain start INFO: Jk running ID=0 time=0/78 config=null 23.03.2010 01:24:41 org.apache.catalina.startup.Catalina start INFO: Server startup in 5855 ms 23.03.2010 01:24:42 org.apache.catalina.startup.HostConfig checkResources INFO: Undeploying context [] 23.03.2010 01:24:45 org.apache.catalina.core.StandardContext start INFO: Container org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/] has already been started Debugging log: Attached JPDA debugger to localhost:11555 Checking data source definitions for missing JDBC drivers... Deploying JDBC driver to /Applications/NetBeans/apache-tomcat-6.0.20/lib/mysql-connector-java-5.1.6-bin.jar Stopping Tomcat process... Waiting for Tomcat... Tomcat server stopped. Starting Tomcat process... Waiting for Tomcat... Tomcat server started. Undeploying ... OK - Undeployed application at context path / In-place deployment at /path/to/project/dir/build/web deploy?config=file%3A%2Fvar%2Ffolders%2FZP%2FZPbqxGrbHFaUlXzAfgWV1%2B%2B%2B%2BTQ%2F-Tmp-%2Fcontext734173871283203218.xml&path=/ OK - Deployed application at context path / start?path=/ Start is in progress... OK - Started application at context path / debug-display-browser: Browsing: http://localhost:8084/ connect-client-debugger: BUILD SUCCESSFUL (total time: 18 seconds) System is Netbeans 6.8 on MacOS 10.6.2. Thank you very much, guys!

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  • Run bat file in Java and wait 2

    - by Savvas Dalkitsis
    This is a followup question to my other question : http://stackoverflow.com/questions/2434125/run-bat-file-in-java-and-wait The reason i am posting this as a separate question is that the one i already asked was answered correctly. From some research i did my problem is unique to my case so i decided to create a new question. Please go read that question before continuing with this one as they are closely related. Running the proposed code blocks the program at the waitFor invocation. After some research i found that the waitFor method blocks if your process has output that needs to be proccessed so you should first empty the output stream and the error stream. I did those things but my method still blocks. I then found a suggestion to simply loop while waiting the exitValue method to return the exit value of the process and handle the exception thrown if it is not, pausing for a brief moment as well so as not to consume all the CPU. I did this: import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class Test { public static void main(String[] args) { try { Process p = Runtime.getRuntime().exec( "cmd /k start SQLScriptsToRun.bat" + " -UuserName -Ppassword" + " projectName"); final BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream())); final BufferedReader error = new BufferedReader(new InputStreamReader(p.getErrorStream())); new Thread(new Runnable() { @Override public void run() { try { while (input.readLine()!=null) {} } catch (IOException e) { e.printStackTrace(); } } }).start(); new Thread(new Runnable() { @Override public void run() { try { while (error.readLine()!=null) {} } catch (IOException e) { e.printStackTrace(); } } }).start(); int i = 0; boolean finished = false; while (!finished) { try { i = p.exitValue(); finished = true; } catch (IllegalThreadStateException e) { e.printStackTrace(); try { Thread.sleep(500); } catch (InterruptedException e1) { e1.printStackTrace(); } } } System.out.println(i); } catch (IOException e) { e.printStackTrace(); } } } but my process will not end! I keep getting this error: java.lang.IllegalThreadStateException: process has not exited Any ideas as to why my process will not exit? Or do you have any libraries to suggest that handle executing batch files properly and wait until the execution is finished?

