Warm-Up: Monday, March 24

Warm-Up: Monday, March 24

List as many commands in Java as you can remember (at least 10)

ReviewPAP Computer Science

Cycle 5

OutputSystem.out.print( )System.out.println( )

Escape sequences\n newline\t tab\\ backslash\’ single quote\” double quote

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

Declaring/Initializing a Variable

Example 1

int x;

x = 5;

Example 2

int x = 5;

Java Programming: Guided Learning with Early Objects 6

Input (Read) StatementThe Scanner class puts data into variables from the

standard input device static Scanner console = new Scanner(System.in);

Next input is: Integer: console.nextInt()Double: console.nextDouble()String: console.next()or console.nextLine()

Math Methodsabs(x) – absolute value

abs(-96.5) 95.6ceil(x) – ceiling operator

ceil(54.13) 55floor(x) – floor operator

floor(54.13) 54exp(x) – returns ex

exp(3) e3 20.0855369232

Math Methodslog(x) – natural logarithm (base e) of

x

log(2) ln(2) 0.69314718056log10(x) – base-10 logarithm of x

log10(100) log10(100) 2.0

max(x,y) – maximum of two numbers

max(15, 25) 25min(x,y) – minimum of two numbers

min(3, 4) 3

Math Methodspow(x,y) – returns xy

pow(2,3) 23 8round(x) – rounds x to the nearest

whole #

round(34.4) 34

round(34.7) 35sqrt(x) – square root of a number

sqrt(121) √121 11

String MethodsString.length( ) – returns the length of

the string (how many letters long it is)String word = “dog”; word.length( ) 3

String.toLowerCase( ) – changes all capital letters to lowercaseString word = “HAHA”; word.toLowerCase( ) “haha”;

String.toUpperCase( ) – changes all lowercase letters to capital lettersString word = “kitty”; word.toUpperCase( ) “KITTY”

More String MethodsString.charAt(x) – returns the letter at

position x in the StringString word = “happy”;word.charAt(2) ‘p’;

String.replace(x,y) – replaces each instance of character ‘x’ with character ‘y’String word = “happy”;word.replace(‘p’,’ r’) “harry”

indexOf( ) indexOf(char) – returns the index, or list

location, of the first instance of letter char String word = “happy”; word.indexOf(‘h’) 0

indexOf(str) – returns the index, or list location, of the first instance of a String str String name = “Alexander”; name.indexOf(“and”) 4

Note: Both of these commands will return -1 if the character or String is not found

String.substring( )String.substring(x, y) – Converts the

characters between list location x of the String (inclusive) and list location y of the String (exclusive) into a new String

String word = “Spring Break”;

word.substring(0,6) “Spring”word.substring(7, 12) “Break”word.substring(3, 9) “ing Br”

TODAYIF YOU ARE MISSING WORK…USE THIS

TIME TO COMPLETE SOME OF YOUR MISSING WORK

IF YOU ARE NOT MISSING WORKcodingbat.com/javaComplete codes within any section

(though String-1 will likely be the easiest)

1 ML:A pass per SECTION STAR completed

Warm-Up: Tuesday, March 25

Give an example of a program that would require you to use an IF statement

EXAMPLE: Output the phrase “Be sure to wear a jacket” if the temperature is less than 55°

IF StatementsPAP Computer Science

Cycle 5

IF Statements

IF statements are used to add branching structure to your codes

They are used to make decisions

Branching Structures

?

Task A Task B

YES NO

IF Statement: Structure

if (condition)

{

//statements

}

STATEMENTS ARE ONLY EXECUTED IF THE CONDITION IS TRUE

Conditions

Conditions evaluate a state or compare two or more numbersWhile the code is runningIf x is greater than yIf the remainder is equal to 0While x + y is less than 7

Conditional OperatorsLess than (<)Greater than (>)Equal to (==)Less than or equal to (<=)Greater than or equal to (>=)Not equal to (!=)

English to Codex is greater than y

x > yx plus y is less than 7

x + y < 7x is an even number

x % 2 == 0the number does not equal our target

number != target

Using Conditions with IF Statements

If the temperature is below 55, output that the user needs a jacket

if (temp < 55)

{

System.out.println(“Bring a jacket!”);

}

Warm-up: Thursday, Mar 27

Write an IF statement for the following:

Given two numbers num1 and num2, output the sum of the numbers ONLY IF the sum is less than 10.

Warm-up: Thursday, Mar 27

Write an IF statement for the following:

Given two numbers num1 and num2, output the sum of the numbers ONLY IF the sum is less than 10.

double sum = a+b;

if (sum < 10) {

System.out.println(sum);

}

Review: IF StatementsUsed to add branching structure to codesMake decisionsAnswer questions

if (condition) {

//statements;

}

Review: Conditional Operators

Less than (<)Greater than (>)Equal to (==)Less than or equal to (<=)Greater than or equal to (>=)Not equal to (!=)

IF-ELSE StatementsUsed for situations with two possible

outcomesNoted by the keyword “otherwise”

ExamplesIf it’s sunny, wear shorts; otherwise, wear

jeansIf it’s a weekday, set the alarm for 7:00,

otherwise, turn off the alarm

IF-ELSE Statement: Structure

if (condition) {

//statements;

}

else {

//statements;

}

*NOTE: There is NO condition after else

Example: IF-ELSEif (weather==“sunny”) {

System.out.println(“Wear shorts”);

}

else {

System.out.println(“Wear jeans”);

}

EVEN MORE BRANCHING!Sometimes, you need EVEN MORE than 2

outcomesFor these situations, you use IF – ELSE-IF –

ELSE statements

ExamplesIf you like dogs, buy a dog, but if you like

cats, but a cat; otherwise, get a different pet.

If your number is divisible by 5, output 1, but if your number is divisible by 7, output 2; otherwise, output 0.

IF – ELSE-IF – ELSE Structure

if (condition1) {

//statements;

}

else if (condition2) {

//statements;

}

else {

//statements;

}

Example IF – ELSE-IF – ELSE

if (num % 5 == 0) {

System.out.println(1);

}

else if (num % 7 == 0) {

System.out.println(2);

}

else {

System.out.println(0);

}

ELSE-IF’s

You can have as many ELSE-IF’s in an IF statement as you want, but you can only have

ONE IF and ONE ELSE

OKAYif ( …) {

}

else if (…) {

}

else if (…) {

}

else {

}

NOT OKAYif ( …) {

}

else if (…) {

}

else {

}

else {

}

OKAY…but it doesn’t mean the same thing…

if ( …) {

}

if (…) {

}

else if (…) {

}

else {

}

OKAY…but it doesn’t mean the same thing…

if ( …) {

}

if (…) {

}

else if (…) {

}

else {

}

Warm-Up: Friday, Mar 28

Write an IF statement for the following situation:

Given two numbers, a and b, output the sum; unless the sum is greater than 20, then output the number 20.

Warm-Up: Thursday, Mar 26

Given two numbers, a and b, output the sum; unless the sum is greater than 20, then output the number 20.

sum = a+b;

if (sum > 20) {

System.out.println(20);

}

else {

System.out.println(sum);

}