Design issue: which is better?

Question

In the situation like below
public class Foo{
    public Foo(){
         Foo1 f1 = new Foo1();
         //other code to start the thread
//Foo1 class
public class Foo1(){
     public synchronized void setData(String s){
           //codes that adds the data to a LinkedList
     public synchronized String getData(){
         //codes
//main class
public class MainClass{
    public MainClass(){
         Foo f = new Foo();
    public static void main(String[] args){
         //code to check the size of list before setting the message
          //code to set message here.
}In the above code, i want to check the size of the message list in the Foo1 at the main class before setting the message.
The condition is that i dont want to set the message when a certain value is reached, and start setting the message when the size of message
drops down to certain value.
My problem is: Which option is better: to use the Observer pattern or
to have a method that returns the size of the message?
any suggestions?
thank you for your comments.

Answer 1

My message code list is like
public class Foo1{
    private LinkedList mList = new LinkedList();
    public synchronized void setMessage(String s){
              mList.addLast(s);
    public synchronized String getMessage(){
             return (String)mList.removeFirst();
    }That is what i have in my Foo1 class.
I want to check the size of the list at the main class before adding the
message.
I hope i am clear.