The Final Quest [Mimi]

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
import java.util.stream.Collectors;

public class _03_TheFinalQuest {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        List<String> words = Arrays.stream(scanner.nextLine()
                .split(" "))
                .collect(Collectors.toList());

        String input = "";
        while (!"Stop".equals(input = scanner.nextLine())) {

            String[] line = input.split(" ");
            String command = line[0];

            switch (command) {
                case "Delete":
                    int index = Integer.parseInt(line[1]);
                    if (index < words.size() - 1) {
                        words.remove(index + 1);
                    }
                    break;
                case "Swap":
                    String word1 = line[1];
                    String word2 = line[2];

                    if (words.contains(word1) && words.contains(word2)) {
                        int firstInd = words.indexOf(word1);
                        int secondInd = words.indexOf(word2);

                        words.set(firstInd, word2);
                        words.set(secondInd, word1);
                    }
                    break;
                case "Put":
                    String word = line[1];
                    int putInd = Integer.parseInt(line[2]);
                    if ((putInd - 1) >= 0 && (putInd - 1) <= words.size()) {
                        words.add(putInd - 1, word);
                    }
                    break;
                case "Sort":
                    Collections.sort(words);
                    Collections.reverse(words);
                    break;
                case "Replace":
                    String firstW = line[1];
                    String secW = line[2];
                    if (words.contains(secW)) {
                        int ind = words.indexOf(secW);
                        words.set(ind, firstW);
                    }
                    break;
            }

        }

        String output = words.toString().replaceAll("[\\[,\\]]", "");
        System.out.println(output.trim());
    }
}