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Accept & Process Command-Line Arguments - Java Program

Java

public class CommandLineDemo {
    public static void main(String[] args) {
 
        // Check if arguments are passed
        if (args.length == 0) {
            System.out.println("No command-line arguments found!");
            return;
        }
 
        System.out.println("Number of arguments: " + args.length);
        System.out.println("Arguments received:");
 
        // Display each argument
        for (int i = 0; i < args.length; i++) {
            System.out.println("Argument " + (i + 1) + ": " + args[i]);
        }
 
        // Example: If arguments are numbers, process them
        try {
            int sum = 0;
            for (String s : args) {
                sum += Integer.parseInt(s); // convert string to number
            }
            System.out.println("Sum of numeric arguments = " + sum);
        } catch (NumberFormatException e) {
            System.out.println("One or more arguments are not numbers. Skipping numeric processing.");
        }
    }
}

Output

 


Output 1 (When Passing Arguments)

Command Used:
java CommandLineDemo Hello Java 123

OUTPUT :
Number of arguments: 3
Arguments received:
Argument 1: Hello
Argument 2: Java
Argument 3: 123
One or more arguments are not numbers. Skipping numeric processing.
 
Output 2 (Numeric Arguments)

Command Used:
java CommandLineDemo 10 20 30

OUTPUT :
Number of arguments: 3
Arguments received:
Argument 1: 10
Argument 2: 20
Argument 3: 30
Sum of numeric arguments = 60

Explanation

✅ Command-line arguments come from args[]

public static void main(String[] args)

args is an array of strings containing values typed after the program name.

Example:

java CommandLineDemo A B C

→ args[0] = "A"
→ args[1] = "B"
→ args[2] = "C"

✅ Checking if arguments are passed

if (args.length == 0)

Stops program if no arguments are provided.

✅ Loop to print each argument

for (int i = 0; i < args.length; i++)

System.out.println("Argument " + (i + 1) + ": " + args[i]);

✅ Convert arguments to integers

sum += Integer.parseInt(s);

Converts each string to integer
If any argument is non-numeric → caught by NumberFormatException

✅ Displays processed result

If data is numeric → sum is printed.

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Introduction to Java

Accept & Process Command-Line Arguments - Java Program

Output

Explanation