Working on a GWT project (2.7.0), i have experienced a very odd client code behaviour.
The following code throws the error "SEVERE: (ReferenceError) : Ljava_io_Serializable_2_classLit_0_g$ is not definedcom.google.gwt.core.client.JavaScriptException: (ReferenceError) : Ljava_io_Serializable_2_classLit_0_g$ is not defined".
The error occurs, when calling Arrays.asList() with a parameter, that has an interface type.
Is this expected behaviour or a GWT bug?
// Working
Integer n1 = 1;
Arrays.asList(n1);
// Not working
Serializable n2 = 1;
Arrays.asList(n2);
GWT 2.7's Super Dev Mode (and from the _g$ in your class literal field, I think that is what you are using) has been observed having other issues like this, but when compiled the issues go away.
If this is indeed what you are seeing, the issue seems to be fixed in 2.8, not yet released: https://groups.google.com/d/topic/google-web-toolkit/RzsjqX2gGd4/discussion
This behavior is definitely not expected, but if you can confirm that this works correctly when compiled for production and in GWT 2.8, then we at least know the bug is fixed.
Well, the typical use of Arrays.asList would be
Object myObj = new Object();
List theList = Arrays.asList(new Object[] {myObj});
This works in GWT with any kind of interface/class/enum you throw at it.
EDIT : I've tested this with GWT 2.5.1 :
public class Foo implements EntryPoint {
public static interface MyInterface {
}
public static class MyObject implements MyInterface {
}
public void onModuleLoad() {
MyInterface myObject = new MyObject();
List<MyInterface> myList = Arrays.asList(myObject);
}
}
Isn't it possible that the problem lies somewhere else?
Related
Is it possible to do Inter Type Declarations with AspectJ on Compiled Class Files at Load Time Weaving?
As an example: I compile some Groovy code and want to add fields or methods with IDT.
Update:
Oh my goodness, you do not need reflection to access members or execute methods. Eclipse shows errors in the editor, but you may just ignore them, the code compiles and runs fine anyway. So the aspect is really much more strightforward and simple:
public aspect LTWAspect {
public static String Application.staticField = "value of static field";
public String Application.normalField = "value of normal field";
public void Application.myMethod() {
System.out.println(normalField);
}
void around() : execution(void Application.main(..)) {
System.out.println("around before");
proceed();
System.out.println("around after");
System.out.println(Application.staticField);
new Application().myMethod();
}
}
Original answer:
Yes, but you have a hen-and-egg problem there, i.e. you cannot just reference the newly introduced fields from your LTW aspect code without reflection. (The last sentence is not true, see update above.) Plus, in order to make your LTW aspect compile, you need the classes to be woven on the project's build path so as to be able to reference them. Example:
Java project
public class Application {
public static void main(String[] args) {
System.out.println("main");
}
}
AspectJ project
import org.aspectj.lang.SoftException;
public aspect LTWAspect {
public static String Application.staticField = "value of static field";
public String Application.normalField = "value of normal field";
public void Application.myMethod() {
try {
System.out.println(Application.class.getDeclaredField("normalField").get(this));
} catch (Exception e) {
throw new SoftException(e);
}
}
void around() : execution(void Application.main(..)) {
System.out.println("around before");
proceed();
System.out.println("around after");
try {
System.out.println(Application.class.getDeclaredField("staticField").get(null));
Application.class.getDeclaredMethod("myMethod", null).invoke(new Application());
} catch (Exception e) {
throw new SoftException(e);
}
}
}
So, e.g. in Eclipse you need to put the Java project on the AspectJ project's build path under "Projects" because only then it can see Java class Application on which you want to declare members. After compilation you just start the Java project and do LTW on the aspect project (don't forget an aop-ajc.xml referencing LTWAspect).
In my example above I declare a static member, a non-static ("normal") member and a non-static method. My advice prints the static member and calls the non-static method, both via reflection. The non-static method then prints the non-static member, again via reflection. This is not nice, but it works and proves the ITD in combination with LTW is possible. There might be a more elegant way, but if so I am unaware of it. (Update: There is a more elegant way: Just ignore the errors marked by Eclipse IDE, see above.)
Program output
around before
main
around after
value of static field
value of normal field
Thanks in advance for your assistance. I have the following exported part:
[Export (typeof(INewComponent))] // orignally tried just [Export} here and importing NewComponent below
public class NewComponent : INewComponent
{
// does stuff including an import
}
The Console test program imports the above:
public class Program
{
[Import] // have tried variations on importing "NewComponent NewComponent" etc
public INewComponent NewComponent
{
get;
set;
}
public static void Main(string[] args)
{
var p = new Program();
var catalog = new AssemblyCatalog(typeof(Program).Assembly);
var container = new CompositionContainer(catalog);
container.ComposeParts(p);
}
The Composition fails with these CompositionExceptions (I removed the namespace to protect the guilty :)):
1) No valid exports were found that match the constraint
'((exportDefinition.ContractName == "INewComponent") AndAlso
(exportDefinition.Metadata.ContainsKey("ExportTypeIdentity") AndAlso
"INewComponent".Equals(exportDefinition.Metadata.get_Item("ExportTypeIdentity"))))',
invalid exports may have been rejected.
