difference between connection.close() and connection= null

Question

If I explicitly close the connection by calling close() on connection object, i have set connection object to null. What is difference in close() and null on connection object? If i close connection ,still connection object maintained in connection pool? for e.g.

Connection dbConnection=null;
PreparedStatement preparedStatement = null;
ResultSet rs;
  try {
           Connection dbConnection= DriverManager.getConnection("jdbc:hsqldb:file:test5","sa", "");
           ...........
           ...........
           dbConnection.close();
           dbConnection=null;
           } catch (Exception e) {
        LOGGER.error("Exception Occured while fetching All record:Item details start method "
                + e.getMessage());
    } finally {

        try
        {
            if (rs!=null)
            {
                rs.close();
                rs=null;
            }

        }
        catch(SQLException e)
        {
            LOGGER.error(RESULTSETCLOSEEXCEPTION
                    + e.getMessage());
        }

        try {
            if (preparedStatement != null) {
                preparedStatement.close();
                preparedStatement=null;
            }
        } catch (SQLException e) {
            LOGGER.error(STATEMENTCLOSEEXCEPTION
                    + e.getMessage());
        }
        try {
            if (dbConnection != null) {
                dbConnection.close();
                dbConnection=null;
            }
        } catch (SQLException e) {
            LOGGER.error(CONNECTIONCLOSEEXCEPTION
                    + e.getMessage());
        }
    }

Is above code is correct way to close connection, prepared statement and resultset?

Answer 1

From the documentation.

close()
Releases this Connection object's database and JDBC resources immediately instead of
waiting for them to be automatically released.