标签：队列 System println int 循环 front ArrayQueueAndCircleQueue out
队列
数组队列
1.初始化队列
private int maxsize;//最大长度
private int front;//指向队首的前一个位置
private int rear;//指向队尾
private int[] arr;
public ArrayQueue(int maxsize) {
this.maxsize = maxsize;
arr = new int[maxsize];
front = -1;
rear = -1;
}
2.判断是否队列已满
// 判断是否队列已满
public boolean isFull() {
return rear == maxsize - 1;
}
3.判断队列是否为空
//判断队列是否为空
public boolean isEmpty() {
return rear == front;
}
4.入队
// 入队
public void addQueue(int n) {
if (isFull())
throw new RuntimeException("队列已满");
arr[++rear] = n;
}
5.出队
// 获取数据，出队
public int getQueue() {
if (isEmpty())
throw new RuntimeException("队列为空~~");
return arr[++front];
}
6.显示队列所有数据
// 显示队列所有数据
public void showQueue() {
if (isEmpty()) {
System.out.println("队列为空，无法遍历");
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.printf("arr[%d]=%d\n", i, arr[i]);
}
}
7.获取队头数据
// 获取队头数据
public int headQueue() {
if (isEmpty())
throw new RuntimeException("队列为空~~");
return arr[front + 1];
}
8.测试代码
/**
* @author 缪广亮
* @version 1.0
* 数组队列
*/
public class ArrayQueueDemo {
public static void main(String[] args) {
ArrayQueue arrayQueue = new ArrayQueue(3);
Scanner scanner = new Scanner(System.in);
char key = ' ';//接收用户输入
boolean loop = true;
while (loop) {
System.out.println("======a(add)======");
System.out.println("======g(get)======");
System.out.println("======h(head)======");
System.out.println("======s(show)======");
System.out.println("======e(exit)======");
System.out.print("请输入菜单选项中的首字母操作：");
key = scanner.next().charAt(0);
switch (key) {
case 'a':
try {
System.out.println("请输入加入队列的一个数：");
int value = scanner.nextInt();
arrayQueue.addQueue(value);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 'g':
int res = 0;
try {
res = arrayQueue.getQueue();
System.out.println("取出的数据是：" + res);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 'h':
try {
int head = arrayQueue.headQueue();
System.out.println("队头数据: " + head);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 's':
arrayQueue.showQueue();
break;
case 'e':
scanner.close();
loop = false;
break;
default:
System.out.println("你的输入有误，请重新输入！");
}
}
System.out.println("程序退出~~~");
}
}
循环队列
1.初始化队列
private int maxsize;
//指向队首元素，即队列的第一个元素front=0
private int front;
//指向队列的最后一个元素的后一个位置，空出一个空间为约定rear=(rear+1)%maxsize
private int rear;
private int[] arr;
public CircleQueue(int maxsize) {
this.maxsize = maxsize;
arr = new int[maxsize];
front=0;
rear=0;
}
2.判断是否队列已满
// 判断是否队列已满
public boolean isFull() {
return (rear + 1) % maxsize == front;
}
3.判断队列是否为空
//判断队列是否为空
public boolean isEmpty() {
return rear == front;
}
4.入队
// 入队
public void addQueue(int n) {
if (isFull())
throw new RuntimeException("队列已满");
arr[rear] = n;
// 指向队列的最后一个元素的后一个位置，考虑取模
rear = (rear + 1) % maxsize;
}
5.获取队列的数据，出队列
// 获取队列的数据，出队列
public int getQueue() {
if (isEmpty())
throw new RuntimeException("队列为空~~");
// 分析出front是指向队列的第一个元素
// 先把front对应的值保留到一个临时变量
// 将临时变量返回
int value = arr[front];
// 将front后移，考虑取模
front = (front + 1) % maxsize;
return value;
}
6.显示队列所有数据
// 显示队列所有数据
public void showQueue() {
if (isEmpty()) {
System.out.println("队列为空，无法遍历");
return;
}
// 从front开始遍历,遍历多少个元素
for (int i = front; i < front + size(); i++) {
// 循环队列的下标要考虑取模
System.out.printf("arr[%d]=%d\n", (i % maxsize), arr[(i % maxsize)]);
}
}
7.当前队列中有效个数
// 当前队列中有效个数
public int size() {
return (rear + maxsize - front) % maxsize;
}
8.获取队头和队尾数据
// 获取队头数据
public int headQueue() {
if (isEmpty())
throw new RuntimeException("队列为空~~");
return arr[front];
}
// 获取队尾元素
public int lastQueue(){
if (isEmpty()){
throw new RuntimeException("队列为空~~");
}
return arr[(rear-1+maxsize)%maxsize];
}
8.测试代码
/**
* @author 缪广亮
* @version 1.0
* 循环队列
*/
@SuppressWarnings({"all"})
public class CircleQueueDemo {
public static void main(String[] args) {
CircleQueue circleQueue = new CircleQueue(4);
Scanner scanner = new Scanner(System.in);
char key = ' ';//接收用户输入
boolean loop = true;
while (loop) {
System.out.println("======a(add)======");
System.out.println("======g(get)======");
System.out.println("======h(head)======");
System.out.println("======s(show)======");
System.out.println("======l(last)======");
System.out.println("======e(exit)======");
System.out.print("请输入菜单选项中的首字母操作：");
key = scanner.next().charAt(0);
switch (key) {
case 'a':
try {
System.out.println("请输入加入队列的一个数：");
int value = scanner.nextInt();
circleQueue.addQueue(value);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 'g':
int res = 0;
try {
res = circleQueue.getQueue();
System.out.println("取出的数据是：" + res);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 'h':
try {
int head = circleQueue.headQueue();
System.out.println("队头数据: " + head);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 's':
circleQueue.showQueue();
break;
case 'l':
try {
int last = circleQueue.lastQueue();
System.out.println("取得的队尾数据："+last);
} catch (Exception e) {
System.out.println(e.getMessage());
}
break;
case 'e':
scanner.close();
loop = false;
break;
default:
System.out.println("你的输入有误，请重新输入！");
}
}
System.out.println("程序退出~~~~");
}
}
标签：队列,
System,
println,
int,
循环,
front,
ArrayQueueAndCircleQueue,
out
From： https://www.cnblogs.com/mglblog/p/17848548.html