Question

I want to perform the following functionality :

From a given paragraph extract the given String, like

String str= "Hello this is paragraph , [e-mail] . i am entering  random  email here as this one  [e-mail] " ; 

What I have to do is to parse the whole paragraph, read the Email address, and print their server names , i have tried it using for loop with substring method , did use indexOf , but might be my logic is not that good to get it , can someone help me with it please?

Answer 1

You need to use Regular Expression for this case.

Try the below Regex: –

String str= "Hello this is paragraph , [e-mail] . i am " +
            "entering  random  email here as this one  [e-mail] " ;

Pattern pattern = Pattern.compile("@(\\S+)\\.\\w+");
Matcher matcher = pattern.matcher(str);
while (matcher.find()) {
     System.out.println(matcher.group(1));
}

OUTPUT: –

yahoo
gmail

UPDATE: –

Here’s the code with substring and indexOf: –

   String str= "Hello this is paragraph , [e-mail] . i am " +
        "entering  random  email here as this one  [e-mail] " ;

   while (str.contains("@") && str.contains(".")) {

        int index1 = str.lastIndexOf("@");  // Get last index of `@`
        int index2 = str.indexOf(".", index1); // Get index of first `.` after @

        // Substring from index of @ to index of .      
        String serverName = str.substring(index1 + 1, index2);
        System.out.println(serverName);

        // Replace string by removing till the last @, 
        // so as not to consider it next time
        str = str.substring(0, index1);

    }