if i have two classes x and y, both extend class w. and x implementing interface z. if i have methods doSomething(w object) and doSomething(x object), what would happen if i call doSomething(x)?

edit: im implementing this on java, more specifically on android. im asking this because some classes which implement a specific interface mostly does the same thing when doSomething() is called. but there are special cases which i would like to single out.