Forgive me if the solution is very obvious but I can't seem to figure out how to do this
public static void main(String[] args) {
Map<String, String> map = new HashMap<>();
map.put("b1", "a1");
map.put("b2", "a2");
map.put("b3", "a1");
Map<String, List<String>> mm = map.values().stream().collect(Collectors.groupingBy(m -> m));
System.out.println(mm);
}
I want to group by based on values in hashmap. I want the output to be {a1=[b1, b3], a2=[b2]}
but it is currently coming as {a1=[a1, a1], a2=[a2]}