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javawindowsnio

Creating a sparse file in Java on NTFS

This command should create a sparse file:

channel = Files.newByteChannel(path, EnumSet.of(CREATE,WRITE,SPARSE));

However, it just creates a regular (non-sparse) file. I can manually turn it into a sparse file using fsutil on the command line, but how can I get the Java Runtime to do this?

I am using Java 11 on Windows 10 (NTFS).

Solution

  • Apparently, creating a sparse file only works with OpenOption CREATE_NEW (which replaces any existing file), but not with CREATE (which only creates the file if it doesn't exist).

    channel = Files.newByteChannel(path, EnumSet.of(CREATE_NEW,WRITE,SPARSE));