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  • Rendering HTML in Java

    - by ferronrsmith
    I am trying to create a help panel for an application I am working on. The help file as already been created using html technology and I would like it to be rendered in a pane and shown. All the code I have seen shows how to render a site e.g. "http://google.com". I want to render a file from my pc e.g. "file://c:\tutorial.html" This is the code i have, but it doesn't seem to be working. import javax.swing.JEditorPane; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JScrollPane; import javax.swing.SwingUtilities; import java.awt.Color; import java.awt.Container; import java.io.IOException; import static java.lang.System.err; import static java.lang.System.out; final class TestHTMLRendering { // ------------------------------ CONSTANTS ------------------------------ /** * height of frame in pixels */ private static final int height = 1000; /** * width of frame in pixels */ private static final int width = 1000; private static final String RELEASE_DATE = "2007-10-04"; /** * title for frame */ private static final String TITLE_STRING = "HTML Rendering"; /** * URL of page we want to display */ private static final String URL = "file://C:\\print.html"; /** * program version */ private static final String VERSION_STRING = "1.0"; // --------------------------- main() method --------------------------- /** * Debugging harness for a JFrame * * @param args command line arguments are ignored. */ @SuppressWarnings( { "UnusedParameters" } ) public static void main( String args[] ) { // Invoke the run method on the Swing event dispatch thread // Sun now recommends you call ALL your GUI methods on the Swing // event thread, even the initial setup. // Could also use invokeAndWait and catch exceptions SwingUtilities.invokeLater( new Runnable() { /** * } fire up a JFrame on the Swing thread */ public void run() { out.println( "Starting" ); final JFrame jframe = new JFrame( TITLE_STRING + " " + VERSION_STRING ); Container contentPane = jframe.getContentPane(); jframe.setSize( width, height ); contentPane.setBackground( Color.YELLOW ); contentPane.setForeground( Color.BLUE ); jframe.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); try { out.println( "acquiring URL" ); JEditorPane jep = new JEditorPane( URL ); out.println( "URL acquired" ); JScrollPane jsp = new JScrollPane( jep, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED ); contentPane.add( jsp ); } catch ( IOException e ) { err.println( "can't find URL" ); contentPane.add( new JLabel( "can't find URL" ) ); } jframe.validate(); jframe.setVisible( true ); // Shows page, with HTML comments erroneously displayed. // The links are not clickable. } } ); }// end main }// end TestHTMLRendering

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  • Keeping files or database records? Java and Python

    - by danpalmer
    My website will use a Neural Network to predict thing based on user data. The user can select the data to be used in training the network and then use their trained network to predict things. I am using a framework to create, train and query the networks. This uses Java. The framework has persistence for saving a network to an XML file. What is the best way to store these files? I can see several potential ideas, but I need help on choosing which is best: Save each network to a separate XML file with a name that is stored in the database. Load this each time. Save all the networks to the same XML file with each network having a different name that is stored in the database. Somehow pass what would normally be written to an XML file to the Django site for writing to the database. This would need to be returned to the Java code when a prediction needs to be made. I am able to do 1 or 2, but I think their performance will be quite limited and I am on shared hosting at the moment, so I don't know how pleased they would be with thousands of files. Also, after adding a few thousand records to one XML file, I was noticing a massive performance hit on saving to it. If I were able to implement version 3 somehow I think it would be best. No issues with separate processes accessing the database and I think performance would be better. Not to mention having no files lying around. However, the stuff in the neural network framework I am using (Encog) for saving to a file needs access to a Java file object, not a string that could be saved to a database. Unless there is some Java magic I can do here (I know very little Java), the only way I can see of doing this would be with a temporary files but I don't know if this is the correct way to do it. I would appreciate any ideas on the best way to implement any of the above 3 ideas or any alternatives. Thanks!

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  • Cannot run public class in one .java from another