The Composition works successfully if I do the composition in the main program like this:
public class Program
{
public static void Main(string[] args)
{
INewComponent newComponent = new NewComponent();
var catalog = new AssemblyCatalog(typeof(Program).Assembly);
var container = new CompositionContainer(catalog);
container.ComposeParts(newComponent);
}
}
Thank You
Is your Exported part contained in the same Assembly as Program? If it is in a separate DLL, you need to include that Assembly in your catalog as well, like this:
var aggregateCatalog = new AggregateCatalog();
aggregateCatalog.Catalogs.Add(new AssemblyCatalog(typeof(Program).Assembly));
aggregateCatalog.Catalogs.Add(new AssemblyCatalog(typeof(NewComponent).Assembly));
var container = new CompositionContainer(aggregateCatalog);
// etc...
If that's doesn't work, then there is a nice open source tool called Visual MEFx that can help you analyze your catalog. Here is a short article about setting it up:
Getting Started With Visual MEFx
In your NewComponent class you wrote this:
// does stuff including an import
If there is a problem with that unshown import, then MEF will complain about the Program.NewComponent import instead of the actual deeper cause. This is called "stable composition". Stable composition can be useful, but it also complicates the debugging of a failed composition.
You can follow the instructions in the MEF documentation about Diagnosing Composition Errors to home in on the actual cause.
In a small program, you can also try to call container.GetExportedValue<ISomeExport>() for a few exports until you find the one that is causing problems.
In my GWT application i'm trying to setup a DI mechanism wihich would allow me to have all the commonly necessary stuff at hand everywhere. I'm using google-gin which is an adaptation of guice for GWT. I have an injector interface defined as this:
#GinModules(InjectionClientModule.class)
public interface MyInjector extends Ginjector {
public PlaceController getPlaceController();
public Header getHeader();
public Footer getFooter();
public ContentPanel getContent();
public EventBus getEventBus();
public PlaceHistoryHandler getPlaceHistoryHandler();
}
My injection module is this:
public class InjectionClientModule extends AbstractGinModule {
public InjectionClientModule() {
super();
}
protected void configure() {
bind(Header.class).in(Singleton.class);
bind(Footer.class).in(Singleton.class);
bind(ContentPanel.class).in(Singleton.class);
bind(EventBus.class).to(SimpleEventBus.class).in(Singleton.class);
bind(PlaceController.class).toProvider(PlaceControllerProvider.class).asEagerSingleton();
bind(PlaceHistoryHandler.class).toProvider(PlaceHistoryHandlerProvider.class).asEagerSingleton();
}
}
When calling MyInjector injector = GWT.create(MyInjector.class); i'm gettign the following exception:
java.lang.NullPointerException: null
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBinding(BindingsProcessor.java:498)
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBindingForUnresolved(BindingsProcessor.java:290)
at com.google.gwt.inject.rebind.BindingsProcessor.createImplicitBindingsForUnresolved(BindingsProcessor.java:278)
at com.google.gwt.inject.rebind.BindingsProcessor.process(BindingsProcessor.java:240)
at com.google.gwt.inject.rebind.GinjectorGeneratorImpl.generate(GinjectorGeneratorImpl.java:76)
at com.google.gwt.inject.rebind.GinjectorGenerator.generate(GinjectorGenerator.java:47)
at com.google.gwt.core.ext.GeneratorExtWrapper.generate(GeneratorExtWrapper.java:48)
at com.google.gwt.core.ext.GeneratorExtWrapper.generateIncrementally(GeneratorExtWrapper.java:60)
at com.google.gwt.dev.javac.StandardGeneratorContext.runGeneratorIncrementally(StandardGeneratorContext.java:647)
at com.google.gwt.dev.cfg.RuleGenerateWith.realize(RuleGenerateWith.java:41)
at com.google.gwt.dev.shell.StandardRebindOracle$Rebinder.rebind(StandardRebindOracle.java:78)
at com.google.gwt.dev.shell.StandardRebindOracle.rebind(StandardRebindOracle.java:268)
at com.google.gwt.dev.shell.ShellModuleSpaceHost.rebind(ShellModuleSpaceHost.java:141)
at com.google.gwt.dev.shell.ModuleSpace.rebind(ModuleSpace.java:585)
at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:455)
at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)
at com.google.gwt.core.client.GWT.create(GWT.java:97)
The problem is that the PlaceController class actually depends on one of the other dependencies. I've implemented it's provider like this:
public class PlaceControllerProvider implements Provider<PlaceController> {
private final PlaceController placeController;
#Inject
public PlaceControllerProvider(EventBus eventBus) {
this.placeController = new PlaceController(eventBus);
}
#Override
public PlaceController get() {
return placeController;
}
}
what should i change for this to work?
