How to properly clean up JDBC resources in Java?

Question

What is considered best practices when cleaning up JDBC resources and why? I kept the example short, thus just the cleaning up of the ResultSet.

finally
{
          


        

Answer 1

This is my approach for JDK 6. If you have JDK 7+ you better use the approach I describe here https://stackoverflow.com/a/9200053/259237

private void querySomething() {
    Connection connection = null;
    PreparedStatement statement = null;
    ResultSet rs = null;
    try {
        // get connection
        // prepare statement
        // execute query
        // and so on
    } catch (SQLException e) {
        throw new MyException("Error while talking to database", e);
    } finally {
        close(connection, statement, rs);
    }
}

// useful because you probably have more than one method interacting with database
public static void close (Connection connection, Statement statement, ResultSet rs) {
    if (rs != null) {
        try { rs.close(); } catch (Exception e) { _logger.warning(e.toString()); }
    }
    if (statement != null) {
        try { statement.close(); } catch (Exception e) { _logger.warning(e.toString()); }
    }
    if (connection != null) {
        try { connection.close(); } catch (Exception e) { _logger.warning(e.toString()); }
    }
}

• It's short.
• It defines a close method that can be statically imported.
• It avoids empty catch blocks.
• It handles any SQLException that may occur (even in getConnection or close methods).
• It's null-safe.