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  • At the Java DEMOgrounds - Oracle Java ME Embedded Enables the “Internet of Things”

    - by Janice J. Heiss
    I caught up with Oracle’s Robert Barnes, Senior Director, Java Product Management, who was demonstrating a new product from Oracle’s Java Platform, Micro Edition (Java ME) product portfolio, Oracle Java ME Embedded 3.2, a complete client Java runtime optimized for microcontrollers and other resource-constrained devices. Oracle’s Java ME Embedded 3.2 is a Java ME runtime based on CLDC 1.1 (JSR-139) and IMP-NG (JSR-228).“What we are showing here is the Java ME Embedded 3.2 that we announced last week,” explained Barnes. “It’s the start of the 'Internet of Things,’ in which you have very very small devices that are on the edge of the network where the sensors sit. You often have a middle area called a gateway or a concentrator which is fairly middle to higher performance. On the back end you have a very high performance server. What this is showing is Java spanning all the way from the server side right down towards the type of chip that you will get at the sensor side as the network.” Barnes explained that he had two different demos running.The first, called the Solar Panel System Demo, measures the brightness of the light.  “This,” said Barnes, “is a light source demo with a Cortex M3 controlling the motor, on the end of which is a sensor which is measuring the brightness of the lamp. This is recording the data of the brightness of the lamp and as we move the lamp out of the way, we should be able using the server to turn the sensor towards the lamp so the brightness reading will go higher. This sends the message back to the server and we can look at the web server sitting on the PC underneath the desk. We can actually see the data being passed back effectively through a back office type of function within a utility environment.” The second demo, the Smart Grid Response Demo, Barnes explained, “has the same board and processor and is still using Java ME embedded with a different app on top. This is a demand response demo. What we are seeing within the managing environment is that people want to track the pricing signals of the electricity. If it’s particularly expensive at any point in time, they may turn something off. This demo sets the price of the electricity as though this is coming from the back of the server sending pricing signals to my home.” The demo had a lamp and a fan and it was tracking the price of electricity. “If I set the price of the electricity to go over 5 cents, then the device will turn off,” explained Barnes. “I can go into my settings and, in this case, change the price to 50 cents and we can wait a minus and the lamp will go off. When I change the pricing signal so that it is lower, the lamp will come back on. The key point is that the Java software we have running is the same across all the different devices; it’s a way to build applications across multiple devices using the same software. This is important because it fixes peak loading on the network and can stops blackouts.” This demo brought me back to a prior decade when Sun Microsystems first promoted  Jini technology, a version of Java that would put everything on the network and give us the smart home. Your home would be automated to tell you when you were out of milk, when to change your light bulbs, etc. You would have access to the web and the network throughout your home.It’s interesting to see how technology moves over time – from the smart home to the Internet of Things.

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  • Java jasper report NullPointerException

    - by William Welch
    I am new to Java and I am running into this issue that I can't figure out. I inherited this project and I have the following code in one of my scriptlets: DefaultLogger.logMessage("DEBUG path: "+ reportFile.getPath()); DefaultLogger.logMessage("DEBUG parameters: "+ parameters); DefaultLogger.logMessage("DEBUG jr: "+ jr); bytes = JasperRunManager.runReportToPdf(reportFile.getPath(), parameters, jr); And I am getting the following results (the fourth line there is line 287 in FootwearReportsServlet.doGet): DEBUG path: C:\Development\JavaWorkspaces\Workspace1\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\RSLDevelopmentStandard\reports\templates\footwear\RslFootwearReport.jasper DEBUG parameters: {class_list_subreport=net.sf.jasperreports.engine.JasperReport@b07af1, signature_path=images/logo_reports.jpg, submission_id=20070213154168780, test_results_subreport=net.sf.jasperreports.engine.JasperReport@5795ce, logo_path=images/logos_3.gif, report_connection_secondary=com.mysql.jdbc.JDBC4Connection@2c39d2, testing_packages_subreport=net.sf.jasperreports.engine.JasperReport@1883d5f, signature_path2=images/logo_reports.jpg, tpid_subreport=net.sf.jasperreports.engine.JasperReport@17531fd, first_page_subreport=net.sf.jasperreports.engine.JasperReport@12504e0} DEBUG jr: net.sf.jasperreports.engine.data.JRMapCollectionDataSource@1630eb6 Apr 29, 2010 4:15:13 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet FootwearReportsServlet threw exception java.lang.NullPointerException at net.sf.jasperreports.engine.fill.JRFiller.fillReport(JRFiller.java:89) at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:601) at net.sf.jasperreports.engine.JasperFillManager.fillReport(JasperFillManager.java:517) at net.sf.jasperreports.engine.JasperRunManager.runReportToPdf(JasperRunManager.java:385) at com.rsl.reports.FootwearReportsServlet.doGet(FootwearReportsServlet.java:287) at javax.servlet.http.HttpServlet.service(HttpServlet.java:617) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) What I can't figure out is where the null reference is. From the debug lines I can see that each parameter has a value. Could it be referring to a bad path to one of the images? Any ideas? For some reason my server won't start in debug mode in Eclipse so I am having trouble figuring this out.

