DataBase.java

package ris_i_bd;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DataBase {
    private static final String CONNECTION_STRING = "jdbc:postgresql:ris_i_bd";
    private static final String USER_NAME = "postgres";
    private static final String PASSWORD = "837hfi37all";

    private static Connection connection;

    private DataBase() {
        throw new UnsupportedOperationException();
    }

    static {
        try {
            Class.forName("org.postgresql.Driver");
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }
    }

    public static Connection getConnection() {
        if(connection == null) {
            try {
                connection =  DriverManager.getConnection(CONNECTION_STRING, USER_NAME, PASSWORD);
                return connection;
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        } else {
            return connection;
        }
    }
}