Variables store values within methods and can change as the method processes data. There are different types of variables such as local variables, which only maintain their value within the block of code they are declared in. Operators are symbols that perform actions in a program, such as assignment (=), mathematical (+,-,*,/), and relational (<,>,==,!=) operators. Constants are variables designated with the final keyword that have a fixed value that cannot be changed.

1. Inside Class Methods
Chapter 4

2. 4
What are variables?
Variables store values within methods
and may change value as the method
processes data.

3. 4
Variables
The scope of a variable determines
how long it holds its value.
Local variables maintain their scope
within the block of code in which they are
declared.
Local variables are not fields of the class.

4. 4
Declaring and Initializing Variables
Declare a variable by identifying its
type and the identifier (name):
double averageSpeed;
Initialization is when you declare a
variable and assign it a value at the
same time:
double averageSpeed = 21.6;

5. 4
What are operators?
Operators are symbols that take action
within a program.
Assignment operator (=) assigns a value
to a field or variable:
averageSpeed = 21.6;
Mathematical operators include:
+, -, *, and /
Relational operators include:
<, >, ==, and !=

6. 4
A Self-Assignment Operator
Manipulates a variable and assigns the
results back to itself.
Self-assignment operators include +=, -=,
*=, and %=
int x = 5;
int y = 6;
x += y;
x has the value (5 + 6) = 11

7. 4
Precedence
Java follows mathematical rules of
precedence.
Multiplication and division are handled
first, followed by addition and subtraction
Use parentheses to force evaluation

8. 4
Increment and Decrement Operators
The increment operator (++) means
increment (add) by one.
++x;
The decrement operator (--) means
decrement (subtract) by one.
--x;

9. 4
Prefix vs. Postfix
Prefix notation increments, then fetches:
int x = 5;
int y = ++x;
Value of y is 6 (1 + 5), value of x is 6
Postfix notation fetches, then increments:
int x = 5;
int y = x++;
Value of y is 5, value of x is 6

10. 4
What is a constant?
A constant is a variable with a fixed
value (cannot be changed).
Use the keyword final to designate a
constant.
Constant identifiers are typically
UPPER_CASE notation to distinguish
them from other variables.

11. 4
Relational Operators
Evaluate the equality or inequality of
two intrinsic types.
Return a boolean value (true or false)
Equality: ==
Inequality: <, >, <=, >=, != (not equal)