Activity 1.1 Hello World!

Introduction

Activity 1.1

Hello World!

Topics

• Output
• User Interfaces
• Comments

Output

Output refers to information that a program produces. It can be sent to the user via some output device.

User Interfaces: GUIs and TUIs

Graphical User Interface - Uses visual elements to let you interact with a program.

User Interfaces: GUIs and TUIs

Terminal user Interface - A user interface that uses text and symbols, rather than graphical elements.

Your First Java Method System.out.println()

System.out.println() is a method that displays a message in a terminal application.

System.out.println("Are you a 1 or a 0?");

Your First Java Method System.out.println()

System.out.println() is a method that displays a message in a terminal application.

System.out.println("Are you a 1 or a 0?");

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Are you a 1 or a 0?

Demo

Call System.out.println(). Write a message of your choice.

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

Hello World!

Comments

Write notes or disable code. Ignored by the Java compiler.

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public class Main {
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    public static void main(String[] args) {
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        // System.out.println("Hello!");
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        System.out.println("Goodbye!");
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    }
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}

Goodbye!

Key Terms

Method

Code that performs a specific action.

Output

Information that a program produces.

Console Output

Text displayed by a program in a command-line interface, like a terminal.

Comments

Notes written within the code that are ignored by the Java compiler, used by to explain or clarify the code.

'F' → Fullscreen

Objectives

• Writing and executing code
• Displaying console output
• Debugging potential syntax errors
• Reading comments

Activity Tasks

• Create a new Java project named 1-1-Output.
• Complete each task individually.

Task 1: Write and Test

• Write each line of code from the section making sure to stay within the main method.
• Run and test your project to ensure it executes as intended.

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public class Main {
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    public static void main(String[] args) {
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        System.out.println("Welcome to the Skynest Nexus.");
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        System.out.println("This class is taught by Mr. Mortimer");
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        System.out.println();
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        //
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    }
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}

Task 2: Add More Code

• Write the additional sections of output under your current print statements.
• Run and test your project to ensure it executes as intended.

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public class Main {
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    public static void main(String[] args) {
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        System.out.println("Welcome to the Skynest Nexus.");
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        System.out.println("This class is taught by Mr. Mortimer");
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        System.out.println();
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        System.out.println("What is the answer to life, the universe, and everything?");
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        System.out.println("The answer is 42.");
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        System.out.println();
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        System.out.println("Sally sells seashells by the seashore.");
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        System.out.println("Sally wants to invite you to invest in a money making opportunity.");
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        System.out.println();
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        System.out.println("If you start to feel overwhelmed, just remember:");
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        System.out.println("Mortimers don't quit, we get fired!");
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        //
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    }
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}

Task 3: Add Space

• Add an additional blank print statement at the end of each section to increase the spacing between the sections.
• Run and test your project to ensure it executes as intended.

Task 4: Write a Custom Section

• Output a three-line paragraph of your choice somewhere in the program. Keep it school appropriate.
• Run and test your project to ensure it executes as intended.

Task 5: Write Comments

• Write the following comments to document and modify the code.
  • Disable the line of code that displays the message 'The answer is 42.' by placing a single-line comment at the beginning of the line.
  • Write a comment at the end of a blank print statement that states 'Displays a blank line'.
• Run and test your project to ensure it executes as intended.

Reflection Questions

1. What is the primary function of System.out.println()? How does it relate to the idea of a program "speaking" to a user?
2. Imagine you typed Sistem.out.println() by mistake. What do you think would happen when you try to run your program? Why is correct spelling so important in programming?
3. What was the most challenging part of writing your first line of code?

Submission

Submit your activity and reflection answers to the appropriate dropbox.

Activity Complete