public static Connection getConnection() throws ConfigurationException {
    try {
      if (conn == null) {
        createConnection();
      }
      return conn;
    } catch (SQLException e) {
        System.out.println();
      throw new ConfigurationException(e);
    }
  }

  private static void createConnection() throws ConfigurationException, SQLException {
    try {
      String url = ConfigHelper.getJdbcUrl();
      String user = ConfigHelper.getJdbcUser();
      String password = ConfigHelper.getJdbcPassword();
      String schema = ConfigHelper.getJdbcSchema();
      String driverName = ConfigHelper.getJdbcDriver();
      Driver driver = (Driver) Class.forName(driverName).newInstance();

      DriverManager.registerDriver(driver);
      conn = DriverManager.getConnection(url, user, password);
      conn.setSchema(schema);
    } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) {
      throw new ConfigurationException(e);
    }
  }

java.sql.SQLException: ORA-01017: invalid username/password; logon denied

at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:445)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:389)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:382)
at oracle.jdbc.driver.T4CTTIfun.processError(T4CTTIfun.java:600)
at oracle.jdbc.driver.T4CTTIoauthenticate.processError(T4CTTIoauthenticate.java:445)
at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:450)
at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:192)
at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:380)
at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:760)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:401)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:546)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:236)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at de.axa.schadenreserveOnline.server.db.DBHelper.createConnection(DBHelper.java:51)
at de.axa.schadenreserveOnline.server.db.DBHelper.getConnection(DBHelper.java:32)
... 73 more