How do I convert from a string into a number?
The first thing you have to be sure of is that your string actually contains a number! If not, then you'll generate a NumberFormatException. We can use the Integer class for converting from a string into an integer (or if we're dealing with decimal numbers, we can use the Double class).
The follow example shows how to convert from a string to an integer.
String numberOne = "123"; String numberTwo = "456"; // Convert numberOne and numberTwo to an int with Integer class Integer myint1 = Integer.valueOf(numberOne); Integer myint2 = Integer.valueOf(numberTwo);
// Add two numbers together int number = myint1.intValue() + myint2.intValue();
You'll notice that when we need to use numbers as a data type (int), we need to convert from an Integer to an int. Confused? An Integer acts as a wrapper for our int data type (making conversion from String to number easy). When we want to use the data type, we call the intValue() method, which returns an int.