Java编程题-使用数组模拟栈

栈：后进先出

// Stack类
public class Stack {
	// 使用数组存储数据
	Object[] elements;

	// 指向栈顶元素上方的一个帧
	int index;

	// 栈默认的初始化容量是5
	Stack() {
		this(2);
	}

	Stack(int max) {
		elements = new Object[max];
	}

	// 压栈方法
	public void push(Object element) throws StackOperationException {
		if (index == elements.length) {
			throw new StackOperationException("栈已满");
		}
		elements[index++] = element;
	}

	// 弹栈方法
	public Object pop() throws StackOperationException {
		if (index == 0) {
			throw new StackOperationException("栈已空！");
		}
		return elements[--index];
	}
}

// 异常类
public class StackOperationException extends Exception {
	public StackOperationException() {
	}

	public StackOperationException(String msg) {
		super(msg);
	}
}

// 测试类
public class StackTest {
	public static void main(String[] args) {
		Stack s = new Stack();

		User u1 = new User("Jack", 20);
		User u2 = new User("Zhang", 21);
		User u3 = new User("Li", 22);

		// 压栈
		try {
			s.push(u1);
			s.push(u2);
			s.push(u3);
		} catch (StackOperationException e) {
			e.printStackTrace();
		}

		// 弹栈
		try {
			System.out.println(s.pop());
			System.out.println(s.pop());
			// System.out.println(s.pop());
		} catch (StackOperationException e) {
			e.printStackTrace();
		}
	}
}

class User {
	String name;
	int age;

	User(String name, int age) {
		this.name = name;
		this.age = age;
	}

	public String toString() {
		return "User[name=" + name + ",age=" + age + "]";
	}
}