JAVA向字符串添加双精度[重复]

Question

我只是有一个关于在JAVA中添加一些货币（$）的问题，我使用NumberFormat.getMONcyInstance（）；以“$”获取我的输出。我的程序是输入一些钱（字符串格式），例如程序只接受（100美元、50美元、20美元...等等），所以我使用了这段代码：

String payment = keyboard.next();
while (!(payment.equals("$100.00")) && (!payment.equals("$50.00")) && (!payment.equals("$20.00")) && (!payment.equals("$10.00")) && (!payment.equals("$5.00")) && (!payment.equals("$2.00")) && (!payment.equals("$1.00")) {
System.out.print("Invalid coin or note. Try again. ");
payment = keyboard.next(); }

如何获取输入（100.00、50.00…）以从总价中减去它们。。例如我想要（100.00-12.00）（12.00是总价）

任何帮助都将不胜感激谢谢

Answer 1

如果您的输入是“$”符号，您可以删除字符串的第一个元素，然后将其转换为双精度。

//method to convert String in Double
public Double getDoubleFromString(String payment) 
{
  payment = payment.substring(1);
  double paymentDouble = Double.parseDouble(payment);
  return paymentDouble;
}

String payment = keyboard.next();
double paymentDouble = getDoubleFromString(payment);

while (paymentDouble != 100.00 && paymentDouble != 50.00 && paymentDouble != 20.00 
           && paymentDouble != 10.00 && paymentDouble != 5.00 
           && paymentDouble != 2.00 && paymentDouble != 1.00) 
      {
         System.out.print("Invalid coin or note. Try again.");
         String payment = keyboard.next();
         paymentDouble = getDoubleFromString(payment);
      }

Answer 2

public double convertPayment(String inputPayment) {   
    String payment = inputPayment.substring(1);
    double paymentValue = Double.parseDouble(payment);
    return paymentValue;
}