Creating a HashMap with ArrayLists

I'm making a Project manager program (a very simple one). Basically there are CoWorkers and their tasks. Now, I made the following structure: I'm using the HashMap keys as the name of the CoWorkers and the value is always the CoWorkers ArryList which contains his or her jobs of course.

My issue is I can create this structure but when I try to add a task one of the ArrayLists I always getting null as a return value.

Here are my code snippets:

HashMap<String, ArrayList<String>> jobs = new HashMap<String, ArrayList<String>>();

public void createJobs(){
    nameReader();
    for(String name:names){
        File f = new File(name+"_job.txt");
        if(f.exists()){
            jobs.put(name, jobReader(name));
        }
    }
    Set set = jobs.entrySet(); 
    Iterator i = set.iterator(); 
    while(i.hasNext()) { 
        Map.Entry me = (Map.Entry)i.next(); 
        System.out.print(me.getKey() + ": "); 
        System.out.println(me.getValue()); 
    } 
}

After this method on the console i see the following result:

George: [do the laundry]

So i assume that i did everything all right.

But then:

public void addJob(String name, String job){
    try{
        List<String> itemsList = jobs.get(name);
    itemsList.add(job);
    }catch(Exception ex){
         System.err.println(ex.getMessage() + jobs.get(name) +name);
    }
}

and I'm calling this method:

addjob("George","Clean up your room!");

the result on the console will be:

nullnullGeorge

UPDATE

public ArrayList jobReader(String name){
    ArrayList<String> tasks = new ArrayList<String>();
    try{
        Scanner s = new Scanner(new File(name+"_job.txt"));
        while (s.hasNext()){
            tasks.add(s.next());
        }
        s.close();
    }catch(IOException ioe){
        System.err.println("IOException: " + ioe.getMessage());
    }
    return tasks;
}

UPDATE 2

This is my hole code:

public class CoWorkers {
    HashMap<String, ArrayList<String>> jobs = new HashMap<String, ArrayList<String>>();
    ArrayList<String> names = new ArrayList<String>();

    public void createJobs(){
        nameReader();
        for(String name:names){
            File f = new File(name+"_job.txt");
            if(f.exists()){
                jobs.put(name, jobReader(name));
            }
        }
        Set set = jobs.entrySet(); 
        Iterator i = set.iterator(); 
        while(i.hasNext()) { 
            Map.Entry me = (Map.Entry)i.next(); 
            System.out.print(me.getKey() + ": "); 
            System.out.println(me.getValue()); 
        } 
    }

    public void addName(String name){
        try{
            String filename= "Names.txt";
            FileWriter fw = new FileWriter(filename,true); 
            fw.write(name+"\n");
            fw.close();
        }
        catch(IOException ioe){
            System.err.println("IOException: " + ioe.getMessage());
        }
    }

    public void addJob(String name, String job){
        DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        Date date = new Date();
        try{
            List<String> itemsList = jobs.get(name);
            itemsList.add(job);
        }catch(Exception ex){
             ex.printStackTrace();
        }
    }

    public ArrayList jobReader(String name){
        ArrayList<String> tasks = new ArrayList<String>();
        try{
            Scanner s = new Scanner(new File(name+"_job.txt"));
            while (s.hasNext()){
                tasks.add(s.next());
            }
            s.close();
        }catch(IOException ioe){
            System.err.println("IOException: " + ioe.getMessage());
        }
        return tasks;
    }

    public void nameReader(){
        names.clear();
        try{
            Scanner s = new Scanner(new File("Names.txt"));
            while (s.hasNext()){
                names.add(s.next());
            }
            s.close();
        }catch(IOException ioe){
            System.err.println("IOException: " + ioe.getMessage());
        }
    }
    public static void main(String[] args) {
        CoWorkers project = new CoWorkers();
        project.createJobs();
        project.addJob("George","Do the laundry");
    }
}