ArrayList as key in HashMap

Question

Would it be possible to add an ArrayList as the key of HashMap. I would like to keep the frequency count of bigrams. The bigram is the key and the

Answer 1

Try this ,this will work.

 public Map getBigramMap (String word1,String word2){
    Map hm = new HashMap();
    List arrList1 = new ArrayList();
    arrList1 = getBigram(word1, word2);     
    if(hm.get(arrList1) !=null){
        hm.put(arrList1, hm.get(arrList1)+1);
    }
    else {
        hm.put(arrList1, 1);
    }

    System.out.println(hm.get(arrList1));
    return hm;
}