Chapter 01: Basics of Programming with Java

This chapter introduces you to the essential elements required to write, understand, and structure Java programs. Instead of going deep into every feature, the focus here is on building an overall mental model of how Java code is written, compiled, executed, and organized in real projects.

After completing this chapter, you should feel comfortable reading a simple Java program, identifying its parts, and explaining how it is executed by the Java platform.

1.1 Writing Your First Java Program

We start with the classic HelloWorld example to illustrate the structure of a minimal Java application. You will see how the class keyword, main method, and basic output statements fit together.

• Understanding the role of the main method
• Compiling with javac and running with java
• Observing how source code becomes bytecode

1.2 Java Architecture & the JVM

Here we look at how Java achieves platform independence through the Java Virtual Machine (JVM) and the Java Runtime Environment (JRE). You will connect the commands you use in the terminal with the internal architecture that actually executes your programs.

• Role of JDK, JRE, and JVM
• Compilation vs. interpretation in Java
• Concept of bytecode and the class loader

1.3 Classes, Objects, and Constructors

Java is a fully object-oriented language. In this section you will see how real-world entities are modeled as classes and how objects are created from those classes.

• Defining classes with fields and methods
• Creating objects using the new keyword
• Understanding constructors and default initialization

1.4 Packages, Class Paths, and Data Types

To keep code organized, Java uses packages and the class path. At the same time, every variable in Java must have a clear data type. This section summarizes how these ideas work together.

• Declaring and importing packages
• Configuring the class path for multi-file projects
• Primitive vs. reference data types

1.5 Conditional Statements & Access Modifiers

Real programs make decisions and enforce boundaries. Conditional statements control the flow of execution, while access modifiers control which parts of your code can be seen or changed from the outside.

• if, else if, and switch
• Visibility keywords: public, private, protected, and package-private
• Designing simple, readable decision logic

1.6 Introduction to Exception Handling

Programs rarely run in perfect conditions. Files may be missing, network connections may fail, or user input may be invalid. Java uses exceptions to signal and handle such abnormal situations.

• Difference between errors and exceptions
• Checked vs. unchecked exceptions
• Basic try, catch, and finally pattern

In later chapters, you will revisit exception handling with more advanced patterns and best practices.