I went through all the manuals out there and all SO questions but still unable to figure this out... 

I have a List (integer represents age):

```
List<Person> people = Arrays.asList
    (
            new Person("bob", 10),
            new Person("sue", 4),
            new Person("tom", 37),
            new Person("jim", 10),
            new Person("boo", 4),
            new Person("ekk", 53),
            new Person("joe", 10)
    );

```

I need to:

* group the list by age,
* sort by group sizes (descending),
* sort by age (descending)

So using the example above the result would have to be like this: 

```
{10=[bob, jim, joe],4=[sue, boo], 53=[ekk], 37=[tom]}

```

**What I tried:** 

I tried with and without streams. I failed on both. 

**Note:** I would lean toward **no stream solution**, because from my testing of the below code it seems like streams are much slower (I used System.nanotime()). These 3 operations will be done thousands of times each time, so it may make a slight difference.

**Using streams here is what I did:**

```
List<List<Person>> grpd = new ArrayList<>
    (
            people.stream()
                    .collect
                            (
                                    groupingBy(Person::getAge, toList())
                            )
                    .values()
    );
grpd = grpd.stream().sorted((a, b) -> Integer.compare(b.size(), a.size())).collect(toList());

```

**No streams approach:**

```
    Map<Integer, List<Person>> grouped = new HashMap<>();
    for (Person person : people)
    {
        if (grouped.containsKey(person._age))
        {
            grouped.get(person._age).add(person);
        } else
        {
            List<Person> p = new ArrayList<>();
            p.add(person);
            grouped.put(person._age, p);
        }
    }

    List<Map.Entry<Integer, List<Person>>> entries = new ArrayList<>(grouped.entrySet());
    Collections.sort(entries, new Comparator<Map.Entry<Integer, List<Person>>>()
    {
        @Override
        public int compare(Map.Entry<Integer, List<Person>> o1, Map.Entry<Integer, List<Person>> o2)
        {
            return Integer.compare(o2.getValue().size(), o1.getValue().size());
        }
    });
    Map<Integer, List<Person>> sortedBySize = new LinkedHashMap<>();
    for (Map.Entry<Integer, List<Person>> entry : entries)
    {
        sortedBySize.put(entry.getKey(), entry.getValue());
    }

```

**Problem:**
I have no idea how to add the final sort on either case.

```
public class Person
{
    public String _name;
    public int _age;
    public int getAge() { return _age; }

    public Person(String name, int age)
    {
        _name = name;
        _age = age;
    }

    @Override
    public String toString()
    {
        return _name;
    }
}

```