MatchResult.start() & MatchResult.end() methods

[Swapna Gouri Kalanidhi]

Hello All

Here are 2 programs given in JavaBeat Mock exam which are behaving differently.

 
package misc_apis;
import java.util.Scanner;
public class ScannerTest4 {
   public static void main(String[] args) {
      Scanner scanner = new Scanner("hai hello");
      scanner.useDelimiter("h");
      scanner.next();
      scanner.next();
      System.out.println(scanner.match().start());
   }
}   

The above program's output is 5
The next program goes like this...

 
package misc_apis;
import java.util.Scanner;
public class ScannerTest6 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner("are u there");
        scanner.useDelimiter("e");
        scanner.next();
        System.out.println(scanner.match().end());
        scanner.next();
        System.out.println(scanner.match().end());
    }
}

And the output of this is 2 followed by 8

In the first program we are using scanner.match.start(). In the second one we are using scanner.match.end(). What's the indexing of these two methods? Do they use zero as starting index or 1? Can any one explain me their behavior??? Thanks all!
[ July 08, 2008: Message edited by: Swapna Gouri Kalanidhi ]

[Ralph Jaus]

Hi Swapna Gouri,

I'll try to explain the results. Let's start with the first one.

1. The first scanner.next() finds "ai ".
2. The second scanner.next() finds "ello".
3. scanner.match().start() returns the starting position of the substring "ello" in the original string "hai hello". This
is 5.
4. scanner.match().end() returns the position after the substring (see API documentation for MatchResult). This is 9.

The second example works in the same fashion. If it still makes problems, just let us know.
[ July 08, 2008: Message edited by: Ralph Jaus ]

[Swapna Gouri Kalanidhi]

Thank you Ralph, I got the point. But I still have a doubt, does these methods,viz., match.start()& match.end() use zero indexing or 1 indexing? I mean should we start counting the alphabets from 0 or from 1??

[Swapna Gouri Kalanidhi]

Hello Ralph
Thanks for explaining the behavior of the start() & end() methods. i have tried both the methods practically & I have understood the concept. Thanks a lot for giving a detailed description how both of them work...!