    - by DIOS
    I have created a basic program that takes whatever is input into two textfields and exports them to a file. I would now like to encrypt that file, and alredy have the encryptor. The problem is that I cannot call it. Here is my code for the encryptor: import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.*; import javax.crypto.Cipher; import javax.crypto.CipherInputStream; import javax.crypto.CipherOutputStream; import javax.crypto.spec.SecretKeySpec; public class FileEncryptor { private String algo; private File file; public FileEncryptor(String algo,String path) { this.algo=algo; //setting algo this.file=new File(path); //settong file } public void encrypt() throws Exception{ //opening streams FileInputStream fis =new FileInputStream(file); file=new File(file.getAbsolutePath()); FileOutputStream fos =new FileOutputStream(file); //generating key byte k[] = "HignDlPs".getBytes(); SecretKeySpec key = new SecretKeySpec(k,algo.split("/")[0]); //creating and initialising cipher and cipher streams Cipher encrypt = Cipher.getInstance(algo); encrypt.init(Cipher.ENCRYPT_MODE, key); CipherOutputStream cout=new CipherOutputStream(fos, encrypt); byte[] buf = new byte[1024]; int read; while((read=fis.read(buf))!=-1) //reading data cout.write(buf,0,read); //writing encrypted data //closing streams fis.close(); cout.flush(); cout.close(); } public static void main (String[] args)throws Exception { new FileEncryptor("DES/ECB/PKCS5Padding","C:\\Users\\*******\\Desktop\\newtext").encrypt();//encrypts the current file. } } Here is the section of my file creator that is failing to call this: FileWriter fWriter = null; BufferedWriter writer = null; try{ fWriter = new FileWriter("C:\\Users\\*******\\Desktop\\newtext"); writer = new BufferedWriter(fWriter); writer.write(Data); writer.close(); f.dispose(); FileEncryptor encr = new FileEncryptor(); //problem lies here. encr.encrypt //public void that does the encryption. new complete(); //different .java that is working fine.

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  • Coroutines in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7?

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  • Java Swing: JWindow appears behind all other process windows, and will not disappear

    - by Kim Jong Woo
    I am using JWindow to display my splash screen during the application start up. however it will not appear in front of all windows as it should, and it will not disappear as well. import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.Font; import java.awt.Toolkit; import javax.swing.BorderFactory; import javax.swing.ImageIcon; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JWindow; public class MySplash { public static MySplash INSTANCE; private static JWindow jw; public MySplash(){ createSplash(); } private void createSplash() { jw = new JWindow(); JPanel content = (JPanel) jw.getContentPane(); content.setBackground(Color.white); // Set the window's bounds, centering the window int width = 328; int height = 131; Dimension screen = Toolkit.getDefaultToolkit().getScreenSize(); int x = (screen.width - width) / 2; int y = (screen.height - height) / 2; jw.setBounds(x, y, width, height); // Build the splash screen JLabel label = new JLabel(new ImageIcon("splash.jpg")); JLabel copyrt = new JLabel("SplashScreen Test", JLabel.CENTER); copyrt.setFont(new Font("Sans-Serif", Font.BOLD, 12)); content.add(label, BorderLayout.CENTER); content.add(copyrt, BorderLayout.SOUTH); Color oraRed = new Color(156, 20, 20, 255); content.setBorder(BorderFactory.createLineBorder(oraRed, 0)); } public synchronized static MySplash getInstance(){ if(INSTANCE==null){ INSTANCE = new MySplash(); } return INSTANCE; } public void showSplash(){ jw.setAlwaysOnTop(true); jw.toFront(); jw.setVisible(true); return; } public void hideSplash(){ jw.setAlwaysOnTop(false); jw.toBack(); jw.setVisible(false); return; } } So in my main class which extends JFrame, I call my splash screen by SwingUtilities.invokeLater(new Runnable(){ @Override public void run() { MySplash.getInstance().showSplash(); } }); However, the JWindow appears behind the all open instances of windows on my computer. Hiding the JWindow also doesn't work. SwingUtilities.invokeLater(new Runnable(){ @Override public void run() { MySplash.getInstance().hideSplash(); } });

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  • Implementing coroutines in Java

