当我运行Java应用程序时,我得到了一个NoClassDefFoundError。造成这种情况的典型原因是什么?


当前回答

当我将另一个模块的Maven依赖添加到我的项目中时,我得到了这个错误,这个问题最终通过添加-Xss2m到我的程序的JVM选项来解决(自JDK5.0以来默认是1m字节)。人们认为程序没有足够的堆栈来加载类。

其他回答

如果有人因为java.lang.NoClassDefFoundError: org/apache/log4j/Logger错误来到这里,在我的例子中,它是因为我使用了log4j 2(但我没有添加它附带的所有文件),而一些依赖库使用了log4j 1。解决方案是添加Log4j 1。X桥:log4j-1.2-api-<version>.jar,随log4j 2而来。更多信息在log4j 2迁移中。

更新[https://www.infoq.com/articles/single-file-execution-java11/]:

在Java SE 11中,可以选择启动单个源代码文件 直接,不需要中间编译。为了方便大家, 所以像你这样的新手不需要运行javac + Java(当然, 让他们感到困惑)。

虽然这可能是由于编译时和运行时之间的类路径不匹配造成的,但这并不一定是真的。

在这种情况下,记住两到三个不同的异常是很重要的:

java.lang.ClassNotFoundException This exception indicates that the class was not found on the classpath. This indicates that we were trying to load the class definition, and the class did not exist on the classpath. java.lang.NoClassDefFoundError This exception indicates that the JVM looked in its internal class definition data structure for the definition of a class and did not find it. This is different than saying that it could not be loaded from the classpath. Usually this indicates that we previously attempted to load a class from the classpath, but it failed for some reason - now we're trying to use the class again (and thus need to load it, since it failed last time), but we're not even going to try to load it, because we failed loading it earlier (and reasonably suspect that we would fail again). The earlier failure could be a ClassNotFoundException or an ExceptionInInitializerError (indicating a failure in the static initialization block) or any number of other problems. The point is, a NoClassDefFoundError is not necessarily a classpath problem.

当我将另一个模块的Maven依赖添加到我的项目中时,我得到了这个错误,这个问题最终通过添加-Xss2m到我的程序的JVM选项来解决(自JDK5.0以来默认是1m字节)。人们认为程序没有足够的堆栈来加载类。

我通过禁用所有模块的preDexLibraries来解决我的问题:

dexOptions {
        preDexLibraries false
        ...