创建固定大小的堆栈

问题描述

我想在Java中创建一个Stack，但要修改大小。例如，创建一个新的Stack，将大小设置为10，然后当我将项目推送到堆栈时它会填满，当它填充到10时，堆栈中的最后一个项目被推下（删除）。我想使用Stack，因为它使用LIFO并且非常符合我的需求。

I want to create a Stack in Java, but fix the size. For example, create a new Stack, set the size to 10, then as I push items to the stack it fills up and when it fills up to ten, the last item in the stack is pushed off (removed). I want to use Stack because it uses LIFO and fits my needs very well.

但是Stack从Vector继承的setSize（）方法似乎并没有实际限制Stack的大小。我想我错过了一些关于Stacks如何工作的东西，或者Stacks并不意味着受到限制所以这是不可能的。请教育我！

But the setSize() method that Stack inherits from Vector doesn't seem to actually limit the size of the Stack. I think I am missing something about how Stacks work, or maybe Stacks weren't meant to be constrained so it is impossible. Please educate me!

推荐答案

你可以像这样创建一个非常简单的堆栈：

You can create a very simple stack like this:

public class FixedStack<T>
{
    private T[] stack;
    private int size;
    private int top;

    public FixedStack<T>(int size)
    {
        this.stack = (T[]) new Object[size];
        this.top = -1;
        this.size = size;
    }

    public void push(T obj)
    {
        if (top >= size)
            throw new IndexOutOfBoundsException("Stack size = " + size);
        stack[++top] = obj;
    }

    public T pop()
    {
        if (top < 0) throw new IndexOutOfBoundsException();
        T obj = stack[top--];
        stack[top + 1] = null;
        return obj;
    }

    public int size()
    {
        return size;
    }

    public int elements()
    {
        return top + 1;
    }
}

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