hmmm

public class List<T> {
    private Node<T> first;
    private int size = 0;

    public List() {
    }

    public void add(T content) {
        Node<T> node = new Node();
        node.setContent(content);
        node.setIndex(size);
        if (this.isEmpty()) {
            first = node;
            size++;
        }
        else {
            Node<T> help = first;
            while (help.getNext() != null) {
                help = help.getNext();
            }
            help.setNext(node);
            size++;
        }
    }

    public void add(int index, T content) {
        if (index >= 0 && index < size) {
            Node<T> node = new Node();
            node.setContent(content);

            Node<T> next = this.getNode(index);
            node.setNext(next);
            node.setIndex(index);

            if (index == 0) {
                first = node;
            }

            if (index > 0) {
                Node<T> predecessor = this.getNode(index - 1);
                predecessor.setNext(node);
            }

            if (next != null) {
                Node<T> toChange = next;;
                while (toChange != null) {
                    toChange.setIndex(toChange.getIndex() + 1);
                    toChange = toChange.getNext();
                }
            }
            size++;
        }
    }

    public void remove(int index) {
        if (!this.isEmpty()) {
            if (index >= 0 && index < size) {
                Node<T> next = this.getNode(index + 1);;

                if (index == 0) {
                    first = first.getNext();
                }

                if (index > 0) {
                    Node<T> predecessor = this.getNode(index - 1);
                    predecessor.setNext(next);
                }

                if (next != null) {
                    Node<T> toChange = next;;
                    while (toChange != null) {
                        toChange.setIndex(toChange.getIndex() - 1);
                        toChange = toChange.getNext();
                    }
                }
                size--;
            }
        }
    }

    public void remove(T content) {
        if (!this.isEmpty()) {
            Node<T> next = first.getNext();

            if (first.getContent() == content) {
                first = next;
                size--;
            }
            else {
                Node<T> predecessor = first;
                while (predecessor != null) {
                    Node<T> node = predecessor.getNext();
                    if (node != null && node.getContent() == content) {
                        next = node.getNext();
                        predecessor.setNext(next);
                        size--;
                        break;
                    }
                    predecessor = node;
                }
            }

            if (next != null) {
                Node<T> toChange = next;
                while (toChange != null) {
                    toChange.setIndex(toChange.getIndex() - 1);
                    toChange = toChange.getNext();
                }
            }
        }
    }

    private Node<T> getNode(int index) {
        if (!this.isEmpty() && index >= 0 && index < size) {
            Node<T> help = first;
            while (help.getIndex() != index) {
                help = help.getNext();
            }
            return help;
        }
        return null;
    }

    public T get(int index) {
        if (!this.isEmpty() && index >= 0 && index < size) {
            Node<T> help = first;
            while (help.getIndex() != index) {
                help = help.getNext();
            }
            return help.getContent();
        }
        return null;
    }

    public boolean isEmpty() {
        return first == null;
    }

    public int size() {
        return size;
    }

    public class Node<T>
    {
        private T content;
        private int index;
        private Node<T> next;

        public Node() {
        }

        public T getContent() {
            return content;
        }

        public void setContent(T content) {
            this.content = content;
        }

        public Node<T> getNext() {
            return next;
        }

        public void setNext(Node<T> next) {
            this.next = next;
        }

        public int getIndex() {
            return index;
        }

        public void setIndex(int index) {
            this.index = index;
        }
    }
}