Callable Interface in Salesforce Apex

With Winter '19 release new Callable Interface has been introduced, which helps in calling methods dynamically between Apex classes or triggers, even for code that works in separate packages.

Class has to implement "Callable" interface along with a method "call(String action, Map args)" which has a return type of Object.

Below is the sample Apex code using callable interface using.

CallableApexTest.apx:

/*
* Purpose: To test new Callable Interface
* Date: OCT302018
*/

public class CallableTest2 implements Callable {
    // Method to return month of the year
    Integer method1(Date d) {
        Integer month = d.month();
        return month;
    }
    
    // Method to return boolean if passed integer is same as current month
    Boolean method2(Integer mnth) {
        if (method1(System.today()) == mnth) {
            return true;
        } else {
            return false;
        }
    }
    
    // To call specific methods dynamically 
    public Object call(String action, Map<String, Object> args) {
        Switch on action {
            when 'Method1' {
                return this.method1((Date)args.get('Date'));
            }
            when 'Method2' {
                return this.method2((Integer)args.get('Integer'));
            }
            when else {
                throw new ExtensionMalformedCallException('Method not implemented');
            }
        }
    }
    
    // To throw exceptions
    public class ExtensionMalformedCallException extends Exception {}
}

Code walkthrough:

Above class has two methods (Method1 with Integer return type and, Method2 with Boolean return type) and they accept Date and Integer as input parameters

We have out of the box method "Call" that accepts String, Map as input parameters. Also we are using Switch statement to check for input action type to call specific method and return values

Testing for success response: Lets go ahead and test above Class code using Developer Console.When we use below piece of code, I should be able to view my results successfully.

// List to store method names
List<String> lstString = new List<String> {'Method1', 'Method2'};
// Map to store specific method input parameter    
Map<String, Object> args = new Map<String, Object> {'Date'=>(Object)System.today(), 'Integer'=>(Object)10};    
  
// Instantiate CallableTest class    
CallableTest cTest = new CallableTest();

for (String iter: lstString) {
    // invoking call method
	Object obj = cTest.call(iter, args);
	System.debug('************Result: ' + obj);        
}

Testing for exception response: When we use below piece of code, I should be able to view exception message.

// List to store method names
List<String> lstString = new List<String> {'Method5'};
// Map to store specific method input parameter    
Map<String, Object> args = new Map<String, Object> {'Date'=>(Object)System.today(), 'Integer'=>(Object)10};    
  
// Instantiate CallableTest class    
CallableTest cTest = new CallableTest();

for (String iter: lstString) {
    // invoking call method
	Object obj = cTest.call(iter, args);
	System.debug('************Result: ' + obj);        
}

Resource Reference Links:

Apex Developer Guide: Callable Interface

Thank you!