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  • Where should I put a method that returns a list of active entries of a table?

    - by darga33
    I have a class named GuestbookEntry that maps to the properties that are in the database table named "guestbook". Very simple! Originally, I had a static method named getActiveEntries() that retrieved an array of all GuestbookEntry objects. Each row in the guestbook table was an object that was added to that array. Then while learning how to properly design PHP classes, I learned some things: Static methods are not desirable. Separation of Concerns Single Responsibility Principle If the GuestbookEntry class should only be responsible for managing single guestbook entries then where should this getActiveEntries() method most properly go? Update: I am looking for an answer that complies with the SOLID acronym principles and allows for test-ability. That's why I want to stay away from static calls/standard functions. DAO, repository, ...? Please explain as though your explanation will be part of "Where to Locate FOR DUMMIES"... :-)

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  • Where to start a software Analysis & Designing?

    - by Muneer
    I am starting a big database oriented software to develop. I have full picture of the software in mind. I need to do the designing using UML. As there are various tools in UML such as usecase, class diagram, statechart, component diagram, deployment diagram, activity diagram and so on, where should I start my designing. Should it be from Usecase or from Class Diagram or from State Chart? which wich approach will help me to put my mind's picture in to design.? Please corporate with me. Thanks.

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  • Are nested classes under-rated?

    - by Aaron Anodide
    I'm not trying to say I know something everyone else doesn't but I've been solving more and more designs with the use of nested classes, so I'm curious to get a feeling for the acceptablilty of using this seemingly rarely used design mechanism. This leads me to the question: am I going down an inherintly bad path for reasons I'll discover when they come back to bite me, or are nested classes maybe something that are underrated? Here are two examples I just used them for: https://gist.github.com/3975581 - the first helped me keep tightly releated heirarchical things together, the second let me give access to protected members to workers...

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  • Designing a single look up entity

    - by altsyset
    In almost every application you have this look up entity that provides a dynamic references. This are things like type, category, etc. These entities will always have id, name, desc So at first I designed different entities for each look up. Like education_type, education_level, degree_type.... But on a second thought I decided to have on entity for each of these kinds of entities. But when I am done with the design and check the relation this entity will be referenced by almost all entities in the system and I don't believe that is appropriate. So What is your take on this? Can you give me some clear pros and cons?

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  • What kind of math should I be expecting in advanced programming?

    - by I_Question_Things_Deeply
    And I don't mean just space shooters and such, because in non-3D environments it's obvious that not much beyond elementary math is needed to implement. Most of the programming in 2D games is mostly going to involve basic arithmetic, algorithms for enemy AI and dimensional worlds, rotation, and maybe some Algebra as well depending on how you want to design. But I ask because I'm not really gifted with math at all. I get frustrated and worn out just by doing Pre-Algebra, so Algebra 2 and Calculus would likely be futile for me. I guess I'm not so "right-brained" when it comes down to pure numbers and math formulas, but the bad part is that I'm no art-expert either. What do you people here suppose I should do? Go along avoiding as much of the extremely difficult maths I can't fathom, or try to ease into more complex math as I excel at programming?

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  • is it allowed to create a app with overscroll feature?

    - by user61664
    As Apple wo lawsuits against Motorola and Samsung with the so called overscroll patent, i am asking myself what the legal consequences of releasing a APP with such a feature are. I think if one releases the APP in IOS it would be okay, but what happens in android or Windows? Am i getting sued ? What happens if i am writing an APP for the Browser? Isn`t this overscroll patent a design patent? It this is true, all apps hat usw overscrolling and not written by apple , would be illegal. Very confusing. Can anyone explain is?

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  • Where would a senior PHP developer locate the method getActiveEntries()?

    - by darga33
    I have a class named GuestbookEntry that maps to the properties that are in the database table named "guestbook". Very simple! Originally, I had a static method named getActiveEntries() that retrieved an array of all GuestbookEntry objects. Each row in the guestbook table was an object that was added to that array. Then while learning how to properly design PHP classes, I learned some things: Static methods are not desirable. Separation of Concerns Single Responsibility Principle If the GuestbookEntry class should only be responsible for managing single guestbook entries then where should this getActiveEntries() method most properly go? Update: I am looking for an answer that complies with the SOLID acronym principles and allows for test-ability. That's why I want to stay away from static calls/standard functions. DAO, repository, ...? Please explain as though your explanation will be part of "Where to Locate FOR DUMMIES"... :-)

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  • Architects into videogames

    - by Ángel
    I'm an architecture student in my last year. I've always been interested in videogames design. I use 3d Max and Photoshop on a daily basis, and I was thinking about aiming for a career in videogames, starting as a level/environment designer. How should approach it? Is it worthy to spend some time learning UDK or CryEngine? Should I try a smaller but more general software? I know some programming already. Finally, will my skills as an architect be something valuable in the indusrty? Thanks in advance.

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  • How can I avoid the engineering mistakes of PDT?

    - by ashy_32bit
    As a developer with enough experience to evaluate a tool, I may say that PDT is very huge in size and slow in performance for a PHP IDE. It gets bigger by release and exponentially slower by the size of the projects. Add some extra syntax coloring rules and it literally crawls, code completion works randomly and building workspace takes like forever. Java black magic (-Xmx etc) eases the pain a little but that's it. So my questions are: Why is PDT like this? What design or engineering factors led to its poor performance? How can I avoid making these same mistakes in my own products?

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  • Oracle OpenWorld 2011????WebLogic Server?????????|WebLogic Channel|??????

