队列接口：
public interface Queue {
public boolean append(Object obj) throws Exception;//入队
public Object delete() throws Exception; //出队
public Object getHead() throws Exception;//获取队头元素
public int size(); //队列大小
public boolean isEmpty(); //判断队列是否为空
public boolean isFull();//判断队列是否已满
public void clear();//置空队列
}
队列实现：
public class LinkListQueue implements Queue {
private static final int defaultSize = 10; //默认大小
private int front; //队头指针
private int rear; //队尾指针
private int count; // 元素个数计数器
private int maxQueueSize; //最大元素个数
private Object[] queue; //对象数组
//带参数的构造函数，创建指定大小的队列空间
public LinkListQueue(int size) {
queue = new Object[size];
maxQueueSize = size;
front = rear = 0;
}
//无参数的构造函数，创建默认大小的队列空间
public LinkListQueue() {
maxQueueSize = defaultSize;
count = 0;
queue = new Object[defaultSize];
}
//入队列
public boolean append(Object obj) throws Exception {
if (!isFull()) { //不满则执行的入队列操作
queue[rear] = obj; //将新元素放入队列
rear = (rear + 1) % maxQueueSize; //加1求模，设定对尾指针
count++; //元素计数器加1
return true;
} else {
System.out.println("队列已满！" + obj + "无法插入队列");
return false;
}
}
public Object delete() throws Exception {
Object oRet = null;
if (!isEmpty()) { //不空则执行出队列操作
oRet = queue[front]; //获取对头元素
front = (front + 1) % maxQueueSize;//加1后求模，设定队头指针的值
count--; //元素计数器减1
} else {
System.out.println("队列已空！");
}
return oRet;
}
public Object getHead() throws Exception {
Object oRet = null;
if (!isEmpty()) { //队列不空
oRet = queue[front]; //获取对头元素
} else {
System.out.println("队列已空！");
}
return oRet;
}
public int size() {
return count;
}
public boolean isEmpty() {
return count == 0;
}
public boolean isFull() {
return (count > 0) && (rear == front);
}
public void clear() {
count = 0; //元素计数器清0
front = rear = 0; //队头指针与对尾指针指向初始位置
}
}
队列测试：
public class Test {
public static void main(String[] args) {
LinkListQueue queue = new LinkListQueue();
int[] a = {1, 2, 3, 4, 5, 6, 7};
try {
for (int i = 0; i < a.length; i++) {
queue.append(new Integer(a[i]));
}
System.out.println("输出队列大小：");
System.out.println(queue.size());
System.out.println("输出队列内容:");
while (!queue.isEmpty()) {
System.out.println(queue.delete().toString());
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}