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  • Java - getClassLoader().getResource() driving me bonkers

    - by Click Upvote
    I have this test app: import java.applet.*; import java.awt.*; import java.net.URL; public class Test extends Applet { public void init() { URL some=Test.class.getClass().getClassLoader().getResource("/assets/pacman.png"); System.out.println(some.toString()); System.out.println(some.getFile()); System.out.println(some.getPath()); } } When I run it from Eclipse, I get the error: java.lang.NullPointerException at Test.init(Test.java:9) at sun.applet.AppletPanel.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Classpath (from .CLASSPATH file) <classpathentry kind="src" path="src"/> In my c:\project\src folder, I have only the Test.java file and the 'assets' directory which contains pacman.png. What am I doing wrong and how to resolve it?

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  • java vs python. In what way is Java Better?

    - by oxinabox.ucc.asn.au
    What are the advantages of Java over Python? What are the disadvantagesof Python, over Java? Why isn't Java more like Python? Like why don't java have an command line iterpretor? I beleive Java must have some advantages, but...I'm yet to see them. Logically all languages have an advantage afaict: I learnt java before python, - a 6 month unicourse. I spend a couple of weeks using python (writting a script to make a C source file). I hated it at first (as it was so differnt from C). I realised I had fallen in love it it, when I noticed that when I went to do a follow on Java Course at uni, I'ld stopped giving my variables types, and was tryign to multiply strings.

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  • Communication between java server and matlab client

    - by user272587
    I'd like to establish a server(Java)/client (Matlab) communication using socket. They can send messages to each other. An example shows how to do this in Java server and Java client, http://java.sun.com/docs/books/tutorial/networking/sockets/clientServer.html. When I try to rewrite the client part in Matlab, I only can get the first message that the Java server sends and display it in the Matlab command window. When I type a message in the Matlab command window, I can't pass it to the Java Server. Jave code: kkSocket = new Socket("localhost", 3434); Matlab equivalent: kkSocket = Socket('localhost', 3434); Java code for client: out = new PrintWriter(kkSocket.getOutputStream(), true); in = new BufferedReader(new InputStreamReader(kkSocket.getInputStream())); What would be a Matlab equivalent for this? Thanks in advance.

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  • What should I learn to improve my Java skills ?

    - by hory.incpp
    Hello, I currently know Java SE and I want to learn something more 'enterprise'. I would like something more distributed (app server, server programming, web, content management system ...) but any suggestion is ok. There are many frameworks which I've heard: spring, hibernate, persistence, ejb, jsp, servlet, jsf, jboss, glassfish, ant etc etc etc etc. I'm very confused where to start. So the question is: Can somebody explain to me what actually there frameworks are; and which one should I start with ? Thank you.

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  • Java newbie problem: package with private access

    - by HH
    Pack.java imports pack.TestPack; but it cannot access it. I cannot understand why it cannot access the class despite the import. Error Pack.java:7: TestPack() is not public in pack.TestPack; cannot be accessed from outside package System.out.println(new TestPack().getHello()); ^ 1 error Pack.java import pack.TestPack; import java.io.*; public class Pack { public static void main(String[] args){ System.out.println(new TestPack().getHello()); } } TestPack.java package pack; import java.util.*; import java.io.*; public class TestPack { private String hello="if you see me, you ar inside class TestPack"; public String getHello(){return hello;} TestPack(){} }

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  • Refactoring a leaf class to a base class, and keeping it also a interface implementation