    - by ???02
    2011?10?2?~6??????????????????????Oracle OpenWorld 2011???????????????????????????????????????????????????WebLogic Server??????????????????????? Fusion Middleware?????? ???????? ?????????????????????????WebLogic Server??????????????????(???)????????????????WebLogic Server――Oracle OpenWorld 2011??????????·?????????????????????????????????????????WebLogic Server?????????????????????????????????WebLogic Server?????????????????????? Oracle OpenWorld 2011???????????????????????????????Oracle Fusion Financial Management????????????????Oracle Fusion Human Capital Management????????????????Oracle Fusion Supply Chain Management???????????????????Oracle Fusion Applications??????????????WebLogic Server????????????????????????????????????????? ?????????????????????·????????????????????????Oracle Fusion Middleware???????????????????????????????????????????????Development Tools???Cloud Application Foundation???Enterprise Management??3???????WebLogic Server??Oracle Coherence?Oracle Tuxedo?????Cloud Application Foundation???????????? ????????????????????????WebLogic Server?????????????????????????????????????????????????????――Oracle OpenWorld 2011??????????????????·????????Oracle Public Cloud????????????Oracle Public Cloud??????WebLogic Server????????????????? ??????????·????·???????Oracle Public Cloud???????·?????1????Java?????????????????????PaaS???WebLogic Server??????????????????????????????Java EE????????????????????????????????????????????????????????????????????????????????????????????????――WebLogic Server????????????????????????? ??????????Oracle Database??????????????WebLogic Server??Oracle Real Application Clusters(RAC)?????????????Oracle Database????????????????????Active GridLink for RAC???????????????????????????????????????WebLogic Server???????????????????????????????????????? ?????????????WebLogic Server???????????Java EE 6????????????????????????????·???????GlassFish 3???Java EE 6????????????WebLogic Server???????????????????????????????WebLogic Server?Java EE 6??????????????·??????????????Java EE 6?????????????????????????????????????? ??Java EE 6????????????????????????????????????????????Web???????????Java EE?????????Web Profile?????????????????WebLogic Server?????????????????????????????????????????????????????????????Oracle Exalogic Elastic Cloud――??????WebLogic Server??????????????·???????????Oracle Exalogic Elastic Cloud??????????????????????????????????? ???WebLogic Server???????????????????·????????????????????????????????????????????????????????????????????????????????????????????????Oracle VM 3.0 for Exalogic?????????????????????????????Exalogic????????????????????????????????????????????????????????????? ?????????????????????Exalogic Control????????????????????????????????????Oracle Enterprise Manager???????????????????????????????????? ???Java EE??????????????????????Virtual Assembly Builder??Exalogic????????????????????????Java EE???????????????????????????????1????????????Exalogic?????????????????? ?????????????????Exalogic??????????InfiniBand????????????Exabus???Oracle Coherence?Oracle Tuxedo??????????????????????Exabus????Exalogic???????????????????????????????????????――Exabus???????????????????????????????? ?????????I/O?????????????????????????·??????TCP/IP??????????????????????????????????????????????????????InfiniBand??????????????????????? ??????Exabus????????????????????????InfiniBand??????????????????????????????????????????????????????????????????????????????????4??????????(??)?6??1????????????Exabus??????API????Oracle Coherence???Exabus Java API?????Tuxedo???Exabus RDMA API????????――???????WebLogic Server?Exalogic???????Java EE?????????????????????????? WebLogic Server?????????Java EE 6??????????????????????????????????????????????????????????????????????? ???Exalogic??????????????Exabus???????????????????????????????????????????????????Java EE??????????????????????????????????Java EE???????????????????????????????????????????????

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  • How to solve JAVA menubar, layout and panel problem ?

    - by Berkay
    i'm not a java guy however i start implementing some security tools with java, in these days i'm creating a gui for my security tools : Here is the how my Gui looks: menuBar = new JMenuBar(); // construct menu bar // hash functions fileMenu = new JMenu("HASH FUNCTIONS"); // define file menu fileMenu.setMnemonic('H'); // shortcut hashes = new JMenuItem("Md5&Sha1"); // define file menu options hashes.setMnemonic('M'); hashes.addActionListener(this); fileMenu.add(hashes); menuBar.add(fileMenu); // add file menu to menu bar // symmetric encryption asMenu = new JMenu("SYMMETRIC ENCRYPTION"); // define format menu asMenu.setMnemonic('S'); // shortcut desItem = new JMenuItem("DES"); // define format menu options desItem.setMnemonic('D'); desItem.addActionListener(this); asMenu.add(desItem); ... ... menuBar.add(helpMenu); // add help menu to menu bar setJMenuBar(menuBar); // put menu bar on application textColor = Color.RED; when from the Menu desitem is selected, desvar is just for not showing the panel multiple times, it calls Panels () else if(e.getSource() == desItem && desvar ==1 ) { // make other panels unvisible. if(hashvar!=1) MyPanel.setVisible(false);//hash functions if(rsavar!=1) MyPanel3.setVisible(false);//rsa function if (dhvar!=1) MyPanel4.setVisible(false);//dh diffie hellman hashvar=1; rsavar=1; dhvar=1; ++desvar; desPanel=true; Panels(); } and in Panels() Method: if (hashPanel){ MyPanel.add("West",radioSHA1); MyPanel.add("West",radioMD5); MyPanel.add("Center", inputField); MyPanel.add("East",SubmitButton); MyPanel.add("South",resultHash); add(MyPanel); validate(); hashPanel=false; } i have many panels for example : -hash functions=mypanel1 , des=mypanel2, rsa functions= mypanel3 , dh= mypanel4 However in may other panals such as rsa function: i have to use some layout properties of the java:in this panel i selected to use gridbaglayout if (dhPanel){ System.out.println("rsa panel burda misin"); MyPanel3.add(pqLabel); MyPanel3.add(pLabel); MyPanel3.add(pTextArea); MyPanel3.add(qLabel); ... ... add(MyPanel3); generate_pqButton.addActionListener(this); calculate_nButton.addActionListener(this); ... ... GridBagLayout layout = new GridBagLayout(); GridBagConstraints gbc = new GridBagConstraints(); setLayout(layout); // x, y, w, h, wx, wy gbc.fill = GridBagConstraints.NONE; add (bit_length_label, gbc, 0, 0, 1, 1, 0, 10); add (p, gbc, 0, 1, 1, 1, 0, 10); add (g, gbc, 0, 2, 1, 1, 0, 10); add (a, gbc, 1, 3, 1, 1, 100, 10); add (x, gbc, 0, 4, 1, 1, 0, 10); add (gx, gbc, 0, 5, 1, 1, 0, 10); add (gxy, gbc, 0, 6, 1, 1, 0, 10); add (b, gbc, 1, 7, 1, 1, 100, 10); add (y, gbc, 0, 8, 1, 1, 0, 10); add (gy, gbc, 0, 9, 1, 1, 0, 10); add (gyx, gbc, 0, 10, 1, 1, 0, 10); add (sk, gbc, 1, 11, 1, 1, 100, 10); add (key, gbc, 0, 12, 1, 1, 0, 10); add (status, gbc, 1, 13, 1, 1, 100, 10); add (dhstart, gbc, 1, 14, 1, 1, 100, 10); add (bit_length_value, gbc, 1, 0, 1, 1, 100, 10); add (p_value, gbc, 1, 1, 1, 1, 100, 10); add (g_value, gbc, 1, 2, 1, 1, 100, 10); add (x_value, gbc, 1, 4, 1, 1, 100, 10); add (gx_value, gbc, 1, 5, 1, 1, 100, 10); add (gxy_value, gbc, 1, 6, 1, 1, 100, 10); add (y_value, gbc, 1, 8, 1, 1, 100, 10); add (gy_value, gbc, 1, 9, 1, 1, 100, 10); add (gyx_value, gbc, 1, 10, 1, 1, 100, 10); validate(); repaint(); rsaPanel=false; } Everthing seems okey however when i swith from one menu to another sometimes components are seen or apper in wrong places or mixed. where i'm doing wrong?

