Question

Java - I need help creating a method that removes a node at the specific index position. The * first node is index 0.

public boolean delAt(int index) {

src code 2 different classes

********************************************

public class Node {
    private String data;
    private Node next;
    public Node(String data, Node next) {
        this.data = data;
        this.next = next;
    }
    public Node() {
    }
    public String getData() {
        return data;
    }
    public void setData(String data) {
        this.data = data;
    }
    public void setNext(Node next) {
        this.next = next;
    }
    public Node getNext() {
        return next;
    }
}

*******************************************************************

package LinkedListLab;

public class LinkListLab {
    private Node top;
    public LinkListLab() {
        top = null;
    }
    /****************************************************************
     *
     * Determines the size, that is, the number of elements in the list
     *
     * @return the size of the list
     *
     ****************************************************************/
    public int getLen() {
        int size =0;
        Node current = top;
        while(current !=null) {
            current = current.getNext();
            size++;
        }
        return size;
        }

    /****************************************************************
     *
     * Inserts a node before a specific index. When the list is empty
     * that is, top = null, then the index must be 0. After the first
     * element is added, index must be: 0 <= index < size of list
     *
     * @param index a specific index into the list.
     *
     * @throws IllegalArgumentStringxception if index < 0 or
     * index >= size of the list
     ****************************************************************/
    public void insertBefore (int index, String data) {

// place your code here
    }
    /****************************************************************
     *
     * Inserts a node after a specific index. When the list is empty
     * that is, top = null, then the index must be 0. After the first
     * element is added, index must be: 0 <= index < size of list
     *
     * @param index a specific index into the list.
     *
     * @throws IllegalArgumentStringxception if index < 0 or
     * index >= size of the list
     ****************************************************************/
    public void insertAfter (int index, String data) {
// place your code here
    }
    /****************************************************************
     *
     * Removes the top element of the list
     *
     * @return returns the element that was removed.
     *
     * @throws RuntimeStringxception if top == null, that is,
     * there is no list.
     *
     ****************************************************************/
    public String removeTop () {
        return null;
    }
    /****************************************************************
     *
     * This Method removes a node at the specific index position. The
     * first node is index 0.
     *
     * @param index the position in the linked list that is to be
     * removed. The first position is zero.
     *
     * @throws IllegalArgumentStringxception if index < 0 or
     * index >= size of the list
     *
     ****************************************************************/
    public boolean delAt(int index) {
        return false;
    }
    // A simple testing program. Not complete but a good start.
    public static void main (String[] args){
        LinkListLab list = new LinkListLab();
        list.display();
        System.out.println ("Current length = " + list.getLen());
        list.insertBefore(0, "apple");
        list.insertBefore(0, "pear");
        list.insertBefore(1, "peach");
        list.insertBefore(1, "cherry");
        list.insertBefore(3, "donut");
        list.insertAfter(0, "apple");
        list.insertAfter(0, "pear");
        list.insertAfter(1, "peach");
        list.insertAfter(1, "cherry");
        list.insertAfter(3, "donut");
        list.display();
        list.removeTop();
        list.delAt(4);
        list.delAt(2);
        list.delAt(0);
        list.removeTop();
        list.removeTop();
        list.display();
    }
    public void display() {
        Node temp = top;
        System.out.println ("___________ List ________________________");
        while (temp != null) {
            System.out.println (temp.getData());
            temp = temp.getNext();
        }
    }
}

Answer 1

public boolean delAt(int index) {
    if (index < 0 || index >= getLen())
        throw new IllegalArgumentException();
    if (index == 0) {
        removeTop();
    } else {
        Node temp = top;
        for (int i = 1; i < index; i++) {
            temp = temp.getNext();
        }
        temp.setNext(temp.getNext().getNext());
    }
    return true;
}