Classe Database con metodi per la connessione, la sconnessione, l'inserimento di uno stato e la lettura dell'elenco di stati da un database con schema per la gestione dei dati degli stati.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Database {
    private String schema;
    private String username;
    private String password;
    private String host;
    private int port;
    
    private Connection conn = null;

    public Database() {
    }

    public Database(String schema, 
            String username, String password, 
            String host, int port) {
        this.schema = schema;
        this.username = username;
        this.password = password;
        this.host = host;
        this.port = port;
    }
    
    public void Connetti() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
             "jdbc:mysql://172.18.11.100:3306/test_personalita",
                    "prova3", "");   
        } catch (Exception ex) {
            Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
        }

        //conn.close();        
    }
    
    public void ConnettiEx() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(
                  "jdbc:mysql://"+host+":"+port+"/"+schema,username,password);            
        } catch (Exception ex) {
            Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
        }

        //conn.close();        
    }    
    
    public void Sconnetti() {
        if (conn != null) try {
            conn.close();
        } catch (SQLException ex) {
            Logger.getLogger(Database.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    
    public ArrayList<Stato> getElencoStati() {
        ArrayList<Stato> ret = new ArrayList<Stato>();
        if (conn != null) {
            try {
               String sql = "select * from country order by name";

               PreparedStatement psd = conn.prepareStatement(sql);

               ResultSet rsd = psd.executeQuery();

               if (rsd != null) {
                 while(rsd.next()) {
                     String name = rsd.getString("name");
                     String code = rsd.getString("code");
                     String region = rsd.getString("region");
                     int population = rsd.getInt("population");
//                     System.out.println("name: "+name+
//                             ", code: "+code+", region: "+region+
//                             ", population: "+ population);
                     Stato st = new Stato(name, code, region, population);
                     ret.add(st);
                 }
               }
            }
            catch(Exception ex) {
                System.out.println("errore query stati " + ex.getMessage());
            }
        }
        
        return ret;
    }
    
    public int addStato(Stato stato) {
       int ret = -1;

       if (conn != null) {
            try {
//               String sql = "insert into country (name) "+
//                            "values ('"+stato.getNome()+"')";
               String sql = "insert into country (name) "+
                            "values (?)";
               
               PreparedStatement psd = conn.prepareStatement(sql);
               psd.setString(1, stato.getNome());
               ret = psd.executeUpdate();
            }
            catch(Exception ex) {
                System.out.println("errore query stati " + ex.getMessage());
            }
        }
        
        
        return ret;
    }
}