Generic Maximum with a Type Bound

/*
 * Problem : Run the commands.
 * Input   : Command lines.
 * Output  : The biggest item.
 * Approach: One generic method
 * Time    : O(n)
 * Space   : O(n)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
        // Step 1: One method for every type. "T extends Comparable<T>" says: T has a compareTo method, so two items can be compared.
        static <T extends Comparable<T>> T maxOf(java.util.List<T> items) {
            T best = items.get(0);
            for (T item : items) {
                if (item.compareTo(best) > 0) {
                    best = item;
                }
            }
            return best;
        }

    // This method solves the task. It receives the input and returns the answer.
    static String[] solve(String[] lines) {
        String[] values = lines[1].split(" ");
        // Step 2: The same method works for a list of Integer and for a list of String.
        if (lines[0].equals("int")) {
            java.util.List<Integer> numbers = new java.util.ArrayList<Integer>();
            for (String value : values) {
                numbers.add(Integer.parseInt(value));
            }
            return new String[] {String.valueOf(maxOf(numbers))};
        }
        return new String[] {maxOf(java.util.Arrays.asList(values))};
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        java.util.List<String> all = new java.util.ArrayList<>();
        while (scanner.hasNextLine()) {
            String line = scanner.nextLine().trim();
            if (!line.isEmpty()) {
                all.add(line);
            }
        }
        String[] lines = all.toArray(new String[0]);
        System.out.println(String.join("\n", solve(lines)));
    }
}