Grazie per la risposta, quindi come dovrei modificare quel costruttore?

codice:
public class UsaLista {
	public static void main(String[] args) {

		Lista lista = new Lista();

		Node n1 = new Node(5);
		Node n2 = new Node(3);
		Node n3 = new Node(7);
		Node n4 = new Node(2);

		System.out.println(n1);

		lista.insert_front(1);
		lista.insert_front(2);
		lista.insert_front(3);
		lista.insert_front(4);

		lista.printList();


	}
}
Usando questo come main mi da questi errori:
C:\...\UsaLista.java:13: error: method push_front in class Lista cannot be applied to given types;
lista.insert_front(1);
^
required: Node
found: int
reason: actual argument int cannot be converted to Node by method invocation conversion
C:\...\UsaLista.java:14: error: method push_front in class Lista cannot be applied to given types;
lista.insert_front(2);
^
required: Node
found: int
reason: actual argument int cannot be converted to Node by method invocation conversion
C:\...\UsaLista.java:15: error: method push_front in class Lista cannot be applied to given types;
lista.insert_front(3);
^
required: Node
found: int
reason: actual argument int cannot be converted to Node by method invocation conversion
C:\...\UsaLista.java:16: error: method push_front in class Lista cannot be applied to given types;
lista.insert_front(4);
^
required: Node
found: int
reason: actual argument int cannot be converted to Node by method invocation conversion
4 errors

Procedura completata con codice di uscita 1