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  • Creating a dynamic proxy generator – Part 1 – Creating the Assembly builder, Module builder and cach

    - by SeanMcAlinden
    I’ve recently started a project with a few mates to learn the ins and outs of Dependency Injection, AOP and a number of other pretty crucial patterns of development as we’ve all been using these patterns for a while but have relied totally on third part solutions to do the magic. We thought it would be interesting to really get into the details by rolling our own IoC container and hopefully learn a lot on the way, and you never know, we might even create an excellent framework. The open source project is called Rapid IoC and is hosted at http://rapidioc.codeplex.com/ One of the most interesting tasks for me is creating the dynamic proxy generator for enabling Aspect Orientated Programming (AOP). In this series of articles, I’m going to track each step I take for creating the dynamic proxy generator and I’ll try my best to explain what everything means - mainly as I’ll be using Reflection.Emit to emit a fair amount of intermediate language code (IL) to create the proxy types at runtime which can be a little taxing to read. It’s worth noting that building the proxy is without a doubt going to be slightly painful so I imagine there will be plenty of areas I’ll need to change along the way. Anyway lets get started…   Part 1 - Creating the Assembly builder, Module builder and caching mechanism Part 1 is going to be a really nice simple start, I’m just going to start by creating the assembly, module and type caches. The reason we need to create caches for the assembly, module and types is simply to save the overhead of recreating proxy types that have already been generated, this will be one of the important steps to ensure that the framework is fast… kind of important as we’re calling the IoC container ‘Rapid’ – will be a little bit embarrassing if we manage to create the slowest framework. The Assembly builder The assembly builder is what is used to create an assembly at runtime, we’re going to have two overloads, one will be for the actual use of the proxy generator, the other will be mainly for testing purposes as it will also save the assembly so we can use Reflector to examine the code that has been created. Here’s the code: DynamicAssemblyBuilder using System; using System.Reflection; using System.Reflection.Emit; namespace Rapid.DynamicProxy.Assembly {     /// <summary>     /// Class for creating an assembly builder.     /// </summary>     internal static class DynamicAssemblyBuilder     {         #region Create           /// <summary>         /// Creates an assembly builder.         /// </summary>         /// <param name="assemblyName">Name of the assembly.</param>         public static AssemblyBuilder Create(string assemblyName)         {             AssemblyName name = new AssemblyName(assemblyName);               AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly(                     name, AssemblyBuilderAccess.Run);               DynamicAssemblyCache.Add(assembly);               return assembly;         }           /// <summary>         /// Creates an assembly builder and saves the assembly to the passed in location.         /// </summary>         /// <param name="assemblyName">Name of the assembly.</param>         /// <param name="filePath">The file path.</param>         public static AssemblyBuilder Create(string assemblyName, string filePath)         {             AssemblyName name = new AssemblyName(assemblyName);               AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly(                     name, AssemblyBuilderAccess.RunAndSave, filePath);               DynamicAssemblyCache.Add(assembly);               return assembly;         }           #endregion     } }   So hopefully the above class is fairly explanatory, an AssemblyName is created using the passed in string for the actual name of the assembly. An AssemblyBuilder is then constructed with the current AppDomain and depending on the overload used, it is either just run in the current context or it is set up ready for saving. It is then added to the cache.   DynamicAssemblyCache using System.Reflection.Emit; using Rapid.DynamicProxy.Exceptions; using Rapid.DynamicProxy.Resources.Exceptions;   namespace Rapid.DynamicProxy.Assembly {     /// <summary>     /// Cache for storing the dynamic assembly builder.     /// </summary>     internal static class DynamicAssemblyCache     {         #region Declarations           private static object syncRoot = new object();         internal static AssemblyBuilder Cache = null;           #endregion           #region Adds a dynamic assembly to the cache.           /// <summary>         /// Adds a dynamic assembly builder to the cache.         /// </summary>         /// <param name="assemblyBuilder">The assembly builder.</param>         public static void Add(AssemblyBuilder assemblyBuilder)         {             lock (syncRoot)             {                 Cache = assemblyBuilder;             }         }           #endregion           #region Gets the cached assembly                  /// <summary>         /// Gets the cached assembly builder.         /// </summary>         /// <returns></returns>         public static AssemblyBuilder Get         {             get             {                 lock (syncRoot)                 {                     if (Cache != null)                     {                         return Cache;                     }                 }                   throw new RapidDynamicProxyAssertionException(AssertionResources.NoAssemblyInCache);             }         }           #endregion     } } The cache is simply a static property that will store the AssemblyBuilder (I know it’s a little weird that I’ve made it public, this is for testing purposes, I know that’s a bad excuse but hey…) There are two methods for using the cache – Add and Get, these just provide thread safe access to the cache.   The Module Builder The module builder is required as the create proxy classes will need to live inside a module within the assembly. Here’s the code: DynamicModuleBuilder using System.Reflection.Emit; using Rapid.DynamicProxy.Assembly; namespace Rapid.DynamicProxy.Module {     /// <summary>     /// Class for creating a module builder.     /// </summary>     internal static class DynamicModuleBuilder     {         /// <summary>         /// Creates a module builder using the cached assembly.         /// </summary>         public static ModuleBuilder Create()         {             string assemblyName = DynamicAssemblyCache.Get.GetName().Name;               ModuleBuilder moduleBuilder = DynamicAssemblyCache.Get.DefineDynamicModule                 (assemblyName, string.Format("{0}.dll", assemblyName));               DynamicModuleCache.Add(moduleBuilder);               return moduleBuilder;         }     } } As you can see, the module builder is created on the assembly that lives in the DynamicAssemblyCache, the module is given the assembly name and also a string representing the filename if the assembly is to be saved. It is then added to the DynamicModuleCache. DynamicModuleCache using System.Reflection.Emit; using Rapid.DynamicProxy.Exceptions; using Rapid.DynamicProxy.Resources.Exceptions; namespace Rapid.DynamicProxy.Module {     /// <summary>     /// Class for storing the module builder.     /// </summary>     internal static class DynamicModuleCache     {         #region Declarations           private static object syncRoot = new object();         internal static ModuleBuilder Cache = null;           #endregion           #region Add           /// <summary>         /// Adds a dynamic module builder to the cache.         /// </summary>         /// <param name="moduleBuilder">The module builder.</param>         public static void Add(ModuleBuilder moduleBuilder)         {             lock (syncRoot)             {                 Cache = moduleBuilder;             }         }           #endregion           #region Get           /// <summary>         /// Gets the cached module builder.         /// </summary>         /// <returns></returns>         public static ModuleBuilder Get         {             get             {                 lock (syncRoot)                 {                     if (Cache != null)                     {                         return Cache;                     }                 }                   throw new RapidDynamicProxyAssertionException(AssertionResources.NoModuleInCache);             }         }           #endregion     } }   The DynamicModuleCache is very similar to the assembly cache, it is simply a statically stored module with thread safe Add and Get methods.   The DynamicTypeCache To end off this post, I’m going to create the cache for storing the generated proxy classes. I’ve spent a fair amount of time thinking about the type of collection I should use to store the types and have finally decided that for the time being I’m going to use a generic dictionary. This may change when I can actually performance test the proxy generator but the time being I think it makes good sense in theory, mainly as it pretty much maintains it’s performance with varying numbers of items – almost constant (0)1. Plus I won’t ever need to loop through the items which is not the dictionaries strong point. Here’s the code as it currently stands: DynamicTypeCache using System; using System.Collections.Generic; using System.Security.Cryptography; using System.Text; namespace Rapid.DynamicProxy.Types {     /// <summary>     /// Cache for storing proxy types.     /// </summary>     internal static class DynamicTypeCache     {         #region Declarations           static object syncRoot = new object();         public static Dictionary<string, Type> Cache = new Dictionary<string, Type>();           #endregion           /// <summary>         /// Adds a proxy to the type cache.         /// </summary>         /// <param name="type">The type.</param>         /// <param name="proxy">The proxy.</param>         public static void AddProxyForType(Type type, Type proxy)         {             lock (syncRoot)             {                 Cache.Add(GetHashCode(type.AssemblyQualifiedName), proxy);             }         }           /// <summary>         /// Tries the type of the get proxy for.         /// </summary>         /// <param name="type">The type.</param>         /// <returns></returns>         public static Type TryGetProxyForType(Type type)         {             lock (syncRoot)             {                 Type proxyType;                 Cache.TryGetValue(GetHashCode(type.AssemblyQualifiedName), out proxyType);                 return proxyType;             }         }           #region Private Methods           private static string GetHashCode(string fullName)         {             SHA1CryptoServiceProvider provider = new SHA1CryptoServiceProvider();             Byte[] buffer = Encoding.UTF8.GetBytes(fullName);             Byte[] hash = provider.ComputeHash(buffer, 0, buffer.Length);             return Convert.ToBase64String(hash);         }           #endregion     } } As you can see, there are two public methods, one for adding to the cache and one for getting from the cache. Hopefully they should be clear enough, the Get is a TryGet as I do not want the dictionary to throw an exception if a proxy doesn’t exist within the cache. Other than that I’ve decided to create a key using the SHA1CryptoServiceProvider, this may change but my initial though is the SHA1 algorithm is pretty fast to put together using the provider and it is also very unlikely to have any hashing collisions. (there are some maths behind how unlikely this is – here’s the wiki if you’re interested http://en.wikipedia.org/wiki/SHA_hash_functions)   Anyway, that’s the end of part 1 – although I haven’t started any of the fun stuff (by fun I mean hairpulling, teeth grating Relfection.Emit style fun), I’ve got the basis of the DynamicProxy in place so all we have to worry about now is creating the types, interceptor classes, method invocation information classes and finally a really nice fluent interface that will abstract all of the hard-core craziness away and leave us with a lightning fast, easy to use AOP framework. Hope you find the series interesting. All of the source code can be viewed and/or downloaded at our codeplex site - http://rapidioc.codeplex.com/ Kind Regards, Sean.

