Initial Commit

CS3 - Demo/Main.java

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+import java.util.Scanner;
+
+/*
+    CS3 Demo
+
+    Variables and Basic Math
+    This demo goes over how to store values in variables. 
+    These values can be predefined in your code, come from 
+    mathematical and other types of operations, or be collected
+    from the user in some way. This demo also covers general 
+    math operations in Java
+*/
+public class Main {
+    public static void main(String[] args) {
+
+        //Below are some examples of program defined variables. Variables
+        //that you would set up in your code, and use elsewhere. There are 4 different
+        //types of variables here, all capable of storing different things. 
+        //String = Text, int = Whole Numbers, double = decimal (real) numbers, boolean = true/false
+        //These are common variable types that you'll use in every Java program, but
+        //there are many other types of variables. Scanner, as we have also seen, is
+        //a type of variable. 
+        //Notice the yellow lines under the variable names, this is just VSCode letting 
+        //us know that the variables we've defined are never used, and therefore not needed
+        //They are here only for an example
+        String someString = "Some string value";
+        int lifeUniverseEverything = 42;
+        double someDouble = 2.22;
+        boolean bananasAreGood = true;
+
+        //Below are several examples on how to retrieve different types of values from the
+        //user. Strings, ints, booleans, and doubles can be grabbed using there appropriate
+        //method, nextLine for Strings, nextInt for ints, nextBoolean for booleans, and
+        //nextDouble for doubles. Each of these values are stored separately and then
+        //reprinted down below to the user. 
+        //Notice how we can use the plus sign to combine other data types with Strings
+        //to be printed. Java is smart enough to know that those values need to be
+        //converted to String in order to combine properly. Just be careful, there 
+        //are scenarios were this won't work. 
+        Scanner scan = new Scanner(System.in);
+
+        System.out.print("Enter a string: ");
+        String string = scan.nextLine();
+
+        System.out.print("Enter a integer: ");
+        int intValue = scan.nextInt();
+
+        System.out.print("Enter a true/false value: ");
+        boolean booleanValue = scan.nextBoolean();
+
+        System.out.print("Enter a double value: ");
+        double doubleValue = scan.nextDouble();
+
+        System.out.println("The values you entered");
+        System.out.println("String: " + string);
+        System.out.println("Integer: " + intValue);
+        System.out.println("Boolean: " + booleanValue);
+        System.out.println("Double: " + doubleValue);
+
+        //Below common math operations are displayed, you should be familiar with 
+        //addition, multiplication, subtraction, and division already. But you may 
+        //not be familiar with modulous or remainder operations (the % sign operation).
+        //This divides two integers (NOT DOUBLES) and rather than return the division result
+        //it returns the remainder, so rather than 5 / 3 = 1, you have 5 % 3 = 2
+        //Notice that the math operations are encased in parenthesis inside the 
+        //call to System.out.println, this is done to ensure Java's automatic String combination
+        //mechanism doesn't get confused, and that our math operations are performed
+        //before trying to combine the result with the rest of the String. 
+        System.out.print("Enter the first double value: ");
+        double firstNumber = scan.nextDouble();
+
+        System.out.print("Enter the second double value: ");
+        double secondNumber = scan.nextDouble();
+
+        System.out.println("" + firstNumber + " + " + secondNumber + " = " + (firstNumber + secondNumber));
+        System.out.println("" + firstNumber + " - " + secondNumber + " = " + (firstNumber - secondNumber));
+        System.out.println("" + firstNumber + " * " + secondNumber + " = " + (firstNumber * secondNumber));
+        System.out.println("" + firstNumber + " / " + secondNumber + " = " + (firstNumber / secondNumber));
+        System.out.println("" + (int)firstNumber + " % " + (int)secondNumber + " = " + (((int)firstNumber) % ((int)secondNumber))); 
+    
+        scan.close();
+    }
+}