You can read perlre and perlretut. I would start with something like this, assuming all methods definition will be in one line:

while (<DATA>) {
    if (/^                  # Matches line start
        \s*                 # None or many spaces
        (?:public|private)? # Matches 'public', 'private' or none (pac
+kages)
        \s+                 # One or many spaces
        (?:\S+)             # Matches one or more non spacing chars (v
+ariable type)
        \s+                 # One or many spaces
        (?:\S+)             # Matches one or more non spacing chars (m
+ethod name)
        \s*                 # None or many spaces
        \(                  # Literal '('
            (.*)            # Matches everything
        \)                  # Literal ')'
        \s*                 # None or many spaces
        $                   # Matches end of line
        /x) {
                print $1, "\n";
        }
}

__DATA__

public void check1(String str, Integer i) 
{

}
[download]