Command Line Arguments Example in Java

Introduction

Command Line Arguments is a classic Java console program that demonstrates the concept with complete source code and sample output. Practical numeric and utility programs — primes, factorial, palindrome and similar classics.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

Command line arguments are optional string arguments that a user can give to a program upon execution. These arguments are passed by the operating system to the program, and the program can use them as input. Programs are normally run by invoking them by name.

Syntax

java Program_name Input_to_the_program

Command Line Arguments Example Program

class CommandLineArgumentsDemo{  
	public static void main(String args[]){  
	for(int i=0;i < args.length;i++){  
		System.out.println(args[i]);  
	}  	// Compile as javac CommandLineArgumentsDemo.java
}		// Run as java CommandLineArgumentsDemo She sells sea shells on the sea shore

Sample Output

She
sells
sea
shells 
on 
the 
sea 
shore

When to use

Use this command line arguments example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. A loop repeats the block until its condition becomes false.

3. A println / print call writes text to the console — part of the sample output below.

4. Compare your console output with the sample output for Command Line Arguments to confirm the program behaves correctly.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.