    - by elcuco
    I am trying to refactor a working code. The code basically derives an interface class into a working implementation, and I want to use this implementation outside the original project as a standalone class. However, I do not want to create a fork, and I want the original project to be able to take out their implementation, and use mine. The problem is that the hierarchy structure is very different and I am not sure if this would work. I also cannot use the original base class in my project, since in reality it's quite entangled in the project (too many classes, includes) and I need to take care of only a subdomain of the problems the original project is. I wrote this code to test an idea how to implement this, and while it's working, I am not sure I like it: #include <iostream> // Original code is: // IBase -> Derived1 // I need to refactor Derive2 to be both indipendet class // and programmers should also be able to use the interface class // Derived2 -> MyClass + IBase // MyClass class IBase { public: virtual void printMsg() = 0; }; /////////////////////////////////////////////////// class Derived1 : public IBase { public: virtual void printMsg(){ std::cout << "Hello from Derived 1" << std::endl; } }; ////////////////////////////////////////////////// class MyClass { public: virtual void printMsg(){ std::cout << "Hello from MyClass" << std::endl; } }; class Derived2: public IBase, public MyClass{ virtual void printMsg(){ MyClass::printMsg(); } }; class Derived3: public MyClass, public IBase{ virtual void printMsg(){ MyClass::printMsg(); } }; int main() { IBase *o1 = new Derived1(); IBase *o2 = new Derived2(); IBase *o3 = new Derived3(); MyClass *o4 = new MyClass(); o1->printMsg(); o2->printMsg(); o3->printMsg(); o4->printMsg(); return 0; } The output is working as expected (tested using gcc and clang, 2 different C++ implementations so I think I am safe here): [elcuco@pinky ~/src/googlecode/qtedit4/tools/qtsourceview/qate/tests] ./test1 Hello from Derived 1 Hello from MyClass Hello from MyClass Hello from MyClass [elcuco@pinky ~/src/googlecode/qtedit4/tools/qtsourceview/qate/tests] ./test1.clang Hello from Derived 1 Hello from MyClass Hello from MyClass Hello from MyClass The question is My original code was: class Derived3: public MyClass, public IBase{ virtual void IBase::printMsg(){ MyClass::printMsg(); } }; Which is what I want to express, but this does not compile. I must admit I do not fully understand why this code work, as I expect that the new method Derived3::printMsg() will be an implementation of MyClass::printMsg() and not IBase::printMsg() (even tough this is what I do want). How does the compiler chooses which method to re-implement, when two "sister classes" have the same virtual function name? If anyone has a better way of implementing this, I would like to know as well :)

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  • Java Prepared Statement Error

    - by Suresh S
    Hi Guys the following code throws me an error i have an insert statement created once and in the while loop i am dynamically setting parameter , and at the end i says ps2.addBatch() again while ( (eachLine = in.readLine()) != null)) { for (int k=stat; k <=45;k++) { ps2.setString (k,main[(k-2)]); } stat=45; for (int l=1;l<= 2; l++) { ps2.setString((stat+l),pdp[(l-1)]);// Exception } ps2.addBatch(); } This is the error java.lang.ArrayIndexOutOfBoundsException: 45 at oracle.jdbc.dbaccess.DBDataSetImpl._getDBItem(DBDataSetImpl.java:378) at oracle.jdbc.dbaccess.DBDataSetImpl._createOrGetDBItem(DBDataSetImpl.java:781) at oracle.jdbc.dbaccess.DBDataSetImpl.setBytesBindItem(DBDataSetImpl.java:2450) at oracle.jdbc.driver.OraclePreparedStatement.setItem(OraclePreparedStatement.java:1155) at oracle.jdbc.driver.OraclePreparedStatement.setString(OraclePreparedStatement.java:1572) at Processor.main(Processor.java:233)

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  • Make a USB Device, Control It In Java

    - by yar
    I'm thinking about making a physical controller (device?) with knobs, buttons, and LEDs. I'd like to interact with it using Java (respond to the knobs, light up LEDs, etc). The reason I mention Java is two-fold: first, I know Java well1. Second, I've written the rest of the program I need to interface with in Java (though there are ways to talk to the Java program from another language). I would like the device to connect via USB and be (computer-)platform independent. I haven't the slightest idea of where to start, except to start reading the Arduino website. Is this my best/only option? Is there something better suited for communicating with Java? Note: I know that Arduino has something to do with Java (not sure what), but it seems like code must be written in a subset of C. How would I get moving on this topic? 1 - No laughter, please.

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  • JPA 2.0 Provider Hibernate

    - by Rooh
    I have very strange problem we are using jpa 2.0 with hibernate annotations based Database generated through JPA DDL is true and MySQL as Database; i will provide some reference classes and then my porblem. @MappedSuperclass public abstract class Common implements serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; @ManyToOne @JoinColumn private Address address; //with all getter and setters //as well equal and hashCode } @Entity public class Parent extends Common{ private String name; @OneToMany(cascade = {CascadeType.MERGE,CascadeType.PERSIST}, mappedBy = "parent") private List<Child> child; //setters and rest of class } @Entity public class Child extends Common{ //some properties with getter/setters } @Entity public class Address implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; private String street; //rest of class with get/setter } as in code you can see that parents and child classes extends Common class so both have address property and id , the problem occurs when change the address refference in parent class it reflect same change in all child objects in list and if change address refference in child class then on merge it will change address refference of parent as well i am not able to figure out is it is problem of jpa or hibernate

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  • How does a template class inherit another template class?

