pass_regex.java

private boolean isPasswordValid(CharSequence pass) {
    /*
    ^                 # start-of-string
    (?=.*[0-9])       # a digit must occur at least once
    (?=.*[a-z])       # a lower case letter must occur at least once
    (?=.*[A-Z])       # an upper case letter must occur at least once
    (?=.*[@#$%^&+=])  # a special character must occur at least once
    .{8,}             # anything, at least eight places though
    $                 # end-of-string
     */
    return pass.toString().matches("^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=]).{8,}$");
}