How to fix classNotFoundException

If you're encountering a ClassNotFoundException for the class, it indicates that the class is not being found on the classpath when you attempt to run it. Here are some steps to troubleshoot and resolve this issue:

Step-by-Step Guide

1. Ensure the Project is Compiled:

   Make sure that the project has been compiled successfully and that the class files are present in the target directory.

   mvn compile
   

2. Check the Classpath:

   Verify that the classpath is correctly set when running the exec:java goal. The exec-maven-plugin should include the compiled classes from the target directory.

3. Correct Command Syntax:

   Ensure that you are using the correct command syntax to run the main method with the exec:java goal.

Example Maven Project Structure

Let's assume the following project structure:

myproject/
├── pom.xml
└── src/
    └── main/
        └── java/
            └── dev/
                └── selenium/
                    └── getting_started/
                        ├── XYZ.java
                        └── AnotherMain.java

Example pom.xml

Ensure your pom.xml includes the necessary dependencies and plugins, even if not explicitly defined (you don't need to modify pom.xml if using the command line approach):

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>myproject</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.seleniumhq.selenium</groupId>
            <artifactId>selenium-java</artifactId>
            <version>4.1.0</version>
        </dependency>
    </dependencies>
</project>

Correct Command to Run the Main Method

Use the following command to run the main method of the XYZ class:

mvn compile
mvn exec:java -Dexec.mainClass="dev.selenium.getting_started.XYZ"

Verify the Package and Class Name

Ensure that the package and class name are correctly specified in the command. The fully qualified name should match the package declaration in your Java file.

Example Java Classes

XYZ.java:

package dev.selenium.getting_started;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class XYZ {
    public static void main(String[] args) {
        System.setProperty("webdriver.chrome.driver", "/path/to/chromedriver");
        WebDriver driver = new ChromeDriver();
        driver.get("http://www.example.com");
        driver.quit();
    }
}

AnotherMain.java:

package dev.selenium.getting_started;

public class AnotherMain {
    public static void main(String[] args) {
        System.out.println("Running another main method!");
    }
}

Common Issues and Resolutions

1. Typo in the Class Name: Ensure there are no typos in the class name. It should exactly match the class name and package structure.

2. Incorrect Package Declaration: Ensure that the package declaration in your Java file matches the directory structure.

3. Compilation Issues: Ensure that there are no compilation errors. The class files should be present in the target/classes directory.

Additional Debugging

If the above steps do not resolve the issue, you can add the -X flag to the mvn command to enable debug output, which might provide more details on what is going wrong.

mvn -X exec:java -Dexec.mainClass="dev.selenium.getting_started.XYZ"

This should give you a detailed output of the classpath being used and other relevant information that can help diagnose the issue.