What is obscuring?

A variable obscures a type with the same name if both are in scope. Say, your instance and local variables have the same name.

public class Base {
  int a = 5;
  public  void f() { 
    int a = 7; //obscuring instance variable a  
    System.out.println(a);  
  }   
}  

Test Code obscuring

public class PolymorphismTest {  
  public static void main(String[] args) {  
   Base b = new DerivedOne();  
   b.f(); //prints 7 -- local varible obscures instance variable  
 }
}  

So, overriding and overloading are good, but avoid method hiding (i.e., having static methods with the same name in parent/child classes), variable shadowing (i.e., having similar variable names in parent/child classes), and variable obscuring (i.e., having the same variable name for instance, static, and local variables).