Java Program to open the command prompt and insert commands

Here, the Runtime class from the java.lang package will be used. Because every Java program has an instance of the Runtime class, this class enables Java applications to alter their executing environment. Let's look at the Runtime class exec() Method to see how the task might be carried out.

java.lang.Runtime.exec(String command): A key method in running the supplied string command is java.lang.Runtime.exec(String command). The java.lang.Runtime.exec(String command) method is a part of the Runtime class, which is found in the java.lang package of the Java programming language. The Method executes a specified string command as a separate process.

Syntax:

Parameters :

Command: The specific Command you intend to execute.

Returns :

A new Process object that allows you to manage the subprocess.

Throws:

SecurityException: The exception is thrown if a security manager exists and its checkExec method denies the creation of the subprocess due to security constraints.

IOException: The exception is thrown if an I/O error occurs while attempting to execute the Command.

NullPointerException: The exception is thrown if the provided Command is null.

IllegalArgumentException: The exception is thrown if the provided Command is an empty string.

How to run Command Prompt

Filename: OpenCommandPrompt.java

public class OpenCommandPrompt {
    public static void main(String[] args) {
        try {
            // Create an instance of the Runtime class
            Runtime runtime = Runtime.getRuntime();

            //Command to open the command prompt (Windows)
            // We use "cmd.exe /c start" to open the command prompt.
            // The /c flag executes the specified Command and then terminates the command prompt.
            String command = "cmd.exe /c start";

            // Execute the Command to open the command prompt
            Process process = runtime.exec(command);

            // Wait for the process to complete
            // The line waits for the Command prompt process to complete.
            // It ensures that our program only proceeds once the command prompt is closed.
            process.waitFor();
        } catch (Exception e) {
            // Handle exceptions
            e.printStackTrace();
        }
    }
}

Output:

Java Program to open the command prompt and insert commands

Insert and run the Command.

You may run certain cmd commands using this code. The given program runs the cmd commands "dir" (list all directories) and "ping" (check the source computer's ability to connect to a given destination machine).

Filename: CommandExecutionExample.java

import java.io.*;

public class CommandExecutionExample {
    public static void main(String[] args) {
        try {
            // Execute the "dir" command to list all directories and files in the current directory
            executeCommand("dir");

            // Execute the "ping" command to test connectivity to google.com
            executeCommand("ping google.com");
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    //Method to execute a command and print its output
    private static void executeCommand(String command) throws IOException, InterruptedException {
        // Create a ProcessBuilder instance with the Command to run
        Process process = new ProcessBuilder("cmd.exe", "/c", command).start();

        // Set up a reader to capture the output of the process
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));

        // Read and print each line of the process's output
        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }

        // Wait for the process to finish and get its exit code
        int exitCode = process.waitFor();
        System.out.println("Process exited with code: " + exitCode);
    }
}

Output: