Multiple instance of class versus array Java

Issue

My question which of the following examples represents the right practice ? What are the advantages and downsides of these approaches. Is there another(right) way to achieve this?

Let's say I have class

public class Person {

    private String name;

    public Person(String name) {
        this.name = name;
    }

    public String print() {
        return this.name;
    }
}

And use of class like:

public static void main(String[] args) {
        List<Person> people = new ArrayList<Person>();
        people.add(new Person("Jane Doe"));
        System.out.println(people.get(0).print());
}

And then another way to do this:

public class Persons {

    private ArrayList<String> persons;

    public Persons() {
        persons = new ArrayList<String>();
    }

    public void putPerson(String name) {
         persons.add(name);
    }

    public String print(int id) {
        return this.persons.get(id);
    }
}

And use of that:

public static void main(String[] args) {
        Persons persons = new Persons();
        persons.putPerson("John Doe");
        System.out.println(persons.print(0));
    }

EDIT:

Assume I have 10 000 of these persons. Is there any downside to creating 10,000 instances of the class?

Solution

I would prefer the first way because there is a rare need to create a wrapper class for keeping a collection (like Persons -> Person). It makes sense if the class Persons gets renamed to a Company/Community, which contains a List of workers/persons and provides specific operations over this list.

public String showAllMembers() { ... }
public void notifyAllMembers() { ... }

Also, the second way breaks the Single responsibility principle. It shouldn't take care about printing a person, the class is responsible for adding/removing them. The Persons can provide to you a specific Person, then you have to call a method print() on a given instance:

Persons persons = ...;
persons.getMember(10).print(); 

---

Lets say i have 10 000 of these persons. Is there any downside to create 10 000 instance of class?

In any case, you will have to create 10000+ instances. Consider,

• 10000 Persons + a List
• 10000 Persons + a Persons + a List

Answered By - Andrew Tobilko