Function Pointers in Java

The Java idiom for function-pointer-like functionality is an an anonymous class implementing an interface, e.g.

Collections.sort(list, new Comparator<MyClass>(){
    public int compare(MyClass a, MyClass b)
    {
        // compare objects
    }
});

Update: the above is necessary in Java versions prior to Java 8. Now we have much nicer alternatives, namely lambdas:

list.sort((a, b) -> a.isGreaterThan(b));

and method references:

list.sort(MyClass::isGreaterThan);