In my java project i have a jar that i generated with some classes. I am able to instantiate the instance of the class that is in my jar:
Alert a = new Alert();
But wen i try to do this:
JAXBContext context = JAXBContext.newInstance(Alert.class);
I get run time exception like this:
java.lang.InternalError:
Error occured while invoking reflection on target classes. Make sure all referenced classes are on classpath: interface javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter
Exception: null
Any idea what could be the issue?
Thank you
This happened to me as I had defined XmlAdapter implementations that were in a different JAR and not on the classpath. When trying to create the JAXBContext, it needs these adapters used by the JAXB type. Now that I figured this out, the message makes more sense, but is still very cryptic. XmlJavaTypeAdapter is the annotation interface and the code fails to call the value() method of the annotation as it returns Class<? extends XmlAdapter>, a class type which is not defined on the classpath.
If you look at the code that throws the exception, this is impossible:
public Class More ...getClassValue(Annotation a, String name) {
try {
return (Class)a.annotationType().getMethod(name).invoke(a);
} catch (IllegalAccessException e) {
// impossible
throw new IllegalAccessError(e.getMessage());
} catch (InvocationTargetException e) {
// impossible
throw new InternalError(e.getMessage());
} catch (NoSuchMethodException e) {
throw new NoSuchMethodError(e.getMessage());
}
}
Would be nice if the cause of the exception was not lost.
Related
Actually i am having a spring main class as follows.
ClassLoader loader = null;
try {
loader = URLClassLoader.newInstance(new URL[]{new
File(plugins + "/" + pluginName + "/" + pluginName +
".jar").toURI().toURL()}, getClass().getClassLoader());
} catch (MalformedURLException e) {
e.printStackTrace();
}
Class<?> clazz = null;
try {
clazz = Class.forName("com.sample.Specific", true, loader);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Method method = null;
try {
method = clazz.getMethod("run",new Class[]{});
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
try {
method.invoke(clazz.newinstance,new Object[]{});
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
Specific Class is follow :
package com.sample
#Service
public class Specific {
#Autowired
private FD fd;
public void run(){
fd.init();
}
}
#Autowired FD comes to be null. Can anyone give me some solution as i also know new operator will not work for #autowired. As i am loading class with new instance then only it becomes null. Can anyone guide me in this thing
Spring has its own way to provide you new objects. As long as you're consistent using #Autowired and #Component/#Service/#Repository/#Controller there should be no problem
And since all "business" object instantiation is handled by Spring you should never use new. If you have no other way of getting an instance (something I realy doubt about it) you can use ApplicationContext.getBean() but as I said, in most cases this is not required (and this is also a bad practice)
If you need several instances of a class instead of injecting them (by using #Autowired) you can inject a Provider<T>
UPDATE
Since the class is known at runtime you need to inject an ApplicationContext and use it to get the bean:
public class TheClassWhereYouAreCreatingTheObject {
#Autowired
private ApplicationContext context; // You definitely need this
public void theMethodWhereYouAreCreatingTheObject() {
Class<?> clazz = ... // getting the object class
Object instance = context.getBean(clazz); // getting and instance trough Spring
// If you know that kind of object you will get cast it at call its methods
((Specific) instance).run();
// If you know anything about the class you will have to use reflection
Method method = clazz.getMethod("run", new Class[]{});
method.invoke(instance, new Object[]{});
}
}
Add Specific Service bean inside your main class. As long as the service is inside one your component scan packages then you shall be fine. Do not use new operator.
#Autowired
private Specific specific;
If you want to take advantage of autowiring then I think we have to think from spring terms.
you can use Beanutils to create a new instance and play with reflections supporting spring features.
