<?xml version="1.0"?>

<chapter xml:id="overview">

<title>Overview</title>

<section xml:id="sec-prerequisites">

<title>Prerequisites</title>

<p>

This book assumes that you are already familiar with the <url href="http://www.python.org" visual="http://www.python.org">Python</url> programming language.

We will use Python as a starting point for our journey into <url href="http://java.sun.com" visual="http://java.sun.com">Java</url>.

We will begin by looking at a very simple Java program, just to see what the language looks like and how we get a program to run.

Next, we will look at the main constructs that are common to most programming languages:

</p>

<blockquote>

<p>

<ul>

<li>

<p>

Data Types

</p>

</li>

<li>

<p>

Loops

</p>

</li>

<li>

<p>

Reading user input

</p>

</li>

<li>

<p>

Conditionals

</p>

</li>

</ul>

</p>

</blockquote>

<p>

Once we have the basics of Java behind us we will move on to look at the features of Java that are both unique and powerful.

</p>

<blockquote>

<p>

<ul>

<li>

<p>

Classes

</p>

</li>

<li>

<p>

Interfaces

</p>

</li>

<li>

<p>

Collections

</p>

</li>

<li>

<p>

Graphical User Interface Programming

</p>

</li>

<li>

<p>

Generic Programming

</p>

</li>

</ul>

</p>

</blockquote>

</section>

<section xml:id="sec-java-development-environment">

<title>Java Development Environment</title>

<introduction>

<note>

<p>

Thank you to Beryl Hoffman for contributing to this section from her CSAwesome: AP Java Programming book.

</p>

</note>

<p>

The tool that we use to compile a Java source file into a Java class file

is called a <term>compiler</term>. Most programmers use an

<term>Integrated Development Environment</term> (IDE) that has the

compiler built in and helps you write, compile, run, and debug programs.

</p>

<p>

You can learn Java by just using the interactive coding panels called

<term>Active Code</term> in this e-book. If you are logged in, the Active

Code will remember your changes and even show you a history of your

changes to the code if you click on Load History.

</p>

<p>

However, it’s a good idea to also try a Java IDE to build code outside of

this e-book, especially to try coding with user input which Active Code

cannot do. There are many Java IDEs available.

</p>

</introduction>

<subsection xml:id="subsec-java-ide-options">

<title>Java IDE Options</title>

<p>

There are a lot of online cloud IDEs where you can code online in many

programming languages. Most are free to start, but offer different

features for a price. These are great options if you are using a

Chromebook or you cannot install software on your computer or you want an

easy no-installation option. Some of the Active Code samples in this

e-book also include a link to online IDEs. These projects can be copied to

make your own copy.

</p>

<p>Here are some popular online IDEs:</p>

<p>

<ul>

<li>

<p>

CodeHS (<url href="https://codehs.com/"

>https://codehs.com/</url>) has a free Sandbox online IDE

(<url href="https://codehs.com/app/sandbox">https://codehs.com/app/sandbox</url>)

where you can run Java and Java Swing programs. Students can share the links

to their code and the history of their code is saved. CodeHS has free and paid features.

Grading features are in the paid version.

</p>

</li>

<li>

<p>

PickCode (<url href="https://pickcode.io/"

visual="https://pickcode.io/">https://pickcode.io/</url>) is another

online IDE that offers many free and paid features for setting up

classrooms. In the free version, tudents can share links to their code and

the history of their code is saved. Classroom features are in the paid version.

</p>

</li>

<li>

<p>

Replit (<url href="https://replit.com/"

visual="https://replit.com/">https://replit.com/</url>) an online

IDE which recently switched to only allowing 3 projects at a time

for free. Be aware that Replit has turned on its AI feature for code

completion for all accounts (<url href="https://replit.com/ai"

visual="https://replit.com/ai">https://replit.com/ai</url>). Each

user can turn the AI on and off at the bottom of the code window,

and use an AI chat window to ask questions of the AI.

</p>

</li>

<li>

<p>

JuiceMind (<url href="https://juicemind.com/"

visual="https://juicemind.com/">https://juicemind.com/</url>) is an

online IDE that offers many free and paid features for teachers to

set up classrooms like Coding Rooms. It has a built-in version of

CSAwesome.

