how to extract double from a string like this

Question

How to extract double values from a string?

For example, s= "1.2+3.4*(3.2+2.3)-12.1/3.4*1.8+5.7"

How do extract the double values, and store it as variables?

Answer 1

You can do it with Pattern matching and grab matching portion out

Pattern p = Pattern.compile("[0-9]*\\.?[0-9]+");
Matcher m = p.matcher("1.2+3.4*(3.2+2.3)-12.1/3.4*1.8+5.7");

while (m.find()) {
  System.out.println(m.group());
}

You can then collect all matched data to a List<Double> or List<Float> based on your requirement

To collect operators as well you need to add another pattern to look for as well see the ORing section

([0-9]*\.?[0-9]+)|(\+|-|\/|\(|\|\)|\*)

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See

• ideone demo