title: Integrate with a jar
body: <p>just a quick question. I have a jar file and I want to integrate it within my project. The decompiled version of the jar file looks like this: </p>
  
  <pre><code>public abstract class SinglyLinkedList
  
  protected SinglyLinkedList.Item head;
  
  public void addFront(String s) {
  if (head == null) {
      head = new SinglyLinkedList.Item(s);
  }
  else {
      SinglyLinkedList.Item insert = new SinglyLinkedList.Item(s);
      next = head;
      head = insert;
  }
  }
  
  public void add(String[] array) { String[] arrayOfString;
  int j = (arrayOfString = array).length; for (int i = 0; i &lt; j; i++) 
  { String s = arrayOfString[i];
  addFront(s);
  }
  }
  
  public String toString()
  {
  if (head == null) {
      return "empty list";
  }
  String s = "";
  
  for (SinglyLinkedList.Item helper = head; next != null; helper = next) {
      s = String.valueOf(s) + value + ", ";
      s = String.valueOf(s) + value;
      return s;
  }
  
  public abstract void sort();
  
  protected class Item
  {
      public Item next;
      public String value;
      public Item(String value) {
          this.value = value;
      }
  }
  }
  </code></pre>
  
  <p>Now I want to create a new linked list in my other class, but this doesnt work:  </p>
  
  <pre><code>private SinglyLinkedList linkedlist;
  
  public SelectionSortableList(){
      this.linkedlist = new SinglyLinkedList();
  }
  </code></pre>
  
  <p>He cannot instantiate it. Can please somebody tell me why he don't want to instantiate it? Thank you in beforehand.</p>