数组实现栈和队列

/**
 * 数组实现栈和队列
 */
public class ArrayToQueueAndStack {

    public static class MyStack<T> {

        public Object[] arr;

        public int size;

        public int limit;

        public MyStack(int limit) {
            this.arr = new Object[limit];
            this.limit = limit;
        }

        public void push(T value) {
            if (size == limit) {
                System.out.println("the stack is full");
                return;
            }
            arr[size++] = value;
        }

        public T pop() {
            if (isEmpty()) {
                System.out.println("the stack is empty");
                return null;
            }
            return (T) arr[--size];
        }

        public boolean isEmpty() {
            return size == 0;
        }

    }

    public static class MyQueue<T> {

        public Object[] arr;

        public int pushIndex;

        public int pollIndex;

        public int size;

        public int limit;

        public MyQueue(int limit) {
            this.arr = new Object[limit];
            this.limit = limit;
        }

        public void push(T value) {
            if (size == limit) {
                System.out.println("the queue is full");
                return;
            }
            arr[pushIndex] = value;
            size++;
            pushIndex = nextIndex(pushIndex);
        }

        public T poll() {
            if (isEmpty()) {
                System.out.println("the queue is empty");
                return null;
            }
            T value = (T) arr[pollIndex];
            size--;
            pollIndex = nextIndex(pollIndex);
            return value;
        }

        public boolean isEmpty() {
            return size == 0;
        }

        private int nextIndex(int pushIndex) {
            return ++pushIndex % limit;
        }

    }

}

/* 如有错误，欢迎批评指正 */