How to make a call to interface method from the class which implements this interface

public interface IA {
void m1();
}
public abstract class A implements IA {
void m2() {/*how to make a call to m1 here*/ }
}
public class AClass extends A {
void m1();
}

For example what is wrong in execute method so that I can't call methods identified in interface.

public class TriggerManager {
    public interface ITriggerHandler {//TriggerManager.ITriggerHandler
        void onBeforeInsert(List<sObject> newRecords);
    
        void onBeforeUpdate(List<SObject> oldRecords, List<SObject> newRecords, Map<ID, SObject> oldRecordsMap, Map<ID, SObject> newRecordsMap);
        
        void onBeforeDelete(List<sObject> oldRecords, Map<ID, sObject> oldRecordsMap);
        
        void onAfterInsert(List<sObject> newRecords, Map<ID, sObject> newRecordsMap);
        
        void onAfterUpdate(List<sObject> oldRecords, List<sObject> newRecords, Map<ID, sObject> oldRecordsMap, Map<ID, sObject> newRecordsMap);
        
        void onAfterDelete(List<sObject> oldRecords, Map<ID, sObject> oldRecordsMap);
    }             
    
    public abstract class TriggerHandler implements ITriggerHandler {
        private void execute(Boolean isBefore, Boolean isAfter, Boolean isInsert, Boolean isUpdate, Boolean isDelete, 
            List<SObject> oldRecords, List<SObject> newRecords, Map<ID, SObject> oldRecordsMap, Map<ID, SObject> newRecordsMap) {
            /*
            if(isBefore) {
                if (isInsert) onBeforeInsert(newRecords);
                else if (isUpdate) onBeforeUpdate(oldRecords, newRecords, oldRecordsMap, newRecordsMap);
                else if (isDelete) onBeforeDelete(oldRecords, oldRecordsMap);
            }
            else {
                if (isInsert) onAfterInsert(newRecords, newRecordsMap);
                else if (isUpdate) onAfterUpdate(oldRecords, newRecords, oldRecordsMap, newRecordsMap);
                else if (isDelete) onAfterDelete(oldRecords, oldRecordsMap);
            } 
            */                               
        }
    }
    
    public static void handle(TriggerHandler handler) {
        handler.execute(
                Trigger.isBefore, 
                Trigger.isAfter, 
                Trigger.isInsert, 
                Trigger.isUpdate, 
                Trigger.isDelete,
                Trigger.old, 
                Trigger.new, 
                Trigger.oldMap,
                Trigger.newMap);
    }
}

What other items did I miss in this architecture?