I'm trying to do the following:
abstract class G { protected var = 0; } class G1 extends G { var = 1; } class G2 extends G { var = 2; } // This is where I'm having a problem public G method() { switch(someVar) { case x: return new G1(); case y: return new G2(); } } Java is complaining that method must return a type of G. How should I go about returning G1 OR G2 (which both extend G)? It very well may be that I'm approaching this entirely wrong...
Thank you.
Your problem is not related to inheritance; you must throw an exception or return something of type G in the case where your switch does not fall into case x or case y.
For example:
public G method() { switch(someVar) { case x: return new G1(); case y: return new G2(); default: // You can return null or a default instance of type G here as well. throw new UnsupportedOperationException("cases other than x or y are not supported."); } } 
Add default option in your switch-case block:
default: .... Its complaining because if someVar is not x or y then it doesn't have any return statement.
Alternatively, you can add a default return statement in the end e.g.
public G method() { switch(someVar) { case x: return new G1(); case y: return new G2(); } return defaultValue; // return default } 
someVar is only x or y?known types.