This snippet should give you the idea:

my $file="Finger.java";
my %comments=();
open(F,"<$file") or die "Can't open $file: $!";
while(defined($_=<F>)){
 $comments{$.}=$_ if( m{...PUT THE MATCH YOU NEED HERE...} );
}
close(F);
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Reading the file line by line like I do has a drawback, though: you now need to take care yourself of multiline comments within /* ... */, and append to the correct string as needed.