08. Simple Text Editor

import java.util.ArrayDeque;
import java.util.Scanner;

public class stack1_Exercises_8Simple_Text_Editor {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = Integer.parseInt(scanner.nextLine());

        ArrayDeque<String> operation = new ArrayDeque<>();
        String text = "";
        for (int i = 0; i < n; i++) {
            String[] tokens = scanner.nextLine().split(" ");
            int command = Integer.parseInt(tokens[0]);

            switch (command) {
                case 1:
                    operation.push(text);
                    text = text + tokens[1];

                    break;
                case 2:
                    operation.push(text);

                    int del = Integer.parseInt(tokens[1]);
                    for (int j = 0; j < del; j++) {
                        text = text.substring(0, text.length() - 1);
                    }

                    break;
                case 3:

                    int count = Integer.parseInt(tokens[1]) - 1;

                    try {
                        System.out.println(text.charAt(count));
                    } catch (Exception e) {
                        e.getMessage();
                    }

                    break;
                case 4:

                    text = operation.pop();

                    break;
            }
        }


    }
}