  Single inheritance has been widely accepted in the current programming
practice to avoid the complication that incurred by multiple inheritance.
Single inheritance enhances the reusability of codes and eliminates the
confusion of identical methods that possibly defined in two superclasses.
However, the mechanism of inner class in Java potentially reintroduces the
problems encountered by multiple inheritance. When the depth of Java inner
class is increased, the problem becomes severe. This paper aims at exposing the
problems of inheritance at the Java inner class. In addition, a measure is
proposed to evaluate the potential problem of inheritance for Java inner class
