Lecture 2

Winter 2019

Charlie McDOWELL

Sample Code

A closer look

A closer look

A closer look

A closer look

A closer look

• Numerical Constants

 

• Characters

 

• String Literals

 

• Booleans

 

• Nill

• 1, 2.2, 0xFF, 1d

 

• ‘d’, ‘A’, '.'

 

• "", "Java", "B"

 

• true, false

 

• null

LITERAL VALUES

• Integers

 

• Floating points

 

• Characters

 

• Boolean

• int, short, byte, long

 

• float, double

 

• char

 

• boolean

 

 

primitive Types

• Variable: A name that refers to a value

• Declaration: Associates a type with a name creating a variable

• Assignment statement: Associates a value with a variable

Basic variable definition

A table of variable values after each statement

Trace

• Boolean Expression

 

• Assignment Expression

 

 

• j == i

 

• i = 2

 

Expressions

Integer

double

Boolean

• Blocks are defined with braces

• A block is the same as a single statement, Why?

• Sometimes we need to execute a group of statements in all or nothing manner

Blocks

• +: add
• ++: increment
• +=: addition assignment
• -: subtract
• --: decrement
• -=: subtraction assignment

• *: multiply
• ​*= multiply assignment
• /: divide
• /=: division assignment
• %: modulus
• %=: modulus assignment

Arithmetic Operators

A Simple Code

Boolean Operators

short circuit Evaluation

• If X is Zero, you will get DivisionByZero error from

​

(x != 0) & (1/x != 2)

 

• But you won’t get the error from

​

(x != 0) && (1/x != 2)

 

 

User Input

• Scanner class handles user input

• Need to import the class by:

​

• Scanner object takes input stream and will provide it upon request

​

Due Soon

• Lab 1 is due Thursday at 10pm
• ZyBooks Chapter 3 is due Monday at noon

Questions?