How to overwrite file via java nio writer?

You want to call the method without any OpenOption arguments.

Files.write(path, content.getBytes());

From the Javadoc:

The options parameter specifies how the the file is created or opened. If no options are present then this method works as if the CREATE, TRUNCATE_EXISTING, and WRITE options are present. In other words, it opens the file for writing, creating the file if it doesn't exist, or initially truncating an existing regular-file to a size of 0

You want to use both StandardOpenOption.TRUNCATE_EXISTING and StandardOpenOption.CREATE options together:

Files.write(path, content.getBytes(),
         StandardOpenOption.CREATE,
         StandardOpenOption.TRUNCATE_EXISTING );