队列是一种满足先进先出原则的数据结构，这里采用数组的方式实现了一个队列，仅仅可以在队列的两端操作，队头取出，队尾插入。
package com.data.structure.queue;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**顺序队列的实现,无论是线性队列还是环形队列，队列中永远有一个位置空着
* @Author: wushuai
* @Date: 2019/8/19 10:38
* @Description:
*/
public class MyQueue<T> {
private T[] arrs;//数组
private int maxSize;
private int size;
private int front;//头指针
private int rear;//末尾指针,指向最后一个元素的下一个位置
public MyQueue(int maxSize){
this.arrs = (T[])new Object[maxSize];
this.maxSize = maxSize;
this.front = 0;
}
/**
* 判断当前队列是空队列
* @return
*/
public boolean isNull(){
if(this.front==this.rear){
return true;
}
return false;
}
/**
* 判断队列是否已满
* @return
*/
public boolean isFull(){
if((this.rear + 1)%maxSize==front){
return true;
}
return false;
}
public void add(T data){
if(isFull()){
resize();
front = 0;
}
rear = (front + size)%maxSize;
arrs[rear] = data;
rear = (rear + 1)%maxSize;
size++;
}
public T remove(){
if(isNull()){
return null;
}
T frontData = (T) arrs[front];
arrs[front] = null;
front = (front+1)%maxSize;
size--;
return frontData;
}
/**
* 扩容
*/
public void resize(){
int oldLen = this.maxSize;
this.maxSize = oldLen*2;
T[] tmp = (T[]) new Object[maxSize];
System.arraycopy(this.arrs,0,tmp,0,oldLen);
this.arrs = tmp;
this.front = 0;
tmp = null;
}
public static void main(String[] args) {
MyQueue<String> queue = new MyQueue<String>(5);
System.out.println(queue.isNull());
queue.add("one");
queue.add("two");
queue.add("three");
queue.add("four");
System.out.println(queue.isFull());
queue.add("five");
System.out.println(queue.isFull());
//数组的扩容采用原数组长度向右位移1位的方法
// List<String> list = new ArrayList<>(4);
System.out.println(queue.remove());
System.out.println(queue.remove());
}
}
| 
转播
