Filtering an Arraylist Object Based on the Most Common Object Attribute Value in Java

Question

I am trying to filter the ArrayList of a Java object based on the value of an object variable.

Sorry if this sounds confusing. Perhaps the code will explain this better.

public static void main(String[] args)
{
    ArrayList<Data> list = new ArrayList<>();

    list.add(new Data("Uvumvew", 10));
    list.add(new Data("Uvumvew", 10));
    list.add(new Data("Uvumvew", 10));
    list.add(new Data("Uvumvew", 11));
    list.add(new Data("Uvumvew", 14));
    list.add(new Data("Uvumvew", 14));
    list.add(new Data("Ossas", 5));
    list.add(new Data("Ossas", 5));
    list.add(new Data("Ossas", 10));
    list.add(new Data("Ossas", 10));
    list.add(new Data("Ossas", 10));
    list.add(new Data("Dummy", 7));
    list.add(new Data("Dummy", 7));
    list.add(new Data("Dummy", 7));
    list.add(new Data("Dummy", 8));
    list.add(new Data("Dummy", 8));
}

and object

private String name;
private double value;

public Data() {
}

public Data(String name, double value) {
    super();
    this.name = name;
    this.value = value;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public double getValue() {
    return value;
}

public void setValue(double value) {
    this.value = value;
}

There will be duplicates in the archarist, as you can see. I can only filter it after it was an arraylist, since I read the files and then put them in an ArrayList.

The result that I am trying to achieve is as follows

Uvumvew,10
Ossas,10
Dummy,7

Since 10,10,7 are the most common value for Uvumvew, Ossas and Dummy respectively. I tried using Collection and filtering the value, but since the object has duplicate values, this is not possible.

My attempt looks like this:

Collection<Data> nonDuplicatedName = list.stream()
               .<Map<String, Data>> collect(HashMap::new,(m,e)->m.put(e.getName(), e), Map::putAll)
               .values();

it produces a result that is incorrect

Dummy 8.0
Uvumvew 14.0
Ossas 10.0

. !

Answer 1

, :

Map<String, Map<Double,Long>> tmpMap = list.stream()
        .collect(
                groupingBy(Data::getName,
                        groupingBy(Data::getValue,counting())
                ));
// {Dummy={8.0=2, 7.0=3}, Ossas={10.0=3, 5.0=2}, Uvumvew={10.0=3, 11.0=1, 14.0=2}}

Data#value . Data#name , , Data#value , value. Map, keys - Data#names values Data#values Uvumvew={10.0=3, 11.0=1, 14.0=2} , , Data - tmpMap Map#key Data#name {10.0=3, 11.0=1, 14.0=2} Data#value

tmpMap.entrySet()
        .stream()
        .map(
                entry -> new Data(
                        entry.getKey(),
                        entry.getValue().entrySet().stream()
                                .max(Map.Entry.comparingByValue()).get().getKey()
                )
        ).collect(toList()); 
//[Data{name='Dummy', value=7.0}, Data{name='Ossas', value=10.0}, Data{name='Uvumvew', value=10.0}]

, .