    - by hkBattousai
    I have a "SquareMatrix" template class which inherits "Matrix" template class, like below: SquareMatrix.h: #ifndef SQUAREMATRIX_H #define SQUAREMATRIX_H #include "Matrix.h" template <class T> class SquareMatrix : public Matrix<T> { public: T GetDeterminant(); }; template <class T> // line 49 T SquareMatrix<T>::GetDeterminant() { T t = 0; // Error: Identifier "T" is undefined // line 52 return t; // Error: Expected a declaration // line 53 } // Error: Expected a declaration // line 54 #endif I commented out all other lines, the files contents are exactly as above. I receive these error messages: LINE 49: IntelliSense: expected a declaration LINE 52: IntelliSense: expected a declaration LINE 53: IntelliSense: expected a declaration LINE 54: error C2039: 'GetDeterminant' : is not a member of 'SquareMatrix' LINE 54: IntelliSense: expected a declaration So, what is the correct way of inheriting a template class? And what is wrong with this code? The "Matrix" class: template <class T> class Matrix { public: Matrix(uint64_t unNumRows = 0, uint64_t unNumCols = 0); void GetDimensions(uint64_t & unNumRows, uint64_t & unNumCols) const; std::pair<uint64_t, uint64_t> GetDimensions() const; void SetDimensions(uint64_t unNumRows, uint64_t unNumCols); void SetDimensions(std::pair<uint64_t, uint64_t> Dimensions); uint64_t GetRowSize(); uint64_t GetColSize(); void SetElement(T dbElement, uint64_t unRow, uint64_t unCol); T & GetElement(uint64_t unRow, uint64_t unCol); //Matrix operator=(const Matrix & rhs); // Compiler generate this automatically Matrix operator+(const Matrix & rhs) const; Matrix operator-(const Matrix & rhs) const; Matrix operator*(const Matrix & rhs) const; Matrix & operator+=(const Matrix & rhs); Matrix & operator-=(const Matrix & rhs); Matrix & operator*=(const Matrix & rhs); T& operator()(uint64_t unRow, uint64_t unCol); const T& operator()(uint64_t unRow, uint64_t unCol) const; static Matrix Transpose (const Matrix & matrix); static Matrix Multiply (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Add (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Subtract (const Matrix & LeftMatrix, const Matrix & RightMatrix); static Matrix Negate (const Matrix & matrix); // TO DO: static bool IsNull(const Matrix & matrix); static bool IsSquare(const Matrix & matrix); static bool IsFullRowRank(const Matrix & matrix); static bool IsFullColRank(const Matrix & matrix); // TO DO: static uint64_t GetRowRank(const Matrix & matrix); static uint64_t GetColRank(const Matrix & matrix); protected: std::vector<T> TheMatrix; uint64_t m_unRowSize; uint64_t m_unColSize; bool DoesElementExist(uint64_t unRow, uint64_t unCol); };

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  • Compile classfile issue in Spring 3

