This classloader is recommended to be used as a parent classloader when it is required to limit access to classes which are not directly loaded by the parent classloader.

An example:
The interface P is loaded from the classloader PCL.
A subinterface of P, S is loaded from the classloader SCL.
We'd like to create an implementation of S in a different classloader, that doesn't have direct access to P. In this case we create a parent exclusive classloader XCL which receives SCL as its parent during construction.
We place our implementation class I which implements S in the XCL classloader. In this case, we achieved that S is visible from XCL, and S can be successfully implemented by I, but P cannot be directly implemented in XCL, as it is not visible from it. In other words, we cannot define a class, that implements P in the classloader XCL.

The ClassLoader.getParent() function of this class will always return null.

When a class loading request is issued to this classloader, the parent will be asked to load the class. If successfull, the classloader will be queried of the loaded class, and the class will only be returned if the identity of the classloader is the same as the parent specified for this instance. This means that classes that are not available through this classloader may still be loaded, and be considered not found by this instance.

This class has limited use-case, and probably not relevant to most users. For informational purposes, one use-case for this classloader is when a class with a given name is present in a hierarchical classpath in multiple levels, and one doesn't want the classes from the upper levels to leak into the lower levels. This can happen when testing frameworks want to test their own implementation, but at the same time have the framework on the classpath for the test runners.