    - by JUST MY correct OPINION
    This question is related to my question on existing coroutine implementations in Java. If, as I suspect, it turns out that there is no full implementation of coroutines currently available in Java, what would be required to implement them? As I said in that question, I know about the following: You can implement "coroutines" as threads/thread pools behind the scenes. You can do tricksy things with JVM bytecode behind the scenes to make coroutines possible. The so-called "Da Vinci Machine" JVM implementation has primitives that make coroutines doable without bytecode manipulation. There are various JNI-based approaches to coroutines also possible. I'll address each one's deficiencies in turn. Thread-based coroutines This "solution" is pathological. The whole point of coroutines is to avoid the overhead of threading, locking, kernel scheduling, etc. Coroutines are supposed to be light and fast and to execute only in user space. Implementing them in terms of full-tilt threads with tight restrictions gets rid of all the advantages. JVM bytecode manipulation This solution is more practical, albeit a bit difficult to pull off. This is roughly the same as jumping down into assembly language for coroutine libraries in C (which is how many of them work) with the advantage that you have only one architecture to worry about and get right. It also ties you down to only running your code on fully-compliant JVM stacks (which means, for example, no Android) unless you can find a way to do the same thing on the non-compliant stack. If you do find a way to do this, however, you have now doubled your system complexity and testing needs. The Da Vinci Machine The Da Vinci Machine is cool for experimentation, but since it is not a standard JVM its features aren't going to be available everywhere. Indeed I suspect most production environments would specifically forbid the use of the Da Vinci Machine. Thus I could use this to make cool experiments but not for any code I expect to release to the real world. This also has the added problem similar to the JVM bytecode manipulation solution above: won't work on alternative stacks (like Android's). JNI implementation This solution renders the point of doing this in Java at all moot. Each combination of CPU and operating system requires independent testing and each is a point of potentially frustrating subtle failure. Alternatively, of course, I could tie myself down to one platform entirely but this, too, makes the point of doing things in Java entirely moot. So... Is there any way to implement coroutines in Java without using one of these four techniques? Or will I be forced to use the one of those four that smells the least (JVM manipulation) instead?

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Java replacement for C macros

    - by thkala
    Recently I refactored the code of a 3rd party hash function from C++ to C. The process was relatively painless, with only a few changes of note. Now I want to write the same function in Java and I came upon a slight issue. In the C/C++ code there is a C preprocessor macro that takes a few integer variables names as arguments and performs a bunch of bitwise operations with their contents and a few constants. That macro is used in several different places, therefore its presence avoids a fair bit of code duplication. In Java, however, there is no equivalent for the C preprocessor. There is also no way to affect any basic type passed as an argument to a method - even autoboxing produces immutable objects. Coupled with the fact that Java methods return a single value, I can't seem to find a simple way to rewrite the macro. Avenues that I considered: Expand the macro by hand everywhere: It would work, but the code duplication could make things interesting in the long run. Write a method that returns an array: This would also work, but it would repeatedly result into code like this: long tmp[] = bitops(k, l, m, x, y, z); k = tmp[0]; l = tmp[1]; m = tmp[2]; x = tmp[3]; y = tmp[4]; z = tmp[5]; Write a method that takes an array as an argument: This would mean that all variable names would be reduced to array element references - it would be rather hard to keep track of which index corresponds to which variable. Create a separate class e.g. State with public fields of the appropriate type and use that as an argument to a method: This is my current solution. It allows the method to alter the variables, while still keeping their names. It has the disadvantage, however, that the State class will get more and more complex, as more macros and variables are added, in order to avoid copying values back and forth among different State objects. How would you rewrite such a C macro in Java? Is there a more appropriate way to deal with this, using the facilities provided by the standard Java 6 Development Kit (i.e. without 3rd party libraries or a separate preprocessor)?

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  • Losing session after Login - Java

