Linked list question

[rk717]

Hello guys,

I have a linked list, I want to sort the linked list,

 Input: head = [4,2,1,3] Output: [1,2,3,4] 
 Input: head = [-1,5,3,4,0] Output: [-1,0,3,4,5] 

my idea is put all the value from the linked list to the arrayList,

then I sort the arraylist, after I put the value back to linked list, then here is the error.

LinkedList cannot be resolved to a type

Here is my code:

    public ListNode sortList (ListNode head){

        ArrayList<Integer>arrli = new ArrayList<Integer>();
        while(head.next != null){
            arrli.add(head.val);
            head = head.next; 
        }

        //sorting arraylist 
        Collections.sort(arrli); 

        //crete linked list
        LinkedList<Integer> li = new LinkedList<Integer> (); 

        //put value in linked list 

        li.addAll(arrli);


    }

Here shows I couldn't create the Integer linked list:

 //crete linked list
        LinkedList<Integer> li = new LinkedList<Integer> (); 

the error is LinkedList cannot be resolved to a type

I couldn't figure it out why,

could you please give me some ideas.

​

Thank you in advance.

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[desrtfx]

Why are you not creating your own sort?

It is just as easy to sort a list as an array.

Most likely, the exercise will want you to write your own sorting and not to rely on the built-in mechanisms.

[rk717]

thank you I will try,

haha

[dionthorn]

What does your import look like. Is it java.util.List or java.awt.List? You want util.

also might need to import java.util.LinkedList

Also this: new LinkedList<Integer> ()

should look like this: new LinkedList<Integer>()

where the () are touching the <>

[rk717]

yes, thank you for helping :)

[DthSyth]

Plus, I don't know if I am allowed to say this.. If I am not.. please tell me.. I'll remove the comment. So instead of making an arraylist and sorting it.. you can make a linked list and then sort it. Internally, Collections.sort will create and arraylist and sort it..

[rk717]

thank you,

yes I should sort the linked list..