Java Quickstart

Complete the steps described in the rest of this page to create a simple Java command-line application that makes requests to the Google Vault API.


To run this quickstart, you need the following prerequisites:

  • Authorization credentials for a desktop application. To learn how to create credentials for a desktop application, refer to Create credentials.
  • A Google account.

Step 1: Prepare the project

To prepare the project:

  1. In your working directory, run the following commands to create a new project structure:

    gradle init --type basic
    mkdir -p src/main/java src/main/resources 
  2. Copy the credentials.json file you downloaded as a prerequisite into the newly-created src/main/resources/ directory.

  3. Open the default build.gradle file and replace its contents with the following code:

    apply plugin: 'java'
    apply plugin: 'application'
    mainClassName = 'Quickstart'
    sourceCompatibility = 11
    targetCompatibility = 11
    version = '1.0'
    repositories {
    dependencies {
        implementation ''
        implementation ''
        implementation ''

Step 2: Set up the sample

To set up the sample:

  1. In src/main/java/, create a new Java file with a name that matches the mainClassName value in your build.gradle file.
  2. Include the following code in your new Java file:

    import java.util.Arrays;
    import java.util.List;
    public class Quickstart {
        /** Application name. */
        private static final String APPLICATION_NAME =
            "Google Vault API Java Quickstart";
        /** Directory to store authorization tokens for this application. */
        private static final DATA_STORE_DIR = new"tokens");
        /** Global instance of the {@link FileDataStoreFactory}. */
        private static FileDataStoreFactory DATA_STORE_FACTORY;
        /** Global instance of the JSON factory. */
        private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
        /** Global instance of the HTTP transport. */
        private static HttpTransport HTTP_TRANSPORT;
        private static final String CREDENTIALS_FILE_PATH = "/credentials.json";
        /** Global instance of the scopes required by this quickstart.
         * If modifying these scopes, delete your previously saved credentials
         * at ~/.credentials/
        private static final List<String> SCOPES =
        static {
            try {
                HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
                DATA_STORE_FACTORY = new FileDataStoreFactory(DATA_STORE_DIR);
            } catch (Throwable t) {
         * Creates an authorized Credential object.
         * @return an authorized Credential object.
         * @throws IOException
        public static Credential authorize() throws IOException {
            // Load client secrets.
            InputStream in =
            if (in == null) {
                throw new FileNotFoundException("Resource not found: " + CREDENTIALS_FILE_PATH);
            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)
            Credential credential = new AuthorizationCodeInstalledApp(
                flow, new LocalServerReceiver()).authorize("user");
                    "Credentials saved to " + DATA_STORE_DIR.getAbsolutePath());
            return credential;
         * Build and return an authorized Vault client service.
         * @return an authorized Vault client service
         * @throws IOException
        public static Vault getVaultService() throws IOException {
            Credential credential = authorize();
            return new Vault.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential)
        public static void main(String[] args) throws IOException {
            // Build a new authorized API client service.
            Vault service = getVaultService();
            // List the first 10 matters.
            ListMattersResponse response = service.matters().list()
            List<Matter> matters = response.getMatters();
            if (matters == null || matters.size() == 0) {
                System.out.println("No matters found.");
            for (Matter matter: matters) {
                System.out.printf("%s (%s)\n", matter.getName(),

Step 3: Run the sample

To run the sample:

  1. Execute the following command:

    gradle run

    This command builds and runs the sample.

  2. (optional). If this is your first time running the sample, the sample opens a new window prompting you to authorize access to your data:

    1. If you are not already signed in to your Google account, you are prompted to sign in. If you are signed in to multiple Google accounts, you are asked to select one account to use for authorization.
    1. Click Accept. The app is authorized to access your data.
  3. The sample executes.

If you have problems, refer to the Troubleshoot the sample section.

Troubleshoot the sample

This section describes a common issue that you can encounter while attempting to run this quickstart.

This app isn't verified

If the OAuth consent screen displays the warning "This app isn't verified," your app is requesting scopes that provide access to sensitive user data. If your application uses sensitive scopes, your app must go through the verification process to remove that warning and other limitations. During the development phase, you can continue past this warning by selecting Advanced > Go to {Project Name} (unsafe).

File not found error for credentials.json

When running the sample, you might receive a file not found or no such file error regarding credentials.json.

This error occurs when you have not authorized the desktop application credentials as detailed in the Prerequisites section above. To learn how to create credentials for a desktop application, go to Create credentials.

Once you create the credentials, make sure the downloaded JSON file is saved as credentials.json. Then move the file to your working directory with the rest of the sample quickstart code.

Further reading

For further information on the APIs used in this quickstart, refer to the following: