How can I find the sum of two numbers which are in String variables?

Question

In this code fragment, I can\'t sum a and b:

String a = \"10\";
String b = \"20\"; 
JOptionPane.showMessageDialog(null,a+b);
         


        

Answer 1

Because you want to concat Strings they won't add up. You have to parse them to an Integer which works like:

Integer.parseInt(a) + Integer.parseInt(b)

To sum this up + concats Strings and doesn't add them up.