How to Resolve 'Source Not Found' Error While Debugging Java Applications in Eclipse?

What causes the 'Source not found' error in Eclipse while debugging Java applications, and how can it be resolved?

When debugging Java applications in Eclipse, the 'Source not found' error arises when the debugger cannot locate the source files corresponding to the bytecode being executed. This typically occurs in cases where the source isn't attached to the project's dependencies or if the files are located in different project workspaces.

// Example to attach source for a Maven dependency in Eclipse:
// Navigate to Build Path -> Configure Build Path. Select the necessary jar, then choose 'Add Source'.

Causes

• The source code files are not attached to the class files in the project's dependencies.
• Using libraries from external Maven repositories without the associated source files.
• Stepping into files from a different project which lacks source attachment in your current workspace.

Solutions

• Ensure that the source files associated with your dependencies are correctly attached in Eclipse settings.
• Use Maven to download source code for your dependencies by enabling "Download Sources" and "Download JavaDoc" options.
• Add external source locations manually using the 'Attach Source' option, though this may be cumbersome for large projects.

Mistake: Not configuring Maven to download sources and JavaDocs, leading to missing source files.

Solution: Enable the option in Eclipse by going to Maven -> Update Project, and then checking 'Download Sources' and 'Download Javadoc'.

Mistake: Attaching the wrong source file or version, meaning the debugger still can't connect to the expected variable context.

Solution: Ensure you attach the correct and corresponding version of the source files that match your dependencies.