The Java virtual machine, for reasons of binary compatibility, already
allows a method to be overridden by a method of the same signature
but with a return type which is a subtype of the method it overrides.

For greater type safety, the Java language should remove the restriction
that overriding methods must have the same return type as the methods
they override.

I will submit a more detailed proposal, including changes to the JLS, in
the future.

Note that this is a 100% compatible change.
(Review ID: 42168)
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Posted Date : 2006-07-13 02:52:11.0

N/A

Good idea. Dealt with as part of the GJ proposal.

  xxxxx@xxxxx   1998-12-01
Duplicate of 4144488 which was added to Tiger (jdk5.0) under JSR-14: 
 
  http://jcp.org/en/jsr/detail?id=14 
 
A complete description of this language feature may be found in the Java Language Specification, Third Edition.  A reasonable place for a reader to being might be section 8.1.2 "Generic Classes and Type Parameters". 
 
  http://java.sun.com/docs/books/jls/third_edition/html/j3TOC.html 
  http://java.sun.com/docs/books/jls/third_edition/html/classes.html#8.1.2
Posted Date : 2006-07-13 02:52:11.0

Also see #4144488

To  be  logical, one should  also  allow  to  the argument 
types  of 
the new  method  to  be  supertypes  of the overridden one. 

It might be logical to allow contravariance of argument
types, that is, to allow argument types of overridding
methods to be supertypes of overridden methods. However,
adding such a capability would break existing Java programs.
Currently, methods with differing argument types are
overloaded methods, and such a change would cause many
overloaded methods to become overridding methods, changing
the behavior of old Java programs.

Adding covariance of return type, on the other hand,
will not change the behavior of any existing Java programs.
To vote for this feature, see bug 4144488.

This is a duplicate of 4144488.

i do think so as well