To build a custom connector, you must first implement the Identity Connector (ICF-based connector) by implementing the ICF SPI. After this, you need to create OIM artifacts to integrate the Identity Connector to Oracle Identity Manager, which can reuse ICProvisioningManager (part of ICF integration) in their Adapter Tasks to invoke provisioning operations on Identity Connector, and also can reuse Reconciliation Tasks that are implemented in ICF integration. Therefore, by using ICF integration, you need not write any integration code in java, ICF integration uses ICF APIs to access the Identity Connectors.
For information about Java APIs related to ICF integration, see Oracle Fusion Middleware Java API Reference for Identity Connector Framework.
For information about Java APIs related to Oracle Identity Manager, see Oracle Fusion Middleware Java API Reference for Oracle Identity Manager.