How do I convert a trigger to an Apex class - triggers

Question

I need to transfer the below trigger logic to an apex class. But in apex class I cant use Trigger.New as it will give error. Once I give the logic in apex call, I can call the method in trigger so, Can anybody please tell me that how can I convert this trigger to an apex class?
trigger updatecontactrolecount on Opportunity(before insert, before update) {
Boolean isPrimary;
Integer iCount;
Map < String, Opportunity > oppty_con = new Map < String, Opportunity > (); //check if the contact role is needed and add it to the oppty_con map
for (Integer i = 0; i < Trigger.new.size(); i++) {
oppty_con.put(Trigger.new[i].id,
Trigger.new[i]);
}
isPrimary = False;
for (List < OpportunityContactRole > oppcntctrle: [select OpportunityId from OpportunityContactRole where(OpportunityContactRole.IsPrimary = True and OpportunityContactRole.OpportunityId in : oppty_con.keySet())]) {
if (oppcntctrle.Size() > 0) {
isPrimary = True;
}
}
iCount = 0;
for (List < OpportunityContactRole > oppcntctrle2: [select OpportunityId from OpportunityContactRole where(OpportunityContactRole.OpportunityId in : oppty_con.keySet())]) //Query for Contact Roles
{
if (oppcntctrle2.Size() > 0) {
iCount = oppcntctrle2.Size();
}
}
for (Opportunity Oppty: system.trigger.new) //Check if roles exist in the map or contact role isn't required
{
Oppty.Number_of_Contacts_Roles_Assigned__c = iCount;
Oppty.Primary_Contact_Assigned__c = isPrimary;
}
}

Answer 1

You can use a TriggerHandler Class to manage your all your triggerred events in the same place:
https://developer.salesforce.com/page/Trigger_Frameworks_and_Apex_Trigger_Best_Practices
In your trigger call your unique class :
trigger OpportunityTrigger on Opportunity (before insert,after insert,before update,after update, before delete,after delete) {
try {
new OpportunityTriggerHandler().run();
}
catch(Exception e) {
System.debug(e);
}
Then do all the logic in the TriggerHandler :
public with sharing class OpportunityTriggerHandler extends TriggerHandler {
private Map<Id, Opportunity> newOpportunityMap;
private Map<Id, Opportunity> oldOpportunityMap;
private List<Opportunity> newOpportunity;
private List<Opportunity> oldOpportunity;
public OpportunityTriggerHandler() {
this.newOpportunityMap = (Map<Id, Opportunity>) Trigger.newMap;
this.oldOpportunityMap = (Map<Id, Opportunity>) Trigger.oldMap;
this.newOpportunity = (List<Opportunity>) Trigger.new;
this.oldOpportunity = (List<Opportunity>) Trigger.old;
}
public override void beforeInsert() {
for (Opportunity o : this.newOpportunity) {
if (o.Name == '...') {
//do your stuff
}
}
}
public override void afterInsert() {
//...
}
}