07. Simple Text Editor

package StacksAndQueues_Exercise;

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

public class SimpleTextEditor_07 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int countCommands = Integer.parseInt(scanner.nextLine());
        StringBuilder currentText = new StringBuilder();

        ArrayDeque<String> textStack = new ArrayDeque<>();

        for (int count = 1; count <= countCommands; count++) {
            String command = scanner.nextLine(); //"{цифра} {параметър}"
            //"1 {string}".split(" ") -> ["1", "{string}"]
            //"2 {count}".split(" ") -> ["2", "{count}"]
            //"3 {index}".split(" ") -> ["3", "{index}"]
            //"4".split(" ") -> ["4"]
            int commandNumber = Integer.parseInt(command.split("\\s+")[0]);// 1, 2, 3, 4
            switch (commandNumber) {
                case 1:
                    textStack.push(currentText.toString());
                    String stringForAppend = command.split("\\s+")[1];
                    //трябва да добавя stringForAppend към сегашния текст
                    currentText.append(stringForAppend);
                    break;
                case 2:
                    textStack.push(currentText.toString());
                    int countElementsForDelete = Integer.parseInt(command.split("\\s+")[1]);
                    //изтриваме countElementsForDelete брой елементи
                    //"abcd"
                    int startIndexForDelete = currentText.length() - countElementsForDelete;
                    currentText.delete(startIndexForDelete, currentText.length());
                    break;
                case 3:
                    int index = Integer.parseInt(command.split("\\s+")[1]);
                    //печатаме елемента на дадения индекс
                    System.out.println(currentText.charAt(index - 1));
                    break;
                case 4:
                    if (!textStack.isEmpty()) {
                        currentText = new StringBuilder(textStack.pop());
                    }
                    break;
            }

        }
    }
}