我将一个Java库打包为JAR,当我试图从它调用方法时,它抛出许多Java .lang. incompatibleclasschangeerror。这些错误似乎是随机出现的。什么样的问题会导致这个错误?
当前回答
在我的例子中:
我有一个项目包含几个模块,包括应用程序,测试,integrationTest 我在app模块中创建了OneElementCache。 然后,我在测试模块中创建了一个文件Cache,该文件包含了一些用于在测试中创建OneElementCache的帮助。 到目前为止,一切都很完美(测试和集成测试都通过了)。 之后,我在app模块中创建了一个文件缓存。 在运行integrationTest时得到:
Caused by: java.lang.IncompatibleClassChangeError:
class app.cache.CacheImpl can not implement app.cache.Cache, because it is not an interface (app.cache.Cache is in unnamed module of loader 'app')
原因是不同模块(app/test)的命名冲突。在测试中更改文件名就可以了。
其他回答
I have also discovered that, when using JNI, invoking a Java method from C++, if you pass parameters to the invoked Java method in the wrong order, you will get this error when you attempt to use the parameters inside the called method (because they won't be the right type). I was initially taken aback that JNI does not do this checking for you as part of the class signature checking when you invoke the method, but I assume they don't do this kind of checking because you may be passing polymorphic parameters and they have to assume you know what you are doing.
示例c++ JNI代码:
void invokeFooDoSomething() {
jobject javaFred = FredFactory::getFred(); // Get a Fred jobject
jobject javaFoo = FooFactory::getFoo(); // Get a Foo jobject
jobject javaBar = FooFactory::getBar(); // Get a Bar jobject
jmethodID methodID = getDoSomethingMethodId() // Get the JNI Method ID
jniEnv->CallVoidMethod(javaFoo,
methodID,
javaFred, // Woops! I switched the Fred and Bar parameters!
javaBar);
// << Insert error handling code here to discover the JNI Exception >>
// ... This is where the IncompatibleClassChangeError will show up.
}
Java代码示例:
class Bar { ... }
class Fred {
public int size() { ... }
}
class Foo {
public void doSomething(Fred aFred, Bar anotherObject) {
if (name.size() > 0) { // Will throw a cryptic java.lang.IncompatibleClassChangeError
// Do some stuff...
}
}
}
I have a web application that deploys perfectly fine on my local machine's tomcat(8.0.20). However, when I put it into the qa environment (tomcat - 8.0.20), it kept on giving me the IncompatibleClassChangeError and it was complaining that I was extending on an interface. This interface was changed to an abstract class. And I compiled the parent and child classes and still I kept on getting the same issue. Finally, I wanted to debug, so, I changed the version on the parent to x.0.1-SNAPSHOT and then compiled everything and now it is working. If someone is still hitting the problem after following the answers given here, please make sure the versions in your pom.xml are also correct. Change the versions to see if that works. If so, then fix the version problem.
另一种可能出现此错误的情况是Emma Code Coverage。
这发生在将Object分配给接口时。我猜这与对象被检测和不再二进制兼容有关。
http://sourceforge.net/tracker/?func=detail&aid=3178921&group_id=177969&atid=883351
幸运的是,这个问题在Cobertura中没有发生,所以我在pom.xml的报告插件中添加了Cobertura -maven-plugin
由于某种原因,当使用JNI并在调用Call*Method()时传递jclass参数而不是jobject时,也会抛出相同的异常。
这与《食人魔诗篇》第33篇中的回答相似。
void example(JNIEnv *env, jobject inJavaList) {
jclass class_List = env->FindClass("java/util/List");
jmethodID method_size = env->GetMethodID(class_List, "size", "()I");
long size = env->CallIntMethod(class_List, method_size); // should be passing 'inJavaList' instead of 'class_List'
std::cout << "LIST SIZE " << size << std::endl;
}
我知道在被问到这个问题5年后再回答这个问题有点晚了,但这是搜索java.lang.IncompatibleClassChangeError时最热门的问题之一,所以我想记录这个特殊情况。
在浪费了太多时间后记录下另一个场景。
确保您的依赖jar中没有包含带有EJB注释的类。
我们有一个普通的jar文件,它有一个@local注释。这个类后来从这个公共项目移到我们的主ejb jar项目中。ejb jar和公共jar都捆绑在ear中。我们的公共jar依赖项的版本没有更新。因此,两个类试图成为具有不兼容的更改的东西。
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