Warm-up: Monday, February 24 - PowerPoint Presentation

Slide1

Warm-up: Monday, February 24

In outputting, what does “\n” do?

In outputting, what is the difference between the

System.out.print

( ) command and the

Serial.out.println

( ) command? Slide2

Warm-up: Monday, February 24

In outputting, what does “\n” do?

Goes to the next line; like hitting “enter”

In outputting, what is the difference between the

System.out.print

( ) command and the

Serial.out.println

( ) command?

p

rint( ) stays on the same line

p

rintln

( ) will go to the next lineSlide3

Arithmetic Operators

PAP Computer Science, Cycle 5Slide4

8 Mathematical Operators

Addition (+)

Subtraction (-)

Multiplication (*)

Division (/)

Modulus (%)

Exponent (^)

Increment (++)

Decrement (--)Slide5

Addition, Subtraction, Multiplication

These operators work identically in programming as in traditional math

5 + 8

 13

10 – 4  6

4 * 3  12Slide6

Division

Works differently for integers (whole numbers) and decimals

If operands are integers, the answer will be an integer

If operands are decimals, the answer will be a decimal

11 / 2

 5

11.0 / 2.0  5.5Slide7

Modulus (%)

Modulus returns the remainder from division

Example: 26 % 5

 1 26 / 5  5Slide8

Incrementing (++)

Increases the value of a variable by 1

Example

int

x = 5;

x++;

System.out.print

(x)

 6Slide9

Decrementing (--)

Decreases the value of a variable by 1

Example

int

x = 5;

x--;

System.out.print

(x)

 4Slide10

Pre- and Post-Incrementing

When incrementing/decrementing, you can put the operator before or after the variable

Example

int

x = 5;

int

y = 5;

x++;

++y;

x

 6 y  6Slide11

Pre- and Post-Incrementing

Example:

int

x = 5;

int

y = x++;

x

 6 y  5

Example:

int

x = 5;

int

y = ++x;

x

 6 y  6Slide12

Order of OperationsSlide13

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6Slide14

OOO Example

3 * 7

– 6 + 2 * 5 / 4 + 6Slide15

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6Slide16

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 +

2 * 5

/ 4 + 6Slide17

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 + 10 / 4 + 6Slide18

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 +

10 / 4

+ 6Slide19

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 + 10 / 4 + 6

21 – 6 + 2 + 6Slide20

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 + 10 / 4 + 6

21 – 6

+

2 + 6Slide21

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 + 10 / 4 + 6

21 – 6 + 2 + 6

15 + 8Slide22

OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

21 – 6 + 2 * 5 / 4 + 6

21 – 6 + 10 / 4 + 6

21 – 6 + 2 + 6

15 + 8

23Slide23

Warm-up: Tuesday, Feb 25

What does the % operator return?

int

x = 6;

x++;

What does ‘x’ equal now? Slide24

Creating Variables

PAP Computer Science, Cycle 5Slide25

Variables

Variables are place-holders for values

Storage locations

They reference a single number, character, or String, and can be called by their name.

Example:

X = 5

Y = X + 5;Slide26

Declaring a Variable

Variables must be declared with two things:

Data type

Name

Initializing a variable (giving it a value) is NOT required when declaring a variableSlide27

Declaring/Initializing a Variable

Example 1

int

x;

x = 5;

Example 2

int

x = 5;Slide28

Initializing a Variable

Variable name ALWAYS goes on the left

x

= 5 NOT 5 = x

y = x

Sets y to whatever is stored in x

Slide29

Naming a Variable

Names in Java must follow certain rules

Naming conventions hold true for variables, methods, classes,

etc

Cannot be a reserved word

int

, float, double, char, void, public, static, return

Can only consist of letters, numbers, _, $

Cannot begin with a number

Case sensitive

X != x VAR !=

var

Test != test Slide30

Legal Identifiers

Variable

s

tr

n

um_of_books

$Amount

integer3

convert2fahrSlide31

Illegal Identifiers (Names)

employee salary

Spaces are not allowed

Hello!

! is not allowed

o

ne+two

+ is not allowed

2nd

Cannot begin an identifier with a numberSlide32

Data Types

Data types refer to the type of data that will be stored in the variable

Lets the computer know how much memory it needs to set aside for the variable

Data Types

Int

, Short, or Long (whole numbers)

Float or Double (decimals)

Byte (binary byte)

Char (single character)

Boolean (true/false)Slide33

Int, Short, Long

Used for whole numbers

Short (16 bits of memory)

-32,768 to 32,767

Int

(32 bits of memory)

-2,147,483,648 to 2,147,483,647

Long (64 bits of memory)

-2

63

to 2

63Slide34

Float and Double

Used for decimal point numbers

Float (32 bits)

-3.4 x 10

38

to 3.4 x 10

38

6 to 7 digits of precision (decimal places)

Double (64 bits)

-1.7 x 10

308

to 1.7 x 10

308

15 digits of precision (decimal places)Slide35

Byte, Char, Boolean

Byte (8 bits)

Used for binary bytes (B11001101)

Char (16 bits)

Used for characters (‘A’)

Boolean (1 bit)

True or falseSlide36

Using Variables in Code

public class Variables

{

public static void main(String[ ]

args

)

{

int

test1 = 90;

float test2 = 86.34;

int

test3 = 23;

float sum = test1+test2+test3;

System.out.println

(“Sum = “ + sum);

}

}Slide37

Warm-up: Wednesday, Feb 26

Write the code to declare a

variable named “number” that

contains the number

45.46Slide38

Strings

PAP-Computer Science, Cycle 5Slide39

Strings

List of multiple characters

Also known as

Character array

Character string

String literal

String constant

In Java, String is a special classSlide40

String Class

As a class, a String has certain properties and methods

Properties

Length – how many letters in the String?

Letter position

Methods

compareTo

startsWith

endWithSlide41

Declaring Strings

Works much the same way as declaring any other variable

Needs data type and a name

Value is optionalSlide42

Declaring a String

String name = “Ms. Alexander”;

String message = “Good luck on your test!”;

String weather = “It is sunny outside.”;Slide43

Example Code - Strings

public class Example

{

public static void main(String[]

args

)

{

int

value = 56;

String

str

= “Your value is “;

System.out.println

(

str

+ value);

}

}