用HashMap模擬一個網上購物車。要求：從鍵盤輸入n本書的名稱、單價、購買數量，將這些資訊存入一個HashMap，然後將該HashMap作為引數呼叫方法getSum（HashMap books），該方法用於計算書的總價並返回。【說明：鍵盤輸入可使用Scanner類】

package 作業2;

public class Books {
	String name;
    double price;
    int numbers;
    
	public Books(String name, double price, int numbers) {
		this.name = name;
		this.price = price;
		this.numbers = numbers;
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((name == null) ? 0 : name.hashCode());
		result = prime * result + numbers;
		long temp;
		temp = Double.doubleToLongBits(price);
		result = prime * result + (int) (temp ^ (temp >>> 32));
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Books other = (Books) obj;
		if (name == null) {
			if (other.name != null)
				return false;
		} else if (!name.equals(other.name))
			return false;
		if (numbers != other.numbers)
			return false;
		if (Double.doubleToLongBits(price) != Double.doubleToLongBits(other.price))
			return false;
		return true;
	}

	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public double getPrice() {
		return price;
	}
	public void setPrice(double price) {
		this.price = price;
	}
	public int getNumbers() {
		return numbers;
	}
	public void setNumbers(int numbers) {
		this.numbers = numbers;
	}
	
    
}
 

package 作業2;
import java.util.*;
public class Booknet {
	static double getSum(HashMap<Integer, Books> map)
	{
		double sum = 0;
		for(int i = 0;i < map.size();i++)
		{
			Books t = map.get(i);
			sum += (t.getPrice() * t.getNumbers());
		}
		return sum;
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		HashMap<Integer, Books> m=new HashMap<Integer, Books>();
		Scanner sc=new Scanner(System.in);
		System.out.print("請輸入書的數量：");
		int n=sc.nextInt();
		for(int i=0;i<n;i++)
		{
			System.out.println("請輸入第"+(i+1)+"本書的姓名,價格，數量：");
			String nm=sc.next();
			double p=sc.nextDouble();
			int nb=sc.nextInt();
			m.put(i, new Books(nm,p,nb));
		}
		double s= getSum(m);
		System.out.print("書的總價為:"+s);
		sc.close();
	}
}