如何在 Java 中将 String 值转换为 Double 或 Int 值？

Question

I have a problem. I have String with the value "$615.00" and I want to convert it to double or int . I have tried the following code but there is an error:

String one = "$615.00";
String two = "$15.00";
double newone = Double.parseDouble( one );
double newtwo = Double.parseDouble( two );

System.out.println(newone-newtwo);

The error is

Exception in thread "main" java.lang.NumberFormatException: For input string: "$615.00"

But I have added the NumberFormatException for the method and still got the error.

Answer 1

As others have said in the comments, NumberFormatException is happening because you are trying to parseDouble without removing the $ from the number.

In this case, you can use substring() to get everything after the first char:

String one = "$615.00";
String two = "$15.00";

double newone = Double.parseDouble( one.substring(1) );
double newtwo = Double.parseDouble( two.substring(1) );

System.out.println(newone-newtwo);

Results in 600.00

Answer 2

$ is a currency designator. It is not part of a numeric value.

If you have a currency value, you should use a currency format to read it:

NumberFormat format = NumberFormat.getCurrencyInstance();
double newone = format.parse(one).doubleValue();
double newtwo = format.parse(two).doubleValue();

If you are not running on a computer configured for the US, you may need to pass a Locale, to force the currency instance to use US dollars:

NumberFormat format = NumberFormat.getCurrencyInstance(Locale.US);
double newone = format.parse(one).doubleValue();
double newtwo = format.parse(two).doubleValue();

Answer 3

Use regular expression to remove symbols like "$" (in other words, all symbols but digits and dot)

String one = "$615.03";
String oneValue = one.replaceAll("[^0-9.]", "");
System.out.println(oneValue); // Output is 615.03, which is correctly parsed by parseDobule()