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  • Facing Null Pointer Exception while using BIRT

    - by srikanth
    Hi, I am using BIRT APIs in a java program.My code is : package com.tecnotree.mdx.product.utils; import java.util.HashMap; import java.util.logging.Level; import org.eclipse.birt.core.exception.BirtException; import org.eclipse.birt.core.framework.Platform; import org.eclipse.birt.report.engine.api.EngineConfig; import org.eclipse.birt.report.engine.api.EngineConstants; import org.eclipse.birt.report.engine.api.HTMLRenderOption; import org.eclipse.birt.report.engine.api.IReportEngine; import org.eclipse.birt.report.engine.api.IReportEngineFactory; import org.eclipse.birt.report.engine.api.IReportRunnable; import org.eclipse.birt.report.engine.api.IRunAndRenderTask; import org.eclipse.birt.report.engine.api.ReportEngine; public class ExampleReport { public static void main(String[] args) { // Variables used to control BIRT Engine instance ReportEngine eng = null; IReportRunnable design = null; IRunAndRenderTask task = null; HTMLRenderOption renderContext = null; HashMap contextMap = null; HTMLRenderOption options = null; final EngineConfig conf = new EngineConfig(); conf .setEngineHome("C:\\birt-runtime-2_5_2\\birt-runtime-2_5_2\\ReportEngine"); System.out.println("conf " + conf.getBIRTHome()); conf.setLogConfig(null, Level.FINE); try { Platform.startup(conf); } catch (BirtException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } IReportEngineFactory factory = (IReportEngineFactory) Platform .createFactoryObject(IReportEngineFactory.EXTENSION_REPORT_ENGINE_FACTORY); System.out.println("Factory : " + factory.toString()); System.out.println(conf.toString()); IReportEngine engine = factory.createReportEngine(conf); System.out.println("Engine : " + engine); try { design = eng .openReportDesign("C:\\birt-runtime-2_5_2\\birt-runtime-2_5_2\\ReportEngine\\samples\\hello_world.rptdesign"); } catch (Exception e) { System.err .println("An error occured during the opening of the report file!"); e.printStackTrace(); System.exit(-1); } task = eng.createRunAndRenderTask(design); renderContext = new HTMLRenderOption(); renderContext.setImageDirectory("image"); contextMap = new HashMap(); contextMap.put(EngineConstants.APPCONTEXT_HTML_RENDER_CONTEXT, renderContext); task.setAppContext(contextMap); options = new HTMLRenderOption(); options.setOutputFileName("c:/temp/output.html"); options.setOutputFormat("html"); task.setRenderOption(options); try { task.run(); } catch (Exception e) { System.err.println("An error occured while running the report!"); e.printStackTrace(); System.exit(-1); } System.out.println("All went well. Closing program!"); eng.destroy(); } } But i am facing NullPointerException while creating the report. STACKTRACE : Exception in thread "main" java.lang.NullPointerException at org.eclipse.birt.report.engine.api.impl.ReportEngine$EngineExtensionManager.<init>(ReportEngine.java:784) at org.eclipse.birt.report.engine.api.impl.ReportEngine.<init>(ReportEngine.java:109) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory$1.run(ReportEngineFactory.java:18) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory$1.run(ReportEngineFactory.java:1) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.birt.report.engine.api.impl.ReportEngineFactory.createReportEngine(ReportEngineFactory.java:14) at com.tecnotree.mdx.product.utils.ExampleReport.main(ExampleReport.java:47) Please help me regarding this... my project deadline has been reached... Appreciate your Reply Thanks in Advance

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  • Problem receving in RXTX

