Kotlin和Dagger：我可以对对象使用@Inject使其仍然为空/可选吗？

我需要一些可以使我的类为空/可选的东西，因为某些设备上正在发生运行时错误

这可能吗

class MyFragment extends Fragment {
    @Inject
    var presenter: MyPresenter? = null
// Other codes here...
}

我想使用

presenter

作为一个选项，因为一些旧的安卓设备尤其会抛出这个错误（这是在我删除lazyinit之前）

代码：

错误：

Fatal Exception: java.lang.RuntimeException: Unable to destroy activity {com.sample.MyActivity}: c.r: lateinit property presenter has not been initialized
       at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3497)
       at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3515)
       at android.app.ActivityThread.access$1400(ActivityThread.java:135)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1249)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:136)
       at android.app.ActivityThread.main(ActivityThread.java:5017)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
       at dalvik.system.NativeStart.main(NativeStart.java)
Caused by c.r: lateinit property presenter has not been initialized
       at com.sample.MyFragment.onDestroy(SourceFile:459)
       at android.support.v4.app.Fragment.performDestroy(SourceFile:2434)
       at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1442)
       at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(SourceFile:1528)
       at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1595)
       at android.support.v4.app.FragmentManagerImpl.dispatchDestroy(SourceFile:2951)
       at android.support.v4.app.FragmentController.dispatchDestroy(SourceFile:271)
       at android.support.v4.app.FragmentActivity.onDestroy(SourceFile:390)
       at android.support.v7.app.AppCompatActivity.onDestroy(SourceFile:209)
       at android.app.Activity.performDestroy(Activity.java:5403)
       at android.app.Instrumentation.callActivityOnDestroy(Instrumentation.java:1117)
       at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:3484)
       at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:3515)
       at android.app.ActivityThread.access$1400(ActivityThread.java:135)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1249)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:136)
       at android.app.ActivityThread.main(ActivityThread.java:5017)
       at java.lang.reflect.Method.invokeNative(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:515)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
       at dalvik.system.NativeStart.main(NativeStart.java)

---

对于这种情况，有什么方法或解决方法吗？

我也遇到了同样的问题，并这样解决了：

@Inject
@JvmField
var presenter: Presenter? = null

---

希望有帮助。

如果您没有需要访问

presenter

字段的Java代码，则无需使用

@JvmField

对其进行注释。相反，您可以这样声明字段：

@set:Inject
var presenter: Presenter? = null

---

非常感谢你。你让我开心！如果没有指定

@JvmField

注释，Kotlin编译器会将其设置为私有，Dagger无法将其注入私有字段。我花了将近一个小时才弄明白。我将我的类迁移到kotlin，我在AndroidJector中遇到了同样的问题，当我尝试在初始化之前注入变量时，但通过这个我解决了问题！谢谢。

@set:Inject
var presenter: Presenter? = null