IntList2.java

// ***************************************************************
// FILE: IntList.java
//
// Purpose: Defines a class that represents a list of integers
//
// ***************************************************************
public class IntList2 {
 private IntNode front; //first node in list
 //-----------------------------------------
 // Constructor. Initially list is empty.
 //-----------------------------------------
 public IntList2() {
   front = null;
  }
  //-----------------------------------------
  // Adds given integer to front of list.
  //-----------------------------------------
 public void addToFront(int val) {
   front = new IntNode(val, front);
  }
  //-----------------------------------------
  // Adds given integer to end of list.
  //-----------------------------------------
 public void addToEnd(int val) {
   IntNode newnode = new IntNode(val, null);
   //if list is empty, this will be the only node in it
   if (front == null) {
    front = newnode;
   } else {
    //make temp point to last thing in list
    IntNode temp = front;
    while (temp.next != null) {
     temp = temp.next;
    }
    //link new node into list
    temp.next = newnode;
   }
  }
  //-----------------------------------------
  // Removes the first node from the list.
  // If the list is empty, does nothing.
  //-----------------------------------------
 public void removeFirst() {
   if (front != null) {
    front = front.next;
   }
  }
  //------------------------------------------------
  // Prints the list elements from first to last.
  //------------------------------------------------
 public void print() {
     System.out.println("--------------------");
     System.out.print("List elements: ");
     IntNode temp = front;
     while (temp != null) {
         System.out.print(temp.val + " ");
         temp = temp.next;
     }
     System.out.println("\n-----------------------\n");
 }
    public void printRec() {
        if (front != null) {
            IntNode current = front;
            System.out.print(current.val + " ");
            if (current.next != null) {
                printRec(current.next);
            }
        }
    }
    private void printRec(IntNode n) {
        if (n.next != null) {
            System.out.print(n.val + " ");
            printRec(n.next);
        } else {
            System.out.println(n.val);
        }
    }
    public void printRecBackwards() {
        if (front != null) {
            IntNode current = front;
            if (current.next != null) {
                printRecBackwards(current.next);
            }
            System.out.println(current.val);
        }
    }
    private void printRecBackwards(IntNode n) {
        if (n.next != null) {
            printRecBackwards(n.next);
            System.out.print(n.val + " ");
        } else {
            System.out.print(n.val + " ");
        }
    }
    //*************************************************************
  // An inner class that represents a node in the integer list.
  // The public variables are accessed by the IntList class.
  //*************************************************************
 private class IntNode {
  public int val; //value stored in node
  public IntNode next; //link to next node in list
  //------------------------------------------------------------------
  // Constructor; sets up the node given a value and IntNode reference
  //------------------------------------------------------------------
  public IntNode(int val, IntNode next) {
   this.val = val;
   this.next = next;
  }
 }
}