Defining Classes II - Absolute Java - page 300

EXAMPLE: (continued)

The entire line is read as a single long string using the method nextLine of the Scanner
class. The long string is decomposed into tokens using the class StingTokenizer . The
tokens are the numbers that were input, but they are in the form of string values, not
values of type double . Finally, the tokens are converted to values of type double using
the method Double.parseDouble .
Note that the String variables are initialized to null . If you omit the nulls,
the compiler will complain that the variables string1 and string2 might not be
initialized before they are used. The compiler is incorrect but it does no good to argue
with it. Including null as initial values for the variables string1 and string2 will
keep the compiler happy and allow you to run the program.

Display 5.18 Use of the Method Double.parseDouble (part 1 of 2)

1 import java.util.Scanner;
2 import java.util.StringTokenizer;

3 public class InputExample
4 {
5 public static void main(String[] args)
6 {
7 Scanner keyboard = new Scanner(System.in);

8 System.out.println("Enter two numbers on a line.");
9 System.out.println("Place a comma between the numbers.");
10 System.out.println("Extra blank space is OK.");
11 String inputLine = keyboard.nextLine();

12 String delimiters = ", "; //Comma and blank space
13 StringTokenizer numberFactory =
14 new StringTokenizer(inputLine, delimiters);

15 String string1 = null ;
16 String string2 = null ;
17 if (numberFactory.countTokens() >= 2)
18 {
19 string1 = numberFactory.nextToken();
20 string2 = numberFactory.nextToken();
21 }
22 else
23 {
24 System.out.println("Fatal Error.");
25 System.exit(0);
26 }