JAVA | 55 - 類集框架 | Stack |

棧是一種先進後出的數據結構，Stack 是 Vector 的子類，但 Stack 並不使用 Vector 的方法。

在進行棧操作的過程中，如果已經棧已經沒有數據了，那麼無法繼續出棧。

import java.util.*;

class Book{
    private String title;
    private int price;
    public Book(String title, int price){
        this.title = title;
        this.price = price;
    }
    @Override
    public String toString() {
        return this.title + " " + this.price;
    }
    @Override
    public int hashCode() {
        return Objects.hash(title, price);
    }
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        final Book other = (Book) obj;
        return Objects.equals(this.title, other.title)
                && Objects.equals(this.price, other.price);
    }
}
public class Main {
    public static void main(String[] args) throws Exception{
        // 設置了泛型，從而保證集合中所有的數據類型都一致
        Book bookA = new Book("java",100);
        Book bookB = new Book("c",89);
        Book bookC = new Book("c++",100);
        Book bookD = new Book("python",100);
        Stack <Book> stack = new Stack <Book>();
        stack.push(bookA);
        stack.push(bookB);
        stack.push(bookC);
        stack.push(bookD);
        System.out.println(stack.pop());
        System.out.println(stack.pop());
        System.out.println(stack.pop());
        System.out.println(stack.pop());
    }
}