Inside Class Methods

1. Chapter 4 Inside Class Methods

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

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

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

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