python get email in string

import re
email=(r'[a-z0-9\-\.]+@[0-9a-z\-\.]+')
emailtest=r'adfasldfjdsl fan02@'
emailset=set()
for em in (emailtest):
    (em)
for em1 in sorted(emailset):
    print(em1)

import re
def emailre(teststr):
    email=(r'[a-z0-9\-\.]+@[0-9a-z\-\.]+')
    emailset=set()  #List
    for em in (teststr):
        (em)
    for eml in sorted(emailset):
        print(eml)
emailtest='sdfdsgf asd03@'
emailre(emailtest)
# or
strtest=r'sdgfsg abc@'
emailre(strtest)

  /**
   * Email from the specified string
   * content The specified string
   */
  public static String parse(String content) {
  String email = null;
  if (content==null || ()<1) {
 return email;
  }
 //Find out the names that contain @
 int beginPos;
 int i;
String token = "@";
String preHalf="";
 String sufHalf = "";

beginPos = (token);
 if (beginPos>-1) {
 //Prior item scanning
 String s = null;
  i= beginPos;
 while(i>0) {
s = (i-1,i);
 if (isLetter(s))
    preHalf = s+preHalf;
  else
    break;
  i--;
  }
 // Posterior item scanning
  i= beginPos+1;
  while( i<()) {
   s = (i,i+1);
   if (isLetter(s))
    sufHalf =  sufHalf +s;
   else
    break;
    i++;  
   }
  //Judgement of legality
  email = preHalf + "@" + sufHalf;
   if (isEmail(email)) {
   return email;
 }
  }
return null;
}

 /**
 * Determine whether it is a legitimate email
* email Email address
/** * email address
public static boolean isEmail(String email) {
 try {
   if (email==null || ()<1 || ()>256) {
   return false;
 }
   
String check = "^([0-9a-zA-Z]+[_.0-9a-zA-Z-]+)@([a-zA-Z0-9-]+[.])+([a-zA-Z]{2,3})$";
 Pattern regex = (check);
 Matcher matcher = (email);
  boolean isMatched = ();
 if(isMatched) {
   return true;
 } else {
  return false;
 }
 } catch (RuntimeException e) {
 return false;
  } 
 }
 
 /**
  * Determine whether the character is legal or not
 * c Characters to be judged
 */
public static boolean isLetter(String c) {
 boolean result = false;
 if (c==null || ()<0) {
  return false;
 }
 //a-z 
 if (("a")>=0 && ("z")<=0) {
  return true;
 }
 //0-9
 if (("0")>=0 && ("9")<=0) {
 return true;
 }
 //. - _
 if ((".") || ("-") || ("_") ) {
 return true;
}
 return result; 
 }