Find the duplicate elements in arraylist and display [closed]

Answer 1

use hashmap
like this:

Map occurrencies = new HashMap();
for (String word : list) {
    occurrencies.put(word, occurrencies.containsKey(word)
    ? occurrencies.get(word) + 1 : 1);
}
for (Entry entry : occurrencies.entrySet()) {
    System.out.println("Word: "+entry.getKey()
                     + ", occurences: "+entry.getValue());
}