CODEWITHSUNDEEP
javacollections
user2899676
user2899676

Reputation: 123

Java ArrayList behaving differently

I have a program that prints the ArrayList in java. The ArrayList should retain the order of insertion right?

import java.util.*;

class Generator {
    String[] s = { "snow", "white", "and", "the", "seven", "dwarfs" };

    String s1;

    static int i = 0;

    String next() {
        s1 = s[i];
        i++;
        if (i == s.length) {
            i = 0;
        }
        return s1;
    }

    public static void main(String[] args) {
        Collection<String> al = new ArrayList<String>();
        // Collection<String> ll=new LinkedList<String>();
        Generator g = new Generator();
        for (int i = 0; i < 10; i++) {

            al.add(g.next());
            // ll.add(g.next());
        }

        System.out.println(al);
        // System.out.println(ll);
    }
}

with the LinkedList object stuff commented, I am getting right output

[snow, white, and, the, seven, dwarfs, snow, white, and, the]

but when I uncomment the LinkedList code I am getting output as:

[snow, and, seven, snow, and, seven, snow, and, seven, snow]
[white, the, dwarfs, white, the, dwarfs, white, the, dwarfs, white]

Can anyone please explain me this behavior? I am confused.

Upvotes: 0

Views: 123

Answers (4)

sky
sky

Reputation: 93

if you uncomment linkedList than first value will be inserted in the ArrayList and second value will be inserted in the LinkedList so both list contains alternate vaues and will be printed in alternate order.

Upvotes: 0

Siva Kumar
Siva Kumar

Reputation: 2006

You can call like below.

    String next = g.next();
    al.add(next);
    ll.add(next);

Instead of calling next() method two times.

Upvotes: 1

forgivenson
forgivenson

Reputation: 4435

g.next() removes the next item and returns it. So when you uncomment the LinkedList code, your loop removes two items each iteration, and adds one to each list.

Upvotes: 0

SJuan76
SJuan76

Reputation: 24780

When you uncomment the linked list, you are calling next() twice in every loop.

The first word is stored in the array list, the second one in the linked list, the third list in the array list...

Next, please!

Upvotes: 2

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