O5SoftUniParking

package O7AssocietiveArrays.Exercise;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedHashMap;

public class O5SoftUniParking {
    public static void main(String[] args) throws IOException {
        BufferedReader reader =
            new BufferedReader(
                new InputStreamReader(
                    System.in
                )
            );

        int n = Integer.parseInt(reader.readLine());

        String input;
        LinkedHashMap<String, String> register = new LinkedHashMap<>();

        for (int i = 0; i < n; i++) {
            input = reader.readLine();

            String[] token = input.split("\\s+");
            String command = token[0].toLowerCase();
            String userName = token[1];

            switch (command) {
                case "register" :
                    String licenseNumber = token[2];

                    if (!register.containsKey(userName)) {
                        register.put(userName, licenseNumber);
                        System.out.println(
                                String
                                        .format
                                                ("%s registered %s successfully",
                                                        userName,
                                                        licenseNumber));
                    } else {
                        System.out.println(
                                String
                                        .format
                                                ("ERROR: already registered " +
                                                        "with plate number %s",
                                                        licenseNumber));
                    }
                    break;

                case "unregister" :

                    if (!register.containsKey(userName)) {
                        System.out.println(
                                String
                                        .format(
                                                "ERROR: user %s not found",
                                                userName
                                        ));
                    } else {
                        System.out.println(
                                String
                                        .format(
                                                "%s unregistered successfully",
                                                userName
                                        ));
                        register
                                .remove(userName);
                    }
                    break;
                default:
                    break;
                    }


            }

        register
                .entrySet()
                .stream()
                .forEach(e->
                        System.out.println(
                                String
                                        .format(
                                                "%s => %s",
                                                e.getKey(),
                                                e.getValue()
                                        )));
    }
}