    - by Patrick Villela
    I'm building an application that needs to login to a certain page and make a navigation. I can login, provided that the response contains a string that identifies it. But, when I navigate to the second page, I can't see the page as a logged user, only as anonymous. I'll provide my code. import java.net.*; import java.security.*; import java.security.cert.*; import javax.net.ssl.*; import java.io.*; import java.util.*; public class PostTest { static HttpsURLConnection conn = null; private static class DefaultTrustManager implements X509TrustManager { @Override public void checkClientTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {} @Override public void checkServerTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {} @Override public X509Certificate[] getAcceptedIssuers() { return null; } } public static void main(String[] args) { try { SSLContext ctx = SSLContext.getInstance("TLS"); ctx.init(new KeyManager[0], new TrustManager[] {new DefaultTrustManager()}, new SecureRandom()); SSLContext.setDefault(ctx); String data = URLEncoder.encode("txtUserName", "UTF-8") + "=" + URLEncoder.encode(/*username*/, "UTF-8"); data += "&" + URLEncoder.encode("txtPassword", "UTF-8") + "=" + URLEncoder.encode(/*password*/", "UTF-8"); data += "&" + URLEncoder.encode("envia", "UTF-8") + "=" + URLEncoder.encode("1", "UTF-8"); connectToSSL(/*login url*/); conn.setDoOutput(true); OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream()); wr.write(data); wr.flush(); BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream())); String line; String resposta = ""; while((line = rd.readLine()) != null) { resposta += line + "\n"; } System.out.println("valid login -> " + resposta.contains(/*string that assures me I'm looged in*/)); connectToSSL(/*first navigation page*/); rd = new BufferedReader(new InputStreamReader(conn.getInputStream())); while((line = rd.readLine()) != null) { System.out.println(line); } } catch(Exception e) { e.printStackTrace(); } } private static void connectToSSL(String address) { try { URL url = new URL(address); conn = (HttpsURLConnection) url.openConnection(); conn.setHostnameVerifier(new HostnameVerifier() { @Override public boolean verify(String arg0, SSLSession arg1) { return true; } }); } catch(Exception ex) { ex.printStackTrace(); } } } Any further information, just ask. Thanks in advance.

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  • How do I detect server status in a port scanner java implementation

    - by akz
    I am writing a port scanner in Java and I want to be able to distinct the following 4 use cases: port is open port is open and server banner was read port is closed server is not live I have the following code: InetAddress address = InetAddress.getByName("google.com"); int[] ports = new int[]{21, 22, 23, 80, 443}; for (int i = 0; i < ports.length; i++) { int port = ports[i]; Socket socket = null; try { socket = new Socket(address, port); socket.setSoTimeout(500); System.out.println("port " + port + " open"); BufferedReader reader = new BufferedReader( new InputStreamReader(socket.getInputStream())); String line = reader.readLine(); if (line != null) { System.out.println(line); } socket.close(); } catch (SocketTimeoutException ex) { // port was open but nothing was read from input stream ex.printStackTrace(); } catch (ConnectException ex) { // port is closed ex.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (socket != null && !socket.isClosed()) { try { socket.close(); } catch (Exception e) { e.printStackTrace(); } } } } The problem is that I get a ConnectionException both when the port is closed and the server cannot be reached but with a different exception message: java.net.ConnectException: Connection timed out: connect when the connection was never established and java.net.ConnectException: Connection refused: connect when the port was closed so I cannot make the distinction between the two use cases without digging into the actual exception message. Same thing happens when I try a different approach for the socket creation. If I use: socket = new Socket(); socket.setSoTimeout(500); socket.connect(new InetSocketAddress(address, port), 1000); I have the same problem but with the SocketTimeoutException instead. I get a java.net.SocketTimeoutException: Read timed out if port was open but there was no banner to be read and java.net.SocketTimeoutException: connect timed out if server is not live or port is closed. Any ideas? Thanks in advance!

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  • Primary language - QtC++, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Random generates same number in java

    - by user1613360
    This is my java code. import java.io.*; import java.util.*; import java.util.concurrent.TimeUnit; class search { private int numelem; private int[] input=new int[100]; public void setNumofelem() { System.out.println("Enter the total numebr of elements"); Scanner yz=new Scanner(System.in); numelem=yz.nextInt(); } public void randomnumber() throws Exception { int max=500,min=1,n=numelem; Random rand = new Random(); for (int j=0;j < n;j++) { input[j]=rand.nextInt(max)+1; } } public void printinput() { int b=numelem,t=0; while(true) if(b!=0) { System.out.print(" "+input[t]); b--; t++; } else break; } } public class mycode { public static void main(String args[]) throws Exception { search a=new search(); a.setNumofelem(); a.randomnumber(); a.printinput(); } } Now the function randomnumber() just returns the same number.The function executes perfectly if I execute it as a separate java program but fails miserably if I call it using an object.I have also tried the following variations but nothing works everything return the same number. Variation 1: public void randomnumber() throws Exception { int max=500,min=1,n=numelem; Random rand = new Random(); for (int j=0;j < n;j++) { TimeUnit.SECONDS.sleep(1); input[j]=rand.nextInt(max)+1; } } Variation 2: public void randomnumber() throws Exception { int max=500,min=1,n=numelem; Random rand = new Random(); for (int j=0;j < n;j++) { rand.setSeed(System.nanoTime()); input[j]=rand.nextInt(max)+1; } } Variation 3: public void randomnumber() throws Exception { int max=500,min=1,n=numelem; Random rand = new Random(); for (int j=0;j < n;j++) { TimeUnit.SECONDS.sleep(1); rand.setSeed(System.nanoTime()); input[j]=rand.nextInt(max)+1; } } Sample input/Output: Enter the number of elements: 5 23 23 23 23 23 23

