overriding

        also called shadowing

 

  Overriding is defined as when a subclass method provides three things which are the same as in the overridden method:

(1) method name, and

(2) parameter list, and

(3) return type.  See signature.

 

  You cannot change the return type of an overridden method. 

 

■ You cannot make the overriding method be less accessible (meaning more private) than the overridden method.  See modifiers.

 

■ The order of this accessibility, from least restrictive to most restrictive, is: 

(least restrictive is) public, then

protected, then

friendly/package/default, and lastly

(most restrictive is)  private 

 

■ You cannot override a public or protected method using no modifiers (which would be assigning friendly/package, which is more restrictive). i.e.

 

  You cannot override a private method either, in any way. (It's private. You cannot override it because it cannot be seen outside its class.) Doing so compiles but becomes overloading in all cases.

 

  When overriding you cannot throw higher level exceptions or exceptions any from different hierarchies.   You can just throw none, the same, fewer, or subclasses of those exceptions already being thrown in the overridden method.

 

  You cannot ever override a non-static method with a static method, or a static method with a non-static method. 

 

  super.methodname( ) calls parent methods which you did not override. 

 

  If an overridden method is synchronized, you can safely ignore the synchronized.

 

  It is not overriding if, in subclasses, you simply re-use the names of higher private methods again.  That is allowed.