Java Development Workflow – Write, Compile & Run Your First Program

Before diving deep into Core Java concepts, it’s essential to understand the Java workflow — how a Java program is written, compiled, and executed.

This guide walks you through each step using simple examples and command-line instructions.

Step 1: Write Your First Java Program

Create a Java file with the .java extension. The file name should match the class name.

Example: HelloWorld.java

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

Explanation:

Every Java program must have a main method to run.

Step 2: Compile Your Program

Compile your source code (.java) into bytecode (.class) using the Java compiler:

Command Line:

javac HelloWorld.java

• On success, this generates HelloWorld.class.
• If there are syntax errors, the compiler will display them with line numbers.

IDE (Eclipse / IntelliJ):

• Click Run or Build; the IDE compiles your program automatically.

Step 3: Run Your Program

Execute the compiled bytecode using the JVM:

Command Line:

java HelloWorld

Output:

Hello, Java!

IDE:

• Eclipse: Right-click → Run As → Java Application
• IntelliJ: Click the green Run button

The JVM reads the bytecode and converts it into machine code for your system.

Step 4: Debug and Iterate

Java development is iterative:

Write → Compile → Run → Fix Errors → Re-run

Common Issues & Fixes:

Optional: Using Build Tools for Larger Projects

For advanced workflows or bigger projects, you can use Maven or Gradle to:

• Automate compilation and execution
• Manage dependencies
• Simplify project structure

Workflow Visualization

1️⃣ Write Java Source Code (.java)
       ↓
2️⃣ Compile (javac) → Bytecode (.class)
       ↓
3️⃣ Run (java) → JVM executes bytecode
       ↓
4️⃣ Output & Debug → Improve Code

Concepts Learned

• Java source code → .java file
• Compilation → converts source code → bytecode (.class)
• Execution → JVM converts bytecode → machine code
• Main method → program entry point
• Iterative development → write → compile → run → debug

Summary Table