# Constants

In this lesson, we will look at constants, values in a program that do not change.

## We'll cover the following

Numeric, character, string, or Boolean values within a Java program that remain unchanged, or constant, during program execution can either have a name or be unnamed.

## Unnamed constants

Earlier, we defined a *literal* as the Java representation of a specific fixed value, that is, a value that does not change. They are, in fact, **unnamed constants**. Literals conform to certain rules according to their data type:

- Integer literals are a sequence of digits without a decimal point or commas but can have a plus or minus sign. For example, 10 and –52 are integer literals.
- Floating-point literals are real numbers without commas but can have a plus or minus sign. They are written in one of two ways:
**Without an exponent**but with a decimal point. For example,`3.14`

,`0.07`

, and`-50.0`

are floating-point literals.**With an exponent**. For example, in mathematics, we might write`0.00001234`

as`12.34 × 10`

. In Java, we could write this value as^{–6}`12.34e-6`

. The letter`e`

, which means “exponent”, represents both the multiplication operator and the`10`

. The number after the`e`

is an integer without a decimal point or comma. A plus sign is optional for positive exponents.- We can omit the decimal point in the number before the
`e`

, as long as we adjust the exponent to produce the correct value.

- Character literals are single characters enclosed in single quotes.
- String literals are sequences of characters enclosed in double quotes.
- Boolean literals are the values
`true`

and`false`

.

Get hands-on with 1200+ tech skills courses.