java - 在java中连接计算税率的类

Question

此行中的类型不匹配:
final Map<String, Double> taxRates = new Map<>();
显然我做错了什么，无法弄清楚它是什么。
该代码应该能够计算不同国家的税率。谢谢

package tax;

import java.util.Scanner;
import java.util.Map;
import java.util.HashMap;

public class application{

private static Scanner reader;

public static void main (String[] args) {
    //constants
    final Map<String, double> taxRates = new Map<>(); 
    taxRates.put( "China", 0.2 );
    taxRates.put( "Japan", 0.1 );
    taxRates.put( "USA", 0.3 );

    reader = new Scanner(System.in);

    //Variables 
    double purchases;  
    double taxespaid;
    double taxRate;   
    String country;

    System.out.print("Enter the country you are purchasing in: ");
    country = reader.nextLine();
    taxRate = taxRates.get( country );
    if( taxRate == null )
    {
        System.out.println( "Could not find country: " + country );
        return; 
    }

    //Request Input 
    System.out.print("Enter your total amount of purchases in " + country + " :"); 
    purchases = reader.nextDouble();

    taxespaid = purchases * taxRate;


    //Display Tax
    System.out.println("The refund amount you owed is $" + taxespaid);
}

}

Answer 1

java.util.Map是接口(interface)，不是类，不能用new实例化。

您将需要选择 Map 的具体实现，例如 HashMap。

但是，您也不能拥有基元的映射，因此需要使用 double 的盒装版本，Double:

final Map<String, Double> taxRates = new HashMap<>();