Please go through below methods:
https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/BeanUtils.html
am using generics and need to create an instance of a generic class at runtime, so I am trying to use getConstructor(). Unfortunately, I receive a NoSuchMethodException despite having the correct signature, so I am at a loss as to what is wrong. I will appreciate your suggestions so I can get beyond this issue. :) I've provided the constructors for CustomerAssembler. I need to create an instance of this class, dynamically, due to generics being used. I've included the snippet of code that I am using. In it, I called getConstructors() to see whether the constructors exist and their signatures. Both constructors exist and I have used the proper signature, so I don't know why I keep getting this exception. Arggg... Hopefully, you will see what I am doing wrong. :)
Thank you for your time and help,
Mike
// Here are the constructors for CustomerAssembler.
public CustomerAssembler()
{
super();
}
public CustomerAssembler(
Class<Customer> entityClass,
Class<CustomerPreviewDTO> entityPreviewDTOClass,
Class<CustomerDetailDTO> entityDetailDTOClass,
Class<CustomerUpdateDTO> entityUpdateDTOClass,
EntityManager entityManager)
{
super(entityClass, entityPreviewDTOClass, entityDetailDTOClass, entityUpdateDTOClass, entityManager);
}
Here is the exception: NoSuchMethodException:
java.lang.NoSuchMethodException: assemblers.CustomerAssembler.<init>(entities.Customer, dtos.CustomerPreviewDTO, dtos.CustomerDetailDTO, dtos.CustomerUpdateDTO, javax.persistence.EntityManager)
Here is the code...
try
{
Class<CustomerAssembler> customerAssemblerClass = CustomerAssembler.class;
Constructor<CustomerAssembler>[] lst = (Constructor<CustomerAssembler>[]) this.customerAssemblerClass.getConstructors();
/* See what the signature is for the non-default constructor, so I can make sure that
getConstructor() is configured properly. Here is what was reported in the debugger:
[0] = {java.lang.reflect.Constructor#10796}"public assemblers.CustomerAssembler()"
[1] = {java.lang.reflect.Constructor#10797}"public assemblers.CustomerAssembler(java.lang.Class,java.lang.Class,java.lang.Class,java.lang.Class,javax.persistence.EntityManager)"
signature = {java.lang.String#10802}"(Ljava/lang/Class<Lentities/Customer;>
Ljava/lang/Class<dtos/CustomerPreviewDTO;>
Ljava/lang/Class<dtos/CustomerDetailDTO;>
Ljava/lang/Class<dtos/CustomerUpdateDTO;>
Ljavax/persistence/EntityManager;)V"
*/
// Configure our constructor call... this.contactAssemblerClass
Constructor<CustomerAssembler> ca =
customerAssemblerClass.getConstructor(
Customer.class,
CustomerPreviewDTO.class,
CustomerDetailDTO.class,
CustomerUpdateDTO.class,
EntityManager.class);
// Create an instance here...
}
catch (NoSuchMethodException e)
{
e.printStackTrace();
}
catch (InstantiationException e)
{
e.printStackTrace();
}
catch (IllegalAccessException e)
{
e.printStackTrace();
}
catch (InvocationTargetException e)
{
e.printStackTrace();
}
catch (Exception e)
{
e.printStackTrace();
}
customerAssemblerClass.getConstructor(
Customer.class,
CustomerPreviewDTO.class,
CustomerDetailDTO.class,
CustomerUpdateDTO.class,
EntityManager.class);
This looks for a constructor that has the following signature:
CustomerAssemble(Customer c,
CustomerPreviewDTO cpDTO,
CustomerDetailDTO cdDTO,
CustomerUpdateDTO cuDTO,
EntityManager em)
Your constructor doesn't take that as argument. It takes 4 instances of Class, and an instance of EntityManager.
