How to send a correct HTTP PUT request in Java

I want to turn my lights off with Java using the Philips HUE Api.
For this, I have the following API: http://192.168.0.53/api/HZ3bJqN3MIb35uNcI4FfsGcqstwbW6qgvuxd7Tmt/lights/1/

This returns:

{
  "state": {
    "on": true,
    "bri": 178,
    "hue": 41044,
    "sat": 56,
    "effect": "none",
    "xy": [
      0.3313,
      0.3447
    ],
    "ct": 181,
    "alert": "select",
    "colormode": "ct",
    "mode": "homeautomation",
    "reachable": true
  },
  "swupdate": {
    "state": "noupdates",
    "lastinstall": "2020-07-03T12:17:24"
  },
  "type": "Extended color light",
  "name": "Hue color spot 1",
  "modelid": "LCG002",
  "manufacturername": "Signify Netherlands B.V.",
  "swconfigid": "9FD98F72"
}

Now I want to modify the "on: true" to "on: false" with Java. For that, I have this code:

    URL url = new URL("http://192.168.0.53/api/HZ3bJqN3MIb35uNcI4FfsGcqstwbW6qgvuxd7Tmt/lights/1/");
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();

    connection.setRequestMethod("PUT");
    connection.setDoOutput(true);
    connection.setDoInput(true);
    connection.setConnectTimeout(60000);
    connection.setReadTimeout(60000);
    connection.setRequestProperty("Content-Type", "application/json");
    JSONObject requestBody = new JSONObject();
    requestBody.put("on", false);

    OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
    writer.write(requestBody.toString());
    writer.flush();
    writer.close();

    // Debug
    int response = connection.getResponseCode();
    System.out.println(requestBody.toString());
    System.out.println(response);

This returns '200' and {"on":false} which would be perfect.
But for some reason, it just does nothing. The light remains on even though the connection exists.

Any ideas why?

You are using the wrong URL for the PUT request.

A GET request to http://192.168.0.53/api/.../lights/1 will return the current state

But to modify you need a PUT request to http://192.168.0.53/api/.../lights/1/state

I am trying to do the same thing, but don't know the Java part.

I got curl to work at the command level with triple quotes:

curl -X PUT -H "Content-Type: application/json" -d {"""on""":false} http://192.168.0.53/api/HZ3bJqN3MIb35uNcI4FfsGcqstwbW6qgvuxd7Tmt/lights/1/state

This code will work with your hue lights, Please share the Java code with me when you get it to work. mike@toggle.is