This is because B is not in the classpath of the system class loader or its parent or ancestor class loaders.
这是因为B不在系统类装入器或者它的双亲或祖先类装入器的类路径中。
The following code will stub the system class Date to always return the same date, say Ground Hog Day, as in Listing 6.
下面的代码对系统类Date 进行stub 以便总是返回相同的日期，比如GroundHog Day，如清单 6 所示。
Here, we use reflection because we have loaded the application using a class loader that is not the system class loader.
这里，我们使用反射的原因是因为我们已经使用非系统类加载器加载了应用程序。
Instead, it has a set of class loaders that are unrelated except that they have the same parent (usually the system class loader).
相反，它有一组类装入器，彼此互不相关，但是有共同的双亲(通常是系统类装入器)。
Also, you will not be able load multiple versions of these JAR files as the classes will all be in the system class loaders namespace.
同样，不能加载这些JAR文件的多个版本，因为类都位于系统类加载器名称空间中。
A system class is a window class registered by the system.
系统窗口类由系统注册。
The research of P2P overlay network is the important gist to confirm the system class as well as the basic part of P2P research.
P2P覆盖网络的研究是确定系统类型的重要依据，是P2P技术研究中基础的部分。
If these classes are available in the classpath, the parent of the URLClassLoader instance, which is the system class loader, will load them.
如果这些类在类路径中可用，URLClassLoader实例的父加载器(即系统类加载器)将加载它们。
The problem with this approach is that the LogManager instance uses the system class loader to instantiate classes from the configuration file.
这种方法的问题是LogManager实例使用了系统类的装载程序从配置文件中对类进行实例化。
Class a is on the classpath of the system class loader, and a's superclass, B, is on the classpath of a user-defined class loader, which is a child of the system class loader.
类a在系统类装入器的类路径中，而A的超类b，在用户自定义的类装入器的类路径中，这个类装入器是系统类装入器的孩子。
To avoid this problem, any classes that are to be serialized should be loaded by a class loader that does not need to be garbage collected — by the system class loader, for example.
为了避免这个问题，凡是要进行序列化的类，都应当由不需要被垃圾收集的类装入器装入——例如由系统类装入器装入。
The system class loader (also known as the application class loader) is the class loader responsible for loading code from the path specified by the CLASSPATH environment variable.
系统(system)类装入器(也称作应用程序类装入器)负责从CLASSPATH环境变量指定的路径装入代码。
This confusion could be resolved in Figure 2 by moving the interface class I into the System class loader's space.
图2中通过将接口类I移至System 类装入器的空间就可以解除这种混淆。
It can be learned from the past by analyzing the testing system, class arrangement and art arguments of the painting academy of Song Dynasty.
分析宋代画院考试制度、课程设置、艺术主张等方面的内容可以借古开今。
These can be references to the file system, class path, source code control system, or Web URLs.
它们可以是对文件系统、类路径、源代码管理系统或WebURL的引用。
These can be references to the file system, class path, source code control system, or Web URLs.
它们可以是对文件系统、类路径、源代码管理系统或WebURL的引用。
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