We use identifiers to name code entities, such as classes, variables, and methods.
An identifier can be sequence of uppercase and lowercase letters, numbers, or the underscore and dollar-sign characters.
They must not begin with a number.
Java identifiers is case-sensitive, so VALUE is a different identifier than Value.
Some examples of valid identifiers are
AvgValue count c1234 $test this_is_a_value
Invalid identifier names include these:
2count //cannot start with digit high-temp //cannot have - Not/ok //cannot have /
The use of an underscore by itself as an identifier is not recommended.
public class Main { public static void main (String[] args) { boolean BooleanVal = true; /* Default is false */ char charval = 'G'; /* Unicode UTF-16 */ charval = '\u0490'; /* Ukrainian letter Ghe(?) */ byte byteval; /* 8 bits, -127 to 127 */ short shortval; /* 16 bits, -32,768 to 32,768 */ int intval; /* 32 bits, -2147483648 to 2147483647 */ long longval; /* 64 bits, -(2^64) to 2^64 - 1 */ float floatval = 10.123456F; /* 32-bit IEEE 754 */ double doubleval = 10.12345678987654; /* 64-bit IEEE 754 */ String message = "Darken the corner where you are!"; message = message.replace("Darken", "Brighten"); } // w w w.j a va 2 s.c o m }