gistfile1.java

Here goes my code 

//Bug fix : Thanks mohit, I missed the serious bug, this should be after insert trigger, as we need caseId here and which is only available once a required is inserted or committed

trigger LazyEmployee on Case(after insert) 
{
	//In a standard Salesforce Scenario Case Owner is actually ownerID which ID field
	// As per the requirement, I am assuming Owner as Text Field, basically  a custom field

	//Clearly Trigger needs to bulkified, I would have created bunch of Utilitiy Class to check for null values
	//To handle Map values and set value , I mean repeted check, very easy to use and maintain (Good engineering)

	//Make set of id to hold unique id, avoiding duplicates of case owners
	Set<id> ownerIds = new Set<Id>();
	
	//populate set with unique values, 
	for(Case c : Trigger.New)
		ownerIds.add(c.Id);
	
    //Make a map that hold cases matching Id in the set we just populated
    //This map will hold all data we need, we can query map and avoid querying salesforce
    Map<id, Case> userToIdMap = new Map<id, Case>([Select Id, Owner, Status From Case Where Id in : ownerIds])

    //Make a list of cases needs to updaed 
    List<Case> caseList = new List<Case>();

    
    //Now we have map, we can avoid SOQL from here and we are getting awesomer now 
    //Loop through each case coming in
    for(Case c : Trigger.New)
    {
    		//close only if status is not closed, get status from Map , yay we avoid SOQL here
    			//but check to see if Map is not empty
    		if(userToIdMap.isNotEmpty())
    		{

				//Close only if status is anything but closed
                                if(userToIdMap(c.Id).status != 'Closed')
		    			
                                     {
		    				c.Status='Closed';
		    				//Check if ownerID is David Liu Id since in sample this is text field so it's easy
		    				
                                                       // since requirement says close all cases and set owner as David regardless
							if(userToIdMap(c.Id).Owner !='David Liu')
							
                                                        //set the Owner (if custom textfield, remember Id is not writeable Field)
                                                        c.Owner='David Liu';
					  		//add only qualified values to list, this will keep list limited in size

					  		caseList.add(c);
		    			}

		    	//User Try-Catch log the update, in case if exception occurs
		    			try
		    			{
		    				//check if list is not empty or null
		    				if(caseList.isNotEmpty() || caseList.Size()!=0 || caseList!=null)
		    					update caseList;	
		    			}Catch(DMLException e)
		    			{	
		    				System.Debug('Error Updating Records in LazyEmployee Trigger '+e.getMessage());
		    			}
		    }			
	 }
    
}