    - by Prajith R
    I have used spring framework 3 for my application. Everything is ok while developed in Netbeans But i need a custom build and done for the same The build created without any issue, but i got the following error The error occurred while calling the following method @RequestMapping(value = "/security/login", method = RequestMethod.POST) public ModelAndView login(@RequestParam String userName, @RequestParam String password, HttpServletRequest request) { ...................... But There is no issue while creating the war with netbeans (I am sure it is about the compilation issue) have you any experiance on this issue ... There is any additional javac argument for compile the same (netbeans used there custom task for the compilation) type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. exception org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.web.bind.annotation.support.HandlerMethodInvocationException: Failed to invoke handler method [public org.springframework.web.servlet.ModelAndView com.mypackage.security.controller.LoginController.login(java.lang.String,java.lang.String,javax.servlet.http.HttpServletRequest)]; nested exception is java.lang.IllegalStateException: No parameter name specified for argument of type [java.lang.String], and no parameter name information found in class file either. org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:659) org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563) javax.servlet.http.HttpServlet.service(HttpServlet.java:637) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) com.mypackage.security.controller.AuthFilter.doFilter(Unknown Source) org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) root cause org.springframework.web.bind.annotation.support.HandlerMethodInvocationException: Failed to invoke handler method [public org.springframework.web.servlet.ModelAndView com.mypackage.security.controller.LoginController.login(java.lang.String,java.lang.String,javax.servlet.http.HttpServletRequest)]; nested exception is java.lang.IllegalStateException: No parameter name specified for argument of type [java.lang.String], and no parameter name information found in class file either. org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:414) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:402) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647) org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563) javax.servlet.http.HttpServlet.service(HttpServlet.java:637) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) com.mypackage.security.controller.AuthFilter.doFilter(Unknown Source) org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) root cause java.lang.IllegalStateException: No parameter name specified for argument of type [java.lang.String], and no parameter name information found in class file either. org.springframework.web.bind.annotation.support.HandlerMethodInvoker.getRequiredParameterName(HandlerMethodInvoker.java:618) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveRequestParam(HandlerMethodInvoker.java:417) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:277) org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:163) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:414) org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:402) org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771) org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716) org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:647) org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563) javax.servlet.http.HttpServlet.service(HttpServlet.java:637) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) com.mypackage.security.controller.AuthFilter.doFilter(Unknown Source) org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.

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  • Java class object from type variable

    - by Alexander Temerev
    Is there a way to get Class object from the type variable in Java generic class? Something like that: public class Bar extends Foo<T> { public Class getParameterClass() { return T.class; // doesn't compile } } This type information is available at compile time and therefore should not be affected by type erasure, so, theoretically, there should be a way to accomplish this. Does it exist?

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  • "state is undetermined" when starting Grails app on CloudFoundry

    - by SeattleStephens
    I have a Grails app that has been running on CloudFoundry for months. I updated the app from Grails 2.0.4 to 2.1.0 and also updated a few plugins I have been using. Now when I push the app to CloudFoundry and do the start, I receive the error: 'appname' state is undetermined, not enough information available. The tomcat Catalina log shows the NoClassDefFoundError below. I've read about issues with the Ivy cache but have not looked into that yet. I have updated vmc to the latest version (0.3.18). SEVERE: Error deploying web application directory ROOT java.lang.NoClassDefFoundError: org/apache/tomcat/PeriodicEventListener at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2818) at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1159) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1647) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1128) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4421) at org.apache.catalina.core.StandardContext.start(StandardContext.java:4734) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079) at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002) at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506) at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317) at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065) at org.apache.catalina.core.StandardHost.start(StandardHost.java:840) at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057) at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463) at org.apache.catalina.core.StandardService.start(StandardService.java:525) at org.apache.catalina.core.StandardServer.start(StandardServer.java:754) at org.apache.catalina.startup.Catalina.start(Catalina.java:595) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414) Caused by: java.lang.ClassNotFoundException: org.apache.tomcat.PeriodicEventListener at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526) ... 34 more

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  • getting IllegalAccessException when accessing a protected method from parent from inner class

    - by EnToutCas
    I got a very weird problem and a weird solution: class Parent { protected void aProtectedMethod() { doSomething(); } } class Child extends Parent { void anotherMethod() { new SomeInterface() { public void interfaceMethod() { aProtectedMethod(); } }; } } When child.anotherMethod() is run, I got IllegalAccessException at myProtectedMethod(), saying my inner class doesn't have access to the Parent class... However, if I add: protected void aProtectedMethod() { super.aProtectedMethod(); } in my Child class, everything is fine... I wonder why this is?

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  • Compare class objects

    - by reto
    I have to compare a class object against a list of pre defined classes. Is it safe to use == or should I use equals()? if (klass == KlassA.class) { } else if (klass == KlassB.class) { } else if (klass == KlassC.class) { } else { } Note: I cannot use instanceof, I don't have an object, I just have the class object. I (mis)use it like an enum in this situation! Thanks!

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  • Can we instantiate abstract class?

