Question

I am trying to extract a linkedlist from an array of linkedlist and am stuck. After extracting this linkedlist, I would need to sum the number of fruits in each basket in each linkedlist. For example, Basket 0 returns 174, Basket 1 returns 147, etc.

I’ve tried using an iterator and listIterator (as well) to extract the number of fruits but I am not getting anywhere. Anyone who can help? Some pointers/hints so I can start coding again.

public class ArrayLinkedList {

    final static int NUM_OF_ROWS = 32767;

    public static void main(String [] args) {

        List[] basket = new List [NUM_OF_ROWS];

        for (int i = 0; i < NUM_OF_ROWS; i++) {
            basket[i] = new LinkedList();
        }

        basket[0].add("1,APPLE,12");
        basket[1].add("2,APPLE,14");
        basket[1].add("3,APPLE,9");
        basket[2].add("4,APPLE,90");
        basket[2].add("5,APPLE,13");

        basket[0].add("1,ORANGE,45");
        basket[0].add("2,ORANGE,19");
        basket[1].add("3,ORANGE,67");
        basket[1].add("4,ORANGE,33");

        basket[0].add("1,BANANA,2");
        basket[0].add("2,BANANA,96");
        basket[1].add("3,BANANA,16");
        basket[1].add("4,BANANA,8");
        basket[2].add("5,BANANA,14");
        basket[2].add("6,BANANA,26");
        basket[3].add("7,BANANA,8");
        basket[3].add("8,BANANA,5");

        for (int i = 0; i < 5; i++) {
           System.out.println("Basket " + i + ": " + rows[i].toString());
        }

    }

}

Answer 1

You should not use a string to store multiple information. This would force you to parse the string each time you want to get a part of the information. I don’t know what "1,APPLE,12" represents, but you should use an object instead of this string :

public class Item {
    private int something;
    private String fruitName;
    private int numberOfFruits;

    public Item(int something, String fruitName, int numberOfFruits) {
        this.something = something;
        this.fruitName = fruitName;
        this.numberOfFruits = numberOfFruits;
    }

    public int getSomething() {
        return this.something;
    }

    public String getFruitName() {
        return this.fruitName;
    }

    public int getNumberOfFruits() {
        return this.numberOfFruits;
    }
}

And then, your array of baskets can be built like this :

List<Item>[] basket = new List<Basket>[NUM_OF_ROWS];

for (int i = 0; i < NUM_OF_ROWS; i++) {
    basket[i] = new LinkedList<Item>();
}

basket[0].add(new Item(1, "APPLE", 12));
basket[1].add(new Item(2, "APPLE", 14));
// ...

Then, you may iterate over one of the baskets and compute the total number of fruits easily :

int totalNumber = 0;
for (Item item : basket[0]) {
    totalNumber += item.getNumberOfFruits();
}