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  • Java web start - Unable to load resource

    - by CD
    Hi all, I've got a jar that loads great with java web starter when I browse through the IP address of the server. Once I try the server name instead I get the following exception: com.sun.deploy.net.FailedDownloadException: Unable to load resource: at com.sun.deploy.net.DownloadEngine.actionDownload(Unknown Source) at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source) at com.sun.deploy.net.DownloadEngine.getCacheEntry(Unknown Source) at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source) at com.sun.deploy.net.DownloadEngine.getResourceCacheEntry(Unknown Source) at com.sun.deploy.net.DownloadEngine.getResource(Unknown Source) at com.sun.javaws.LaunchDownload$DownloadTask.call(Unknown Source) at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Any idea what should I look for?

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  • java casting a list

    - by dcp
    Let's say I had: protected void performLogic(List<Object> docs) { ... } In the code where I'm going to be calling this method, I have a List<String> list. I want to call performLogic, passing this list. But it won't work because the lists are 2 different types: public void execute() { List<String> docs = new ArrayList<String>(); performLogin(docs); // won't work } I tried casting to List<Object> also, but that won't work either. So is the only way to do this is to make a new ArrayList of Object and just add the values and then pass it? Just seems cumbersome. I wondered if there was a better way to do it. Thanks.

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  • GWT dev mode throws ArrayIndexOutOfBoundsException when compile GinjectorImpl.java

    - by Jiang Zhu
    I'm getting following exception when open my GWT app in development mode. the exact same code can compile successfully using mvn gwt:compile Caused by: java.lang.ArrayIndexOutOfBoundsException: 3667 at com.google.gwt.dev.asm.ClassReader.readClass(ClassReader.java:1976) at com.google.gwt.dev.asm.ClassReader.accept(ClassReader.java:464) at com.google.gwt.dev.asm.ClassReader.accept(ClassReader.java:420) at com.google.gwt.dev.shell.rewrite.HasAnnotation.hasAnnotation(HasAnnotation.java:45) at com.google.gwt.dev.shell.CompilingClassLoader.findClass(CompilingClassLoader.java:1100) at com.google.gwt.dev.shell.CompilingClassLoader.loadClass(CompilingClassLoader.java:1203) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at com.google.gwt.dev.shell.ModuleSpace.loadClassFromSourceName(ModuleSpace.java:665) at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:468) at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49) at com.google.gwt.core.shared.GWT.create(GWT.java:57) at com.google.gwt.core.client.GWT.create(GWT.java:85) at ... I overdid ModuleSpace.java and printed out the class name at line 665 before Class.forName() which points out it is trying to load the generated GinjectorImpl.java I found out my generated GinjectorImpl.java is about 9MB and with 100K+ lines of code. When I randomly remove some modules from my GWT app it works again, so I'm guessing it is too large for ASM to compile. Any suggestions? Thanks Environment: GWT 2.5.0, GIN 1.5.0, gwt-maven-plugin 2.5.0, Java 6 SE

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  • Read-only view of a Java list with more general type parameter

    - by Michael Rusch
    Suppose I have class Foo extends Superclass. I understand why I can't do this: List<Foo> fooList = getFooList(); List<Superclass> supList = fooList; But, it would seem reasonable for me to do that if supList were somehow "read-only". Then, everything would be consistent as everything that would come out of an objList would be a Foo, which is a Superclass. I could probably write a List implementation that would take an underlying list and a more general type parameter, and would then return everything as the more general type instead of the specific type. It would work like the return of Collections.unmodifiableList() except that the type would be made more general. Is there an easier way? The reason I'm considering doing this is that I am implementing an interface that requires that I return an (unmodifiable) List<Superclass>, but internally I need to use Foos, so I have a List<Foo>. I can't just cast.

