So, here's the thing, what you have is not a generic method. What you have is a generic class.

Now, it's a clearly defined generic class, but, it is not what the question asked for. (as a generic class it has a number of issues too, but let's get the method/class issue resolved first).

##Generic methods

A generic method is just that, a method, except the parameters (or return value) are of a generic type. A generic method always has a <...> structure before the return-type declaration. A normal method is:

public RType methodName(P1Type p1, P2Type p2, ....) {...} 

(where RType is the return type, and P1Type is parameter1 type, etc.).

A generic method has the <...> before the return type, and that construct is used somewhere in the method signature... for example:

public <T> RType methodName(T t, SomeType sparm) {....} 

The above is a generic method that has the generic type T as a parameter.

##Your Class

So, having stated that your solution is a generic class, not a generic method, let's assume the exercise goal was to produce a generic class. What then?

1. Unless you have exceptional reasons, don't extend ArrayList, "compose" it instead. Have a class that does not extend ArrayList, and have a class field instead, like:

    class MaximalElementList<E extends Comparable<E>> { List<E> data = ...... 

2. Your generics here are OK, no problem with <E extends Comparable<E>>

3. Your code should use a guard-condition instead of an else... let me explain. Your code has an if/else:

   public E getMaxInRange(int begin, int end) { E max; if (isEmpty()) throw new IllegalStateException("Can't get a max element from an empty list."); else { max = this.get(begin); for (E elem : this.subList(begin, end)) { if (elem.compareTo(max) > 0) { max = elem; } } } return max; } 

   That should instead be:

    public E getMaxInRange(int begin, int end) { if (isEmpty()) { throw new IllegalStateException("Can't get a max element from an empty list."); } E max; max = this.get(begin); for (E elem : this.subList(begin, end)) { if (elem.compareTo(max) > 0) { max = elem; } } return max; } 

4. Note now, that the max is a messy variable, it can just be:

    E max = this.get(begin); for (E elem : this.subList(begin, end)) { if (elem.compareTo(max) > 0) { max = elem; } } return max; 

5. Your use of a sublist is smart, but I would consider it to be overkill in this case. How about a simpler implementation:

    E max = this.get(begin); for (int i = begin + 1; i < end; i++) { if (get(i).compareTo(max) > 0) { max = get(i); } } return max; 

That is now some logic which I think would work well.

##Making it a method

Putting that logic in a generic method would "simply" mean:

public <E extends Comparable<E>> E max(List<E> data, int begin, int end) { E max = data.get(begin); for (int i = begin + 1; i < end; i++) { if (data(i).compareTo(max) > 0) { max = data.get(i); } } return max; } 

With that method, for example, you could do:

List<String> data = Files.readAllLines(Paths.get("some file.txt")); String maxLine = max(data, 0, 10);