So the code should be
customerAssemblerClass.getConstructor(
Class.class,
Class.class,
Class.class,
Class.class,
EntityManager.class);
I'm doing a little class to save and load information from a game, by the moment I have coded this:
import java.io.FileReader;
import java.io.FileWriter;
import org.exolab.castor.xml.MarshalException;
import org.exolab.castor.xml.Marshaller;
import org.exolab.castor.xml.Unmarshaller;
import org.exolab.castor.xml.ValidationException;
class InformationToStoreLoad{
public InformationToStoreLoad(){
}
}
public class GameSaverLoader {
/*
* Save the current game
*/
public void saveXML(){
FileWriter writer;
try {
writer = new FileWriter("save.xml");
Marshaller.marshal(new InformationToStoreLoad(), writer);
writer.close();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* Load a game saved before
*/
public void loadXML()
{
try {
FileReader reader = new FileReader("article.xml");
InformationToStoreLoad gameToLoad =
(InformationToStoreLoad) Unmarshaller.unmarshal(InformationToStoreLoad.class, reader);
} catch (IOException e1) {
e1.printStackTrace();
}
}
}
I have been working on .NET platforms and I'm a little bit noob with Java, so I'm not sure if I have done everything right. To export the Castor libraries I have right clicked on my project, I have selected Properties, then Java Build Path, then libraries, and finally I have clicked "Add external JAR" and I have exported this JAR: "castor-1.3.1-xml.jar"
However, I have the following error while using the marshaller and unmarshaller classes
Unhandled exception type ValidationException
If I select "Add catch clause to surrounding try" on quick fixes, then I get this errors instead:
No exception of type MarshalException can be thrown; an exception type must be a subclass of Throwable
The method printStackTrace() is undefined for the type MarshalException
No exception of type ValidationException can be thrown; an exception type must be a subclass of Throwable
The method printStackTrace() is undefined for the type ValidationException
Also in the quick fixes I have the option to make this:
public void saveXML() throws MarshalException, ValidationException{
then I get this error:
No exception of type MarshalException can be thrown; an exception type must be a subclass of Throwable
No exception of type ValidationException can be thrown; an exception type must be a subclass of Throwable
I don't know how to fix any of those errors, anyone can advise me how to solve this problems?
Best regards
So I'm new at Java, and I'm trying to work with the try, catch and finally features. As my limited understanding goes, a try-catch block allows me to handle exceptions instead of the compiler throwing an error that I can't return to execution from. Is this right? Also, my program doesn't seem to be working, as the compiler throws "Extracur is abstract, cannot be instantiated!" during compilation. How do I get it to display my error message (and execute my finally block) instead?
try {
extracur student1 = new extracur();
} catch (InstantiationException e) {
System.out.println("\n Did you just try to create an object for an interface? Tsk tsk.");
} finally {
ReportCard student = new ReportCard("Progress Report for the year 2012-13");
student.printReportCard();
}
PS- extracur is an interface.
Interfaces can never be directly instantiated.
extracur student1=new extracur(); // not possible
And you should capitalize interface names. You need instead:
Extracur student1 = new Extracur() {
// implement your methods
};
Explanation: The code does not instantiate the interface, but an anonymous inner class which implements the interface.
You should also understand that the compiler throws an error at compile time while you are trying to catch an error at runtime (too late in this case).
Interface cannot be instantiated.It will cause compile error.If you want a test .Try this:
try {
extracur student1 = new stud();
} catch (InstantiationException e) {
System.out
.println("\n Did you just try to create an object for an interface? Tsk tsk.");
} finally {
}
This is a class that impements interface extracur
class stud implements extracur{
public stud()throws InstantiationException{
throw new InstantiationException();
}
}
I have a JBOSS ESB that uses a standard out of the box EJBProcessor action. How do I get hold of an exception, if the exception be thrown in the method call that was run in the EJB?
Any advice would be helpful.
You can subclass EJBProcessor and override the process method like this:
#Override
public Message process(Message pMessage) {
try {
pMessage = super.process(pMessage);
} catch (Throwable wEx) {
handleProcessError(pMessage, wEx);
}
return pMessage;
}
You will more than likely catch an instance of ActionProcessingException, and you can look at the cause to see the exception in your EJB.
Your action configuration in your jboss-esb.xml will remain exactly the same, except you will substitute the name of your subclass for org.jboss.soa.esb.actions.EJBProcessor.