Java Programmer Skills Programme

📘LESSON 4

3.1 Lesson Outcomes

After completing this lesson, learners will be able to:

Explain the structure of a simple Java project.
Identify Java source and class directories.
Compile Java source code.
Run compiled Java programs.
Explain the Java compilation and execution process.

3.2 Overview

Java applications are developed within organized project structures that contain source files, compiled class files, and supporting resources. Java programs must first be compiled before they can be executed.

This lesson introduces learners to Java project organization and explains how Java source code is compiled and executed using the Java compiler and JVM.

Compilation and execution are important processes in:

software development,
enterprise systems,
Java application deployment,
and programming environments.

Understanding Java project structures and execution processes is important because they form the foundation of Java application development.

KT0401 — Simple Java Project

A Java project is an organized collection of:

Java source files,
packages,
libraries,
and resources.

A simple Java project contains:

source code,
compiled files,
and project folders.

Example of a Simple Java Project Structure

MyProject
 ├── src
 ├── bin
 └── libraries

Components of a Java Project

Component	Purpose
src Folder	Stores source code
bin Folder	Stores compiled files
libraries	External dependencies

Importance of Java Projects

Java projects support:

organized development,
easier maintenance,
and project management.

KT0402 — Java Source and Class Directories

Java projects contain separate directories for source files and compiled files.

Source Directory

The source directory stores:

.java

files written by developers.

Example Source File

Main.java

Class Directory

The class directory stores:

.class

files generated after compilation.

Example Class File

Main.class

Comparison of Directories

Directory	Purpose
Source Directory	Stores source code
Class Directory	Stores compiled bytecode

Importance of Directories

Directories help developers:

organize projects,
separate source code,
and manage compiled files.

KT0403 — Compiling the Java Source Code

Compilation is the process of converting Java source code into bytecode.

Java source code is compiled using:

javac

Example Java Source Code

public class Main {

    public static void main(String[] args) {

        System.out.println("Hello World");
    }
}

Compilation Command

javac Main.java

Result of Compilation

Compilation produces:

Main.class

Importance of Compilation

Compilation:

checks syntax,
converts source code into bytecode,
and prepares programs for execution.

KT0404 — Running the Compiled Java Code

After compilation, Java programs are executed using the Java Virtual Machine (JVM).

Java programs are executed using:

java

command.

Execution Command

java Main

Program Output

Hello World

Java Execution Process

Step	Process
Write Code	Create source code
Compile	Generate bytecode
Execute	JVM runs program

Importance of Program Execution

Execution allows:

applications to run,
output to be displayed,
and software to perform tasks.

3.5 Key Notes / Summary

Java projects organize application resources.
Source directories store .java files.
Class directories store .class files.
Compilation converts source code into bytecode.
javac compiles Java programs.
The JVM executes compiled Java programs.
Java execution follows compile-and-run processes.