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  • java: useful example of a shutdown hook?

    - by Jason S
    I'm trying to make sure my Java application takes reasonable steps to be robust, and part of that involves shutting down gracefully. I am reading about shutdown hooks and I don't actually get how to make use of them in practice. Is there a practical example out there? Let's say I had a really simple application like this one below, which writes numbers to a file, 10 to a line, in batches of 100, and I want to make sure a given batch finishes if the program is interrupted. I get how to register a shutdown hook but I have no idea how to integrate that into my application. Any suggestions? package com.example.test.concurrency; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.PrintWriter; public class GracefulShutdownTest1 { final private int N; final private File f; public GracefulShutdownTest1(File f, int N) { this.f=f; this.N = N; } public void run() { PrintWriter pw = null; try { FileOutputStream fos = new FileOutputStream(this.f); pw = new PrintWriter(fos); for (int i = 0; i < N; ++i) writeBatch(pw, i); } catch (FileNotFoundException e) { e.printStackTrace(); } finally { pw.close(); } } private void writeBatch(PrintWriter pw, int i) { for (int j = 0; j < 100; ++j) { int k = i*100+j; pw.write(Integer.toString(k)); if ((j+1)%10 == 0) pw.write('\n'); else pw.write(' '); } } static public void main(String[] args) { if (args.length < 2) { System.out.println("args = [file] [N] " +"where file = output filename, N=batch count"); } else { new GracefulShutdownTest1( new File(args[0]), Integer.parseInt(args[1]) ).run(); } } }

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  • Error with my Android Application httpGet

