队列——循环队列与非循环队列（Java版）

非循环循环队列

• 判满：(rear+1) % maxsize == front
• 判空：frOnt== rear
• 队列元素个数：rear = (rear + maxsize - front) % maxsize
• front 指针移动方式：frOnt= (front + 1) % maxsize
• rear指针移动方式：rear= (rear+ 1) % maxsize

import java.awt.Font;
import java.util.Scanner;
import javax.management.RuntimeErrorException;public class CircleArrayQueueDemo {public static void main(String[] args) {//创建队列CircleArrayQueue circleArrayQueue = new CircleArrayQueue(4);char key = &＃39; &＃39;;Scanner scanner = new Scanner(System.in);boolean loop = true;while(loop) {System.out.println("s(show):显示队列");System.out.println("e(exit):退出程序");System.out.println("a(add):添加数据到队列");System.out.println("g(get):从队列取出数据");System.out.println("h(head):查看队列头的数据");key = scanner.next().charAt(0);switch (key) {case &＃39;s&＃39;:circleArrayQueue.showQueue();break;case &＃39;e&＃39;:circleArrayQueue.showQueue();break;case &＃39;a&＃39;:System.out.println("输入一个数");int value = scanner.nextInt();circleArrayQueue.addQueue(value);break;case &＃39;g&＃39;:try {int res = circleArrayQueue.getQueue();System.out.printf("取出的数据是%d\n",res);}catch (Exception e) {System.out.println(e.getMessage());}break;case &＃39;h&＃39;:try {int res = circleArrayQueue.headQueue();System.out.printf("队列头的数据是%d\n",res);}catch (Exception e) {System.out.println(e.getMessage());}break;default:scanner.close();loop = false;break;}}System.out.println("程序退出");}}
//队列
class CircleArrayQueue{private int maxsize;private int front;private int rear;private int[] arr;//构造器public CircleArrayQueue(int arrmaxsize) {maxsize = arrmaxsize;front = 0;rear = 0;arr = new int[maxsize];}//判满public boolean isFull() {return (rear+1)%maxsize == front;}//判空public boolean isEmpty() {return rear == front;}//入队public void addQueue(int n) {if(isFull()) {System.out.println("队列已满，不能再添加！");return;}//添加数据arr[rear] = n;//rear后移rear = (rear + 1) % maxsize;}//出队public int getQueue() {if(isEmpty()) {throw new RuntimeException("队列为空，不可取出元素！");}//取值int value = arr[front];//front后移front = (front + 1)%maxsize;return value;}//遍历public void showQueue() {if(isEmpty()) {System.out.println("队列为空!");return;}for(int i = front; i < front + size(); i++) {System.out.printf("arr[%d]=%d\n",i % maxsize, arr[i % maxsize]);}}//求队列有效数据的个数public int size() {return (rear + maxsize - front) % maxsize;}//显示队头元素public int headQueue() {if(isEmpty()) {throw new RuntimeException("队列为空，不可取出元素！");}return arr[front];}
}

结果示意图

循环队列

• 判满：(rear+1) % maxsize == front
• 判空：frOnt== rear
• 队列元素个数：rear = (rear + maxsize - front) % maxsize
• front 指针移动方式：frOnt= (front + 1) % maxsize
• rear指针移动方式：rear= (rear+ 1) % maxsize

import java.awt.Font;
import java.util.Scanner;
import javax.management.RuntimeErrorException;public class CircleArrayQueueDemo {public static void main(String[] args) {//创建队列CircleArrayQueue circleArrayQueue = new CircleArrayQueue(4);char key = &＃39; &＃39;;Scanner scanner = new Scanner(System.in);boolean loop = true;while(loop) {System.out.println("s(show):显示队列");System.out.println("e(exit):退出程序");System.out.println("a(add):添加数据到队列");System.out.println("g(get):从队列取出数据");System.out.println("h(head):查看队列头的数据");key = scanner.next().charAt(0);switch (key) {case &＃39;s&＃39;:circleArrayQueue.showQueue();break;case &＃39;e&＃39;:circleArrayQueue.showQueue();break;case &＃39;a&＃39;:System.out.println("输入一个数");int value = scanner.nextInt();circleArrayQueue.addQueue(value);break;case &＃39;g&＃39;:try {int res = circleArrayQueue.getQueue();System.out.printf("取出的数据是%d\n",res);}catch (Exception e) {System.out.println(e.getMessage());}break;case &＃39;h&＃39;:try {int res = circleArrayQueue.headQueue();System.out.printf("队列头的数据是%d\n",res);}catch (Exception e) {System.out.println(e.getMessage());}break;default:scanner.close();loop = false;break;}}System.out.println("程序退出");}}
//队列
class CircleArrayQueue{private int maxsize;private int front;private int rear;private int[] arr;//构造器public CircleArrayQueue(int arrmaxsize) {maxsize = arrmaxsize;front = 0;rear = 0;arr = new int[maxsize];}//判满public boolean isFull() {return (rear+1)%maxsize == front;}//判空public boolean isEmpty() {return rear == front;}//入队public void addQueue(int n) {if(isFull()) {System.out.println("队列已满，不能再添加！");return;}//添加数据arr[rear] = n;//rear后移rear = (rear + 1) % maxsize;}//出队public int getQueue() {if(isEmpty()) {throw new RuntimeException("队列为空，不可取出元素！");}//取值int value = arr[front];//front后移front = (front + 1)%maxsize;return value;}//遍历public void showQueue() {if(isEmpty()) {System.out.println("队列为空!");return;}for(int i = front; i < front + size(); i++) {System.out.printf("arr[%d]=%d\n",i % maxsize, arr[i % maxsize]);}}//求队列有效数据的个数public int size() {return (rear + maxsize - front) % maxsize;}//显示队头元素public int headQueue() {if(isEmpty()) {throw new RuntimeException("队列为空，不可取出元素！");}return arr[front];}
}

结果示意图