java - 如何在 Kotlin 中声明原始类型？

Question

在 Java 中我可以声明这个

private List a;

//onCreate
a = new ArrayList()

但在 Kotlin 中它显示错误，它迫使我指定一个类型

private List<String> a

有时我不想提供类型(我不需要)，但它在 Kotlin 中显示错误例如在Java中

public abstract class BaseActivity<T extends ViewDataBinding> extends AppCompatActivity {
 //something
}

public abstract class BaseFragment {
 private BaseActivity activity;
 //something
}

//in kotkin I can't write
lateinit var activity: BaseAtivity //show error here (I have to specific a type but this is the base class and I do not want to specific a type here). I just want a reference of BaseActivity

@Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof BaseActivity) { //good in java but show error 
                                              //in kotlin because I have to //specific a type like BaseAtivity<something>
            BaseActivity activity = (BaseActivity) context;
            this.mActivity = activity;
            activity.onFragmentAttached();
        }
    }

我可以在 Kotlin 中编写什么来在 java 中实现相同的代码

Answer 1

您可以使用 star projections

例如

private List<*> a