public static void main(String [] args){

HashMap<String, Integer> map = new HashMap<>();

map.put("D", 4);

map.put("B", 2);

map.put("C", 3);

map.put("A", 1);

// sort the hashmap based on keys

Map<String, Integer> sortedMap = map.entrySet()

.stream()

.sorted(Map.Entry.comparingByKey())

.collect(Collectors.toMap(Map.Entry::getKey,

Map.Entry::getValue,(oldValue, newValue)-> oldValue, LinkedHashMap::new));

for(Map.Entry<String, Integer> entry : sortedMap.entrySet()){

System.out.println("Key: " + entry.getKey() + ", Value: " + entry.getValue());

}

}