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  • Java generic return type

    - by Colby77
    Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

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  • How to declare a Generics Action in struts2.xml file ?

    - by Rasatavohary
    Hi everyone, My problems is in a Struts2 action, where I have a class : public class MyAction<T> extends ActionSupport with a private member like this : private T myData; And I would like to declare this aciton in the struts.xml file, how can i manage to do so ? Thanks for the answer. Ps : I've tried without declaration of T, but it did not work

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  • What should i do to test EasyMock objects when using Generics ? EasyMock

    - by Arthur Ronald F D Garcia
    See code just bellow Our generic interface public interface Repository<INSTANCE_CLASS, INSTANCE_ID_CLASS> { void add(INSTANCE_CLASS instance); INSTANCE_CLASS getById(INSTANCE_ID_CLASS id); } And a single class public class Order { private Integer id; private Integer orderNumber; // getter's and setter's public void equals(Object o) { if(o == null) return false; if(!(o instanceof Order)) return false; // business key if(getOrderNumber() == null) return false; final Order other = (Order) o; if(!(getOrderNumber().equals(other.getOrderNumber()))) return false; return true; } // hashcode } And when i do the following test private Repository<Order, Integer> repository; @Before public void setUp { repository = EasyMock.createMock(Repository.class); Order order = new Order(); order.setOrderNumber(new Integer(1)); repository.add(order); EasyMock.expectLasCall().once(); EasyMock.replay(repository); } @Test public void addOrder() { Order order = new Order(); order.setOrderNumber(new Integer(1)); repository.add(order); EasyMock.verify(repository) } I get Unexpected method call add(br.com.smac.model.domain.Order@ac66b62): add(br.com.smac.model.domain.Order@ac66b62): expected: 1, actual: 0 Why does it not work as expected ??? What should i do to pass the test ???

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  • Null Pointer Exception while using Java Compiler API

    - by java_geek
    MyClass.java: package test; public class MyClass { public void myMethod(){ System.out.println("My Method Called"); } } Listing for SimpleCompileTest.java that compiles the MyClass.java file. SimpleCompileTest.java: package test; import javax.tools.*; public class SimpleCompileTest { public static void main(String[] args) { String fileToCompile = "test" + java.io.File.separator +"MyClass.java"; JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); int compilationResult = compiler.run(null, null, null, fileToCompile); if(compilationResult == 0){ System.out.println("Compilation is successful"); }else{ System.out.println("Compilation Failed"); } } } I am executing the SimpleCompileTest class and getting a NullPointerException. The ToolProvider.getSystemJavaCompiler() is returning null. Can someone tell me what is wrong with the code

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  • Converting non-generic List type to Generic List type in Java 1.5

    - by Shaun F
    I have a List that is guaranteed to contain just one type object. This is created by some underlying code in a library that I cannot update. I want to create a List<ObjectType> based on the incoming List object so that my calling code is talking to List<ObjectType>. What's the best way to convert the List (or any other object collection) to a List<ObjectType>.

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  • Java generic Comparable where subclasses can't compare to eachother

    - by dege
    public abstract class MyAbs implements Comparable<MyAbs> This would work but then I would be able to compare class A and B with each other if they both extend MyAbs. What I want to accomplish however is the exact opposite. So does anyone know a way to get the generic type to be the own class? Seemed like such a simple thing at first... Edit: To explain it a little further with an example. Say you have an abstract class animals, then you extend it with Dogs and ants. I wouldn't want to compare ants with Dogs but I however would want to compare one dog with another. The dog might have a variable saying what color it is and that is what I want to use in the compareTo method. However when it comes to ants I would rather want to compare ant's size than their color. Hope that clears it up. Could possibly be a design flaw however.