    - by satheesh.droid
    I don't understand whether we can instantiate abstract class by any means because I have read we can inherit the abstract class but in have found we can create an object by calling method of other class.For example LocationProvider is an abstract class but we can create object for the same by calling getProvider() function in LocationManager class. By the following code LocationManager lm=getSystemService(Context.LOCATION_PROVIDER) LocationProvider lp=lm.getProvider("gps");

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  • Hibernate not Loading a class

    - by Noor
    Hi, I have a class Auction that contains a Class Item and Users but when I am getting the class, the class item and Users are not being loaded. Auction Class Mapping File: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Dec 28, 2010 9:14:12 PM by Hibernate Tools 3.4.0.Beta1 --> <hibernate-mapping> <class name="com.BiddingSystem.Models.Auction" table="AUCTION"> <id name="AuctionId" type="long"> <column name="AUCTIONID" /> <generator class="native" /> </id> <property name="StartTime" type="java.util.Date"> <column name="STARTTIME" /> </property> <property name="EndTime" type="java.util.Date"> <column name="ENDTIME" /> </property> <property name="StartingBid" type="long"> <column name="STARTINGBID" /> </property> <property name="MinIncrement" type="long"> <column name="MININCREMENT" /> </property> <many-to-one name="CurrentItem" class="com.BiddingSystem.Models.Item" fetch="join" cascade="all"> <column name="ItemId" /> </many-to-one> <property name="AuctionStatus" type="java.lang.String"> <column name="AUCTIONSTATUS" /> </property> <property name="BestBid" type="long"> <column name="BESTBID" /> </property> <many-to-one name="User" class="com.BiddingSystem.Models.Users" fetch="join"> <column name="UserId" /> </many-to-one> </class> </hibernate-mapping> When I am doing this: Query query=session.createQuery("from Auction where UserId="+UserId); List <Auction> AllAuctions= new LinkedList<Auction>(query.list()); The Users and Item are null

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  • Is null a class in java?

    - by Somerandomeguy
    According to, http://www.freshvanilla.org:8080/display/www/Java+Interview+Questions Under, Which class is the superclass of every class? null seems to be the answer. I found that new Object().getClass().getSuperClass() verifies the answer as correct. But can null be considered a class? I see all primitive data types are represented as Class objects from java[dot]sun.com/j2se/1.4.2/docs/api/java/lang/Class.html

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  • Problem with Java Mail : No provider for smtp

    - by user359198
    Hello all. I am using JavaMail to do a simple application that sends an email when it finds some files in a directory. I managed to get it worked from Eclipse. I Run the application and it sent the email with no errors. But, when I created the jar, and executed it, it fails in the email sending part. It gives this exception. javax.mail.NoSuchProviderException: No provider for smtp at javax.mail.Session.getProvider(Session.java:460) at javax.mail.Session.getTransport(Session.java:655) at javax.mail.Session.getTransport(Session.java:636) at main.java.util.MailManager.sendMail(MailManager.java:69) at main.java.DownloadsMail.composeAndSendMail(DownloadsMail.java:16) at main.java.DownloadsController.checkDownloads(DownloadsController.java:51) at main.java.MainDownloadsController.run(MainDownloadsController.java:26) at java.lang.Thread.run(Unknown Source) I am using the library in this method: public static boolean sendMail(String subject, String text){ noExceptionsThrown = true; try { loadProperties(); } catch (IOException e1) { System.out.println("Problem encountered while loading properties"); e1.printStackTrace(); noExceptionsThrown = false; } Properties mailProps = new Properties(); String host = "mail.smtp.host"; mailProps.setProperty(host, connectionProps.getProperty(host)); String tls = "mail.smtp.starttls.enable"; mailProps.setProperty(tls, connectionProps.getProperty(tls)); String port = "mail.smtp.port"; mailProps.setProperty(port, connectionProps.getProperty(port)); String user = "mail.smtp.user"; mailProps.setProperty(user, connectionProps.getProperty(user)); String auth = "mail.smtp.auth"; mailProps.setProperty(auth, connectionProps.getProperty(auth)); Session session = Session.getDefaultInstance(mailProps); //session.setDebug(true); MimeMessage message = new MimeMessage(session); try { message.setFrom(new InternetAddress(messageProps.getProperty("from"))); message.addRecipient(Message.RecipientType.TO, new InternetAddress( messageProps.getProperty("to"))); message.setSubject(subject); message.setText(text); Transport t = session.getTransport("smtp"); try { t.connect(connectionProps.getProperty("user"), passwordProps .getProperty("password")); t.sendMessage(message, message.getAllRecipients()); } catch (Exception e) { System.out.println("Error encountered while sending the email"); e.printStackTrace(); noExceptionsThrown = false; } finally { t.close(); } } catch (Exception e) { System.out.println("Error encountered while creating the message"); e.printStackTrace(); noExceptionsThrown = false; } return noExceptionsThrown; } I am loading these values from properties files. mail.smtp.host=smtp.gmail.com mail.smtp.starttls.enable=true mail.smtp.port=587 mail.smtp.auth=true I have tried to change the host by ssl://smtp.gmail.com, the port by 465 (just for trying something different), but it doesn't work either. Anyway, if it works fine from Eclipse with the original parameters, I guess that the values are correct, but the problem is creating the jar. I don't know very much about the possible results or changes when creating a jar. Could the JavaMail libraries someway go wrong when the jar is created? Do you have any ideas? Thank you very much for your help.

