The Google Cloud Shell has application default credentials from its compute instance which will allow you to run samples without having to obtain GOOGLE_APPLICATION_CREDENTIALS. Go to the Datastore Client Readme to run each sample in the Cloud Shell.

1. First set up the GOOGLE_CLOUD_PROJECT environment variable.

2. Obtain authentication credentials.

   Create local credentials by running the following command and following the oauth2 flow (read more about the command here):

    gcloud auth application-default login
   

   Or manually set the GOOGLE_APPLICATION_CREDENTIALS environment variable to point to a service account key JSON file path.

   Learn more at Setting Up Authentication for Server to Server Production Applications.

Now you can run a sample:

1. cd samples/snippets - all samples are located in the java-datastore/samples/snippets directory.
2. mvn compile exec:java -Dexec.mainClass="com.google.datastore.snippets.TaskList" - this runs the TaskList sample.