---------------------------------------------接口定义----------------------------------
package .hbut.dao;
public interface Queue {
public void clear();
public int length();
public boolean full();
public boolean empty();
//入队
public boolean enque(Object e);
//出队，需要删除第一个元素
public Object dlque();
//获取队头元素
public Object getf();
}
---------------------------------------------具体的实现--------------------------------
package .hbut.daoImpl;
import .hbut.dao.Queue;
/**
* @author Administrator
* 循环队列的实现
*/
public class SqQueue implements Queue{
Object [] elem;
int front,rear;
int len;
public SqQueue() {
len =100;
elem = new Object[len];
front=rear=0;
}
public SqQueue(int maxsz) {
len = maxsz;
elem = new Object[len];
front = rear =0;
}
@Override
public void clear() {
front = rear =0;
}
@Override
public int length() {
//循环队列需要考虑全部队满后全部出队，再入队后rear为0，而front为len-1
return (rear-front+len)%len;
}
@Override
public boolean full() {
return (rear+1)%len==front;
}
@Override
public boolean empty() {
return front==rear;
}
@Override
public boolean enque(Object e) {
if(full()){
return false;
}
elem[rear]=e;
rear = rear+1%len;
return true;
}
//元素出队，删除队首元素
@Override
public Object dlque() {
if(empty()){
return null;
}
Object obj =elem[front];
front = (front+1)%len;
return obj;
}
@Override
public Object getf() {
if(empty()){
return null;
}
return elem[front];
}
//--------------------------------测试循环队列------------------------------
public static void main(String[] args) {
//创建一个循环队列，最多容纳元素数8
SqQueue sque = new SqQueue(8);
//开始入队
sque.enque(1);
sque.enque(2);
sque.enque(3);
sque.enque(4);
System.out.println("队列元素个数:"+sque.length());
System.out.println("队首元素:"+sque.getf());
System.out.println("队列是否为空:"+sque.empty());
System.out.println("队列是否已满"+sque.full());
System.out.println("当前出队的元素:"+sque.dlque());
System.out.println("出队后的队首元素:"+sque.getf());
}
}
测试结果:
队列元素个数:4
队首元素:1
队列是否为空:false
队列是否已满false
当前出队的元素:1
出队后的队首元素:2
