// ์๋ฐ์ ์ด๋ฉ์ผ ํ์ ์ฒดํฌํ๋ ๋ผ์ด๋ธ๋ฌ๋ฆฌ Patterns
Pattern pattern = Patterns.EMAIL_ADDRESS;
if(pattern.matcher(email).matches() == false){
//if(! pattern.matcher(email).matches() ){}๋ก ์จ๋ ๋๊ฐ๋ค.
Snackbar.make(btnRegister,"์ด๋ฉ์ผ ํ์์ ๋ฐ๋ฅด๊ฒ ์์ฑํ์ธ์.",Snackbar.LENGTH_SHORT).show();
return;
}