warm-up: monday, march 24
DESCRIPTION
Warm-Up: Monday, March 24. List as many commands in Java as you can remember (at least 10) . Review. PAP Computer Science Cycle 5. Output. System.out.print ( ) System.out.println ( ) Escape sequences \n newline \t tab \\ backslash \’ single quote - PowerPoint PPT PresentationTRANSCRIPT
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);
}