OpenDJ SDK Developer's Guide
Chapter 4. Using the LDAP SDK

For synchronous operations your application gets a connection from the LDAPConnectionFactory and requests operations on the connection. When finished, your application closes the connection.

final LDAPConnectionFactory factory = new LDAPConnectionFactory(host, port);
Connection connection = null;

try {
    connection = factory.getConnection();

    // Perform operations on the connection, such as connection.bind(),
    // connection.search(), connection.modify(), etc.

    } catch (final ErrorResultException e) {
        System.err.println(e.getMessage());
        System.exit(e.getResult().getResultCode().intValue());
        return;
    } finally {
        if (connection != null) {
            connection.close();
        }
    }

For a complete example in context, see Search.java, one of the OpenDJ LDAP SDK examples.

For asynchronous operations, your application passes a result handler to LDAPConnectionFactory.getConnectionAsync() that implements the ResultHandler<Connection> interface.

private static final class ConnectResultHandlerImpl
        implements ResultHandler<Connection> {
    @Override
    public void handleErrorResult(final ErrorResultException error) {
        ...
    }

    @Override
    public void handleResult(final Connection connection) {
        // Connect succeeded: save connection and initiate bind.
        SearchAsync.connection = connection;

        final BindRequest request =
                Requests.newSimpleBindRequest(userName, password.toCharArray());
        connection.bindAsync(request, null, new BindResultHandlerImpl());
    }
}

// Main method initiates async operations by getting a connection...
final LDAPConnectionFactory factory = new LDAPConnectionFactory(hostName, port);
factory.getConnectionAsync(new ConnectResultHandlerImpl());

...

if (connection != null) {
    connection.close();
}

When the connection result handler gets a connection, your application can pass result handlers for other operations using methods on the connection named *Async(). For most operations, your application implements ResultHandler. For searches, your application implements SearchResultHandler. The result handler is notified upon completion of the operation.

Asynchronous methods are non-blocking, returning a FutureResult whose get() method lets you retrieve the result. Your application must coordinate concurrency when you use asynchronous operations.

For a complete example in context, see SearchAsync.java, one of the OpenDJ LDAP SDK examples.