Regex - Matcher class

[Joshua Antony]

public static void main( String args[] )
{
String  x    = "ab";
Pattern p    = Pattern.compile( x );
Matcher matcher = p.matcher( "abcdefab" );
 
System.out.println( "test" );
 
if( matcher.find())
{
System.out.println( "start: " + matcher.start() + "   group:  " + matcher.group() + "\n" );
}
}

Above code works fine and prints test
start: 0 group: ab in the output.

But if I comment out the if condition i.e if( matcher.find()) then
I get Exception in thread "main" java.lang.IllegalStateException: No match available

Why is it so. I am confused.

[Barry Gaunt]

1. read the error message text.
2. read the API for Matcher.find(), Matcher.start(), and Matcher.group()

You should then immediately see the answer, I did.

Or you can wait until someone spoils it all by telling you the answer directly.
[ September 22, 2006: Message edited by: Barry Gaunt ]

[Joshua Antony]

Thanks Barry I got it.

From API:

public int start()
Throws:
IllegalStateException - If no match has yet been attempted, or if the previous match operation failed

public String group()
Throws:
IllegalStateException - If no match has yet been attempted, or if the previous match operation failed