You might try something more like this:

if ($line =~ /^\s*public(*.);\s*$/) {
  # do something
}
[download]

The use of anchors (^ and $) at the beginning and end of your pattern will ensure that nothing (except some optional space characters) will appear before the 'public' or after the ';'. You may be able to adapt this to your needs.

while ( $javacode =~ s{ (/\*\* .*? \*/) }{ <!--REPLACED_COMMENT--> }xm
+s ){
   push @comments, $1;
}

my @lines = ();
LINE:
foreach my $line (split "\n",  $javacode) {
   push @lines, $line;
   next LINE if $line =~ m { \A \s* // }xms;
   # change lines
   $lines[-1] =~ ...
}

$javacode = join "\n", @lines;
my $comment_id = 0;
$javacode =~ s{<!--REPLACED_COMMENT-->}{$comment[$comment_id++]}eg;
[download]

cant i have a solution like

$str ="check this out";
[download]

if this sentence has out do not replace it

if($str =~ s#check this [^out]#check this one#){
}
[download]

is there some way to achieve this
one more thing i am not traversing line by line.
the whole java file i am taking as a single line
using undef $/;

Hi neeha, you cannot use character class here, rather you have to use negative look head.

change

if($str =~ s#check this [^out]#check this one#){
}
[download]

into

$str ="$str ="check this out check this here";";

$str =~ s#check this ((?!out).)+#check this one#gs;

print $str;
[download]

Prasad

my problem is

/**
* public void method1();
* is deprecated
*/
public void method1();
[download]

in this case my code replaces to

/**
* replaced code
*/
public void method1();
[download]

It dont want to replace anything in the comments
and my code reads the entire java file as a single line.

my $inComment = 0;
while(<>) {
  next if $inComment;
  s|//.*$||; # remove // comments
  s|/\*.*?\*/||; # remove /*..*/ comments
  s|^.*\*/|| and $inComment = 0; 
  s|/\*.*$|| and $inComment = 1; 
  # do your pattern matching on $_ here
}
[download]

For that, I think you'll need to chunk through the data in the style of a parser, copying pieces to a separate string variable as you go, and modifying only the pieces that are uncommented public declarations. Something like this might be a start (untested):

# assume $src contains a whole file of java code...

# first, split $src code into an array, on "/* ... */" style comments,
# making sure to keep these comments as array elements

my @chunks = split m{ (/\* .*? \*/) }sx, $src;

# now go through the chunks, and look for uncommented "public" methods

my $mod;  # this will be the output string

for ( @chunks ) {
    if ( m{^/\*} ) {  # this is a "/*...*/" comment
        $mod .= $_;   # so just copy it to output
    }
    else {
        my @lines = split /[\r\n]+/;
        for ( @lines ) {
            if ( m{^\s*public\s+\w+} ) {
                # this line looks like a public declaration
                # so do something special with it
            }
            $mod .= $_;  # copy line to output
        }
    }
}

print $mod;
[download]