Identifiers and Literals
Identifier
An Identifier is needed to name a variable.
An identifier is sequence of character, of any length, comprising uppercase and lowercase letters (a-z
, A-Z
), digits (0-9z
), underscore _
and dollar sign $
.
Java imposes the following rules on identifiers
- White space (
blank
, tab
, newline
) and other special characters (such as +
, -
, *
, /
, @
, &
, commas
, etc.) are not allowed.
- An identifier must begin with letter (
a-z
, A-Z
) or underscore (_
).
- It cannot begin with digits (
0-9
).
- Identifiers begin with dollar sign
$
are reserved for system-generated entities. So, you can not use it.
- An identifier cannot be a reserved keyword or a reserved literals (e.g.
class
, int
, double
, if
, else
, for
, true
, false
, null
).
- Identifiers are case sensitive. A Tutorialink is not same as TUTORIALINK and tutorialink.
Literals
- A literal is a specific constant value or raw data, such as 123, -456, 3.14, 'a', "hello", that is used in the program source.
- They are called literals because they literally and explicitly identify their values.
- It can be of any Java data types.
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