    - by drhorrible
    I've been using RXTX for about a year now, without too many problems. I just started a new program to interact with a new piece of hardware, so I reused the connect() method I've used on my other projects, but I have a weird problem I've never seen before. The Problem The device works fine, because when I connect with hyperterminal, I send things and receive what I expect, and Serial Port Monitor(SPM) reflects this. However, when I run the simple hyperterminal-clone I wrote to diagnose the problem I'm having with my main app, bytes are sent, according to SPM, but nothing is received, and my SerialPortEventListener never fires. Even when I check for available data in the main loop, reader.ready() returns false. If I ignore this check, then I get an exception, details below. Relevant section of connect() method // Configure and open port port = (SerialPort) CommPortIdentifier.getPortIdentifier(name) .open(owner,1000) port.setSerialPortParams(baud, databits, stopbits, parity); port.setFlowControlMode(fc_mode); final BufferedReader br = new BufferedReader( new InputStreamReader( port.getInputStream(), "US-ASCII")); // Add listener to print received characters to screen port.addEventListener(new SerialPortEventListener(){ public void serialEvent(SerialPortEvent ev) { try { System.out.println("Received: "+br.readLine()); } catch (IOException e) { e.printStackTrace(); } } }); port.notifyOnDataAvailable(); Exception java.io.IOException: Underlying input stream returned zero bytes at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:268) at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306) at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158) at java.io.InputStreamReader.read(InputStreamReader.java:167) at java.io.BufferedReader.fill(BufferedReader.java:136) at java.io.BufferedReader.read(BufferedReader.java:157) at <my code> The big question (again) I think I've eliminated all possible hardware problems, so what could be wrong with my code, or the RXTX library? Edit: something interesting When I open hyperterminal after sending a bunch of commands from java that should have gotten responses, all of the responses appear immediately, as if they had been put in the buffer somewhere, but unavailable. Edit 2: Tried something new, same results I ran the code example found here, with the same results. No data came in, but when I switched to a new program, it came all at once. Edit 3 The hardware is fine, and even a different computer has the same problem. I am not using any sort of USB adapter. I've started using PortMon, too, and it's giving me some interesting results. Hyperterminal and RXTX are not using the same settings, and RXTX always polls the port, unlike HyperTerminal, but I still can't see what settings would affect this. As soon as I can isolate the configuration from the constant polling, I'll post my PortMon logs. Edit 4 Is it possible that some sort of Windows update in the last 3 months could have caused this? It has screwed up one of my MATLAB mex-based programs once. Edit 5 I've also noticed some things that are different between HyperTerminal, RXTX, and a separate program I found that communicates with the device (but doesn't do what I want, which is why I'm rolling my own program) HyperTerminal - set to no flow control, but Serial Port Monitor's RTS and DTR indicators are green Other program - not sure what settings it thinks it's using, but only SPM's RTS indicator is green RXTX - no matter what flow control I set, only SPM's CTS and DTR indicators are on. From Serial Port Monitor's help files (paraphrased): the indicators display the state of the serial control lines RTS - Request To Send CTS - Clear To Send DTR - Data Terminal Ready

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  • How to make a character jump, both on objects and just normal jump.

    - by haxerflaxer
    Hi, I'm kind of a beginner when it comes to java programming, and I have a project in school where I'm going to create a game much like Icy Tower. And my question is, how am I going to write to make the character stand on the ground and be able to jump up on objects? Here's my code so far: Part one package Sprites; import java.awt.Image; import java.awt.event.KeyEvent; import javax.swing.ImageIcon; public class jumper { private String jump = "oka.png"; private int dx; private int dy; private int x; private int y; private Image image; public jumper() { ImageIcon ii = new ImageIcon(this.getClass().getResource(jump)); image = ii.getImage(); x = 50; y = 100; } public void move() { x += dx; y += dy; } public int getX() { return x; } public int getY() { return y; } public Image getImage() { return image; } public void keyPressed(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = -5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oki.png")); image = ii.getImage(); } if (key == KeyEvent.VK_RIGHT){ dx = 5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oka.png")); image = ii.getImage(); } if (key == KeyEvent.VK_SPACE) { dy = -5; } if (key == KeyEvent.VK_DOWN) { dy = 5; } } public void keyReleased(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = 0; } if (key == KeyEvent.VK_RIGHT){ dx = 0; } if (key == KeyEvent.VK_SPACE) { dy = 0; } if (key == KeyEvent.VK_DOWN) { dy = 0; } } } Part two package Sprites; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.JPanel; import javax.swing.Timer; public class board extends JPanel implements ActionListener { private Timer klocka; private jumper jumper; public board() { addKeyListener(new TAdapter()); setFocusable(true); setBackground(Color.WHITE); setDoubleBuffered(true); jumper = new jumper(); klocka = new Timer(5, this); klocka.start(); } public void paint(Graphics g) { super.paint(g); Graphics2D g2d = (Graphics2D)g; g2d.drawImage(jumper.getImage(), jumper.getX(), jumper.getY(), this); Toolkit.getDefaultToolkit().sync(); g.dispose(); } public void actionPerformed(ActionEvent e) { jumper.move(); repaint(); } private class TAdapter extends KeyAdapter { public void keyReleased(KeyEvent e) { jumper.keyReleased(e); } public void keyPressed(KeyEvent e) { jumper.keyPressed(e); } } } Part three package Sprites; import javax.swing.JFrame; public class RType extends JFrame { public RType() { add(new board()); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setSize(800, 600); setLocationRelativeTo(null); setTitle("R - type"); setResizable(false); setVisible(true); } public static void main(String[] args) { new RType(); } } I really appreciate all the help I can get!

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  • How do you make a character jump, both on objects and just normal jump?

    - by haxerflaxer
    Hi, I'm kind of a beginner when it comes to java programming, and I have a project in school where I'm going to create a game much like Icy Tower. And my question is, how am I going to write to make the character stand on the ground and be able to jump up on objects? Here's my code so far: Part one package Sprites; import java.awt.Image; import java.awt.event.KeyEvent; import javax.swing.ImageIcon; public class jumper { private String jump = "oka.png"; private int dx; private int dy; private int x; private int y; private Image image; public jumper() { ImageIcon ii = new ImageIcon(this.getClass().getResource(jump)); image = ii.getImage(); x = 50; y = 100; } public void move() { x += dx; y += dy; } public int getX() { return x; } public int getY() { return y; } public Image getImage() { return image; } public void keyPressed(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = -5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oki.png")); image = ii.getImage(); } if (key == KeyEvent.VK_RIGHT){ dx = 5; ImageIcon ii = new ImageIcon(this.getClass().getResource("oka.png")); image = ii.getImage(); } if (key == KeyEvent.VK_SPACE) { dy = -5; } if (key == KeyEvent.VK_DOWN) { dy = 5; } } public void keyReleased(KeyEvent e) { int key = e.getKeyCode(); if (key == KeyEvent.VK_LEFT) { dx = 0; } if (key == KeyEvent.VK_RIGHT){ dx = 0; } if (key == KeyEvent.VK_SPACE) { dy = 0; } if (key == KeyEvent.VK_DOWN) { dy = 0; } } } Part two package Sprites; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.JPanel; import javax.swing.Timer; public class board extends JPanel implements ActionListener { private Timer klocka; private jumper jumper; public board() { addKeyListener(new TAdapter()); setFocusable(true); setBackground(Color.WHITE); setDoubleBuffered(true); jumper = new jumper(); klocka = new Timer(5, this); klocka.start(); } public void paint(Graphics g) { super.paint(g); Graphics2D g2d = (Graphics2D)g; g2d.drawImage(jumper.getImage(), jumper.getX(), jumper.getY(), this); Toolkit.getDefaultToolkit().sync(); g.dispose(); } public void actionPerformed(ActionEvent e) { jumper.move(); repaint(); } private class TAdapter extends KeyAdapter { public void keyReleased(KeyEvent e) { jumper.keyReleased(e); } public void keyPressed(KeyEvent e) { jumper.keyPressed(e); } } } Part three package Sprites; import javax.swing.JFrame; public class RType extends JFrame { public RType() { add(new board()); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setSize(800, 600); setLocationRelativeTo(null); setTitle("R - type"); setResizable(false); setVisible(true); } public static void main(String[] args) { new RType(); } } I really appreciate all the help I can get!

