import com.coinbase.android.sdk.OAuth;

// ...

OAuth.beginAuthorization(this, CLIENT_ID, "user", REDIRECT_URI, null);

// Completing the authorization must be done in an async task since it requires network communication...
public class CompleteAuthorizationTask extends RoboAsyncTask<OAuthTokensResponse> {
  private Intent mIntent;

  public CompleteAuthorizationTask(Intent intent) {
    super(MainActivity.this);
    mIntent = intent;
  }

  @Override
  public OAuthTokensResponse call() throws Exception {
    return OAuth.completeAuthorization(MainActivity.this, CLIENT_ID, CLIENT_SECRET, mIntent.getData());
  }

  @Override
  public void onSuccess(OAuthTokensResponse tokens) {
    // Success, now do something with the tokens
    new DisplayEmailTask(tokens).execute();
  }

  @Override
  public void onException(Exception ex) {
    mTextView.setText("There was an error fetching access tokens using the auth code: " + ex.getMessage());
  }
}

// In the Activity we set up to listen to our redirect URI
@Override
protected void onNewIntent(final Intent intent) {
  if (intent != null && intent.getAction() != null && intent.getAction().equals("android.intent.action.VIEW")) {
    new CompleteAuthorizationTask(intent).execute();
  }
}