data_structures_free

net/datastructures/Queue.java

@@ -0,0 +1,43 @@
+ package net.datastructures;
+/**
+  * Interface for a queue: a collection of elements that are inserted
+  * and removed according to the first-in first-out principle.
+  *
+  * @author Michael T. Goodrich
+  * @author Natasha Gelfand
+  * @author Mark Handy
+  * @author Roberto Tamassia
+  * @see EmptyQueueException
+  */
+
+//begin#fragment Queue
+public interface Queue<E> {  
+ /** 
+  * Returns the number of elements in the queue.
+  * @return number of elements in the queue.
+  */
+  public int size();  
+ /** 
+  * Returns whether the queue is empty.
+  * @return true if the queue is empty, false otherwise.
+  */
+  public boolean isEmpty(); 
+ /**
+  * Inspects the element at the front of the queue.
+  * @return element at the front of the queue.
+  * @exception EmptyQueueException if the queue is empty.
+  */
+  public E front() throws EmptyQueueException; 
+ /** 
+  * Inserts an element at the rear of the queue.
+  * @param element new element to be inserted.
+  */
+  public void enqueue (E element); 
+ /** 
+  * Removes the element at the front of the queue.
+  * @return element removed.
+  * @exception EmptyQueueException if the queue is empty.
+  */
+  public E dequeue() throws EmptyQueueException; 
+}
+//end#fragment Queue