int = integer(number)
String = text, usually declared with 2 double qoute "text"
Double = number with decimals
char = character,usually declared with 2 single qoute 'a' (Letters a-z, numbers 0-9)

Declaration of variables

int (var name) = Integer.parseInt(br.readLine());
String (var name)=br.readLine();
Double (var name) =Double.parseDouble(br.readLine());
char (var name) = br.readLine();