Hello

1.  When I have an Class FooBar  implementing the interfaces Foo and Bar

if some other class  has the two methods
    1.  void doSomething(Foo foo) {}
    2.  void doSomething(Bar bar) {}

Which method will be called when I give an instance of FooBar as
parameter? Where is the best place to search for answers on such
questions maybe Language-Specifications?

2. If I write a program that is made for opening some filetype, and I
wan't only one instance of my program to be open  i.e. open some tab in
running instance myself when the user doubleclicks on a file ...

Is there some easy solution to do this in java or do I need to create
for example a tcp connection to my running instance and tell it the file
parameter that way?

Thanks for any Help
C.O.