Resolving the Module not found Error in Ant with Java 9 Modularity

Discover how to fix the `Module not found` error when transitioning to Java 9 modules using Ant. Get step-by-step guidance for a smooth migration.
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Understanding the Module not found Error in Ant and Java 9 Modularity

Transitioning from Java 8 to Java 9 can be challenging, especially with the introduction of the Java Platform Module System (JPMS). One common issue developers face during this migration is the dreaded Module not found error. If you're dealing with this problem, you're not alone, and this guide will guide you through solving it effectively.

The Problem: The Module not found Error

When migrating your Java project, you might encounter an error message like this:

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Investigation: Checking Your Setup

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At first glance, everything seems to be configured correctly. So, what is the actual issue? Let's dive deeper into the Ant build file that compiles your Java code.

The Solution: Switching from Classpath to Modulepath

The problem you are experiencing is rooted in how you're adding dependencies in your Ant build file. The original configuration tries to include a classpath instead of a module path, which is incompatible with Java modules. Here’s how the fix looks:

Before Fixing

The initial build configuration in your Ant script resembles this:

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After Fixing

To resolve the Module not found error, you need to change <classpath> to <modulepath>. The updated section would look like this:

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This defines the paths for your dependencies, which now needs to be referenced correctly as a module path.

Conclusion: Smooth Migration to Java 9 Modularity

By adjusting your Ant build file to use modulepath instead of classpath, you can resolve the Module not found error and establish a smoother transition from Java 8 to Java 9. Keeping in mind how Java modules require a more structured approach to modularization will significantly ease your development process.

If you run into further issues or have questions, don't hesitate to reach out for additional resources and support. Happy coding and enjoy the new features that come with Java 9!