BufferedWriter is not writing data properly

What is wrong in the below code? in console it is printing proper data but in file there is no data. it is creating 0-byte file.

 JsonObjectBuilder mainObj= Json.createObjectBuilder();
	    mainObj.add("delete",delete);
	    mainObj.add("update", update);
	    mainObj.add("add",add);
	   
	    String data = mainObj.build().toString();
	    System.out.println(data); **//This line printing output**
	    BufferedWriter out = new BufferedWriter(new FileWriter("D:/test.json"));
	    out.write(data);

Below output is getting printed to console but it is creating 0-byte file.

{"delete":[{"canonicalName":"Amazon"}],"update":[{"canonicalName":"Infosys"},{"canonicalName":"Google HYD"}],"add":[{"canonicalName":"Apple computers"},{"canonicalName":"Microsoft India"},{"canonicalName":"Amazon"},{"canonicalName":"Google India"},{"canonicalName":"CSC"},{"canonicalName":"INFY"}]}

As mentioned in the comments you forgot to close the writer.
Instead of out.close() you can also use the new syntax try-with-resources since Java 7:

try (BufferedWriter out = new BufferedWriter(new FileWriter("D:/test.json"))) {
    out.write(data);
}

This will automatically close all Closeables at the end of the try block.
Attention: the FileWriter will not be closed by the try-with-resource mechanism as there is no variable created for the FileWriter. Luckily the BufferedWriter.close() will also close the passed FileWriter.