Find duplicates in array list using Map<String, Integer> with input order

Question

Hi everyone I am trying to print all the duplicated elements, this works fine but the outputs are not in order (either from user input or from the text file). I want to print all elements with order (duplicates are not printed). How do I do that? The codes are from this Find the duplicate elements in arraylist and display Thanks @Cory Kendall for the codes.

**********updated question: the code now works perfect with LinkedHashMap. Now I want the outputs to be printed with number bullets (ie, 1. name1 = 2 ) incrementally. Thanks

List<String> strings = new ArrayList<String>();
// suppose datas are entered by user incrementally or from a text files.

Map<String, Integer> counts = new HashMap<String, Integer>();

for (String str : strings) {
    if (counts.containsKey(str)) {
        counts.put(str, counts.get(str) + 1);
    } else {
        counts.put(str, 1);
    }
}

for (Map.Entry<String, Integer> entry : counts.entrySet()) {
    System.out.println(entry.getKey() + " = " + entry.getValue());
}

Answer 1

If you want to remember insertion order in your Map, you need to use LinkedHashMap. In your case you have to replace

Map<String, Integer> counts = new HashMap<String, Integer>();

with

Map<String, Integer> counts = new LinkedHashMap<String, Integer>();