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  • Problem changing Java version using alternatives

    - by Brian Lewis
    I'm not quite sure how I got into this mess, but for some reason I'm not able to change the current version of Java using alternatives. I can run alternatives --config java and type my selection but when I echo the version number for either java or javac, it spits back out 1.5 every time (despite alternatives showing the current version is 1.6). The server I'm working with is running RHEL5, by the way. I have verified that the paths used in alternatives are pointing to the correct directories. Here's some output from my session: [brilewis@myserver]$ sudo /usr/sbin/update-alternatives --config java There are 3 programs which provide 'java'. Selection Command ** 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java + 2 /usr/java/jdk1.5.0_10/bin/java 3 /usr/java/jdk1.6.0_16/bin/java Enter to keep the current selection[+], or type selection number: 3 [brilewis@myserver]$ java -version java version "1.5.0_10" Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_10-b03) Java HotSpot(TM) Server VM (build 1.5.0_10-b03, mixed mode) [brilewis@myserver]$ sudo /usr/sbin/update-alternatives --config java There are 3 programs which provide 'java'. Selection Command ** 1 /usr/lib/jvm/jre-1.4.2-gcj/bin/java 2 /usr/java/jdk1.5.0_10/bin/java + 3 /usr/java/jdk1.6.0_16/bin/java Enter to keep the current selection[+], or type selection number:

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  • Java enums in generic type

    - by Marcin Cylke
    Hi, I'd like to create a generic enum-based mapper for IBatis. I'm doing this with the below code. This does have compile time errors, which I don't know how to fix. Maybe my solution is just plain wrong (keep in mind the use of IBatis), in such case please suggest something better. Any help appreciated. What I want to achieve is to define subsequent mappers as: public class XEnumTypeHandler extends CommonEnumTypeHandler<X> { } The current code: public class CommonEnumTypeHandler<T extends Enum> implements TypeHandlerCallback { public void setParameter(ParameterSetter ps, Object o) throws SQLException { if (o.getClass().isAssignableFrom(**T**)) { ps.setString(((**T**) o).value().toUpperCase()); } else throw new SQLException("Excpected ParameterType object than: " + o); } public Object getResult(ResultGetter rs) throws SQLException { Object o = valueOf(rs.getString()); if (o == null) throw new SQLException("Unknown parameter type: " + rs.getString()); return o; } public Object valueOf(String s) { for (T pt : T.**values()**) { if (pt.**value()**.equalsIgnoreCase(s)) return pt; } return null; } } I've added error markings to the above code, the error messages are in order: T cannot be resolved The method value() is undefined for the type T The method values() is undefined for the type T The method values() is undefined for the type T

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  • Ways to improve Java Generics and dont say get rid of wildcards and reification.

    - by mP
    Sometimes i like to write up template classes and use type parameters to make the abstract methods more type safe. Template<X> { abstract void doStuff( X ); // NOT public } While type safety is great etc, the problem remains that even though X is not visible to outside code, one must still include the type to avoid warnings. My solution in this case would be to make it possible to define a scope for type parameters (now they are always public). Would other original features besides the obvious would you like.

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  • Java generic return tpye

    - by Colby77
    Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

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  • java , eclipse jar problem

    - by Raxvan
    Hello , i'm kind of new to java. I use eclipse and i imported some jar files with some classes by going to properties - Add External Jars; The problem is that when i try to use a class from the jar i get the following exception: Exception in thread "main" java.lang.NoClassDefFoundError: nextapp/echo2/app/event/ActionListener at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$000(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at Program.main(Program.java:12) Caused by: java.lang.ClassNotFoundException: nextapp.echo2.app.event.ActionListener at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) ... 13 more The class is supposed to create a window, i guess that the jar has to import somehow other stuff or something like that, How can i fix this? PS. Sorry for the bad code , i don't know tags here. thansk, Raxvan

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  • Java: using generic wildcards with subclassing

    - by gibberish
    Say I have a class Foo, a class A and some subclass B of A. Foo accepts A and its sublclasses as the generic type. A and B both require a Foo instance in their constructor. I want A's Foo to be of type A , and B's Foo to be of type B or a superclass of B. So in effect, So I only want this: Foo<X> bar = new Foo<X>; new B(bar); to be possible if X is either A, B, or a both subclass of A and superclass of B. So far this is what I have: class Foo<? extends A>{ //construct } class A(Foo<A> bar){ //construct } class B(Foo<? super B> bar){ super(bar); //construct } The call to super(...) doesn't work, because <A> is stricter than <? super B>. Is it somehow possible to use the constructor (or avoid code duplication by another means) while enforcing these types? Edit: Foo keeps a collection of elements of the generic parameter type, and these elements and Foo have a bidirectional link. It should therefore not be possible to link an A to a Foo.

