Interview Question [Java]

InterviewQ2.java

/**
Desired Output
---------------

Country - India
        State - Gujarat
              City - Ahmedabad
              City - Vadodara
        State - MP
              City - Bhopal
              City - Indore
              City - Reva
              City - Ujjain

Country - UK
        State - Dartford
              City - Dartford
        State - Greater London
              City - Eltham
              City - London
        State - Hampshire
              City - Winchester
 
Country - USA
        State - Arizona
              City - Phoenix
        State - California
              City - Los Angeles
        State - Illinois
              City - Chicago
        State - New York
              City - New York
        State - Texas
              City - Houston
**/


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collections;
import java.util.TreeMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class InterviewQ2 {
	private TreeMap countryMap = new TreeMap();
	private TreeMap stateMap;
	private ArrayList cityList;

	/** * Fetch the data */
	public void fetchData() {
		try {
			Class.forName("com.mysql.jdbc.Driver");
			String url = "jdbc:mysql://localhost:3306/db_name";
			Connection con = DriverManager.getConnection(url, "username", "password");
			Statement stmt = con.createStatement();
			ResultSet rs = stmt.executeQuery("SELECT * from countrydata");
			while (rs.next()) {
				String country = rs.getString("country");
				String state = rs.getString("state");
				String city = rs.getString("city");
				if (countryMap.containsKey(country)) {
					stateMap = (TreeMap) countryMap.get(country);

					// Check whether the stateMap contains the state or not
					if (stateMap.containsKey(state)) {
						cityList = (ArrayList) stateMap.get(state);
						cityList.add(city);
						stateMap.put(state, cityList);

					} else {
						cityList = new ArrayList();
						cityList.add(city);
						stateMap.put(state, cityList);
					}
					countryMap.put(country, stateMap);
				} else {
					stateMap = new TreeMap();
					cityList = new ArrayList();
					cityList.add(city);
					stateMap.put(state, cityList);
					countryMap.put(country, stateMap);
				}
			}
		} catch (SQLException ex) {
			System.out.println(ex.getMessage());
		} catch (ClassNotFoundException ex) {
			System.out.println(ex.getMessage());
		}
	}

	/** * Print the data */
	void printData() {
		Iterator countryIterator = countryMap.keySet().iterator();
		while (countryIterator.hasNext()) {
			String country = (String) countryIterator.next();
			System.out.println("Country - " + country);
			TreeMap stateMapL = (TreeMap) countryMap.get(country);
			Iterator stateIterator = stateMapL.keySet().iterator();
			while (stateIterator.hasNext()) {
				String state = (String) stateIterator.next();
				System.out.println("\tState - " + state);
				List<String> stateList = (ArrayList) stateMapL.get(state);
				if (stateList != null) {
					Collections.sort(stateList);
					for (String city : stateList) {
						System.out.println("\t\tCity - " + city);
					}
				}
			}
		}
	}
}