Queue.java

import java.util.*; 
//the Queue class with a LinkedList field 
 
public class Queue  
{     
    protected LinkedList list;          
    //queue object has been initialized     
    public Queue()     
    {         
        list = new LinkedList();     
    } //default constructor 
 
    //check whether queue object has no elemet or otherwise     
    public boolean isEmpty()     
    {        
        return list.isEmpty();     
    }//method isEmpty 
 
    //determine the no of elements in the queue object    
    public int size()      
    {        
        return list.size();     
    }// method size 
 
    //insert element at the back of the queue object     
    public void enqueue(Object element)     
    {       
        list.addLast(element);    
    } //method enqueue 
 
    //remove the front element from the queue object    
    public Object dequeue()      
    {    
        return list.removeFirst();    
    } //method dequeue 
 
    //the element at the front of the queue object has been returned     
    public Object front()      
    {      
        return list.getFirst();    
    } //method front 
 
    //the element at the end of the queue object has been returned   
    public Object rear()     
    {  
        return list.getLast();   
    } //method rear 
 
} // Queue class