Adding an unknown number of objects to an arraylist

Question

i have a school assignment which requires me to add an unknown number of instances of a class "fruit" in to an arraylist "basket" and print out the details of each fruit object, my code adds the fruits to the arraylist but seems to override the previous entry each time leaving me with an arraylist of the same project. This is my code so far:

import java.util.*;
public class Question1
{
   public static void main(String[]Augs)
   {
      List<Fruit> basket = new ArrayList<Fruit>();
      int input;
      Scanner inp = new Scanner(System.in);
      String name;
      String colour;
      double mass;
      int k = -1;
      while (true)
      {
         System.out.println("Enter option: (1) add fruit (2) quit:");
         input = inp.nextInt();
         if (input==2)
            break;
         else
         {
             k++;
            System.out.println("Enter name, colour and mass in kg separated by space");
            name = inp.next();
            colour = inp.next();
            mass = inp.nextDouble();
            Fruit temp = new Fruit(name, colour, mass);
            basket.add(temp);
         }
      }
      for (int i = 0; i<basket.size(); i++)
      {
         System.out.println(basket.get(i));
      }
   }
}

//fruit class
public class Fruit
{
   private String name;
   private String colour;
   private double mass;
   public Fruit(String name, String colour, double mass)
   {
      this.name=name;
      this.colour=colour;
      this.mass=mass;
   }
   public String toString()
   {
      return name + " " + colour + " " + mass;
   }
}

score 3 · Accepted Answer · answered Sep 15 '13 at 00:21

3

Your code looks just fine in terms of adding the fruits to the basket. I think what's getting you is System.out.println(basket.get(i)). You are essentially asking a Fruit object to be printed, but the run time does not know how to do that and as such tries to convert the Fruit to some String representation by calling the toString() method on it. I think your Fruit class prints the same String no matter what's inside it. Try overriding the toString() method to get the correct results.

public class Fruit
{
    @Override
    public String toString()
    {
        return this.getName() + " " + this.getColor() + " " + this.getMass();
    }
}

answered Sep 15 '13 at 00:21

Ameen

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17

Sorry I didn't mention it but I do have a toString method that overides the default – Thusoluminati Al-Zawahiri Khar Sep 15 '13 at 00:25
ah, I see my problem now, I had set my variables as public static for some odd reason, thank you. And if I wanted to go further and sort my list first by alphabetical order on the name, then by colour, then by mass (ascending order) how would i go about it? – Thusoluminati Al-Zawahiri Khar Sep 15 '13 at 00:33
Look into http://stackoverflow.com/questions/2784514/sort-arraylist-of-custom-objects-by-property for sorting. – Ameen Sep 15 '13 at 00:37

Adding an unknown number of objects to an arraylist

1 Answers1