APCSA Vocab

Week 1

• Objects have attributes which are characteristics of an object
• A class is the blueprint that objects are created from. Instantiating an object calls the constrcutor to create an object.

• A constructor is code that has the same name as the class and tells the computer how to create a new object

• Parameter: a variable in the method/constructor signature that defines the type of value to receive when the method or constructor is called
  • in the definition of a function
• Argument: a value passed to a method/constructor when the method or constructor is called
  • when calling the function

  # Collegeboard Unit Lessons

  Unit Lesson Notes from Class Presentations

• toc: true
• badges: true
• comments: true
• categories: [jupyter]
• image: images/acorn.png

  Unit 1: Primitive Types

• Primitives Example:

• GPA Calculator

• Primitive Types
  • Boolean
  • Numeric
    • Character
      • char
    • Integral
      • Integer
        • byte
        • short
        • int
        • long
      • FLoating-point
        • float
        • double
• Wrapper Classes (Non-Primitive)
  • String, Array, etc.
  • Like an object so has methods
• Additional W1 Notes:
  • Input
    • Scanner input;
    • input = new Scanner(System.in);
    • System.out.print("Enter an integer: ");
    • input.close();
  • Output
    • System.out.println();

      Unit 2: Using Objects

      Unit 3: Booleans Expressions and if Statements

Compound Boolean Expressions

• De Morgan’s Law - helps simplify boolean expressions
• !(a&&b)= (!a || !b)
• Truth tables to visualize Boolean identities

Comparing Objects

• use == to see if two obj references are aliases for the same obj or to see if an obj is null
• use .equals() to see if the attributes of two obj are the same

  Unit 4: Iteration

While Loops

• do something while a condition is true

int x = 5;

// The boolean expression in this case is x > 0 while (x > 0) { System.out.println(x); x–; }

• while loops can be used to iterate over elements int[] array = {3, 7, 0, 2, 4, 5, 9, 1, 3, 6, 3}; int total = 0; int i = 0;

while (i < array.length) { total += array[i]; i++; }

System.out.println(total);

• infinite while loops - run over and over permanently since boolean condition true at all times import java.util.Scanner;

Scanner input = new Scanner(System.in); String choice;

while (true) { System.out.println(“Would you like to continue: “); choice = input.nextLine(); if (choice.equals(“No”)) { break; } }

Unit 5 Writing Classes

• Class - blueprint to create objects
  • instance variables/attributes (data)
  • constructors
  • methods
    • accessors/getters
    • mutators/setters
    • main method (tester)
• Objects are instances of a class
• Methods are what an object can do
• public means it can be accessed outside the class
• private means its restricted to accessing it inside the class
• Constructors
  • initialize instance variables when an object is created public class Cow {

  // instance variables private String cowType; private String sound; private int numMilkings;

  // constructor public Cow (String cowType, String sound){ this.numMilkings = 0; this.cowType = cowType; this.sound = sound; }

  public String getSound(){ return sound; } }

public class CowDriver{ public static void main(String[] args) { Cow myCow = new Cow(“holstein”, “moo”); System.out.println(myCow.getSound()); // myCow.sound = “bark!”; } }

CowDriver.main(null); public class Song {

/** Verse - prints out a verse of the song

• @param number - a String like “one”, “two”, etc.
• @param rhyme - a String like “thumb”, “shoe”, etc. */ public void verse(String number, String rhyme) { System.out.println(“This old man, he played “ + number); System.out.println(“He played knick knack on my “ + rhyme); }

// The chorus method public void chorus() { System.out.println(“With a knick knack paddy whack, give a dog a bone.”); System.out.println(“This old man came rolling home.”); }

public static void main(String args[]) { Song mySong = new Song(); mySong.verse(“one”, “thumb”); mySong.chorus(); mySong.verse(“two”, “shoe”); mySong.chorus(); mySong.verse(“three”, “knee”); mySong.chorus(); mySong.verse(“four”, “door”); mySong.chorus(); } }

Song.main(null);

Unit 6 Arrays

• Arrays Team Lesson
• Traversing Arrays 6.2
• Team Lesson