Lectures

We define the contract for the File Organizer console utility: which parameters the configuration accepts ( sourceDir, targetDir, allowedExt, dryRun), which modes are specified type-safely via enum ( Mode, ConflictPolicy), how to normalize user input ( trim(), lowercase()), and how to do fail-fast validation via require() before any bulk disk operations. At the end, we outline the result model ( OpResult) and a main skeleton.

We break down a safe “first stage” of File Organizer: how to traverse a directory tree with walkTopDown(), filter to files only via isFile, carefully extract an extension with lastIndexOf, normalize and compare it with allowedExt, and then build a relative path inside the source using Path.relativize(...). At the end, we assemble the CandidateFile model and go over typical mistakes.

We break down a “clean” file layout as a computation: how to determine a category by extension via enum class Category, how to safely build a target path with Path and resolve(), and how to represent name conflicts in the plan ahead of time via PlanItem and PlannedConflict. At the end — practical nuances ( relativize(), checking startsWith()) and common mistakes.

We break down how to build a “bulk file operations engine” in Kotlin: we represent processing as a pipeline “plan → operation on a single file → result”, introduce the result model OpResult and statuses Status, learn to collect statistics via groupBy, handle conflicts correctly ( ConflictPolicy), and make processing resilient by using a narrow try/ catch at the single-item level—including cases where renameTo() returns false without throwing an exception.

We break down how to make a file utility more reliable: we add a dry-run mode (planning without real file system changes), write a simple event log to a file via LocalDateTime, and build the final report separately in memory and save it atomically via a temporary file and renameTo(). In practice, we assemble a single workflow using cfg.dryRun, OpResult results, and status grouping via groupBy.