Error MessageSystem.NullPointerException: Attempt to de-reference a null object
Stack TraceClass.sendmailexample.processSelected: line 26, column 1
Class.sendmailexample1test.runTest1: line 37, column 1
 

@isTest
public class sendmailexample1test{  
static testMethod void runTest1(){
  Account account = new Account();
       account.Name = 'Acc3';
       insert account;         

       Contact contact = new Contact();
       contact.FirstName = 'Todda';
       contact.LastName = 'Wilmss';
       contact.AccountID = account.Id;
       contact.Email = 'twilms@verisign.conm';
       contact.MobilePhone = '918527116723';
       insert contact; 
       
        ApexPages.StandardController sc2 = new ApexPages.StandardController(Contact);
        apexpages.currentpage().getparameters().put('ID',contact.id);
        String  conId = ApexPages.currentPage().getParameters().get('Id');
        String  EmailCon =[Select email from Contact where Id=:conId ].email;
        sendmailexample testDObj1 = new sendmailexample(sc2);
        testDObj1.AddRecep='twilms@verisign.conm';
        testDObj1.to ='twilms@verisign.conm';
        testDObj1.EmailCon ='twilms@verisign.conm'; 
        testDObj1.Email ='twilms@verisign.conm';
        testDObj1.body='abc';
         testDObj1.subject='abc'; 
         
            
test.StartTest();
PageReference pageRef = page.sendmail;
Test.setCurrentPage(pageRef);
ApexPages.StandardController sc = new ApexPages.standardController(Contact);
apexpages.currentpage().getparameters().put('Id',contact.id);
sendmailexample testDObj = new sendmailexample(sc);
testDObj.EmailCon ='twilms@verisign.conm'; 

testDObj.processSelected(); 
test.StopTest();
}
  
}

 

Public  class sendmailexample1{ 
    public String to{get; set;}
    public String AddRecep{get; set;}
    public String subject {get; set;}
    public String body {get; set;}
public List<wrapContact> wrapContactList {get; set;}
    public List<Contact> selectedContacts{get;set;}
    Public String selectId {get;set;}
    public sendmailexample1(){
        body = apexpages.currentpage().getparameters().get('att');
     
            if(wrapContactList == null) {
            wrapContactList= new List<wrapContact>();
            for(Contact a: [SELECT  Name,FirstName,LastName,Email,Title FROM Contact ORDER by Name ASC]) {
                wrapContactList.add(new wrapContact(a));
           }
        }
        
       
        body = '';         
      
    }         
    public void processSelected() {
        AddRecep = '';
        selectedContacts = new List<Contact>();
        for(wrapContact wrapContactObj : wrapContactList) {
            if(wrapContactObj.selected == true) {
                selectedContacts.add(wrapContactObj.acc);
                if (AddRecep == '') {
                    AddRecep = wrapContactObj.acc.Email;
                } else {
                    AddRecep += ';' + wrapContactObj.acc.Email ;
                }
            }
        }
    }
    public class wrapContact {
        public Contact acc {get; set;}
        public Boolean selected {get; set;}
        public wrapContact (Contact a) {
            acc = a;
            selected = false;
        }
    }   
}