</p>

</li>

</ul>

</p>

</subsection>

<subsection>

<title>Github Classroom and Codespaces</title>

<p>

Github provides many free opportunities for students and teachers (<url

href="https://docs.github.com/en/education/quickstart"

visual="https://docs.github.com/en/education/quickstart">https://docs.github.com/en/education/quickstart</url>).

Github Classroom (<url href="https://classroom.github.com/"

visual="https://classroom.github.com/">https://classroom.github.com/</url>)

allows teachers to set up a classroom based on github repositories. Github

and git are both widely used in the computer industry, so learning to use

them is great experience for students. Github now has a cloud IDE called

Codespaces (<url href="https://github.com/features/codespaces"

visual="https://github.com/features/codespaces">https://github.com/features/codespaces</url>)

which you can use for 60 hours a month for free or completely free if you

join as a school or get approved as a teacher or student. In Codespaces,

you can start from a blank template or a repo, open a .java file in the

VSCode editor, follow prompts to install the Extension Pack for Java,

click on the Run and Debug (play button), follow the prompts to install

the Java debugger, and see the output of your code in the terminal. You

can also use Copilot (<url href="https://github.com/features/copilot"

visual="https://github.com/features/copilot">https://github.com/features/copilot</url>),

which is a coding AI based on GPT, for free if you are approved for

educational use.

</p>

<p>

Students will need to sign up for a free Github account (<url

href="https://github.com/signup"

visual="https://github.com/signup">https://github.com/signup</url>) if

they don’t already have one in order to use Codespaces.

</p>

</subsection>

<subsection>

<title>VSCode</title>

<p>

VSCode (<url href="https://code.visualstudio.com"

visual="https://code.visualstudio.com">https://code.visualstudio.com</url>)

is a widely used coding editor which you can download on your local

computers. It has many useful extensions. The code can be run in a

terminal window in the editor. See <url

href="https://code.visualstudio.com/docs/languages/java"

visual="https://code.visualstudio.com/docs/languages/java">https://code.visualstudio.com/docs/languages/java</url>

for Java support. This editor is different than Microsoft Visual Studio

which is a very large IDE.

</p>

</subsection>

<subsection>

<title>Dr. Java</title>

<p>

DrJava (from <url href="http://DrJava.org"

visual="http://DrJava.org">http://DrJava.org</url>) is a free, simple,

easy to install and use development environment. One nice feature is the

interactions pane at the bottom which lets you try out Java code without

having to create a class first.

</p>

</subsection>

<subsection>

<title>BlueJ</title>

<p>

BlueJ (<url href="https://www.bluej.org/"

visual="https://www.bluej.org/">https://www.bluej.org/</url>) is a free

Java IDE designed for beginners. It is built to explore objects and

object-oriented programming and has a teachers’ community as well as a

playlist of videos online <url

href="https://www.youtube.com/playlist?list=PLYPWr4ErjcnzWB95MVvlKArO6PIfv1fHd"

visual="https://www.youtube.com/playlist?list=PLYPWr4ErjcnzWB95MVvlKArO6PIfv1fHd">https://www.youtube.com/playlist?list=PLYPWr4ErjcnzWB95MVvlKArO6PIfv1fHd</url>

to go with the BlueJ Object-First Java book.

</p>

</subsection>

<subsection>

<title>jGRASP</title>

<p>

jGRASP (<url href="https://www.jgrasp.org/"

visual="https://www.jgrasp.org/">https://www.jgrasp.org/</url>) is a free

lightweight development environment, created specifically to provide

automatic generation of software visualizations. jGRASP is implemented in

Java, and runs on all platforms with a Java Virtual Machine (Java version

1.5 or higher). jGRASP produces Control Structure Diagrams (CSDs) for

Java, C, C++, Objective-C, Python, Ada, and VHDL; Complexity Profile

Graphs (CPGs) for Java and Ada; UML class diagrams for Java; and has

dynamic object viewers and a viewer canvas that work in conjunction with

an integrated debugger and workbench for Java. The site includes both

intro video and PDF tutorials.

</p>

</subsection>

<subsection>

<title>IntelliJ</title>

<p>

IntelliJ (<url href="https://www.jetbrains.com/idea/"

visual="https://www.jetbrains.com/idea/">https://www.jetbrains.com/idea/</url>)

is a free Java IDE from JetBrains which many professionals use. It is a

little easier to configure than Eclipse below. Here is a guide on how to

set up IntelliJ: <url

href="https://www.jetbrains.com/help/idea/install-and-set-up-product.html"

visual="https://www.jetbrains.com/help/idea/install-and-set-up-product.html">https://www.jetbrains.com/help/idea/install-and-set-up-product.html</url>.