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  • java.sql.SQLException: ORA-06502: PL/SQL: numeric or value error: character string buffer too small

    - by jack
    Hi I got an email from a user when he sees the following error output when he's using our web site. java.sql.SQLException: ORA-06502: PL/SQL: numeric or value error: character string buffer too small ORA-06512: at "WEB_OWNER.SSFP_GET_WE_OBJ", line 300 ORA-06512: at line 1 at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:137) at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:315) at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:281) This is error from oracle webconnect, Oracle Application Server Containers for J2EE 10g (10.1.2.3.0). Any idea?

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  • Java Class path problem in cent os..

    - by Ramesh
    I have installed java in centos5 classpath is not working .... my bash_profile export PATH=$PATH:/zzz/jdk1.6.0_03/bin/ export JAVA_HOME=/zzz/jdk1.6.0_03/bin/java/ export CLASSPATH=$CLASSPATH:/zzz/aa/mysql.jar:. java -version java version "1.6.0" OpenJDK Runtime Environment (build 1.6.0-b09) OpenJDK Server VM (build 1.6.0-b09, mixed mode)

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  • Problems with calendar application on Android 2.1

    - by Rick
    Hi, I have compiled the android 2.1 source code and I can start the emulator. But I can't launch calendar application. Every time I tried to lauch the calendar application, it crashed. The log is as following: // CRASH: com.android.calendar (pid 272) // Short Msg: java.lang.NullPointerException // Long Msg: java.lang.NullPointerException // Build Label: android:generic/generic/generic/:2.1-update1/ERE27/eng.root.20100317.113135:eng/test-keys // Build Changelist: -1 // Build Time: 1268798948 // ID: // Tag: AndroidRuntime // java.lang.NullPointerException: // at com.android.providers.calendar.CalendarSyncAdapter.onAccountsChanged(CalendarSyncAdapter.java:1400) // at android.content.AbstractSyncableContentProvider$1.onAccountsUpdated(AbstractSyncableContentProvider.java:189) // at android.accounts.AccountManager$10.run(AccountManager.java:826) // at android.os.Handler.handleCallback(Handler.java:587) // at android.os.Handler.dispatchMessage(Handler.java:92) // at android.os.Looper.loop(Looper.java:123) // at android.app.ActivityThread.main(ActivityThread.java:4363) // at java.lang.reflect.Method.invokeNative(Method.java:-2) // at java.lang.reflect.Method.invoke(Method.java:521) // at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) // at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) // at dalvik.system.NativeStart.main(NativeStart.java:-2) has anyone met this problem, or any suggestions on how to fix it? Thanks very much!! Rick

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  • htmlunit eofexception

    - by ihtram
    hi, i am using htmlunit to parse a page. but when i tried to get page from url i got an exception, lets have a look on my code: WebClient wc = new WebClient(BrowserVersion.FIREFOX_3); HtmlPage page = wc.getPage(strUrl); when compilet goes to wc.getPage(strUrl) it throws an exception i.e. java.io.EOFException at java.util.zip.GZIPInputStream.readUByte(Unknown Source) at java.util.zip.GZIPInputStream.readUShort(Unknown Source) at java.util.zip.GZIPInputStream.readHeader(Unknown Source) at java.util.zip.GZIPInputStream.(Unknown Source) at java.util.zip.GZIPInputStream.(Unknown Source) at com.gargoylesoftware.htmlunit.WebResponseData.getBody(WebResponseData.java:129) at com.gargoylesoftware.htmlunit.WebResponseData.(WebResponseData.java:87) at com.gargoylesoftware.htmlunit.HttpWebConnection.newWebResponseDataInstance(HttpWebConnection.java:452) at com.gargoylesoftware.htmlunit.HttpWebConnection.makeWebResponse(HttpWebConnection.java:432) at com.gargoylesoftware.htmlunit.HttpWebConnection.getResponse(HttpWebConnection.java:104) at com.gargoylesoftware.htmlunit.WebClient.loadWebResponseFromWebConnection(WebClient.java:1407) at com.gargoylesoftware.htmlunit.WebClient.loadWebResponse(WebClient.java:1340) at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:299) at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:360) at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:345) at com.htmlunit.test.IHGHotelTest.main(IHGHotelTest.java:39) any one have an idea about it

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  • Why do I get a null pointer exception from TabWidget?

