Files by definition are named sequences of bytes stored on permanent storage device.
Files are managed by OS component named file system. File system operates with term "file" and translates this term to lower level terms like volume, sector, block etc.
Mapping between file name (and path) and blocks on your disk where the information is actually stored is named files table and is managed by file system.
When you delete file you ask file system to remove appropriate entry from file table. This means that indeed the file content is not deleted from disk physically and if you are lucky enough can probably be restored. Why probably? Because once the file entry is removed from the table the space occupied by file can be re-used and therefore other information can be stored there.
There are tools that try to restore the information. These tools work on level under file system, i.e. use lower level APIs. Probably they are talking directly to driver. Java does not provide API for doing this.
Therefore you have the following solutions.
- Implement this task in native language.
- Use existing tools that do this task and provide either API or command line interface.