Old question but having the same problem I kept falling here. I finally found the way to know which class is messing during ginjection.
When I launch my app in development mode and put stack to Trace, I noticed there is a step called : "Validating newly compiled units".
Under this, I had an error but I didn't notice it since I had to expand 2 nodes which weren't even in red color.
The error was "No source code available for type com.xxx.xxxx ...", which was due to a bad import on client side which couldn't be converted to Javascript.
Hope this may help other here !
While I'm not actually seeing how the errors you're getting are related to the PlaceController being injected, I do see that the provider is returning a singleton PlaceController even if the provider were not bound as an eager singleton or in a different scope. The correct way to write that provider would be:
public class PlaceControllerProvider implements Provider<PlaceController> {
private final EventBus eventBus;
#Inject
public PlaceControllerProvider(EventBus eventBus) {
this.eventBus = eventBus;
}
#Override
public PlaceController get() {
return new PlaceController(eventBus);
}
}
Let guice handle the scoping i.e. "Letting guice work for you".
Other than that, I almost bet that your problem is due to the use of asEagerSingleton. I recommend you try this with just in(Singleton.class) and I further posit that you didn't really need the singleton to be eager. It seems others had problems with the behavior too, there's some indication that it has to do with overusing asEagerSingleton or misunderstanding the #Singleton annotation in a few cases.
I also got a lot of NullPointerException warnings using GIN 1.x with no real explanation of what happened. When I upgraded to gin 2.0 I was told with high accuracy what the error was. You might be helped by upgrading to the 2.0 version that was released a year after you asked this question.
Had the same problem problem, same trace, and the error was that I used "server" classes in my "client" classes, so GIN can't find these classes.
I mean by "server" and "client" the packages in my project.
Hope this could help
I am working in J2EE 5 using JPA, I have a working solution but I'm looking to clean up the structure.
I am using EntityListeners on some of the JPA objects I am persisting, the listeners are fairly generic but depend on the beans implementing an interface, this works great if you remember to add the interface.
I have not been able to determine a way to tie the EntityListener and the Interface together so that I would get an exception that lead in the right direction, or even better a compile time error.
#Entity
#EntityListener({CreateByListener.class})
public class Note implements CreatorInterface{
private String message;....
private String creator;
....
}
public interface CreatorInterface{
public void setCreator(String creator);
}
public class CreateByListener {
#PrePersist
public void dataPersist(CreatorInterface data){
SUser user = LoginModule.getUser();
data.setCreator(user.getName());
}
}
This functions exactly the way I want it to, except when a new class is created and it uses the CreateByListener but does not implement the CreatorInterface.
When this happens a class cast exception is thrown somewhere deep from within the JPA engine and only if I happen to remember this symptom can I figure out what went wrong.
I have not been able to figure a way to require the interface or test for the presence of the interface before the listener would be fired.
Any ideas would be appreciated.
#PrePersist
public void dataPersist(Object data){
if (!(data instanceof CreatorInterface)) {
throw new IllegalArgumentException("The class "
+ data.getClass()
+ " should implement CreatorInterface");
}
CreatorInterface creatorInterface = (CreatorInterface) data;
SUser user = LoginModule.getUser();
creatorInterface.setCreator(user.getName());
}
This does basically the same thing as what you're doing, but at least you'll have a more readable error message indicating what's wrong, instead of the ClassCastException.
I've tried to learn the JSF 2.0 by implementing the managed bean via the NetBeans 7. By overview it contains the property as a data object which implements the interface as the following: -
public interface MyInterface1 {
void setName(String name);
String getName();
}
public interface MyInterface2 extends MyInterface1 {
void setPhone(String phone);
String getPhone();
}
public class MyInfo implements MyInterface2 {
//...Getter, Setter
}
#ManagedBean(name="myBean")
public class MyManagedBean {
private MyInfo myInfo = new MyInfo();
//..Getter, Setter
}
When I enter the EL at the JSF/XHTML as
#{myBean.myInfo....}
the methods which are defined at the Super Interface, the MyInterface1 is not displayed.
I'm not sure if it is a tool limitation or I may do something wrong or not.
Could you please help to advise further? Thank you very much for your help in advance. I'm looking forward to hearing from you soon.
Regards,
Charlee Ch.
This is definitely a limitation of the Netbeans editor. I've constantly struggled with similar issues in NB 6.9, code completion would sometimes not work at all, sometimes missing out interfaces/methods, etc. But hey, you can go ahead and type in the method name yourself - it should work.