# Inside Class Methods - PowerPoint PPT Presentation

1 / 11

Chapter 4. Inside Class Methods. 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.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Inside Class Methods

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Chapter 4

## Inside Class Methods

### 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)