Replace comma with newline in java

Simply use following code:

String emailList="AA,BB,CC";
emailList=emailList.replaceAll(",", "\n");
System.out.println(emailList);

Output

AA
BB
CC

Now based on above your code, your method looks like following:

public String getFormattedEmails(String emailList) {
String emails=emailList.replaceAll(",", "\n");
return emails;
}

Hope it helps:

String emails = emailList.replaceAll(",", "\n");

you can use Scanner too

String emails = "AA,BB,CC"
String emailsNew = replaceCommas(emails);

String replaceCommas(String a){
    StringBuilder result = new StringBuilder();
    Scanner scan = new Scanner(a);
    scan.useDelimiter(",");
    while(scan.hasNext()){
        result.append(scan.next());
        result.append("\n");
    }
    return result.toString();
}

System.out.println(emailsNew); will print:

AA
BB
CC