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  • Transfering a set with a Wildcarded Generic to a List in Java

    - by Daniel Bingham
    I have a data type that contains a set and a method that expects List<? extends MyClass>. The data type has Set<? extends MyClass>. I need to be able to move the stuff out of the set and into the List. The order it goes into the list doesn't matter, it just needs to start keeping track of it so that it can be reordered when displayed. Suffice to say that changing the Set into a List in the data type is out of the question here. This seems pretty easy at first. Create a new method that takes a Set instead of a List, changes it into a list and then passes it on to the old method that just took a list. The problem comes in changing the set to a list. public void setData(Set<? extends MyClass> data) { List<? extends Myclass> newData = ArrayList< /* What goes here? */ >(); for(ConcordaEntityBean o : data) { newData.add(o); } setData(newData); } Obviously, I can't instantiate an ArrayList with a wildcard, it chokes. I don't know the type at that point. Is there some way to pull the type out of data and pass it to ArrayList? Can I just instantiate it with MyClass? Is there some other way to do this?

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  • How to properly mix generics and inheritance to get the desired result?

    - by yamsha
    My question is not easy to explain using words, fortunately it's not too difficult to demonstrate. So, bear with me: public interface Command<R> { public R execute();//parameter R is the type of object that will be returned as the result of the execution of this command } public abstract class BasicCommand<R> { } public interface CommandProcessor<C extends Command<?>> { public <R> R process(C<R> command);//this is my question... it's illegal to do, but you understand the idea behind it, right? } //constrain BasicCommandProcessor to commands that subclass BasicCommand public class BasicCommandProcessor implements CommandProcessor<C extends BasicCommand<?>> { //here, only subclasses of BasicCommand should be allowed as arguments but these //BasicCommand object should be parameterized by R, like so: BasicCommand<R> //so the method signature should really be // public <R> R process(BasicCommand<R> command) //which would break the inheritance if the interface's method signature was instead: // public <R> R process(Command<R> command); //I really hope this fully illustrates my conundrum public <R> R process(C<R> command) { return command.execute(); } } public class CommandContext { public static void main(String... args) { BasicCommandProcessor bcp = new BasicCommandProcessor(); String textResult = bcp.execute(new BasicCommand<String>() { public String execute() { return "result"; } }); Long numericResult = bcp.execute(new BasicCommand<Long>() { public Long execute() { return 123L; } }); } } Basically, I want the generic "process" method to dictate the type of generic parameter of the Command object. The goal is to be able to restrict different implementations of CommandProcessor to certain classes that implement Command interface and at the same time to able to call the process method of any class that implements the CommandProcessor interface and have it return the object of type specified by the parametarized Command object. I'm not sure if my explanation is clear enough, so please let me know if further explanation is needed. I guess, the question is "Would this be possible to do, at all?" If the answer is "No" what would be the best work-around (I thought of a couple on my own, but I'd like some fresh ideas)

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  • Reflection for Class of generic parameter in Java?

    - by hatboysam
    Imagine the following scenario: class MyClass extends OtherClass<String>{ String myName; //Whatever } class OtherClass<T> { T myfield; } And I am analyzing MyClass using reflection specifically (MyClass.class).getDeclaredFields(), in this case I will get the following fields (and Types, using getType() of the Field): myName --> String myField --> T I want to get the actual Type for T, which is known at runtime due to the explicit "String" in the extends notation, how do I go about getting the non-genetic type of myField?

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  • Java - How to pass a Generic parameter as Class<T> to a constructor

    - by Joe Almore
    I have a problem here that still cannot solve, the thing is I have this abstract class: public abstract class AbstractBean<T> { private Class<T> entityClass; public AbstractBean(Class<T> entityClass) { this.entityClass = entityClass; }... Now I have another class that inherits this abstract: @Stateless @LocalBean public class BasicUserBean<T extends BasicUser> extends AbstractBean<T> { private Class<T> user; public BasicUserBean() { super(user); // Error: cannot reference user before supertype contructor has been called. } My question is how can I make this to work?, I am trying to make the class BasicUserBean inheritable, so if I have class PersonBean which inherits BasicUserBean then I could set in the Generic the entity Person which also inherits the entity BasicUser. And it will end up being: @Stateless @LocalBean public class PersonBean extends BasicUserBean<Person> { public PersonBean() { super(Person.class); } ... I just want to inherit the basic functionality from BasicUserBean to all descendants, so I do not have to repeat the same code among all descendants. Thanks!.

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