Java 泛型数组实现栈：pop、push、peek 操作

下面是用数组实现的一个泛型栈类，包含pop、push和peek方法：

public class ArrayStack<E> {
    private Object[] array;
    private int top;
    private int capacity;
    
    public ArrayStack(int capacity) {
        this.capacity = capacity;
        array = new Object[capacity];
        top = -1;
    }
    
    public void push(E element) {
        if (top == capacity - 1) {
            throw new StackOverflowError("Stack is full");
        }
        array[++top] = element;
    }
    
    public E pop() {
        if (top == -1) {
            throw new EmptyStackException();
        }
        E element = (E) array[top];
        array[top--] = null;
        return element;
    }
    
    public E peek() {
        if (top == -1) {
            throw new EmptyStackException();
        }
        return (E) array[top];
    }
}

使用示例：

public class Main {
    public static void main(String[] args) {
        ArrayStack<Integer> stack = new ArrayStack<>(5);
        stack.push(1);
        stack.push(2);
        stack.push(3);
        
        System.out.println(stack.peek()); // 输出 3
        
        System.out.println(stack.pop()); // 输出 3
        System.out.println(stack.pop()); // 输出 2
        
        stack.push(4);
        stack.push(5);
        
        System.out.println(stack.pop()); // 输出 5
        System.out.println(stack.pop()); // 输出 4
        System.out.println(stack.pop()); // 输出 1
        
        // System.out.println(stack.pop()); // 抛出 EmptyStackException 异常
    }
}