队列的2种实现方式（Java完整版）

1：基于简单循环数组实现队列 

public class Queue {
      private int [] queArray;
      private int maxSize;
      public int front;   //存储队头元素的下标
      public int rear;    //存储队尾元素的下标
      public static int length; //队列元素个数
      //构造方法，初始化队列
      public Queue(int maxSize){
             this.maxSize = maxSize;
             queArray = new int[maxSize];
             front = 0;
             rear = -1;
             length = 0;
      }
      //插入
      public void insert(int elem) throws Exception{
             if(isFull()){
                    throw new Exception("队列已满，不能进行插入操作！");
             }
             //如果队尾指针已到达数组的末端，插入到数组的第一个位置
             if(rear == maxSize-1){
                   rear = -1;
             }
             queArray[++rear] = elem;
             length++;
      }
      //删除
      public int remove() throws Exception{
             if(isEmpty()){
                    throw new Exception("队列为空，不能进行移除操作！");
             }
             //如果队头指针已到达数组末端，则移到数组第一个位置
             if(front == maxSize){
                    front = 0;
             }
             int item = queArray[front++];
             length--;
             return item;
      }
      //查看队头元素
      public int peek() throws Exception{
             if(isEmpty()){
                    throw new Exception("队列内没有元素！");
             }
             return queArray[front];
      }
      //获取队列长度
      public int size(){
             return length;
      }
      //判空
      public boolean isEmpty(){
             return (length == 0);
      }     
      //判满
      public boolean isFull(){
             return (length == maxSize);
      }    
      public static void main(String[] args) throws Exception{
    	  Queue que = new Queue(10);
    	  que.insert(1);
    	  que.insert(2);
    	  que.insert(3);
    	  que.insert(4);
    	  que.insert(5);
    	  que.insert(6);
    	  System.out.println(que.peek());
    	  System.out.println(length);
    	  System.out.println(que.remove());
    	  System.out.println(que.peek());
      }
}

运行结果：

1
6
1
2

2：基于动态循环数组实现队列

//基于动态循环数组实现队列
public class Queue {
	public int[] queArray;
	public static int length;//数组中元素的个数
	public int maxsize;
	public int rear;//队尾元素的下标
	public int front;//队首元素的下标
	//通过构造方法实现对队列的初始化
	public Queue(int maxsize){
		this.maxsize = maxsize;
		queArray = new int[maxsize];
		length = 0;
		rear = -1;
		front = 0;
	}
	//插入
	public int insert(int item){
		if(isFull()){
			doubleArray();
		}
		if(rear == maxsize-1){
			rear = -1;
		}
		queArray[++rear] = item;
		length++;
		return item;
	}
	public void doubleArray(){
		int[] newArray = new int[maxsize*2];
		for(int i = 0;i<maxsize;i++){
			newArray[i] = queArray[i];
		}
		maxsize = maxsize*2;
		queArray = newArray;
	}
	//删除
	public int delete() throws Exception{
		if(isEmpty()){
			throw new Exception("队列为空，不能执行删除操作");
		}
		if(front == maxsize){
			front = 0;
		}
		int elem = queArray[front++];
		length--;
		return elem;
	}
	//判空
	public boolean isEmpty(){
		return (length == 0);
	}
	//判满
	public boolean isFull(){
		return (length == maxsize);
	}
	//查看队头元素
	public int seek() throws Exception{
		if(isEmpty()){
			throw new Exception("队列为空，不能查看队头元素");
		}
		return queArray[front];
	}
	public static void main(String[] args) throws Exception{
		Queue que = new Queue(5);
		que.insert(1);
		que.insert(2);
		que.insert(4);
		que.insert(5);
		que.insert(6);
		que.insert(8);
		que.insert(10);
		System.out.println(que.seek());
		System.out.println(length);
		que.delete();
		System.out.println(length);
	}
}

运行结果：

1
7
6