LinkedList/LinkedList.java

public class LinkedList {
  private Node first;
  private Node last;
  private Node current;
  private int size;
  
  public LinkedList() {}

  public void toFirst() {
    current = first;
  }

  public void toLast() {
    current = last;
  }

  public Node getFirst() {
    return first;
  }

  public Node getLast() {
    return last;
  }

  public void toNext() {
    if (hasAccess()) {
      current = current.getNextNode();
    }
  }

  public boolean isEmpty() {
    if (first == null && last == null) {
      return true;
    }
    return false;
  }

  public boolean hasAccess() {
    if (current == null) { 
      return false;
    }
    return true;
  }

  public void append(Object content) {
    Node newNode = new Node(content);
    if (isEmpty()) {
      first = newNode;
      last = newNode;
      current = newNode;
    } else {
      last.setNextNode(newNode);
      last = newNode;
    }
    size++;
  }

  public int getSize() {
    return size;
  }

  public void insert(Object content, Object prev) {
    toFirst();

    while(current.getContent() != prev && hasAccess()) {
      toNext();
    }
    
    if (hasAccess()) {
      Node newNode = new Node(content);
      
      newNode.setNextNode(current.getNextNode());
      current.setNextNode(newNode);
      size++;
    }
  }

  public void remove() {
    if (hasAccess()) {
      if (first == last) {
        first = null;
        last = null;
        current = null;
        return;
      }
      
      Node newCurrent = current.getNextNode();
      Node pointer = first;
      while(pointer.getNextNode() != current) {
        pointer = pointer.getNextNode();
      }
      current = newCurrent;
      pointer.setNextNode(current);
    }
    size--;
  }

  public void concat(LinkedList weaponList) {
    if (!isEmpty()) {
      last.setNextNode(weaponList.getFirst());
      last = weaponList.getLast();
      size = weaponList.getSize();
      return;     
    }
    first = weaponList.getFirst();
    last = weaponList.getFirst();
    current = first;
    size += weaponList.getSize();
  }

  public Object getCurrentContent() {
    return current.getContent();
  }
}