IntList.java

// ***************************************************************
// FILE: IntList.java
//
// Purpose: Defines a class that represents a list of integers
//
// ***************************************************************
public class IntList {
 private IntNode front; //first node in list
 //-----------------------------------------
 // Constructor. Initially list is empty.
 //-----------------------------------------
 public IntList() {
   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 int length() {
      int counter;
      if (front == null) {
          counter = 0;
      } else {
         IntNode current = front;
         counter = 1;
          while (current.next != null) {
              counter++;
              current = current.next;
          }
      }
      return counter;
  }
  public void removeLast() {
      if (front != null) {
          IntNode current = front;
          IntNode previous = null;
          while (current.next != null) {
              previous = current;
              current = current.next;
          }
          previous.next = null;
      }
  }
  public void replace (int oldVal, int newVal) {
      if (front != null) {
          IntNode current = front;
          while (current.next != null) {
              if (current.val == oldVal) {
                  current.val = newVal;
              }
              current = current.next;
          }
          if (current.val == oldVal) {
              current.val = newVal;
          }
      }
  }



    //*************************************************************
  // 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;
  }

 }
}