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  • Should I use a collection here?

    - by Eva
    So I have code set up like this: public interface IInterface { public void setField(Object field); } public abstract class AbstractClass extends JPanel implements IInterface { private Object field_; public void setField(Object field) { field_ = field; } } public class ClassA extends AbstractClass { public ClassA() { // unique ClassA constructor stuff } public Dimension getPreferredSize() { return new Dimension(1, 1); } } public class ClassB extends AbstractClass { public ClassB() { // unique ClassB constructor stuff } public Dimension getPreferredSize() { return new Dimension(42, 42); } } public class ConsumerA { public ConsumerA(Collection<AbstractClass> collection) { for (AbstractClass abstractClass : collection) { abstractClass.setField(this); abstractClass.repaint(); } } } All hunky-dory so far, until public class ConsumerB { // Option 1 public ConsumerB(ClassA a, ClassB b) { methodThatOnlyTakesA(a); methodThatOnlyTakesB(b); } // Option 2 public ConsumerB(Collection<AbstractClass> collection) { for (IInterface i : collection) { if (i instanceof ClassA) { methodThatOnlyTakesA((ClassA) i); else if (i instanceof ClassB) { methodThatOnlyTakesB((ClassB) i); } } } } public class UsingOption1 { public static void main(String[] args) { ClassA a = new ClassA(); ClassB b = new ClassB(); Collection<AbstractClass> collection = Arrays.asList(a, b); ConsumerA consumerA = new ConsumerA(collection); ConsumerB consumerB = new ConsumerB(a, b); } } public class UsingOption2 { public static void main(String[] args) { Collection<AbstractClass> collection = Arrays.asList(new ClassA(), new ClassB()); ConsumerA = new ConsumerA(collection); ConsumerB = new ConsumerB(collection); } } With a lot more classes extending AbstractClass, both options get unwieldly. Option1 would make the constructor of ConsumerB really long. Also UsingOption1 would get long too. Option2 would have way more if statements than I feel comfortable with. Is there a viable Option3? If it helps, ClassA and ClassB have all the same methods, they're just implemented differently. Thanks for slogging through my code!

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  • Why shouldn't I be using public variables in my Java class?

