Warm-up: Tuesday, March 11

In programming, what is the difference between an object and a class?

Objects and ClassesPAP Computer ScienceCycle 5

Review: Output/Input Output

System.out.println( );

Input int number = console.nextInt( ); double decimal = console.nextDouble( ); String word = console.next( );

Classes Characterize an object

Category of information used to collect and contain properties/methods for related pieces of information

Objects are one instance of that class

Example Class: Superheroes Class properties

Name, costume, colors, sidekick, main villain, powers, universe (Marvel vs DC)

Class methods Fly, use a super power, talk, rescue a

damsel in distress Object instances

Superman, Spiderman, Wolverine, Flash

Jeroo Connection Class properties

how many flowers is it holding, what direction is it facing

Class methods hop( ), plant( ), pick( ), toss( ), turn( ),

give( ) Object instances

Jeroo bobby = new Jeroo

Classes We’ve Seen So Far String

String word = “some text”;

Scanner static Scanner console = new

Scanner(System.in)

Creating an Object Recall…an object is an instance of a

class

Standard format:Class name = new Class(parameters)

Example:Jeroo bobby = new Jeroo(2);

Keyword New The keyword new is used when creating

objects

It sets aside memory in the computer for the object

It only has to be used once per object creation, much like declaring a variable

Using an Object – Dot Operator

To access the properties and methods associated with a class, you first type the name of your object, followed by a dot (.), then put the command you want to run

Jeroo bobby = new Jeroo( ); //create objectbobby.hop( ); //use the object

Examples

static Scanner console = new Scanner(System.in);

int number = console.nextInt( );

String name = “Spring Break”;int length = name.length( );

float circumference = 2*radius*Math.PI

Review Classes are a way to bundle the

properties and methods of related information.

Class objects are instances of a class. Use the operator new to create a class

object. In Java, the dot (.) separates the object

name from the property or method name

Warm-Up: Wednesday, March 12

What is the difference between class properties and class methods?

Class MathCycle 5Week 4

Review Classes are a way to bundle the

properties and methods of related information.

Class objects are instances of a class. Use the operator new to create a class

object. In Java, the dot (.) separates the object

name from the property or method name

Math Operators Basics

Addition (+) Subtraction (-) Multiplication (*) Division (/) Modulus (%)

Other math functions must be accessed using the Math class

Using class Math The class Math is stored within the

java.lang package

At the beginning of each code, be sure to add the following line:

import static java.lang.Math.*

This allows you to drop the Math. prefix when using Math methods and constants

Math Constants Math.E = 2.718281828459045

Math.PI = 3.141592653589793

Math Methods abs(x) – absolute value

abs(-96.5) 95.6

ceil(x) – ceiling operatorceil(54.13) 55

floor(x) – floor operatorfloor(54.13) 54

exp(x) – returns ex

exp(3) e3 20.0855369232

Math Methods log(x) – natural logarithm (base e) of x

log(2) ln(2) 0.69314718056

log10(x) – base-10 logarithm of xlog10(100) log10(100) 2.0

max(x,y) – maximum of two numbersmax(15, 25) 25

min(x,y) – minimum of two numbersmin(3, 4) 3

Math Methods pow(x,y) – returns xy

pow(2,3) 23 8

round(x) – rounds x to the nearest whole #round(34.4) 34 round(34.7) 35

sqrt(x) – square root of a numbersqrt(121) √121 11

import static java.lang.Math.*;public class MathProblems { public static void main(String[] args) {int x = pow(10, 3);System.out.println(“10^3 = “ + x);

int m = max(24, 67);System.out.println(“Max of 24 and 67 = “ + m);

double a = 2*PI*4;System.out.print(“Area of a circle with radius ”);System.out.print(“of 4 = “ + a); }}

Warm-up: Thursday, March 13 What class are each of these packages

associated with?

a. java.util.*

b. javax.swing.*

c. java.lang.Math.*

Warm-up: Thursday, March 13 What class are each of these packages

associated with?

a. java.util.*Scanner

b. javax.swing.*JOptionPane (pop-up boxes)

c. java.lang.Math.*Math

Class StringCycle 5Week 4

Strings - Review Class used to manipulate character

arrays, or words

Declared like variables String name = “Alexander”;

Can be combined using the + operator String break = “Spring ” + “break”;

String Methods String.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 lowercase String word = “HAHA”; word.toLowerCase( ) “haha”;

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

Strings as Lists Strings are essentially a list of letters Strings are indexed just like lists String indices begin counting at 0

String word = “happy”;word[0] = ‘h’word[1] = ‘a’word[2] = ‘p’word[3] = ‘p’word[4] = ‘y’

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

position x in the String String 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”