In how many ways we can invoke the Salesforce Apex Class?

Ways to invoke apex class are

• Call from Trigger
• Call from another Apex class
• Schedule a batch class
•  Invoke from the Console
• External WEB service call
• Javascript using custom button

Hi,

Apex invoking refers to the process of executing the Apex class. Apex class can only be executed when it is invoked via one of the ways listed below −

Triggers and Anonymous block
A trigger invoked for specified events
Asynchronous Apex
Scheduling an Apex class to run at specified intervals, or running a batch job
Web Services class
Apex Email Service class
Apex Web Services, which allow exposing your methods via SOAP and REST Web services
Visualforce Controllers
Apex Email Service to process inbound email
Invoking Apex Using JavaScript
The Ajax toolkit to invoke Web service methods implemented in Apex

Hope this helps!