Warm-up: Monday, February 24

+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?

+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? print( ) stays on the same line println( ) will go to the next line

+

Arithmetic OperatorsPAP Computer Science, Cycle

5

+8 Mathematical Operators Addition (+)Subtraction (-)Multiplication (*)Division (/)Modulus (%)Exponent (^) Increment (++)Decrement (--)

+Addition, Subtraction, MultiplicationThese operators work identically in

programming as in traditional math

5 + 8 1310 – 4 64 * 3 12

+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 5.5

+Modulus (%)Modulus returns the remainder from

divisionExample: 26 % 5 1 26 / 5 5

+Incrementing (++)

Increases the value of a variable by 1

Exampleint x = 5;x++;System.out.print(x) 6

+Decrementing (--)

Decreases the value of a variable by 1

Exampleint x = 5;x--;System.out.print(x) 4

+Pre- and Post-Incrementing When incrementing/decrementing, you can

put the operator before or after the variable

Exampleint x = 5; int y = 5;x++; ++y; x 6 y 6

+Pre- and Post-IncrementingExample:

int x = 5;int y = x++;

x 6 y 5Example:

int x = 5;int y = ++x;

x 6 y 6

+Order of Operations

( ) •Parenthesis

++ --

•Increment•Decrement

^ •Exponents

* / %•Multiplication•Division•Modulus

+ - •Addition•Subtraction

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

21 – 6 + 2 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

21 – 6 + 2 + 6

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

21 – 6 + 2 + 615 + 8

+OOO Example

3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6

21 – 6 + 2 + 615 + 8

23

+Warm-up: Tuesday, Feb 25

What does the % operator return?

int x = 6;x++;

What does ‘x’ equal now?

+

Creating Variables

PAP Computer Science, Cycle 5

+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;

+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 variable

+Declaring/Initializing a VariableExample 1

int x;x = 5;

Example 2int x = 5;

+Initializing a Variable

Variable name ALWAYS goes on the left

x = 5 NOT 5 = x

y = xSets y to whatever is stored in x

+Naming a VariableNames in Java must follow certain rules

Naming conventions hold true for variables, methods, classes, etc

1. Cannot be a reserved word int, float, double, char, void, public, static,

return2. Can only consist of letters, numbers, _, $3. Cannot begin with a number4. Case sensitive

X != x VAR != var Test != test

+Legal Identifiers

Variablestrnum_of_books$Amount integer3convert2fahr

+Illegal Identifiers (Names)employee salary

Spaces are not allowedHello!

! is not allowedone+two

+ is not allowed2nd

Cannot begin an identifier with a number

+Data TypesData types refer to the type of data that

will be stored in the variableLets 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)

+Int, Short, LongUsed 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) -263 to 263

+Float and DoubleUsed for decimal point numbers

Float (32 bits) -3.4 x 1038 to 3.4 x 1038

6 to 7 digits of precision (decimal places)Double (64 bits)

-1.7 x 10308 to 1.7 x 10308

15 digits of precision (decimal places)

+Byte, Char, BooleanByte (8 bits)

Used for binary bytes (B11001101)

Char (16 bits) Used for characters (‘A’)

Boolean (1 bit) True or false

+ Using Variables in Codepublic 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);

}

}

+Warm-up: Wednesday, Feb 26Write the code to declare a variable

named “number” that contains the number 45.46

+

Strings

PAP-Computer Science, Cycle 5

+Strings

List of multiple charactersAlso known as

Character array Character string String literal String constant

In Java, String is a special class

+String ClassAs a class, a String has certain properties

and methodsProperties

Length – how many letters in the String? Letter position

Methods compareTo startsWith endWith

+Declaring Strings

Works much the same way as declaring any other variable

Needs data type and a nameValue is optional

+Declaring a String

String name = “Ms. Alexander”;

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

String weather = “It is sunny outside.”;

+Example Code - Stringspublic class Example

{

public static void main(String[] args)

{

int value = 56;

String str = “Your value is “;

System.out.println(str + value);

}

}