Staring with the canonical "Hello, World!" program, we will move on to more complex programs, and then to full projects.

Study the code, and then discuss it. What does it do? How does it do it? What are the parts of the code? What are the parts of the code doing?

What is that public static void main(String[] args) thing? What is System.out.println("Hello, World!") doing? (Don't over think it!)

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Now, what does this code do? How does it do it? What are the parts of the code? What are the parts of the code doing?

import java.util.Scanner;

public class SomethingWeird {
    public static void main(String[] args) {
        int aNumber = (int) (Math.random() * 100); // Generate a random number between 0 and 99
        int attempts = 0;
        boolean wellHuh = false;

        Scanner scanner = new Scanner(System.in);

        System.out.println("Welcome to SomethingWeird!");

        while (!wellHuh) {
            System.out.print("Enter your strouhal (between 0 and 99): ");
            int strouhal = scanner.nextInt();
            attempts++;

            if (strouhal == aNumber) {
                System.out.println("Congratulations! What ever it was, you did it in " + attempts + " attempts.");
                wellHuh = true;
            } else if (strouhal < aNumber) {
                System.out.println("Too low! Poor doggie.");
            } else {
                System.out.println("Too high! Poor kitty.");
            }
        }

        scanner.close();
    }
}

Why are the variables named the way they are? What is the while loop doing? What is the if statement doing? What is the else if statement doing? What is the else statement doing?

Scanner? What's a scanner? What is the scanner object doing? What is the scanner.nextInt() method doing? What is the scanner.close() method doing?

What is the import java.util.Scanner; statement doing? Imagine why we need that? What would happen if we didn't have it?

int and boolean? What do they represent?

The code generates a random number between 0 and 99. The user is asked to guess the number. If the user's guess is too low, the program tells the user that the guess is too low. If the user's guess is too high, the program tells the user that the guess is too high. If the user's guess is correct, the program tells the user that the guess is correct and how many attempts it took to get the correct guess.

This description is a good start, but it doesn't explain the code.

What is the strouhal number? What is the strouhal number used for in this code? (hint, absolutely NOTHING, it's a red herring.)

What is the aNumber variable used for? What is the attempts variable used for? What is the wellHuh variable used for?

The wellHuh variable is a flag variable. What is a flag variable? It is used to control the flow of the program.

What is the scanner object used for? What is the scanner.nextInt() method used for? What is the scanner.close() method used for? A Scanner is a class in Java that allows you to take input from the user. The scanner.nextInt() method reads the next integer from the user. The scanner.close() method closes the scanner object.

What is the import java.util.Scanner; statement used for? It is used to import the Scanner class from the java.util package. We need to import the Scanner class because it is not part of the core Java language. If we didn't have the import statement, the compiler would not know what the Scanner class is. And it would give us an error.

What is the int keyword used for? What is the boolean keyword used for? The int keyword is used to declare an integer variable. The boolean keyword is used to declare a boolean variable. These tow variable contain the state of the program. They change as the program runs. As soon as the user guesses the correct number, the wellHuh variable is set to true. This causes the while loop to stop running.

What is the while loop used for? The while loop is used to keep asking the user for input until the user guesses the correct number.

What is the if statement used for? What is the else if statement used for? What is the else statement used for? The if statement is used to check if the user's guess is correct. The else if statement is used to check if the user's guess is too low. The else statement is used to check if the user's guess is too high. This is logic of the program. It is the thinking part of the program. It makes decisions, based on the user's input, and controls the flow of the program. (_Control flow) is the order in which the program's code is executed. (There are several means by which you modify the control flow of a program, including if statements, for loops, and while loops.)

Rename the variables to something more meaningful. wellHUh is not a good name for a variable. What would be a better name? Do the other variables as well. And based on what you know now that the class does, what would be a better name for the class?

What would you do to make the program more user friendly? What would you do to make the program more fun?

Java provides ways to organize your code. Classes give us a means to organize our code into logical units. What would be a good name for the class? What would be a better name for the method?

If you replaced the main() method with a method that created an Object of type SomethingWeird and called a method on that object, what would you name the method? (well, don't overthink it!)

How about a method that would generate a random number? What would you name that method? How about a method that would take the user's input? What would you name that method? Give me an example of a method that would check the user's input against the random number. What would you name that method?

Each of these ideas are different ways to structure the game's code. They are different ways to think about the problem. They are different ways to think about the solution.

Coding is all about thinking about the problem and thinking about how to frame a possible solution.

public class SimpleProgram {
    public static void main(String[] args) {
        int a = 5;
        int b = 10;
        int c = a + b;

        System.out.println("The sum of " + a + " and " + b + " is " + c);
    }
}

What's going on in this code?

What are the variables a, b, and c used for? What is the + operator used for? What is the System.out.println() method used for?

What is the int keyword used for? What is the String keyword used for? What is the void keyword used for? The int keyword is used to declare an integer variable. The String keyword is used to declare a string variable. The void keyword is used to declare a method that does not return a value.

import java.util.HashMap;
import java.util.Scanner;

public class AnimalProgram {
    public static void main(String[] args) {
        HashMap<String, String> animals = new HashMap<>();
        animals.put("dog", "Woof! Dogs are known for their loyalty and are often referred to as man's best friend.");
        animals.put("cat", "Meow! Cats are independent and have a reputation for being mysterious and aloof.");
        animals.put("cow", "Moo! Cows are domesticated animals that are primarily raised for milk and meat production.");
        animals.put("duck", "Quack! Ducks are aquatic birds that are known for their webbed feet and ability to swim.");

        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter an animal: ");
        String animal = scanner.nextLine();

        if (animals.containsKey(animal)) {
            String sound = animals.get(animal);
            System.out.println("The sound of a " + animal + " is " + sound);
        } else {
            System.out.println("Sorry, I don't know the sound of that animal.");
        }

        scanner.close();
    }
}

What is the HashMap class used for? What is the Scanner class used for? What is the System.out.println() method used for? (are you getting tired of seeing println yet?)(get over it, println is here to stay!)

Add more animals to this program, where would you add them? How would you add them?

Try to explain the code in your own words. What is the code doing? What is that animals object> What is the animals.put() method doing? What is the animals.containsKey() method doing? What is the animals.get() method doing?

The HashMap class in Java is used to store and retrieve data using key-value pairs. It is a part of the Java Collections Framework and provides an efficient way to store and retrieve data based on unique keys.

In this program, the HashMap<String, String> is used to store information about different animals and their corresponding sounds. The keys in the HashMap are the names of the animals (e.g., "dog", "cat", "cow", "duck"), and the values are the sounds associated with each animal (e.g., "Woof!", "Meow!", "Moo!", "Quack!").

The HashMap allows us to quickly retrieve the sound of an animal by providing its name as the key. For example, if the user enters "dog", the program will use the animals.containsKey(animal) method to check if the HashMap contains the key "dog". If it does, the program will use the animals.get(animal) method to retrieve the corresponding sound ("Woof!") and display it using System.out.println().

By using a HashMap, we can easily associate each animal with its sound and retrieve the sound efficiently based on the animal's name. It provides a convenient way to organize and access data in this program.