    - by Omega
    In school, I've been told many times to stop using public for my variables. I haven't asked why yet. This question: Are Java's public fields just a tragic historical design flaw at this point? seems kinda related to this. However, they don't seem to discuss why is it "wrong", but instead focus on how can they use them instead. Look at this (unfinished) class: public class Reporte { public String rutaOriginal; public String rutaNueva; public int bytesOriginales; public int bytesFinales; public float ganancia; /** * Constructor para objetos de la clase Reporte */ public Reporte() { } } No need to understand Spanish. All this class does is hold some statistics (those public fields) and then do some operations with them (later). I will also need to be modifying those variables often. But well, since I've been told not to use public, this is what I ended up doing: public class Reporte { private String rutaOriginal; private String rutaNueva; private int bytesOriginales; private int bytesFinales; private float ganancia; /** * Constructor para objetos de la clase Reporte */ public Reporte() { } public String getRutaOriginal() { return rutaOriginal; } public String getRutaNueva() { return rutaNueva; } public int getBytesOriginales() { return bytesOriginales; } public int getBytesFinales() { return bytesFinales; } public float getGanancia() { return ganancia; } public void setRutaOriginal(String rutaOriginal) { this.rutaOriginal = rutaOriginal; } public void setRutaNueva(String rutaNueva) { this.rutaNueva = rutaNueva; } public void setBytesOriginales(int bytesOriginales) { this.bytesOriginales = bytesOriginales; } public void setBytesFinales(int bytesFinales) { this.bytesFinales = bytesFinales; } public void setGanancia(float ganancia) { this.ganancia = ganancia; } } Looks kinda pretty. But seems like a waste of time. Google searches about "When to use public in Java" and "Why shouldn't I use public in Java" seem to discuss about a concept of mutability, although I'm not really sure how to interpret such discussions. I do want my class to be mutable - all the time.

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  • Should the 12-String be in it's own class and why?

    - by MayNotBe
    This question is regarding a homework project in my first Java programming class (online program). The assignment is to create a "stringed instrument" class using (among other things) an array of String names representing instrument string names ("A", "E", etc). The idea for the 12-string is beyond the scope of the assignment (it doesn't have to be included at all) but now that I've thought of it, I want to figure out how to make it work. Part of me feels like the 12-String should have it's own class, but another part of me feels that it should be in the guitar class because it's a guitar. I suppose this will become clear as I progress but I thought I would see what kind of response I get here. Also, why would they ask for a String[] for the instrument string names? Seems like a char[] makes more sense. Thank you for any insight. Here's my code so far (it's a work in progress): public class Guitar { private int numberOfStrings = 6; private static int numberOfGuitars = 0; private String[] stringNotes = {"E", "A", "D", "G", "B", "A"}; private boolean tuned = false; private boolean playing = false; public Guitar(){ numberOfGuitars++; } public Guitar(boolean twelveString){ if(twelveString){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = 12; } } public int getNumberOfStrings() { return numberOfStrings; } public void setNumberOfStrings(int strings) { if(strings == 12 || strings == 6) { if(strings == 12){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = strings; } if(strings == 6) numberOfStrings = strings; }//if else System.out.println("***ERROR***Guitar can only have 6 or 12 strings***ERROR***"); } public void getStringNotes() { for(int i = 0; i < stringNotes.length; i++){ if(i == stringNotes.length - 1) System.out.println(stringNotes[i]); else System.out.print(stringNotes[i] + ", "); }//for }

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  • Should the 12-String be in it's own class and why? Java

    - by MayNotBe
    This is my first question here. I will amend it as instructed. This is regarding a homework project in my first Java programming class (online program). The assignment is to create a "stringed instrument" class using (among other things) an array of String names representing instrument string names ("A", "E", etc). The idea for the 12-string is beyond the scope of the assignment (it doesn't have to be included at all) but now that I've thought of it, I want to figure out how to make it work. Part of me feels like the 12-String should have it's own class, but another part of me feels that it should be in the guitar class because it's a guitar. I suppose this will become clear as I progress but I thought I would see what kind of response I get here. Also, why would they ask for a String[] for the instrument string names? Seems like a char[] makes more sense. Thank you for any insight. Here's my code so far (it's a work in progress): public class Guitar { private int numberOfStrings = 6; private static int numberOfGuitars = 0; private String[] stringNotes = {"E", "A", "D", "G", "B", "A"}; private boolean tuned = false; private boolean playing = false; public Guitar(){ numberOfGuitars++; } public Guitar(boolean twelveString){ if(twelveString){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = 12; } } public int getNumberOfStrings() { return numberOfStrings; } public void setNumberOfStrings(int strings) { if(strings == 12 || strings == 6) { if(strings == 12){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = strings; } if(strings == 6) numberOfStrings = strings; }//if else System.out.println("***ERROR***Guitar can only have 6 or 12 strings***ERROR***"); } public void getStringNotes() { for(int i = 0; i < stringNotes.length; i++){ if(i == stringNotes.length - 1) System.out.println(stringNotes[i]); else System.out.print(stringNotes[i] + ", "); }//for }

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