📚 数据结构基础：（2）栈的基本实现

需要用到自定义数组类：https://www.cnblogs.com/cenjw/p/custom-array-class.html

先定义一个栈的接口

public interface Stack<E> {

    int getSize();
    boolean isEmpty();
    void push(E e);
    E pop();
    E peek();
}

接口的实现类

class ArrayStack<E> implements Stack<E> {

    Array<E> array;

    // 构造函数
    public ArrayStack(int capacity) {
        array = new Array<>(capacity);
    }

    public ArrayStack() {
        array = new Array<>();
    }

    @Override
    public int getSize() {
        return array.getSize();
    }

    @Override
    public boolean isEmpty() {
        return array.isEmpty();
    }

    public int getCapacity() {
        return array.getCapacity();
    }

    @Override
    public void push(E e) {
        array.addLast(e);
    }

    @Override
    public E pop() {
        return array.removeLast();
    }

    @Override
    public E peek() {
        return array.getLast();
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        res.append("Stack: ");
        res.append("[");
        for (int i = 0 ; i < array.getSize(); i++) {
            res.append(array.get(i));
            if (i != getSize()-1) {
                res.append(",");
            }
        }
        res.append("] top");
        return res.toString();
    }
}