ArrayList vs LinkedList

Both ArrayList vs LinkedList, are the implementation of List interface in java. But they have different use cases and characteristics.

CustomList.java

 public interface CustomList {
    int size();
    boolean isEmpty();
    void add(String value);
    void add(int index, String value);
    void remove(int index);
    String get(int index);
}

CustomLinkedList.java

package com.godel.ds.implementation;

import com.godel.ds.interfaces.CustomList;

@SuppressWarnings("unchecked")
public class CustomLinkedList implements CustomList {
    Node head;
    int size;

   public CustomLinkedList () {
        this.head = null;
        this.size = 0;
    }

    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    @Override
    public void add(String value) {
        Node newNode = new Node<>(value);
        if (size == 0)
            this.head = newNode;
       else {
           Node currentNode = this.head;
           while (currentNode.nextNode != null)
                currentNode = currentNode.nextNode;
           currentNode.nextNode = newNode;
       }
       size++;
    }

    @Override
    public void add(int index, String value) {
        Node newNode = new Node<>(value);
        Node currentNode = this.head;
        for (int i = 0 ; i < index - 1; i++)
            currentNode = currentNode.nextNode;
        newNode.nextNode = currentNode.nextNode;
        currentNode.nextNode = newNode;
        size++;
    }

    @Override
    public void remove(int index) {
        Node currentNode = head;
        for(int i = 0; i < index - 2; i++) {
            currentNode = currentNode.nextNode;
        }

        currentNode.nextNode = currentNode.nextNode.nextNode;
    }

    @Override
    public String get(int index) {
        Node currentNode = head;
        for(int i = 0; i < index - 1; i++) {
            currentNode = currentNode.nextNode;
        }
        return currentNode.data;
    }

    private static class Node {
        String data;
        Node nextNode;

        Node(String data) {
            this.data = data;
            this.nextNode = null;
        }
    }
}

CustomArrayList.java

 import com.godel.ds.interfaces.CustomList;
 import java.util.Arrays;

 public class CustomArrayList implements CustomList {
    private int defaultCapacity = 10;
    private String[] elements;
    private int size;

    public CustomArrayList() {
        this.elements = new String[defaultCapacity];
        this.size = 0;
    }

    public CustomArrayList(int initialCapacity) {
        if (initialCapacity <= 0) {
            throw new IllegalArgumentException("Initial capacity cannot be 

negative value");
        }
        this.elements = new String[initialCapacity];
        this.size = 0;
    }
    @Override
    public int size() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size == 0;
    }

    @Override
    public void add(String value) {
        ensureCapacity();
        elements[size] = value;
        size++;
    }

    @Override
    public void add(int index, String value) {

        if (index >= size || index < 0) {
            throw new IllegalArgumentException("Index out of bounds");
        }
        ensureCapacity();
        System.arraycopy(elements, index, elements, index+1, size-index);
        elements[index] = value;
        size++;
    }

    @Override
    public void remove(int index) {
        if (index >= size || index < 0) {
            throw new IllegalArgumentException("Index out of bounds");
        }
        String element = elements[index];
        System.arraycopy(elements, index+1, elements, index, (size-index)-1);
        System.out.println("Deleted: "+ element);
        size--;
    }

    @Override
    public String get(int index) {
        if (index >= size || index < 0) {
            throw new IllegalArgumentException("Index out of bounds");
        }
        return elements[index];
    }

    private void ensureCapacity() {
        int newSize = elements.length * 2;
        elements = Arrays.copyOf(elements, newSize);
    }
 }