Adding a constructor's properties to an ArrayList?

Question

I'm trying to add a Person which has been defined within a constructor to an ArrayList so that I can then call a method which is in another class. I'm having issues with actually adding a Person to the ArrayList however. Here is what I have so far:

GrownUp class updated

public class GrownUp extends Person
{
    ArrayList<Person> people;



GrownUp(int age, String name)  
{
    super(age, name);
    this.people = new ArrayList<>();        
    name = "Bill";
    age = 36;        
}  

public ArrayList<Person> getGrownUp()
{
   return people;
}

public void setGrownUp(int age, String name)
{
    //how to add a GrownUp? 
}

So what needs to be done is:

Add Person who has been defined as "Bill" aged 36 to ArrayList people.

Any help is appreciated, thanks.

I previously asked a question similar ot this but was not clear in what I was asking so I've changed my question so that hopefully it makes more sense in what I'm trying to achieve. I've added a get method but I can't figure out how to do the set method. how would I relate the Person constructor to the ArrayList to add a person into it?

Einar · Accepted Answer · 2016-12-03 07:48:32Z

3

I think it's a bit strange to have the people array within the GrownUp class. Try to map it to the real world. Would it make sense to have people within a GrownUp? I would rather have that array outside and do this:

List<People> people = new ArrayList<>();
people.add(new GrownUp(25, "Alice"));
people.add(new GrownUp(36, "Bill"));
people.add(new Child(5, "Nina"));

The GrownUp class would then look like this:

public class GrownUp extends Person {

    public GrownUp(int age, String name) {
        super(age, name)
    }
}

I guess you are planning to add more properties that is specific to the GrownUp class, like Optional<DriversLicense> getDriversLicense() or similar.

edited Dec 3, 2016 at 7:48

answered Dec 3, 2016 at 7:17

Einar

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4 Comments

Harry Over a year ago

Thanks for the feedback, if I was to say call a method on that GrownUp, how would I do this if the method was called eat()?

Einar Over a year ago

If all persons (including children) were to eat: people.stream().foreach(person -> person.eat()); If just GrownUps were to eat: people.stream().filter(person -> person instanceof GrownUp.class).foreach(grownUp -> grownUp.eat());

Einar Over a year ago

To get all driversLicences.

List<DriversLicense> driversLicenses = people.stream().filter(person -> person instanceof GrownUp.class).foreach(grownUp -> ((GrownUp) grownUp).getDriversLicense()).collect(Collectors.toList());

Einar Over a year ago

It looks a bit messy here, but if you break lines before the dots it should look better. You can of course also use traditional for-loops instead of the stream API for this.

user1211 · Accepted Answer · 2016-12-03 07:16:12Z

1

This should help you.

public void setGrownUp(int age, String name)
{
people.add(new GrownUp(age,name));
}

answered Dec 3, 2016 at 7:16

user1211

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