This format is used for very large and very small numbers. Any numerical literal that contains a decimal point or exponential is a literal of type double . Even for integer literals, there are some complications. Ordinary integers such as 177777 and -32 are literals of type byte , short , or int , depending on their size. These literals are typed just as I've written them here, without quotes, but they represent values, not variables.
Boolean values occur most often as the values of conditional expressions.
Of course, boolean values can also be assigned to variables of type boolean . For the most part, we are not concerned with objects for the time being. A String is a sequence of characters. However, they are not part of the actual string value, which consists of just the characters between the quotes. Within a string, special characters can be represented using the backslash notation.