    - by rushinge
    I'm writing an android program in which I have an activity that uses tabs. The Activity public class UnitActivity extends TabActivity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); TabHost tabHost = getTabHost(); TabSpec spec; Resources res = getResources(); LayoutInflater.from(this).inflate(R.layout.unit_view, tabHost.getTabContentView(), true); spec = tabHost.newTabSpec("controls"); spec.setIndicator("Control", res.getDrawable(R.drawable.ic_tab_equalizer)); spec.setContent(R.id.txtview); tabHost.addTab(spec); } } The XML referenced by R.layout.unit_view <?xml version="1.0" encoding="utf-8"?> <TabHost xmlns:android="http://schemas.android.com/apk/res/android" android:id="@android:id/tabhost" android:layout_width="fill_parent" android:layout_height="fill_parent"> <LinearLayout android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="5dp"> <TabWidget android:id="@android:id/tabs" android:layout_width="fill_parent" android:layout_height="wrap_content"/> <FrameLayout android:id="@android:id/tabcontent" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="5dp"> <TextView android:id="@+id/txtview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:gravity="bottom" android:text="nullpointer this!" /> </FrameLayout> </LinearLayout> </TabHost> As far as I can see I'm doing the same thing I see in the tabs1 api sample from the android sdk. I've tried "getLayoutInflator()" instead of "LayoutInflator.from(this)" with the same result. If I replace the LayoutInflater line with "setContentView(R.layout.unit_view)" my program doesn't crash with a null pointer exception but my content is completely blank and empty. I get the tab and that's it. I've checked to make sure R.layout.unit_view and tabHost are not null when it runs the LayoutInflater line and they seem to be fine. They're defenitely not null. I've also checked to make sure LayoutInflater.from(this) returns a valid layout inflater object and it does. The logcat indicating the error says E/AndroidRuntime( 541): java.lang.NullPointerException E/AndroidRuntime( 541): at android.widget.TabWidget.dispatchDraw(TabWidget.java:206) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.View.draw(View.java:6538) E/AndroidRuntime( 541): at android.widget.FrameLayout.draw(FrameLayout.java:352) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1531) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.ViewGroup.drawChild(ViewGroup.java:1529) E/AndroidRuntime( 541): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1258) E/AndroidRuntime( 541): at android.view.View.draw(View.java:6538) E/AndroidRuntime( 541): at android.widget.FrameLayout.draw(FrameLayout.java:352) E/AndroidRuntime( 541): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1830) E/AndroidRuntime( 541): at android.view.ViewRoot.draw(ViewRoot.java:1349) E/AndroidRuntime( 541): at android.view.ViewRoot.performTraversals(ViewRoot.java:1114) E/AndroidRuntime( 541): at android.view.ViewRoot.handleMessage(ViewRoot.java:1633) E/AndroidRuntime( 541): at android.os.Handler.dispatchMessage(Handler.java:99) E/AndroidRuntime( 541): at android.os.Looper.loop(Looper.java:123) E/AndroidRuntime( 541): at android.app.ActivityThread.main(ActivityThread.java:4363) E/AndroidRuntime( 541): at java.lang.reflect.Method.invokeNative(Native Method) E/AndroidRuntime( 541): at java.lang.reflect.Method.invoke(Method.java:521) E/AndroidRuntime( 541): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) E/AndroidRuntime( 541): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) E/AndroidRuntime( 541): at dalvik.system.NativeStart.main(Native Method) I/Process ( 61): Sending signal. PID: 541 SIG: 3 I/dalvikvm( 541): threadid=7: reacting to signal 3 I/dalvikvm( 541): Wrote stack trace to '/data/anr/traces.txt' Anybody have any idea how I can get this content into a tab without crashing my application? My actual program is more complex and has more than one tab but I simplified it down to this in an attempt to find out why it's crashing but it still crashes and I don't know why. If I don't use LayoutInflator my program doesn't crash but I don't get any content either, just tabs.

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  • OutOfMemoryError trying to upload to Blobstore locally

    - by jeanh
    Hi all, I am trying to set up a basic file upload to blobstore, but I get this OutOfMemoryError: WARNING: Error for /_ah/upload/ aghvbWdkcmVzc3IcCxIVX19CbG9iVXBsb2FkU2Vzc2lvbl9fGMACDA java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:2786) at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:71) at javax.mail.internet.MimeMultipart.readTillFirstBoundary(MimeMultipart.java: 316) at javax.mail.internet.MimeMultipart.parse(MimeMultipart.java:186) at javax.mail.internet.MimeMultipart.getCount(MimeMultipart.java:109) at com.google.appengine.api.blobstore.dev.UploadBlobServlet.handleUpload(UploadBlobServlet.java: 135) at com.google.appengine.api.blobstore.dev.UploadBlobServlet.access $000(UploadBlobServlet.java:72) at com.google.appengine.api.blobstore.dev.UploadBlobServlet $1.run(UploadBlobServlet.java:100) at java.security.AccessController.doPrivileged(Native Method) at com.google.appengine.api.blobstore.dev.UploadBlobServlet.doPost(UploadBlobServlet.java: 98) at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java: 511); I used the Memory Analyzer on Eclipse and it said that the memory leak suspect is QueuedThreadPool. I found this information about a memory leak bug: http://jira.codehaus.org/browse/JETTY-1188 Has anyone else had this issue? Thanks, Jean

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  • What are the disadvantages of self-encapsulation?

    - by Dave Jarvis
    Background Tony Hoare's billion dollar mistake was the invention of null. Subsequently, a lot of code has become riddled with null pointer exceptions (segfaults) when software developers try to use (dereference) uninitialized variables. In 1989, Wirfs-Brock and Wikerson wrote: Direct references to variables severely limit the ability of programmers to re?ne existing classes. The programming conventions described here structure the use of variables to promote reusable designs. We encourage users of all object-oriented languages to follow these conventions. Additionally, we strongly urge designers of object-oriented languages to consider the effects of unrestricted variable references on reusability. Problem A lot of software, especially in Java, but likely in C# and C++, often uses the following pattern: public class SomeClass { private String someAttribute; public SomeClass() { this.someAttribute = "Some Value"; } public void someMethod() { if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { return this.someAttribute; } } Sometimes a band-aid solution is used by checking for null throughout the code base: public void someMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Value" ) ) { // do something... } } public void anotherMethod() { assert this.someAttribute != null; if( this.someAttribute.equals( "Some Default Value" ) ) { // do something... } } The band-aid does not always avoid the null pointer problem: a race condition exists. The race condition is mitigated using: public void anotherMethod() { String someAttribute = this.someAttribute; assert someAttribute != null; if( someAttribute.equals( "Some Default Value" ) ) { // do something... } } Yet that requires two statements (assignment to local copy and check for null) every time a class-scoped variable is used to ensure it is valid. Self-Encapsulation Ken Auer's Reusability Through Self-Encapsulation (Pattern Languages of Program Design, Addison Wesley, New York, pp. 505-516, 1994) advocated self-encapsulation combined with lazy initialization. The result, in Java, would resemble: public class SomeClass { private String someAttribute; public SomeClass() { setAttribute( "Some Value" ); } public void someMethod() { if( getAttribute().equals( "Some Value" ) ) { // do something... } } public void setAttribute( String s ) { this.someAttribute = s; } public String getAttribute() { String someAttribute = this.someAttribute; if( someAttribute == null ) { setAttribute( createDefaultValue() ); } return someAttribute; } protected String createDefaultValue() { return "Some Default Value"; } } All duplicate checks for null are superfluous: getAttribute() ensures the value is never null at a single location within the containing class. Efficiency arguments should be fairly moot -- modern compilers and virtual machines can inline the code when possible. As long as variables are never referenced directly, this also allows for proper application of the Open-Closed Principle. Question What are the disadvantages of self-encapsulation, if any? (Ideally, I would like to see references to studies that contrast the robustness of similarly complex systems that use and don't use self-encapsulation, as this strikes me as a fairly straightforward testable hypothesis.)

