can any one please help me in this code. I am having a error.

Trigger :
trigger Trg_CheckLeadEmail on Lead (before insert,before update) {  
if(trigger.isBefore  && trigger.isInsert || Trigger.isUpdate))
{
    Trg_ClassCheckLeadEmail.CheckEmail(Trigger.new,Trigger.oldMap);
  }
}


Class:
public class Trg_ClassCheckLeadEmail {

 public static void CheckEmail ( List<Lead> newLeadList, map<String, Contact> OldMapContacts){
    
    // List<Lead> newLeadList= new list<Lead>();
    map<String,Contact>  ContMapSet = new map<String, Contact>();
    list<Contact> conlst = [SELECT Id, Email FROM Contact];
    
    for (Contact cont:conlst) {
        ContMapSet.put(cont.Email, cont);
    } 
    for(lead led : newLeadList) 
    {
        if((led.Email != null) && (trigger.isInsert || (led.Email != OldMapContacts.get(led.id).Email))) 
        {
            if(ContMapSet.containsKey(led.Email))
            {
                led.Email.addError('Email Already Exists !!!');
            }
        }               
       }
    }
}


Error: Compile Error: Method does not exist or incorrect signature: void CheckEmail(List<Lead>, Map<Id,Lead>) from the type Trg_ClassCheckLeadEmail at line 7 column 29

Hi All,
I'm new to salesforce and started working on Trailhead's. I facing issue with the Trigger Challenge. Here is the triger code im writing 

trigger AccountAddressTrigger on Account (before insert) {
    for(Account a : Trigger.new){
        if(a.Match_Billing_Address__c && a.BillingPostalCode != null){
            a.ShippingPostalCode = a.BillingPostalCode;
        }
    }
    
}

but i'm getting the following error. Not sure where i'm doing wrong. can someone please help me here. Thanks in advance.

System.DmlException: Insert failed. First exception on row 0; first error: CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY, TestTrigger: execution of AfterInsert caused by: System.NullPointerException: Attempt to de-reference a null object Trigger.TestTrigger: line 3, column 1: []

Hi,
I am not able to understand the below question correctly Please help me out. - 
Create a class that has a method accepting two strings. The method searches for contacts that have a last name matching the first string and a mailing postal code (API name: MailingPostalCode) matching the second. It gets the ID and Name of those contacts and returns them.The Apex class must be called 'ContactSearch' and be in the public scope.
The Apex class must have a public static method called 'searchForContacts'.
The 'searchForContacts' method must accept two incoming strings as parameters, find any contact that has a last name matching the first, and mailing postal code matching the second string. The method should return a list of Contact records with at least the ID and Name fields.
The return type for 'searchForContacts' must be 'List<Contact>'.

Hello developer heroes!

I'm working through the Apex modules on Trailhead and can't seem to get past this one: https://developer.salesforce.com/en/trailhead/force_com_programmatic_beginner/apex_triggers/apex_triggers_bulk.

Hopefully this doesn't read like a 'please complete the course for me' kinda post, but I have written a trigger that I believe meets the criteria but it isn't passing the check, so I wanted to seek the guidance of the experts.

The challenge is to do this:

Create an Apex trigger for Opportunity that adds a task to any opportunity set to 'Closed Won'.

To complete this challenge, you need to add a trigger for Opportunity. The trigger will add a task to any opportunity inserted or updated with the stage of 'Closed Won'. The task's subject must be 'Follow Up Test Task'.The Apex trigger must be called 'ClosedOpportunityTrigger'

- With 'ClosedOpportunityTrigger' active, if an opportunity is inserted or updated with a stage of 'Closed Won', it will have a task created with the subject 'Follow Up Test Task'.
- To associate the task with the opportunity, fill the 'WhatId' field with the opportunity ID.
- This challenge specifically tests 200 records in one operation.

And here is the trigger I have come up with, which compiles OK and stands up to a manual (though admittedly unbulkified) test:

trigger ClosedOpportunityTrigger on Opportunity (after insert, after update) {

    List<Task> taskList = new List<Task>();
    
    for (Opportunity opp : [SELECT Id, StageName FROM Opportunity WHERE StageName = 'Closed Won' AND Id IN :Trigger.new]){
                    
            taskList.add(new Task(Subject = 'Follow Up Test Task',
                                  WhatId = opp.Id));
       
    }

    if(taskList.size()>0){
        
        insert taskList;
        
    }
    
}

I have tried replacing the SOQL with a straightforward 'for (Opportunity opp : Trigger.new)' and having the taskList.add inside an IF that checks for Closed Won - no luck. I also thought about checking to see if the stage was being changed to Closed Won, rather than the trigger firing on every edit, but I don't think this is what the module is asking for.

Where do you think I'm going wrong?

Huge thanks in advance!