Unit 1 Primitives

Notes

Primitative Types include
Boolean (true/false), one bit
Int (integer values), 2-3 bits
Double (Decimal values) 64 bits
Short, Byte, Floats, Char
Operators include
/+ is addition
/- is subtraction
/ is division
is modulus (remainder)
/* is multiplication
++ ex ++x is x=x+1
-- ex --x is x= x-1
+= ex x+=3 is x=x+3
-=ex x-=3 is x=x-3
Compound assignment operators (+=. -=) can be used in place of regular assignment operators
++ and -- are increase and decrease operators

public class CompOpsDemo {
    public static void main(String[] args) {
        int x = 6;
        x += 7;
        x -= 7;
        x *= 3;
        x /= 5;
        x %= 3;
    }
}

Practice

import java.util.Scanner;
public class testScoreApp {
 
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
       
 
 
       {
           // display operational messages
           System.out.println("Please enter test scores that range from 0 to 100.");
           System.out.println("To end the program enter 999.");
           System.out.println();  // print a blank line
 
           // initialize variables and create a Scanner object
            
           Scanner sc = new Scanner(System.in);
           String choice = "y";
 
           // get a series of test scores from the user
           while (!choice.equalsIgnoreCase("n"))
           {
               int scoreTotal = 0;
               int scoreCount = 0;
               int testScore = 0;
               System.out.println("Enter the number of test score to be entered: ");
               int numberOfTestScores = sc.nextInt();
 
               for (int i = 1; i <= numberOfTestScores; i++)
               {
                    // get the input from the user
                    System.out.print("Enter score " + i + ": ");
                    testScore = sc.nextInt();
 
                    // accumulate score count and score total
                    if (testScore <= 100)
                    {
                         scoreCount = scoreCount + 1;
                         scoreTotal = scoreTotal + testScore;
                     
                      
                    }
                    else if (testScore > 100) 
                 System.out.println("Invalid entry, not counted");
                     
 
 
                }
                double averageScore = scoreTotal / scoreCount;
                String message = "\n" +
                     "Score count:   " + scoreCount + "\n"
                   + "Score total:   " + scoreTotal + "\n"
                   + "Average score: " + averageScore + "\n";
                System.out.println(message);
                System.out.println();
                System.out.println("Enter more test scores? (y/n)");
                choice= sc.next();
          }
 
 
 
    // display the score count, score total, and average score
 
 
 
    }
}
    }

Unit 2 Objects

Notes

Object-oriented programming, refered to as OOP, is a programming paradigm that organizes software design around objects allowing data to operate and be bound together
Classes are a template from which objects are created. Objects created under the same class will share common methods and attributes.
Objects are instances of a class.
Methods, or functions, are a set of code that perform a specific task.
Ex: class vegetables would have objects carrot, tomato, etc.
Class attributes (which the objects will inherit) could be calorie count, quantity, or other values relevant to the class
Methods of the class would be actions relevant to the class like consume or save
Classes in Java can contain data members, methods, constructors, nested classes, and interfaces.
To initialize an object, you would use a class constructor
Defining and calling methods is advantageous because it allows for code reuse, optimization, and organization.
Calling a method: methodName(parameter1, parameter2);
Calling an object's method: objectReference.methodName(parameter1, parameter2);

Examples

Painter myPainter = new Painter(); //Object initialized by calling a constructor


public int max(int x, int y) // modifier, return-type, method=name, parameter-list
{
    if (x>y)
        return x;
    else 
        return y;
}


methodName(parameter1, parameter2); //Calling a method
objectReference.methodName(parameter1, parameter2); //Calling an object's method

Practice

Creating a class w/ a method

public class Science { // class created
    
    public void printTypes(){   // method
        System.out.println("Physics");
        System.out.println("Astrology");
        System.out.println("Chemistry");
        System.out.println("Biology");
    }

    public static void main(String[] args){  // main class that runs
        Science myObject = new Science();    // creating an object from class
        myObject.printTypes();    
    }   

}

Science.main(null);

Physics
Astrology
Chemistry
Biology

Inheriting a Class

public class ScienceTypes extends Science{  // extending class
    public ScienceTypes(){    // new class now has all the old class attributes
    }

    public static void main(String[] args){  // main class
        ScienceTypes mySecondObject = new ScienceTypes();    // creates an object from the new class
        mySecondObject.printTypes();      // reference methods and attributes from the inherited class
    }
}

ScienceTypes.main(null);

Physics
Astrology
Chemistry
Biology