The java.lang.reflect package is new in Java 1.1. It contains classes and interfaces that support the new Reflection API. Reflection refers to the ability of a class to reflect upon itself, or look inside of itself, to see what it can do. The new JavaBeans API depends upon the Reflection API, as does the object-serialization functionality in Java 1.1.
The Reflection API makes it possible to discover the variables, methods, and constructors of any class and manipulate those members as appropriate. For example, you can use a Method object to call a particular method in an object, even if your code was not compiled with any information about the class that contains that method. The java.lang.reflect package also defines an Array class that can be used to manipulate arbitrary arrays.
All of the classes in java.lang.reflect work in conjunction with the Class class in the java.lang package.
See Chapter 13, The java.lang.reflect Package, for complete reference material on all of the classes in the java.lang.reflect package.