如何将一个字符串一次添加到HashMap >？

This function loops through a dictionary (allWords) and uses the getKey function to generate a key. wordListMap is a HashMap> so I need to loop through and put the key and and a List. If there is not a list I put one if there is I just need to append the next dictionary word. This is where I need help. I just can't figure out the syntax to simply append the next word to the list that is already there. Any Help would be appreciated. This function loops through a dictionary (allWo