Splitting a comma separated string through serial (Arduino)

void setup(){
    Serial.begin(9600);
}
void loop(){
    String first  = Serial.readStringUntil(',');
    Serial.read(); //next character is comma, so skip it using this
    String second = Serial.readStringUntil(',');
    Serial.read();
    String third  = Serial.readStringUntil('\0');
    //parse your data here. example:
    //double x = Double.parseDouble(first);
}