Question

I am trying to figure out how to do two things :

1. Change a number from a String to a double and back to a String.
2. How to manipulate different parts of a double.

To explain :

In the first case, I would like the user to be able to input a number into the a JTextArea so I can store the input in a variable (simple). Then, I would like to perform operations on the number that is inputted, but this cannot be done with a string. Is there any way to convert input into a double?

Then, I would like to take this string, after it has been converted into a double, and analyze the specific digits, and the digits of its decimal places (tenths, hundredths, etc.) as well using if-else and for statements (I can do this part). My understanding of strings is that, if I say NameofString[0], I will get the first letter of the string, but can this be done with a Number?

Lastly, I would like to convert this double back into a String.

Answer 1

You can parse a string using (assuming x is a double variable and s a string)

x = Double.parseDouble(s);

and convert the number back to a string via

s = Double.toString(x);

If you want to format the value according to a specific format you may want to use String.format instead.