how to use Iterator in object arraylist

Question

Here I got

public class Planet
{

    ArrayList<Person> person  = new ArrayList<>();
    Iterator<Person> itr = person.iterator();

    public String getFemaleName()
    {

        for (int a = 0;a < person.size();a++)
        {
            if (person.getGender == "female")
            {
                return person.get(a).getName();
            }
        }
    }
}

Now I'm having 2 problems, 1st is i just want return female's name,but it seems I have to return something even there is no female in my ArrayList. 2nd is how to use an Iterator instead of using a for loop.

Do you need to use the Iterator explicitly, or is it enough if you use the enhanced for-loop which uses Iterator internally? — Mick Mnemonic
– Mick Mnemonic, Commented Jan 16, 2016 at 3:41
What's the requirement for what you need to return when you don't find find a female? — Jon Thoms
– Jon Thoms, Commented Jan 16, 2016 at 5:08

Rameshwar Bhaskaran · Accepted Answer · 2016-01-16 05:58:01Z

1

For the case when no female is present , simply putting a return null in the end of the function will do the job, because your first return statement won't be executed at all.
For the second question, using an iterator .. just replace your for loop with

while(itr.hasNext()) { Person newPerson=itr.next(); if(newPerson.getGender().equals("female") return newPerson.getName(); }

answered Jan 16, 2016 at 5:58

Rameshwar Bhaskaran

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Gaktan · Accepted Answer · 2016-01-16 05:04:40Z

1

for (Person p : persons) // you should name your lists with plural
{
    if (p.getGender().equals("female")) // use .equals() to compare strings, since == works in weird ways
    {
        return p.getName();
    }
}
return null;

answered Jan 16, 2016 at 5:04

Gaktan

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1 Comment

Aaditya Gavandalkar Over a year ago

Its always suggested to use literals on the LHS for equals comparison like "female".equals(p.getGender()) to avoid NullPointerException issue

user unknown · Accepted Answer · 2016-01-16 07:19:42Z

0

Advanced for loop:

for(Person person: persons)
   if(person.getGender.equals("female"))
      return person.getName();

return null;

Iterator:

Iterator<Person> personsIter = persons.iterator();
while (personsIter.hasNext()) {
    Person current = personIter.next(); 
    if(person.getGender.equals("female"))
       return person.getName();
}
return null

edited Jan 16, 2016 at 7:19

user unknown

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answered Jan 16, 2016 at 5:20

CMPS

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