Java: Getting the subclass from a superclass list -

i'm new java , have 2 questions following code:

class animal { } class dog extends animal { } class cat extends animal { } class rat extends animal { }  class main {   list<animal> animals = new arraylist<animal>();    public void main(string[] args) {     animals.add(new dog());     animals.add(new rat());     animals.add(new dog());     animals.add(new cat());     animals.add(new rat());     animals.add(new cat());      list<animal> cats = getcertainanimals( /*some parameter specifying want cat instances*/ );   } } 

1) there way either dog or cat instances aminal list? 2) if yes, how should correctly build getcertainanimals method?

animal = animals.get(i);     if  (a instanceof cat) {     cat c = (cat) a; }  else if (a instanceof dog) {     dog d = (dog) a; }  

nb: compile if not use instanceof, allow cast a cat or dog, if a rat. despite compiling, classcastexception on runtime. so, make sure use instanceof.