BankDealsActivity.java

public class BankDealsActivity extends AppCompatActivity {
  
  //Params
  protected String mMerchantPublicKey;
  
  @Override
  protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_bank_deals);
      
      mMerchantPublicKey = this.getIntent().getStringExtra("merchantPublicKey");
      
      MercadoPago mercadoPago = new MercadoPago.Builder()
              .setContext(this)
              .setPublicKey(mMerchantPublicKey)
              .build();
      getBankDealsAsync(mercadoPago);
  }

  protected void getBankDealsAsync(MercadoPago mercadoPago) {

    mercadoPago.getBankDeals(new Callback<List<BankDeal>>() {
      @Override
      public void success(List<BankDeal> bankDeals, Response response) {
        // Listo, aquí ya tienes las promociones
        // para contarle a tu usuario 
      }
  
      @Override
      public void failure(RetrofitError error) {
        // Ups, ha ocurrido un error.
      }
    });
  }
}