Variables are containers for storing data values.
Declaring (Creating) Variables
To create a variable, you must specify the type and assign it a value:
|
|
where type is one of Java’s types (such as
int or String), and variable is the name of the variable (such as x or name).
The equal sign is used to assign values to the variable.
To create several variables that store integers, look at the following example:
|
|
Identifiers
All Java variables must be identified with unique names. These unique names are called identifiers. Identifiers can be short names (like
x and y) or more descriptive names (age, sum, and totalVolume).
The general rules for constructing names for variables (unique identifiers) are
- Names can contain letters, digits, underscores, and dollar signs,
- Names should begin with a letter,
- Names can also begin with
$and_, - Names are case sensitive (
myVarandmyvarare different variables), - Names should start with a lowercase letter and it cannot contain whitespace, and
- Reserved words (like Java keywords, such as
intorString) cannot be used as names.
| Review: Identifier.java (checking identifier names) |
public class Identifier {
public static void main( String[ ] args ) {
int this = 2; // correct incorrect
Integer that = 2; // correct incorrect
short _under; // correct incorrect
byte 1UND; // correct incorrect
String str@ = "Hello"; // correct incorrect
boolean Bool; // correct incorrect
Float number; // correct incorrect
}
}
|
| Result: |