Classify variables according to their values

Question

I have 5 variables with the following values.

int john = 0;
int caleb = 0;
int justin = 0;
int loic = 0;
int lala = 0;




DatabaseReference productRef = FirebaseDatabase.getInstance().getReference().child("Product");
    productRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for (DataSnapshot ds: dataSnapshot.getChildren()){
                String getName = ds.child("name").getValue(String.class);

                if (getName.equals("john")){
                    john++;
                }else if (getName.equals("caleb")){
                    caleb++;
                }else if (getName.equals("justin")){
                    justin++;
                }else if (getName.equals("loic")){
                    loic++;
                }else if (getName.equals("lala")){
                    lala++;
                }
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

after getting data from database, i have:

int john = 3;
int caleb = 15;
int justin = 30;
int loic = 20;
int lala = 0;

what I want is to classify them to have the first, the second, the third ..... according to their values, to have something like that.

justin = 30;
loic = 20;
caleb = 15;
john = 3;
lala = 0;

I'm using java, Android studio. thank you in advance.

Are you sure you only have those 5 names? Or do you want a ranking of all names? — charles-allen, Oct 13 '19 at 00:58
@AjahnCharles for the moment there is that these 5 name but how would I do if I want to ranking of all names — deslok, Oct 14 '19 at 10:17

Villat · Accepted Answer · 2019-10-15T03:47:05.950

2

So, instead of having your 5 variables, initialize a map this way:

Map<String, Integer> map = new HashMap<>();
map.put("john", 0);
map.put("caleb", 0);
map.put("justin", 0);
map.put("loic", 0);
map.put("lala", 0);

And then, your method should be:

@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
    Integer currentCount = 0;
    for (DataSnapshot ds: dataSnapshot.getChildren()){
        String getName = ds.child("name").getValue(String.class);
        currentCount = map.get(getName);
        map.put(getName, currentCount+1);
    }
    //You can print your values using this
    List<Map.Entry<String, Integer>> entryList = new ArrayList<>(map.entrySet());
    entryList.sort(Map.Entry.comparingByValue(Comparator.reverseOrder()));

    for (Map.Entry<String, Integer> entry : entryList) {
        System.out.printf("%s = %s; \n", entry.getKey(), entry.getValue());
    }
}

edited Oct 15 '19 at 03:47

answered Oct 11 '19 at 23:30

Villat

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I'd swap key and value – Marcin Orlowski Oct 11 '19 at 23:38
Thanks.... but how to put the variables into Hashmap programmably – deslok Oct 12 '19 at 00:13
@MarcinOrlowski I've edited my answer. – Villat Oct 12 '19 at 00:17
@user12010856 I need more information about your method in order to help you, please add to your post how are you using that method and where do the values come from. – Villat Oct 12 '19 at 00:17
I created and initialized these variables manually – deslok Oct 12 '19 at 00:56
1

@user12010856 if you create the variables manually then you don't need to do anything programmatically – Villat Oct 12 '19 at 01:35
FYI, I *think* `stream()` is only available on Android API 21+ (OP mentioned using Android Studio as IDE). You could use a `TreeMap`. – charles-allen Oct 12 '19 at 03:02
1

Apparently it's API 24+ (https://stackoverflow.com/questions/39515035/is-it-possible-to-use-the-java-8-stream-api-on-android-api-24) – charles-allen Oct 12 '19 at 03:06
@AjahnCharles great, my answer was based on assumptions because the question is not clear enough – Villat Oct 12 '19 at 03:18
@user12010856 try now – Villat Oct 12 '19 at 22:47
Im getting : call requires API 24(current min is 16) javq.util.Collection#stream – deslok Oct 14 '19 at 10:11
@Villat Im getting : call requires API 24(current min is 16) javq.util.Collection#stream – deslok Oct 14 '19 at 10:19
@user12010856 I've updated my answer, please try again and let me know – Villat Oct 15 '19 at 03:47

Classify variables according to their values

1 Answers1