CODEWITHSUNDEEP
javaarrayslinked-list
Michael Fogarty
Michael Fogarty

Reputation: 301

how to convert an Array to a linked list in Java

I am a fairly new Java programmer and I am currently learning about converting lists to arrays. The problem that I am having is that when I try to link the list the output I am getting is not the same as what is in the array. The linked list output is all null values while the array has random values as it should. Here is my code: 

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

public class InsertingElements {
    public static void main(String[] args) {
        Integer[] numbers = new Integer[25];
        List<Integer> linkList = new LinkedList<>(Arrays.asList(numbers));

        for (int i = 0; i < numbers.length; i++) {
            numbers[i] = (int) (Math.random() * 100 + 1);
        }

        System.out.println("Numbers Generated: " + Arrays.toString(numbers));

        numbers = linkList.toArray(new Integer[linkList.size()]);

        System.out.println("Numbers: ");
        for (Integer number : numbers) {
            System.out.println(number);
        }
    }
}

And here is the output: 

Numbers Generated: [92, 61, 25, 8, 48, 80, 85, 89, 53, 18, 48, 38, 48, 
41, 93, 94, 24, 73, 83, 21, 18, 52, 3, 14, 10]
Numbers: 
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null
null

Upvotes: 3

Views: 19876

Answers (3)

GiGaNtIc BuRgEr
GiGaNtIc BuRgEr

Reputation: 1

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

    public class InsertingElements {
        public static void main(String[] args) {
            Integer[] numbers = new Integer[25];

            for (int i = 0; i < numbers.length; i++) {
            numbers[i] = (int) (Math.random() * 100 + 1);
           }

           List<Integer> linkList = new LinkedList<>(Arrays.asList(numbers));
           System.out.println("Numbers Generated: " + Arrays.toString(numbers));

          numbers = linkList.toArray(new Integer[linkList.size()]);

          System.out.println("Numbers: ");
          for (Integer number : numbers) {
          System.out.println(number);
        }
      }
    }

Upvotes: 0

John3136
John3136

Reputation: 29266

Move List<Integer> linkList = new LinkedList<> (Arrays.asList(numbers)); to after where you populate the array otherwise your linked list is just a list of default values.

Upvotes: 16

AbdusSalam
AbdusSalam

Reputation: 497

Try this one

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

    public class InsertingElements {
        public static void main(String[] args) {
            Integer[] numbers = new Integer[25];

            for (int i = 0; i < numbers.length; i++) {
            numbers[i] = (int) (Math.random() * 100 + 1);
           }

           List<Integer> linkList = new LinkedList<>(Arrays.asList(numbers));
           System.out.println("Numbers Generated: " + Arrays.toString(numbers));

          numbers = linkList.toArray(new Integer[linkList.size()]);

          System.out.println("Numbers: ");
          for (Integer number : numbers) {
          System.out.println(number);
        }
      }
    }

Upvotes: 0

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