How to create a folder in root and get its ID in Google Drive REST API v3 in Android

Question

In the "Work with Folders" Guide at https://developers.google.com/drive/v3/web/folder, this is the code to create a folder and get its ID.

File fileMetadata = new File();
fileMetadata.setName("Invoices");
fileMetadata.setMimeType("application/vnd.google-apps.folder");

File file = driveService.files().create(fileMetadata)
        .setFields("id")
        .execute();
System.out.println("Folder ID: " + file.getId());

But I just can't figure out what is driveService in the above code snippet? Can any one guide me please.

Answer 1

driveService is defined at Drive service = getDriveService(); of JAVA's Quickstart. You can use your script by changing from service to driveService for the Quickstart.

If you will use Quickstart, you can use following sample script. I added your script to the Quickstart. If you use this script, please setup by following this.

Script modified Quickstart :

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;

import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.*;
import com.google.api.services.drive.Drive;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;

public class Quickstart {
    /** Application name. */
    private static final String APPLICATION_NAME =
        "Drive API Java Quickstart";

    /** Directory to store user credentials for this application. */
    private static final java.io.File DATA_STORE_DIR = new java.io.File(
        System.getProperty("user.home"), ".credentials/drive-java-quickstart");

    /** Global instance of the {@link FileDataStoreFactory}. */
    private static FileDataStoreFactory DATA_STORE_FACTORY;

    /** Global instance of the JSON factory. */
    private static final JsonFactory JSON_FACTORY =
        JacksonFactory.getDefaultInstance();

    /** Global instance of the HTTP transport. */
    private static HttpTransport HTTP_TRANSPORT;

    /** Global instance of the scopes required by this quickstart.
     *
     * If modifying these scopes, delete your previously saved credentials
     * at ~/.credentials/drive-java-quickstart
     */
    private static final List<String> SCOPES =
        Arrays.asList(DriveScopes.DRIVE);

    static {
        try {
            HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
            DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
        } catch (Throwable t) {
            t.printStackTrace();
            System.exit(1);
        }
    }

    /**
     * Creates an authorized Credential object.
     * @return an authorized Credential object.
     * @throws IOException
     */
    public static Credential authorize() throws IOException {
        // Load client secrets.
        InputStream in =
            Quickstart.class.getResourceAsStream("/client_secret.json");
        GoogleClientSecrets clientSecrets =
            GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

        // Build flow and trigger user authorization request.
        GoogleAuthorizationCodeFlow flow =
                new GoogleAuthorizationCodeFlow.Builder(
                        HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
                .setDataStoreFactory(DATA_STORE_FACTORY)
                .setAccessType("offline")
                .build();
        Credential credential = new AuthorizationCodeInstalledApp(
            flow, new LocalServerReceiver()).authorize("user");
        System.out.println(
                "Credentials saved to " + DATA_STORE_DIR.getAbsolutePath());
        return credential;
    }

    /**
     * Build and return an authorized Drive client service.
     * @return an authorized Drive client service
     * @throws IOException
     */
    public static Drive getDriveService() throws IOException {
        Credential credential = authorize();
        return new Drive.Builder(
                HTTP_TRANSPORT, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME)
                .build();
    }

    public static void main(String[] args) throws IOException {
        // Build a new authorized API client service.
        Drive driveService = getDriveService();

        // Your script is here.
        File fileMetadata = new File();
        fileMetadata.setName("Invoices");
        fileMetadata.setMimeType("application/vnd.google-apps.folder");

        File file = driveService.files().create(fileMetadata)
                .setFields("id")
                .execute();
        System.out.println("Folder ID: " + file.getId());
    }
}

Result :

Folder ID: ### folder ID ###

If I misunderstand your question, I'm sorry.