    - by Coombes
    Basically I'm getting a strange issue with my Android application, it's supposed to grab a JSON Array and print out some values, the class looks like this: ShowComedianActivity.class package com.example.connecttest; public class ShowComedianActivity extends Activity{ TextView name; TextView add; TextView email; TextView tel; String id; // Progress Dialog private ProgressDialog pDialog; //JSON Parser class JSONParser jsonParser = new JSONParser(); // Single Comedian url private static final String url_comedian_details = "http://86.9.71.17/connect/get_comedian_details.php"; // JSON Node names private static final String TAG_SUCCESS = "success"; private static final String TAG_COMEDIAN = "comedian"; private static final String TAG_ID = "id"; private static final String TAG_NAME = "name"; private static final String TAG_ADDRESS = "address"; private static final String TAG_EMAIL = "email"; private static final String TAG_TEL = "tel"; public void onCreate(Bundle savedInstanceState){ super.onCreate(savedInstanceState); setContentView(R.layout.show_comedian); // Getting Comedian Details from intent Intent i = getIntent(); // Getting id from intent id = i.getStringExtra(TAG_ID); new GetComedianDetails().execute(); } class GetComedianDetails extends AsyncTask<String, String, String>{ protected void onPreExecute(){ super.onPreExecute(); pDialog = new ProgressDialog(ShowComedianActivity.this); pDialog.setMessage("Fetching Comedian details. Please wait..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected String doInBackground(String... params) { runOnUiThread(new Runnable(){ public void run(){ int success; try{ //Building parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("id",id)); // Getting comedian details via HTTP request // Uses a GET request JSONObject json = jsonParser.makeHttpRequest(url_comedian_details, "GET", params); // Check Log for json response Log.d("Single Comedian details", json.toString()); //JSON Success tag success = json.getInt(TAG_SUCCESS); if(success == 1){ // Succesfully received product details JSONArray comedianObj = json.getJSONArray(TAG_COMEDIAN); //JSON Array // get first comedian object from JSON Array JSONObject comedian = comedianObj.getJSONObject(0); // comedian with id found name = (TextView) findViewById(R.id.name); add = (TextView) findViewById(R.id.add); email = (TextView) findViewById(R.id.email); tel = (TextView) findViewById(R.id.tel); // Set text to details name.setText(comedian.getString(TAG_NAME)); add.setText(comedian.getString(TAG_ADDRESS)); email.setText(comedian.getString(TAG_EMAIL)); tel.setText(comedian.getString(TAG_TEL)); } } catch (JSONException e){ e.printStackTrace(); } } }); return null; } } } And my JSON Parser class looks like: package com.example.connecttest; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } // function get json from url // by making HTTP POST or GET method public JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } Now when I run a debug it's querying the correct address with ?id=1 on the end of the URL, and when I navigate to that url I get the following JSON Array: {"success":1,"comedian":[{"id":"1","name":"Michael Coombes","address":"5 Trevethenick Road","email":"[email protected]","tel":"xxxxxxxxxxxx"}]} However my app just crashes, the log-cat report looks like this: 03-22 02:05:02.140: E/Trace(3776): error opening trace file: No such file or directory (2) 03-22 02:05:04.590: E/AndroidRuntime(3776): FATAL EXCEPTION: main 03-22 02:05:04.590: E/AndroidRuntime(3776): android.os.NetworkOnMainThreadException 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 03-22 02:05:04.590: E/AndroidRuntime(3776): at libcore.io.IoBridge.connect(IoBridge.java:112) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.net.Socket.connect(Socket.java:842) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 03-22 02:05:04.590: E/AndroidRuntime(3776): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.JSONParser.makeHttpRequest(JSONParser.java:62) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.example.connecttest.ShowComedianActivity$GetComedianDetails$1.run(ShowComedianActivity.java:89) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.handleCallback(Handler.java:615) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Handler.dispatchMessage(Handler.java:92) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.os.Looper.loop(Looper.java:137) 03-22 02:05:04.590: E/AndroidRuntime(3776): at android.app.ActivityThread.main(ActivityThread.java:4745) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invokeNative(Native Method) 03-22 02:05:04.590: E/AndroidRuntime(3776): at java.lang.reflect.Method.invoke(Method.java:511) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 03-22 02:05:04.590: E/AndroidRuntime(3776): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 03-22 02:05:04.590: E/AndroidRuntime(3776): at dalvik.system.NativeStart.main(Native Method) From this I'm guessing the error is in the jsonParser.makeHttpRequest however I can't for the life of me figure out what's going wrong and was hoping someone brighter than I could illuminate me.

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  • Finding the best practice for a game simulating tool

    - by Tougheart
    I'm studying Java right now, and I'm thinking of this tool as my practice project. The game is "League of Legends" in case anyone knows it, I'm not actually simulating the game as in simulating game play, I'm just trying to create a tool that can compare different champions to each other based on their own abilities and items bought inside the game. The game basics are: Every player has a champion in a team of 5 players playing against another team. Each champion has a different set of abilities (usually 4) that s/he uses to do damage to opposing champions. Each champion gets stronger by buying different items, increasing the attack it deals or decreasing the damage received. What I want to do is to create a tool to be used outside the game enabling players to try out different builds for their champions and compare the figures against other champions they usually fight against. The goal is to enable players get a deeper understanding of the different item combinations (builds) that can be used during the games, instead of trying them out in real games which can be somehow very time consuming. What I'm stuck at is the best practice I should follow to make this possible using Java, I can't figure out which classes should inherit from which, should I make champions and items specs in the code or extracted from other files, specially that I'm talking about hundreds of items and champions to use in that tool. I'm self studying Java, and I don't have much practice at it, so I would really appreciate any broad guidelines regarding this, and sorry if my question doesn't fit here, I tried to follow the rules. English isn't my native language, so I'm really sorry if I wasn't clear enough, I would be more than happy to explain anything that's not understood.

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