(Java) BatchModify - Add a Label to each Message in Search Results

Searchs GMail for messages meeting a criteria and adds a label to each message found.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    boolean success;

    CkHttp http = new CkHttp();
    http.put_AuthToken("GMAIL-ACCESS-TOKEN");

    String userId = "me";
    http.SetUrlVar("userId",userId);

    String query = "subject:questions";
    http.SetUrlVar("query",query);

    String url = "https://www.googleapis.com/gmail/v1/users/{$userId}/messages?q={$query}";

    CkStringBuilder sb = new CkStringBuilder();
    success = http.QuickGetSb(url,sb);
    if (success != true) {
        System.out.println(http.lastErrorText());
        return;
        }

    CkJsonObject json = new CkJsonObject();
    json.LoadSb(sb);
    json.put_EmitCompact(false);
    System.out.println(json.emit());

    if (http.get_LastStatus() != 200) {
        System.out.println("Failed.");
        return;
        }

    // If successful, the received JSON looks like this:
    // {
    //   "messages": [
    //     {
    //       "id": "166f583051d36144",
    //       "threadId": "166f583051d36144"
    //     },
    //     {
    //       "id": "166f5815e1f36144",
    //       "threadId": "166f5815e1f36144"
    //     },
    // 	...
    //     {
    //       "id": "166f580639e36144",
    //       "threadId": "166f580639e36144"
    //     },
    //     {
    //       "id": "15dbc2e28ec789c6",
    //       "threadId": "15dbc2e28ec789c6"
    //     }
    //   ],
    //   "nextPageToken": "13434766102274844688",
    //   "resultSizeEstimate": 103
    // }
    // 

    // Next, we'll be sending an HTTP POST to add the label "questions" to each message in the
    // search results.  The JSON to be sent for the batchModify is this:

    // 	{
    // 	  "ids": [
    // 	    string
    // 	  ],
    // 	  "addLabelIds": [
    // 	    string
    // 	  ],
    // 	  "removeLabelIds": [
    // 	    string
    // 	  ]
    // 	}

    // We'll omit "removeLabelIds" because we're not removing any labels.
    // We are parsing the JSON search results, and at the same time building the batchModify JSON.

    CkJsonObject json2 = new CkJsonObject();

    int i = 0;
    int numMessages = json.SizeOfArray("messages");
    while ((i < numMessages)) {
        json.put_I(i);
        String id = json.stringOf("messages[i].id");
        json2.put_I(i);
        json2.UpdateString("ids[i]",id);
        i = i+1;
        }

    // We need the id of the label (not the name).
    // I know the name of the label is "questions", but I need to know the id.
    // See this example: Get Label Id by Name
    // The id of my label named "questions" is "Label_43"
    String labelId = "Label_43";
    json2.UpdateString("addLabelIds[0]",labelId);
    json2.UpdateNewArray("removeLabelIds");

    json2.put_EmitCompact(false);
    System.out.println(json2.emit());

    // Send the batchModify
    url = "https://www.googleapis.com/gmail/v1/users/{$userId}/messages/batchModify";
    CkHttpResponse resp = http.PostJson3(url,"application/json",json2);
    if (http.get_LastMethodSuccess() != true) {
        System.out.println(http.lastErrorText());
        return;
        }

    System.out.println("status = " + resp.get_StatusCode());

    // A 204 response status indicate success.
    if (resp.get_StatusCode() != 204) {
        System.out.println(resp.bodyStr());
        System.out.println("Failed.");

        return;
        }

    // The 204 response has an empty response body..

    System.out.println("BatchModify success!");
  }
}