Command‑Line Arguments in Java: A Practical Guide with Code Examples

What Are Command‑Line Arguments in Java?

In Java, a command‑line argument is any value you provide after the program name when you launch it from a terminal or console. Those values are captured as strings in the String[] args parameter of the main method.

Key Points to Remember

Arguments are passed as plain strings, so you can supply any text you need.
There is no limit to the number of arguments you can supply.
They are commonly used to inject configuration data (file paths, flags, credentials, etc.) into an application at startup.
The args array holds the values in the exact order you typed them.

Hands‑On Example

Write the following Java class:

class Demo {
    public static void main(String[] args) {
      System.out.println("First argument: " + args[0]);
      System.out.println("Second argument: " + args[1]);
    }
  }

Compile it: javac Demo.java
Run it with arguments: java Demo apple orange

After executing the command above, the console will display:

First argument: apple
Second argument: orange

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