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Exploring Command Line Arguments in Java

A Java command-line parameter is a value supplied to the Java application when it is executed. In Java, command line arguments sent via the console can be accepted and utilised as input.

Users can pass parameters during execution, bypassing command-line arguments within the main() function. They provide flexibility and enable programs to handle different inputs without changing the source code.

In this article, we will learn about the practical use of command-line arguments in Java.

What are Command Line Arguments?

Command line arguments are inputs provided to a program when It is executed. These inputs can customise the program’s execution by specifying different options, configurations, or data. In Java, command line arguments are passed to the ‘main’ method as an array of ‘String’ Objects.

Program

Output

Also Read: Java Tutorial

How to Pass Command Line Arguments in Java 

To pass command line arguments to a Java program. If you are a Windows user, specify them after the class name in the command line or terminal window.

Example:

Here, ‘arg1’, ‘arg2’ and ‘arg3’ are command line arguments that will be passed to the ‘main’ method.

Accessing Command Line Arguments

In Java, we can access the command line arguments using the main method using the ‘args’ array. The ‘args’ array contains the arguments as strings; you can access each argument by index.

The following program demonstrates “how to read the command  line arguments in Java”

Program

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Here, we will see some programs in command line arguments in Java programs.

Example: Sum of Integers

The following program calculates the sum of integers passed as command-line arguments.

Program

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Example: File Reader

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Best Practices for Using Command Line Arguments

Let’s examine the best practice for using command-line arguments in Java.

• Validate Input: Always validate the command line arguments to ensure they meet the expected format and constraints.

• Provide Help: Provide a way for users to get help or usage information, typically through the’ a –help’ or ‘-h’ argument.

• Handling Error Gracefully:  Provide meaningful error messages and handle exceptions gracefully to improve user experience.

• Document Arguments: Document the expected arguments and their usage in the program’s documentation.

Conclusion

Command line arguments provide a powerful way to pass information into a Java program from the outside, enabling flexible and dynamic execution. By understanding how to handle these arguments, developers can create a versatile application that responds to user input without requiring code changes. Key points include the structure of the ‘main’ method, parsing and using arguments, handling various data types, and managing errors. Mastery of command-line arguments enhances the robustness and user-friendliness of Java applications.