Как подключиться к базе данных java

💻 ~ $ sudo -u postgres createdb mydb

💻 ~ $ psql mydb

mydb=# CREATE TABLE cars (
           name  varchar(255),
           color varchar(255),
           age	 integer );
CREATE TABLE

mydb=# INSERT INTO cars VALUES ('VW', 'white', 3);
INSERT 0 1

mydb=# INSERT INTO cars VALUES ('TOYOTA', 'black', 4);
INSERT 0 1

mydb=# SELECT * FROM cars;
  name  | color | age
--------+-------+-----
 VW     | white |   3
 TOYOTA | black |   4
(2 rows)

mydb=#\q

💻 ~ $

dependencies {
    implementation 'org.postgresql:postgresql:42.5.4'
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class App {
    public static void main(String[] args) {
        Connection connection = null;
        Statement statement = null;
        try {
            Class.forName("org.postgresql.Driver");
            connection = DriverManager
                    .getConnection("jdbc:postgresql://localhost:5432/mydb",
                            "postgres", "");
            statement = connection.createStatement();
            ResultSet result = statement.executeQuery( "SELECT * FROM CARS;" );

            while (result.next()) {
                String  name = result.getString("name");
                String  color = result.getString("color");
                int age  = result.getInt("age");

                System.out.print( "NAME = " + name );
                System.out.print( "   COLOR = " + color );
                System.out.println( "   AGE = " + age );
                // => NAME = VW   COLOR = white   AGE = 3
                // => NAME = TOYOTA   COLOR = black   AGE = 4
            }

            result.close();
            statement.close();
            connection.close();
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println(e.getClass().getName()+": "+e.getMessage());
        }
    }
}