Dagger2でActivityのprivateなフィールドにInjectする。

compile 'com.google.dagger2.7'

エラー

MainActivity.java

public class MainActivity extends AppCompatActivity {

    @Inject
    private BooksPresenter presenter;

}

成功

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private BooksPresenter presenter;

    @Inject
    public void setPresenter(BooksPresenter presenter) {
        this.presenter = presenter;
    }

}