Creating a class that stores all objects created in an ArrayList?

Question

So I created three class called "Address", "Job" and "Person" with "Person" being my primary class. I test these by:

Address person2Address = new Address(1054, "Pico St", "Los Angeles", "CA", "97556");
    Address person2JobAddress = new Address(5435, "James St", "New York", "NY", "56565");
    ArrayList<String> person2Phone = new ArrayList<String>();
    person2Phone.add("555-555-55");
    Job person2Job = new Job("Mechanic", 35000.00, person2JobAddress);
    Person person2 = new Person("Rollan Tico", "New York", 'M', person2Address, person2Job, person2Phone);
    System.out.println(person2.toString());

They print everything correctly. Now, this is where I am stuck. How would I create a different class called Persons that stores each Person created in a ArrayList? Would there be any constrcunert? I know that an Arrayist is created by ArrayList<Person> List = new ArrayList<Person>();, but got a feeling I am missing something.

You don't need a separate class. Assuming you're looking for an immutable list, you can use List<Person> persons = Arrays.asList(person1, person2, ...); — Jacob G.
– Jacob G., Commented Jan 27, 2017 at 3:04
@JacobG. Arrays.asList() is not immutable, just fixed-size. — shmosel
– shmosel, Commented Jan 27, 2017 at 3:20

harivis · Accepted Answer · 2017-01-27 05:07:15Z

1

You can have Collection like

Collection<Person> persons = new ArrayList<Person>(); persons.add(person2);

Or in some case, like JSON serialization you cannot seralize a list as the root element. so,

import java.util.*

public class Persons {

  private Collection<Person> persons;

  //If you want the clients to have flexibility to choose the implementation of persons collection.
  //Else, hide this constructor and create the persons collection in this class only.
  public Persons(Collection<Person> persons) {
    this.persons = persons;
  }

  public void addPerson(Person person) {
   persons.add(person);
  }
}

answered Jan 27, 2017 at 5:07

harivis

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3 Comments

minigeek Over a year ago

Can't i pass arraylist directly :/ ? Can u elaborate please why did u use collection if one can do it with Arraylist as well @harivis

harivis Over a year ago

Yes, you can.

List<Person> personList = new ArrayList<Person>();  personList.add(person1); //and so on.. Persons persons = new Persons(personList);

You do not need this new class if you are well off with just having a Collection<Person> field.

minigeek Over a year ago

ohk thanx :) so i don't need to type .add everytime to add new person if i use collectionlist ,right? @harivis +1

Mustafa sabir · Accepted Answer · 2017-01-27 05:17:28Z

0

If you create a class for an object like Person, you don't need to create a Persons class just to store multiple Person objects. Unless you have to define operations which involves multiple Person Objects, like for example a Group class with operations performed on group pf persons, in which case creating a Persons or Group class makes sense. In your case I would assume you just need to store multiple Person objects and for that ArrayList<Person> will suffice.

ArrayList<Person> persons = new ArrayList<Person>();
persons.add(new Person(.....)); //add Person
.
.
Person person1=persons.get(1); //get Person by index

answered Jan 27, 2017 at 5:17

Mustafa sabir

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