Validating email address with java regex

/** isEmailValid: Validate email address using Java reg ex. 
* This method checks if the input string is a valid email address. 
* @param email String. Email address to validate 
* @return boolean: true if email address is valid, false otherwise. 
*/  

public static boolean isEmailValid(String email){  
boolean isValid = false;  
  
/* 
Email format: A valid email address will have following format: 
        [\\w\\.-]+: Begins with word characters, (may include periods and hypens). 
    @: It must have a '@' symbol after initial characters. 
    ([\\w\\-]+\\.)+: '@' must follow by more alphanumeric characters (may include hypens.). 
This part must also have a "." to separate domain and subdomain names. 
    [A-Z]{2,4}$ : Must end with two to four alaphabets. 
(This will allow domain names with 2, 3 and 4 characters e.g pa, com, net, wxyz) 
 
Examples: Following email addresses will pass validation 
abc@xyz.net; ab.c@tx.gov 
*/  
  
//Initialize reg ex for email.  
String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";  
CharSequence inputStr = email;  
//Make the comparison case-insensitive.  
Pattern pattern = Pattern.compile(expression,Pattern.CASE_INSENSITIVE);  
Matcher matcher = pattern.matcher(inputStr);  
if(matcher.matches()){  
isValid = true;  
}  
return isValid;  
}