TreeMap复制键并且不放置值

f is a LinkedList with different words of a text in it.I am trying to analyze the list and put everything in a TreeMap (m) with the words as key and the amount of it appearing as the value. My code is working somehow but not 100%. It is for example producing an output (m) e.g "Er"=6 , Er Here the second "Er" doesn't have a value assigned and it doesn't get added to the first "Er" key somehow.f is a LinkedList with different words of a tex