Sorting an ArrayList by two different properties - arraylist

Question

So I have a HashMap<String, Integer> which represents the number of times a certain word has been encountered in a sentence. What I want to do is put all the words in an ArrayList<String>, sorted first by the number of times a word has been encountered, and then break ties by alphabetical order. How would I go about doing that? My code looks something like this:
public class MyClass {
private HashMap<String, Integer> map;
public ArrayList<String> Order() {
ArrayList<String> temp = new ArrayList<>();
(...)
}

Answer 1

You'll need to use a custom comparator. For the comparison method, you'll need to return a negative value if the first argument should be treated as less than the second, 0 if they are equal, and a positive value if the first argument should be treated as greater than the second.
Note that this sorts the ArrayList in descending order according to the integer value
import java.util.Comparator;
import java.util.HashMap;
public class CustomComparator implements Comparator<String>
{
HashMap<String, Integer> map;
public CustomComparator(HashMap<String, Integer> comparisonMap)
{
map = comparisonMap;
}
#Override
public int compare(String s1, String s2)
{
int count1 = map.get(s1);
int count2 = map.get(s2);
if (count1 == count2)
return s1.compareTo(s2);
return count2 - count1;
}
}
Two steps to create and sort the ArrayList:
First, add every key from the HashMap to the ArrayList
ArrayList<String> result = new ArrayList<String>(map.size());
result.addAll(map.keySet());
Then, sort the ArrayList using the custom comparator:
Collections.sort(result, new CustomComparator(map));