How to delete a file or folder

Short answer

Files.deleteIfExists() deletes the file and returns true, or false if there was no file:

void main() throws IOException {
    Path file = Path.of("temp.txt");
    Files.writeString(file, "data");
 
    IO.println(Files.deleteIfExists(file));
    IO.println(Files.deleteIfExists(file));
}

Output:

true
false

Strict deletion

Files.delete() throws if the file is missing — useful when its absence means an error:

void main() throws IOException {
    Files.delete(Path.of("missing.txt"));
}

Output:

Exception in thread "main" java.nio.file.NoSuchFileException: missing.txt

A folder with contents

You cannot delete a non-empty folder. Walk it with Files.walk() and delete from the deepest entries first:

void main() throws IOException {
    Path root = Path.of("build");
    Files.createDirectories(root.resolve("classes"));
    Files.writeString(root.resolve("classes/App.class"), "x");
 
    try (var paths = Files.walk(root)) {
        for (Path p : paths.sorted(Comparator.reverseOrder()).toList()) {
            Files.delete(p);
        }
    }
    IO.println(Files.exists(root));
}

Output:

false

Common mistake

Calling delete() on a non-empty folder:

void main() throws IOException {
    Path dir = Files.createDirectories(Path.of("logs"));
    Files.writeString(dir.resolve("a.log"), "x");
    Files.delete(dir);
}

Output:

Exception in thread "main" java.nio.file.DirectoryNotEmptyException: logs

Files deleted this way do not go to the recycle bin — you cannot restore them.

Thanks for reading!

Short answer

Strict deletion

A folder with contents

Common mistake

Functions used in this recipe

Thanks for reading!