Compare two HashMap in Java - list

Question

How to fetch the HashMap based on Max-key field
Eaxmple:-
List<Map<String, Integer>> data = new ArrayList<Map<String, Integer>>();
Map<String, Integer> map1 = new HashMap<>();
map1.put("A", 10);
map1.put("B", 15);
map1.put("C", 20);
Map<String, Integer> map2 = new HashMap<>();
map2.put("A", 20);
map2.put("B", 30);
map2.put("C", 50);
Map<String, Integer> map3 = new HashMap<>();
map3.put("A", 50);
map3.put("B", 60);
map3.put("C", 70);
data.add(map1);
data.add(map2);
data.add(map3);
Here I have 3 maps that I'm storing in the List.
Now I want to filter a map based on max A key value.
In the above map3 A value has the max integer value.
Expected out is:-
In the last only the map3 should present inside the List.
Is it possible to filter using java8?
Any suggestions would be helpful

Answer 1

I finally able to do this with help of comparator
Here is the code that will filter based filtering based on max date:-
Result is stored in the firstMap variable...
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class Main {
public static void main(String args[]) throws ParseException {
Map<String, String> s = test();
System.err.println(s.toString());
}
public static Map<String, String> test() throws ParseException {
List<Map<String, String>> data = new ArrayList<Map<String, String>>();
Map<String, String> map1 = new HashMap<>();
map1.put("A", "2021-03-08");
Map<String, String> map2 = new HashMap<>();
map2.put("A", "2021-03-23");
Map<String, String> map3 = new HashMap<>();
map3.put("A", "2021-03-21");
data.add(map1);
data.add(map2);
data.add(map3);
SimpleDateFormat si = new SimpleDateFormat("yyyy-MM-dd");
Date firstMax = si.parse(data.get(0).get("A"));
Map<String, String> firstMap = data.get(0);
for (Map<String, String> map : data) {
Date loopMax = si.parse(map.get("A"));
if (firstMax.compareTo(loopMax) < 0) {
firstMax = loopMax;
firstMap = map;
}
}
return firstMap;
}
}
Output:-
{A=2021-03-23}