CODEWITHSUNDEEP
javalinked-list
Liam
Liam

Reputation: 568

Reverse a linkedList from a array

I am trying to add a reverse linked list back to a linked list from an array.

public void reverse(){
        //Calling function to take a linked list and put it inside an array
        int[] myArray = this.toArray();
    //Populate list using array             
    for (int i= 0; i < myArray.length; i++){

            this.addHead(myArray[i]);

        }

        System.out.println(this.toString());

    }

Here is my method this works fine but it only set the linked list to the last index and stops.

EX.

[1,7,7,6]

lS.reverse()

=> [6]

Here is the to array function 

//Return int array of list values
    public int[] toArray(){

        //Creating a array of the size of linkedList
        //New copy of head
        int f[] = new int[this.size()];
        Node newHead = head;  
        int arrayIndex = 0;

        while(newHead != null){

            //Set the current Index to the data at head location
            f[arrayIndex] = newHead.data();

            //Moves the head to next postion 
            newHead = newHead.next(); 

            //Increment index
            arrayIndex = arrayIndex + 1;
        }

        return f;

    }

The result I am looking to acheive is after reverse() is called I will get from

[1,7,7,6]

To A linked list

6,7,7,1

Upvotes: 1

Views: 83

Answers (1)

Koenigsberg
Koenigsberg

Reputation: 1798

Don't know what you are trying to achieve, but if the initial list is given, there is no need for an array conversion. You can implement something along these lines:

public <T> List<T> reverseList( List<T> list )
    {
        List<T> newList = new ArrayList<T>();
        for( int i = 0; i < list.size(); i++ )
        {
            newList.add( list.get( list.size() - ( i + 1 ) ) );
        }

        return newList;
    }

If arrays are absolutely needed for some reason, you can use this analogously. Create an array, fill up by reversing index order.

Upvotes: 1

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