自己写的JAVA数据结构5

package edu.basejava.util;

public class Queue<V>
{

 private static final int defaultSize = 10;

 private int size;

 private int front;
 
 private int rear;

 private V[] value;

 public Queue()
 {
  this.setup(Queue.defaultSize);
 }

 public Queue(int size)
 {
  this.setup(size);
 }

 public void enqueue(V value)
 {
  if (this.isFull())
   Log.error("队列容量已满");
  else
  {
   this.rear=(this.rear+1)%this.size;
   this.value[this.rear] = value;
  }

 }

 public V dequeue()
 {
  if (this.isEmpty())
   return null;
  else
   this.front = (this.front+1)%this.size;
   return this.value[this.front];
 }

 public V peek()
 {
  return this.firstValue();
 }

 public V firstValue()
 {
  if (this.isEmpty())
   return null;
  else   
   return this.value[(this.front+1)%this.size];
 }
 public void clear()
 {
  this.front =this.rear= 0;
  for (@SuppressWarnings("unused")
  V v : this.value)
   v = null;
 }
 public boolean isEmpty()
 {
  return this.front == this.rear;
 }

 public boolean isFull() // true if stack is full
 {
  return (this.front == (this.rear+1)%this.size);
 }

 @SuppressWarnings("unchecked")
 private void setup(int size)
 {
  if (size < 0)
   throw new IllegalArgumentException("错误的队列容量参数: " + size);
  else
  {
   this.size = size+1;
   this.value = (V[]) new Object[size+1];
  }
 }
}