public class LoginActivity extends AppCompatActivity {

    private ViewHolder viewHolder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        viewHolder = new ViewHolder(findViewById(R.id.layout_raiz));

        // faz algumas tarefas que poderiam deixar o código
        // da Activity sujo
        new VerificarLogin(viewHolder);
    }

    static class ViewHolder {
        @BindView(R.id.et1)
        EditText email;
        @BindView(R.id.et2)
        EditText senha;

        ViewHolder(View view) {
            ButterKnife.bind(this, view);
        }
    }
}