Situation

When I launch the Eclipse debugger, this sometimes kicks off a rebuild of my project. Why does this happen? Is there a way to avoid this build?

Cause

By default Eclipse looks for changes in files inside the project since the last build was performed, and if it detects any, will force a build as part of launching the debugger. This helps ensure that the debugging experience is correct, because without it there is the risk of looking at updated source that does not match what happens during execution.

Resolution

If you wish to suppress this automatic build, there is a setting in Eclipse preferences for this. From the Eclipse menu, go to "Window -> Preferences" then "Run/Debug -> Launching". The setting is  "Build (if required) before launching", and if this is unchecked, the automatic build will not occur.

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