trigger copystreetaddress on Join_object__c(after insert)
{
list<contact> conlist=new list<contact>();    
    if(trigger.isUpdate)
    {
        Set<Id> accountId = new Set<Id>();
        Set<Id> contactId = new Set<Id>();
        for(Join_object__c tempJ : Trigger.new)
        {
            accountId.add(tempJ.Account__c);
            contactId.add(tempJ.Contact__c);
        }
       
        List<Account> AccountList = [Select id,Name,BillingStreet from Account where id in: accountId];
       
        List<Contact> ContactList = [Select id,Name,mailingStreet from Contact where id in: contactId];
       
        for(Join_object__c tempJ : Trigger.new)
        {
            for(Account tempAcc : AccountList)
            {
                if(tempJ.Account__c == tempAcc.Id)
                {
                    for(Contact tempCon : ContactList)
                    {
                        if(tempJ.Contact__c == tempCon.Id)
                        {
                            tempCon.mailingstreet = tempAcc.BillingStreet;
                            conlist.add(tempcon);
                        }                  
                   
                    }
               
                }
           
            }  
           
        }      
          
    }
     update ConList;  
}