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## PowerPoint Slideshow about 'Inside Class Methods' - peri

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Presentation Transcript

What are variables?

- Variables store values within methods and may change value as the method processes data.

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.

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;

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 !=

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

Precedence

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

Increment and Decrement Operators

- The increment operator (++) means increment (add) by one.
- ++x;
- The decrement operator (--) means decrement (subtract) by one.
- --x;

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

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.

Relational Operators

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

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