I'm building an optimization program using Optaplanner 6.2.0.CR4, and I'm running into reflection issues with the ReflectionPropertyAcessor class, line 63: return readMethod.invoke(bean) and the other invoke methods in this class. Debugging the code, I'm usually able to "Step-into" the code into whatever of my classes it's calling, but Eclipse throws an error every time it reaches the end of whatever method is being called. This results in Method.invoke(Object, Object) line not available, DelegatingMethodAccesorImpl.invoke(Object, Object[]) line not available, GeneratedMethodAccessor5.invoke(Object, Object[]) line not available and then a screen asking me to change the attached source.
I'm running JRE 1.8, and I have the source code for Optaplanner imported into Eclipse as its own Maven project, with my code as its own separate Java project for now. I'm pretty new to using Maven and build tools in general. Could this error be a result of bad dependencies, classpath, etc? Is there a better way to set up my project? I'm in the process of moving my code into a Maven project also.
What stacktrace are you getting in a normal run?
The call readMethod.invoke(bean) can fail if bean isn't an instance of the class for which the readMethod applies. If that's the case, I'd be interested in seeing the code, because optaplanner might be able to detect that fail-fast with a helpful error message.
Debugging won't work because Method.invoke is probably a native implementation (C instead of Java) in the JDK.
Related
Motivation:
In our code we have a few places where some methods are run by their name. There are some big if-else-if blocks with each function name and call of the corresponding method (I use the term function to describe just names, for example function X01 might correspond to method SomeClass.functionX01). I've been looking into ways to improve that
Goal:
Write just methods that are annotated with some custom annotation, removing the need to update or even include if-else-if blocks in order to run specific function. Have access to any generated code if any code is generated.
What I did:
I've created first prove of concept using runtime annotations and it proved successful, but slower then if-else-if. Next attempt was with source annotation
I've followed this link for an example, however it did not seam to run in IntelliJ. What I wanted is to have - in this case PersonBuilder class generated, instead there was none. In some cases an error was raised Error:java: Bad service configuration file, or exception thrown while constructing Processor object: javax.annotation.processing.Processor: Provider BuilderProcessor not found
After some Googling and failing to find anything I've turned to book (Core Java, Volume II - Advanced Features - 9th Edition, Polish translation) and there was reccomended to run the following commands:
javac [AbstractProcessor implementation]
javac -processor [Compiled Processor] [other source files to compile]
This worked, however is unsatisfactory as it needs to happen inside IDE (NetBeans and IntelliJ to be specific) automatically during build. Code does not need to be generated on the fly, but programmer must have access to it after build (as in - be able to call methods of generated classes)
Question:
How to have and use generated code used in NetBeans and IntelliJ without the need of using external tools? Is it possible, or using reflection, runtime annotations or external tools is the only way?
Additional info (just in case):
Language level: Java 1.8
JVM versions: 12 and 13
IDEs: NetBeans and IntelliJ
I have a plugin that used to work with Eclipse Indigo, Kepler,Luna and Mars (4.5). It supports the Frege programming language (http://www.frege-lang.org/fregide/). It is based on the IMP framework, which is, unfortunately, not maintained anymore (and I don't have the source code).
Tonight I checked for updates, and it found Eclipse 4.5.1.
After updating, eclipse had a fancy new splash screen that says "MARS.1".
Yet it can't initialize the plugin anymore!
In the Error Log, I get the message:
Plug-in "frege.ide" was unable to instantiate class "frege.imp.builders.FregeBuilder".
and the stack trace seems to indicate that some method has vanished from the Eclipse API:
java.lang.NoSuchMethodError: org.eclipse.ui.internal.registry.FileEditorMapping.setDefaultEditor(Lorg/eclipse/ui/internal/registry/EditorDescriptor;)V
at org.eclipse.imp.language.LanguageRegistry.addUniversalEditorMappings(LanguageRegistry.java:393)
at org.eclipse.imp.language.LanguageRegistry.initializeRegistryAsNeeded(LanguageRegistry.java:268)
at org.eclipse.imp.language.LanguageRegistry.findLanguage(LanguageRegistry.java:206)
at frege.imp.builders.FregeBuilderBase.<clinit> (FregeBuilderBase.java:53)
...
Here are my questions:
Does anybody know why this method is gone?
How can I restrict installation of my plugin to LUNA, KEPLER and INDIGO only?
Would it be possible to supply a fake setDefaultEditor method that does whatever must be done now to register the Editor for the plugin?
The setDefaultEditor method does still exist in FileEditorMapping but it now takes an IEditorDescriptor argument instead of EditorDescriptor. This will cause the NoSuchMethodError. Since this class is an internal class and therefore not part of the API this is a valid change.
According to the IMP Wiki the IMP project has moved to a github project, you may be able to get up to date code from there (or at least get the source).
I am working on moving code from R2007a to R2013a. I am getting a java.lang.NoClassDefFoundError during my run in R2013a which does not appear in R2007a. It occurs when I call.
feval('get',fname,jevent);
Where fname is a product.ProxyField object for an Object Filter and jevent is a product.format.java.internal.JavaEvent.
The class is in a jar file on the path and is being accessed by another class in the same jar file. The stack trace does not leave the realm of the product if that helps.
I do not have access to the original code for the jar file. I do have access to code derived from that original code and both classes are in the same package. I'm guessing this has something to do with differences in the java version but I'm not sure what to do since I don't have the original code to recompile.
Unfortunately I can't provide actual source or full detail but a google search only yielded results for MATLAB startup issues. Any thoughts?
Seems like the difference between R2007a and R2013a is that the first uses 1.5 jre and second uses 1.6 jre. It would be easier to help you if you provided the stack trace showing the exception. Sometimes classes get moved around in between jvm versions, so having the actual missing classes would help in determining if the missing class is a class that was just moved around to a different package. You could take the missing class, google it adding the same exception message as you put above and seeing who else ran into similar issues.
I am trying to get Thrift working in Eclipse and having some issues. The project is a standard maven project.
I used the thrift compiler to compile the thrift file to Java code, which was successful. The generated code was placed under src/main/generated-sources//
(Is this acceptable practise?)
In eclipse, I added the src folder from the build menu, but then I get:
Cannot reduce the visibility of the inherited method from ProcessFuction<I,...
I am not using the maven thrift plugin as the source is already generated and within the source tree (again, is this advisable?).
How should I configure this setup?
seems like the Thrift compiler is not as good as thought.
Cannot reduce the visibility of the inherited method
shows that a inherited method from an abstract class or an interface has originally a higher visibility, e.g. "public" while you have "private" in your code.
I would try to set that to "public" and see what happens. The code might compile sweet, as I expect that mismatch to be generated due to compiling/transformation of code with missing visibility setting on the method as one can write a method header without specifying the visiblitiy:
void doany(){
// nothing
}
The method uses the classes visibility in that case (mostly "public") - which the compiler will have misunderstood.
I'm getting:
NoSuchMethodError: com.foo.SomeService.doSmth()Z
Am I understanding correctly that this 'Z' means that return type of doSmth() method is boolean? If true, then that kind of method really does not exist because this method returns some Collection. But on the other hand if I call this method, I'm not assigning its return value to any variable. I just call this method like this:
service.doSmth();
Any ideas why this error occurs? All necessary JAR files exist and all other methods from this class seems to exist.
Looks like method exists in classpath during compilation, but not during running of your application.
I don't think return type is a problem. If it was, it wouldn't compile. Compiler throws error when method call is ambiguous, and it is when two methods differ only by return type.
Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
In short - a class/jar file at runtime is not the same that you used at compile time.
This is probably a difference between your compile-time classpath and you run-time classpath.
Here is what seems to be going on:
The code is compiled with a class path that defines the doSmth() method returning a boolean. The byte-code refers to the doSmth()Z method.
At runtime, the doSmth()Z method isn't found. A method returning a Collection is found instead.
To correct this problem, check your (compile time) classpath.
The current reply just tell you why is failing. Usually is even nicer to know how to fix problems. As it is mentioned, the problem usually is that you built your program but when running or exporting it, the library is not included. So the solution is...
If you are running, check the the run configuration
Select Run tab -> Run configurations -> Select the configuration you are running -> Check the Classpath tab -> Ensure the libraries you need are there
If you are exporting (for example a war file), follow this
Select project -> Select properties -> Select Deployment Assembly -> Press Add -> Select Java Build Path Entries -> Select the libraries you want to be included in your exported file (for example a war file)
In both cases, ensure the library which you are referencing in included.
Other frequent problems for this error are not the right type of parameters or visibility but then, the compiler will detect the error before running. In this case, just check the documentation to match the function and package visibility, and ensure that the library is found in Java Build Path in your project properties.
Maybe still can help somebody, but this exception can happen also when you have on the classpath two classes in different jar files that have the same exact signature but they haven't the same public methods.
For example:
On file mylibrary1.jar you have class com.mypackage.mysubpackage.MyClass with method doSmth()
On file mylibrary2.jar you have class com.mypackage.mysubpackage.MyClass without method doSmth()
When searching the class, the classloader may find first mylibrary2.jar depending on the path precedence but can't find the method on that class.
Be sure you don't have the same package + class on two different files.
I noticed this problem occurring while testing some experimental changes in multiple linked projects, after updating them from SVN in Eclipse.
Specifically, I updated all projects from SVN, and reverted the .classpath file rather than edit it manually to keep things simple.
Then I re-added the linked projects to the path, but forgot to remove the related jars. This was how the problem occurred for me.
So apparently the run time used the jar file while the compiler used the project files.
Another way this can happen and is difficult to find:
If a signature of a method in an external jar changes in a way that there is no error found in the IDE because it's still compatible with how you call it the class might not be re-compiled.
If your build checks the files for changes and only then recompiles them, the class might not be recompiled during the build process.
So when you run it this might lead to that problem. Although you have the new jar, your own code expects still the old one but does never complain.
To make it harder it depends on the jvm if it can handle such cases. So in the worst case it runs on the test server but not on the live machine.