Lecture 2

Fall 2018

Narges Norouzi

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

Constants

Primitive data types

  • Data type is a set of values and operations defined on those values

  • Integers

 

  • Floating points

 

  • Characters

 

  • Boolean

 

  • Void
  • int, short, byte, long

 

  • float, double

 

  • char

 

  • boolean

 

 

categories

  • Variable: A name that refers to a value

​

  • 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

5 minutes break

  • +: add
  • ++: increment
  • +=: addition assignment
  • -: subtract
  • --: decrement
  • -=: subtraction assignment
  • *: multiply
  • ​*= multiply assignment
  • /: divide
  • /=: division assignment
  • %: modulus
  • %=: modulus assignment

Arithmetic Operators

A Simple Code

  • &: logical and
  • &&: short-circuit and
  • |: logical or
  • ||: short-circuit or
  • !: logical not
  • ==: equal to
  • !=: not equal to
  • ^: logical xor

Boolean Operators

Warning

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

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(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

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Zybooks chapters

  • Chapter 1 (some sections)
  • Chapter 2 (some sections)

Questions?