Java Intro #

This lab will walk you through setting up the IntelliJ Integrated Development Environment (IDE) and introduce you to the the basics of Java.

[0] Setup #

GitHub Configuration #

You will have received an email inviting you to join. You can also log in to github.com to accept the invitation.

💻 Select [Projects] > [Get from VCS]

💻 Select [Github]

💻 Click [Authorize]

Clone the Repository #

💻 select [Projects] > [Get from VCS] > [Repository URL] #

Be sure to change yourgithubusername to your actual GitHub username.

https://github.com/isf-dp-cs/lab_intro_yourgithubusername

Cannot Find JDK 17 - Fix click to expand ⬇️

💻 Select [File] > [Project Structure]

💻 From the SDK: dropdown, select Java 21

[1] Variables #

In Java, you have to specify the data type of each variable as you declare it, like this:

int videosWatched = 353;

Java has 8 primitive data types:

You can print variables and text to the console like this:

System.out.println("Number of videos watched: " + videosWatched);

💻 Add each of the following variables to your code, and print each one to the console. Be sure to use an appropriate data type.

// add a variable that stores your username
// add a variable that stores the number of videos youve uploaded
// add a variable that stores the average rating you give to videos
// add a variable that stores the theme setting as 'D' 'L' or 'A' for dark mode, light mode, or auto
// add a variable that stores whether you are signed in or not
// add a variable that stores the name of your country

[2] Strings #

Strings are more complex objects that come with certain features. Here are some examples:

String firstName = "John";
String lastName = "Doe";
System.out.println(firstName + " " + lastName); // add Strings together

String txt = "Hello! World";
int length = txt.length(); // get the length of a String

String first = "java programming";
String second = "java programming";

boolean result1 = first.equals(second); // compare first and second Strings

String txt = "Hello World";
char letter = txt.charAt(2); // returns character at index 2

ANSI Codes #

ANSI escape codes are special codes that can change the formatting when you print to the console

String yellowBackground = "\u001b[43;1m";
String reset = "\u001b[0m";
System.out.println(yellowBackground + "the sun is yellow" + reset);

The 256 Background Colors follow a simple forumula: \u001b[48;5; + n + m

[3] Conditionals #

User Input #

In java, you get user input like this:

Scanner scanner = new Scanner(System.in); // create a Scanner object
System.out.print("Are you having a good class so far? (y/n)");
String input = scanner.nextLine(); // get the user input

Modulo #

Just like in pseudocode, we can use the modulo operator to calculate the remainder of division. In java, we will use the % operator for mod.

int a = 15;
int b = 8;
int remainder = a % b; // calculate the remainder

• ask the user for their name
• ask the user for their favorite color
• ask the user for their second favorite color
• print out the user’s name, alternating between the two colors for each letter

[4] Wordle #

Now it’s time to put all your new skills to good use! You will be coding the game Wordle.

Looping #

Right now, the code picks a random 5-letter word, and allows the user a single guess. Not much of a game!

💻 Add a loop to the code, so that the user gets 6 guesses. You can reference your code from the other files to write your loop.

Highlight #

A big part of Wordle is the feedback from the game. After each guess, the user is shown their guess, and each letter is highlighted according to these rules:

• GRAY backround: guess letters not included in the word
• YELLOW backround: guess letters in the wrong location
• GREEN backround: guess letters in the correct location

End the loop early #

Right now, the user will be asked for 6 guesses no matter what. However, if they guess correctly, the loop should end early. Here are three examples of while loops:

// java while loop
while (i < 6) {
	System.out.println("Hello World");
	i++;
}

// java while loop with OR logic 
while (i < 6 || i < 1) {
	System.out.println("Hello World");
	i++;
}

// java while loop with AND logic 
while (i < 6 && i > 0) {
	System.out.println("Hello World");
	i++;
}

Example steps for Wordle #

// first some setup
create variable yellowBackground, set to \u001b[47;1m
create variable greenBackground, set to \u001b[42;1m
create variable greyBackground, set to \u001b[47;1m
create variable reset, set to \u001b[0m

print “Enter a 5-letter word”
create variable found, set to false

// begin the guessing
create variable i, set to 0
loop while i <= 6 and found is false

create variable input, set to the user’s input

// let’s check if they got it right
if input is the same as word

print “Well done! You guessed the word!”
set found to true

end if

// we need to format the output string correctly
create variable output set to an empty string

//now we loop through each letter to format it correctly
loop j from 0 to the length of the input

create variable wordLetter, set to the letter from the actual word // (use .charAt(j))
create variable guessLetter, set to the letter from the input //(use .charAt(j))
create variable formattedLetter, set to the guessLetter with the grey background

// should the letter be green?
if the letters wordLetter and guessLetter match

set formattedLetter to the guessLetter with green background

// should the letter be yellow?
else

loop h from 0 to length of the word
create variable compareLetter, set to the letter from the word // (use .charAt(h))

if the compareLetter matches the guessLetter

set formattedLetter to the guessLetter with yellow background

end if

end loop

end if
add the formattedLetter to the end of the output end loop

print the output increment i
end loop

[5] Deliverables #

✋ If you would like teacher feedback, begin your commit message with #feedback

⚡✨

💻 Select Commit from the menu on the left.

Select all your updated files. Be sure to include a descriptive commit message.

💻 Click Commit and Push

💻 Click Push