queue.java

来自「ALGAE是一个快速创建算法演示的框架。目前支持的算法实现语言包括java和c」· Java 代码 · 共 73 行

/**
 * Queue.java
 *
 *
 * Created: Fri Apr 17 10:57:59 1998
 *
 * @author Steven J. Zeil
 * @version
 */
package edu.odu.cs.zeil.AlgAE;

public class Queue {

  class QueueNode 
  {
    Object data;
    QueueNode next;

    QueueNode (Object o) {data = o; next = null;}
  }

  private QueueNode front;
  private QueueNode rear;
  private int theSize;
  
  public Queue() {
    front = null;
    rear = null;
    theSize = 0;
  }

  public Object getFront()
  {
    return front.data;
  }

  public void removeFront()
  {
    if (front != null) {
      front = front.next;
      if (front == null) {
	rear = null;
      }
      --theSize;
    }
  }

  public void addToRear(Object newElement)
  {
    QueueNode qn = new QueueNode (newElement);
    if (front == null) {
      front = qn;
      rear = qn;
    }
    else {
      rear.next = qn;
      rear = qn;
    }
    ++theSize;
  }

  public int size()
  {
    return theSize;
  }

  public boolean isEmpty()
  {
    return (theSize == 0);
  }
  
} // Queue