</p>

</subsection>

<subsection>

<title>Netbeans</title>

<p>

Netbeans (<url href="https://netbeans.org/"

visual="https://netbeans.org/">https://netbeans.org/</url>) is one of the

original Java IDEs. Here is a tutorial on how to set it up: <url

href="https://netbeans.org/kb/docs/java/quickstart"

visual="https://netbeans.org/kb/docs/java/quickstart">https://netbeans.org/kb/docs/java/quickstart</url>.

</p>

</subsection>

<subsection>

<title>Eclipse</title>

<p>

Eclipse (<url href="https://www.eclipse.org/downloads/packages/installer"

visual="https://www.eclipse.org/downloads/packages/installer">https://www.eclipse.org/downloads/packages/installer</url>)

is what many professional Java programmers use. It may be a little complex

for beginners. Here are some installation and configuration instructions

for Eclipse for Java beginners: <url

href="http://skylit.com/javamethods/faqs/Eclipse.pdf"

visual="http://skylit.com/javamethods/faqs/Eclipse.pdf">http://skylit.com/javamethods/faqs/Eclipse.pdf</url>.

</p>

</subsection>

</section>

<section xml:id="why-another-programming-language">

<title>Why Another Programming Language?</title>

<p>

Python is a nice language for beginning programming for several reasons.

First the syntax is sparse, and clear.

Second, the underlying model of how objects and variables work is very consistent.

Third, you can write powerful and interesting programs without a lot of work.

However, Python is representative of one kind of language, called a dynamic language.

You might think of Python as being fairly informal.

There are other languages, like Java and C++ that are more formal.

</p>

<p>

These languages have some advantages of their own.

First, is speed: Java and C++ code will generally give better performance than Python code. (See <xref ref="note-python-performance"/>.)

Second is their maintainability.

A lot of what makes Python easy to use is that you must remember certain things.

For example if you set variable <c>x</c> to reference a turtle, and forget later that <c>x</c> is a turtle but try to invoke a string method on it, you will get an error.

Java and C++ protect you by forcing you to be upfront and formal about the kind of object each variable is going to refer to.

</p>

<p>

In one sense Python is representative of a whole class of languages, sometimes referred to as &#x201C;scripting languages.&#x201D; Other languages in the same category as Python are Ruby and Perl.

Java is representative of what I will call industrial strength languages.

Industrial strength languages are good for projects with several people working on the project where being formal and careful about what you do may impact lots of other people.

Languages in this category include Rust, C++, C#, and Ada.

</p>

<p>

Programming languages will always change.

As the field of computer science advances there will be new programming languages and you will need to learn them.

It is important to learn several programming languages so that you know what to expect.

There are certain features that most programming languages have in common; variables, loops, conditionals, functions.

And there are some features that are unique.

If you know what is common in languages that is a good place to start.

</p>

<note xml:id="note-python-performance">

<title>A Note about Python Performance</title>

<p>

Although Python code is generally slower than Java and C++ code, in practice Python programs can achieve equivalent performance.

This can be done by compiling Python code to C code (see: <url href="https://cython.org" visual="https://cython.org">Cython</url>) or by calling high-performance libraries from Python (e.g., <url href="https://numpy.org" visual="https://numpy.org">NumPy</url>, <url href="https://scikit-learn.org/stable/" visual="https://scikit-learn.org/stable/">scikit-learn</url>, etc.).

So native language performance is just one criteria to consider when deciding which language to use for a program.

</p>

</note>

</section>

<section xml:id="sec-why-java-why-not-c-or-c">

<title>Why Learn Java? Why not C or C++?</title>

<p>

It is easier to learn to create interesting programs in Java than in C or C++, for several reasons:

</p>

<p>

<ul>

<li>

<p>

Java includes a larger standard library than C or C++, which means that sophisticated programs can be created in Java without including external dependencies.

The Java Standard Edition contains thousands of built-in classes that support tasks like file input/output, networking, data structures, and graphical interfaces.