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  • Cannot understand NullPointerException with custom adapter

    - by ganesh
    hi, I am trying to create a list view which as TextView that can display html content , an WebView and other basic TextViews.I tried to extend SimpleAdapter but i struck with the problem ,I will be glad if someone can point out the mistake i am doing. In onCreate method ArrayList mylist= resultfromXmlparser(); adap = new MyAdapter(TourLandingPage.this, mylist, R.layout.row, new String[] {"Name", "desc","Duration","Price","imgurl"}, new int[] {R.id.productname,R.id.des,R.id.duration,R.id.pricefrom,R.id.photo}); setListAdapter(adap); My custom Adapter looks like this private class MyAdapter extends SimpleAdapter { ArrayList<HashMap<String,String>> elements; Context ctx; public MyAdapter(Context context, ArrayList<HashMap<String,String>> mylist,int textViewResourceId,String[] names,int[] resouceid) { super(context, mylist,textViewResourceId, names,resouceid); this.elements=mylist; this.ctx=context; } @Override public int getCount() { return elements.size(); } @Override public Object getItem(int position) { return elements.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { RelativeLayout rowLayout; if (convertView == null) { rowLayout = (RelativeLayout) LayoutInflater.from(ctx).inflate(R.layout.rowfor_tourlist, parent, false); } else { rowLayout = (RelativeLayout) convertView; } TextView in = (TextView)rowLayout.findViewById(R.id.introduction); TextView du = (TextView)rowLayout.findViewById(R.id.duration); TextView pf = (TextView)rowLayout.findViewById(R.id.pricefrom); TextView pn = (TextView)rowLayout.findViewById(R.id.productname); WebView wv=(WebView)rowLayout.findViewById(R.id.photo); in.setText(Html.fromHtml(mylist.get(position).get("desc"))); du.setText(mylist.get(position).get("Duration")); pf.setText(mylist.get(position).get("Price")); pn.setText(mylist.get(position).get("Name")); wv.getSettings().setJavaScriptEnabled(true); wv.loadUrl(mylist.get(position).get("imgurl")); return convertView; } }//class and my row.xml file looks like RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" TextView android:id="@+id/productname" ...... LinearLayout android:layout_width="wrap_content" android:layout_height="60dip" android:layout_margin="5dip" android:layout_below="@id/productname" android:orientation="horizontal" android:id="@+id/lay1" WebView android:id="@+id/photo" .... TextView android:id="@+id/introduction" ...... LinearLayout TextView android:id="@+id/duration" .... TextView android:id="@+id/pricefrom" ..... RelativeLayout The error i was getting was 04-28 19:46:17.749: ERROR/AndroidRuntime(976): Uncaught handler: thread main exiting due to uncaught exception 04-28 19:46:17.769: ERROR/AndroidRuntime(976): java.lang.NullPointerException 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.setupChild(ListView.java:1693) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.makeAndAddView(ListView.java:1671) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.fillDown(ListView.java:637) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.fillFromTop(ListView.java:694) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.layoutChildren(ListView.java:1521) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.AbsListView.onLayout(AbsListView.java:1113) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1108) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:920) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:918) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:918) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.ViewRoot.performTraversals(ViewRoot.java:996) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.ViewRoot.handleMessage(ViewRoot.java:1633) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.os.Handler.dispatchMessage(Handler.java:99) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.os.Looper.loop(Looper.java:123) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.app.ActivityThread.main(ActivityThread.java:4338) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at java.lang.reflect.Method.invokeNative(Native Method) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at java.lang.reflect.Method.invoke(Method.java:521) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at dalvik.system.NativeStart.main(Native Method) 04-28 19:46:17.789: INFO/Process(52): Sending signal. PID: 976 SIG: 3 04-28 19:46:17.799: INFO/dalvikvm(976): threadid=7: reacting to signal 3 04-28 19:46:17.829: INFO/dalvikvm(976): Wrote stack trace to '/data/anr/traces.txt'

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  • Rotation of viewplatform in Java3D

    - by user29163
    I have just started with Java3D programming. I thought I had built up some basic intuition about how the scene graph works, but something that should work, does not work. I made a simple program for rotating a pyramid around the y-axis. This was done just by adding a RotationInterpolator R to the TransformGroup above the pyramid. Then I thought hey, can I now remove the RotationInterpolator from this TransformGroup, then add it to the TransformGroup above my ViewPlatform leaf. This should work if I have understood how things work. Adding the RotationInterpolator to this TransformGroup, should make the children of this TransformGroup rotate, and the ViewingPlatform is a child of the TransformGroup. Any ideas on where my reasoning is flawed? Here is the code for setting up the universe, and the view branchgroup. import java.awt.*; import java.awt.event.*; import javax.media.j3d.*; import javax.vecmath.*; public class UniverseBuilder { // User-specified canvas Canvas3D canvas; // Scene graph elements to which the user may want access VirtualUniverse universe; Locale locale; TransformGroup vpTrans; View view; public UniverseBuilder(Canvas3D c) { this.canvas = c; // Establish a virtual universe that has a single // hi-res Locale universe = new VirtualUniverse(); locale = new Locale(universe); // Create a PhysicalBody and PhysicalEnvironment object PhysicalBody body = new PhysicalBody(); PhysicalEnvironment environment = new PhysicalEnvironment(); // Create a View and attach the Canvas3D and the physical // body and environment to the view. view = new View(); view.addCanvas3D(c); view.setPhysicalBody(body); view.setPhysicalEnvironment(environment); // Create a BranchGroup node for the view platform BranchGroup vpRoot = new BranchGroup(); // Create a ViewPlatform object, and its associated // TransformGroup object, and attach it to the root of the // subgraph. Attach the view to the view platform. Transform3D t = new Transform3D(); Transform3D s = new Transform3D(); t.set(new Vector3f(0.0f, 0.0f, 10.0f)); t.rotX(-Math.PI/4); s.set(new Vector3f(0.0f, 0.0f, 10.0f)); //forandre verdier her for å endre viewing position t.mul(s); ViewPlatform vp = new ViewPlatform(); vpTrans = new TransformGroup(t); vpTrans.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE); // Rotator stuff Transform3D yAxis = new Transform3D(); //yAxis.rotY(Math.PI/2); Alpha rotationAlpha = new Alpha( -1, Alpha.INCREASING_ENABLE, 0, 0,4000, 0, 0, 0, 0, 0); RotationInterpolator rotator = new RotationInterpolator( rotationAlpha, vpTrans, yAxis, 0.0f, (float) Math.PI*2.0f); RotationInterpolator rotator2 = new RotationInterpolator( rotationAlpha, vpTrans); BoundingSphere bounds = new BoundingSphere(new Point3d(0.0,0.0,0.0), 1000.0); rotator.setSchedulingBounds(bounds); vpTrans.addChild(rotator); vpTrans.addChild(vp); vpRoot.addChild(vpTrans); view.attachViewPlatform(vp); // Attach the branch graph to the universe, via the // Locale. The scene graph is now live! locale.addBranchGraph(vpRoot); } public void addBranchGraph(BranchGroup bg) { locale.addBranchGraph(bg); } }

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