java dynamic class instance creation

Question

Suppose you have a java class called Chicken but the number of Chicken instances is not know before run time because it depends on user input. How do you make new instances of Chicken during run time, depending on user input?

Make a List<Chicken> and then keep adding new Chicken() to the list as needed. — Henry Keiter
– Henry Keiter, Commented Mar 8, 2014 at 16:31
Using a loop. I'm sure you've learnt loops before learning classes and objects. — JB Nizet
– JB Nizet, Commented Mar 8, 2014 at 16:32

jstover · Accepted Answer · 2014-03-08 16:42:11Z

1

If you need to dynamically create new objects and assign them to a variable, I would utilize a map with the key used to simulate naming a variable and the value as the newly created Chicken object: e.g.

    new HashMap<nameOfVariable, Chicken>()

This will get you around not knowing the number or name of your instances at runtime. For example, if you were reading in a file from a user that was a list of named Chicken objects.

answered Mar 8, 2014 at 16:42

jstover

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Naruto Biju Mode · Accepted Answer · 2014-03-08 16:57:19Z

-1

Here's how to make new instances of Chicken during run time, depending on user input :

import java.util.Scanner;
import java.util.Vector;

public class A
{
    public static void main(String[] args)
    {
        System.out.println("Enter number of chikens :");
        Scanner scanner = new Scanner(System.in);
        int numberOfChukens = scanner.nextInt();

        Vector chikenArray = new Vector<>();

        for(int i=0;i<numberOfChukens;i++)
        {
            chikenArray.add(new Chiken());
        }       
    }
}

answered Mar 8, 2014 at 16:57

Naruto Biju Mode

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1 Comment

JB Nizet Over a year ago

Please, don't suggest using Vector. It shouldn't be used anymore for 15 years. And use generic collections. They've been existing for 10 years, since Java 5.

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