We could not begin to scratch the surface of these classes even if we devoted all of class time! However, we will cover many useful and powerful features of the Java standard library this semester.

</p>

</li>

<li>

<p>

Java incorporates automatic garbage collection of memory, whereas C and C++ programs typically include some degree of manual memory management.

This makes programming in those languages more challenging.

</p>

</li>

<li>

<p>

C++&#x2019;s syntax is more complicated than Java&#x2019;s, making it more difficult to learn.

For example, C++ supports a feature called operator overloading, which makes it possible to change the behavior of operators like <c>+</c>.

This can make it more difficult to understand what a C++ program is doing.

</p>

</li>

</ul>

</p>

<p>

Certainly, C and C++ are important languages, and are worth learning.

But for these and other reasons, we&#x2019;ve decided to use Java for this course.

Learning Java will be a good preparation for learning these and other languages!

</p>

</section>

<section xml:id="overview_summary">

<title>Summary &amp; Reading Questions</title>

<p><ol>

<li>

<p>Learning multiple programming languages helps programmers adapt to different styles and environments.</p>

</li>

<li>

<p>Python is a dynamic scripting language that is beginner-friendly, but it is less strict with types and generally slower than compiled languages.</p>

</li>

<li>

<p>Languages like Java and C++ are statically typed and offer better performance and maintainability for large-scale projects.</p>

</li>

<li>

<p>Java has a simpler syntax than C++ and includes automatic garbage collection, which reduces the complexity of memory management.</p>

</li>

<li>

<p>Java’s extensive standard library enables the development of sophisticated programs without relying on external dependencies.</p>

</li>

</ol></p>

<reading-questions xml:id="rqs-learnlang2">

<exercise label="summary-lang-1">

<statement>

<p>Which of the following best describes Python as a programming language?</p>

</statement>

<choices>

<choice>

<statement><p>Statically typed and high-performance</p></statement>

<feedback><p>No. This better describes languages like Java or C++.</p></feedback>

</choice>

<choice correct="yes">

<statement><p>Dynamically typed and beginner-friendly</p></statement>

<feedback><p>That’s right! Python is dynamically typed and easy for beginners.</p></feedback>

</choice>

<choice>

<statement><p>Industrial strength and verbose</p></statement>

<feedback><p>No. Python is more informal and concise.</p></feedback>

</choice>

<choice>

<statement><p>Memory-managed and pointer-based</p></statement>

<feedback><p>No. That describes lower-level languages like C or C++.</p></feedback>

</choice>

</choices>

</exercise>

<exercise label="summary-lang-2">

<statement>

<p>Why is Java a better language for beginners compared to C++?</p>

</statement>

<choices>

<choice>

<statement><p>It requires more manual memory management</p></statement>

<feedback><p>No. Java manages memory automatically.</p></feedback>

</choice>

<choice>

<statement><p>It has a smaller standard library</p></statement>

<feedback><p>No. Java has a very large standard library.</p></feedback>

</choice>

<choice correct="yes">

<statement><p>It avoids complex syntax and has automatic garbage collection</p></statement>

<feedback><p>Correct! These features make Java easier for beginners.</p></feedback>

</choice>

<choice>

<statement><p>It supports operator overloading</p></statement>

<feedback><p>No. That's a C++ feature and it adds complexity.</p></feedback>

</choice>

</choices>

</exercise>

<exercise label="summary-lang-3">

<statement>

<p>What is a major benefit of learning multiple programming languages?</p>

</statement>

<choices>

<choice>

<statement><p>You can standardize all projects using one universal syntax</p></statement>

<feedback><p>No. Each language has its own syntax and is suited for different tasks.</p></feedback>

</choice>

<choice>

<statement><p>You will minimize runtime errors across all platforms</p></statement>

<feedback><p>No. Runtime errors depend more on logic and environment than the number of languages you know.</p></feedback>

</choice>

<choice correct="yes">

<statement><p>You gain exposure to different language features and paradigms</p></statement>

<feedback><p>Great choice! This helps you become a more adaptable and well-rounded programmer.</p></feedback>

</choice>

<choice>

<statement><p>You can bypass the need for understanding compilation and interpretation</p></statement>

<feedback><p>No. Understanding how code is executed remains essential regardless of how many languages you know.</p></feedback>

</choice>

</choices>

</exercise>

</reading-questions>

</section>

</chapter>