Android Kotlin-IllegalArgumentException:指定为非null的参数为null

我将数据传递给bundle中的某个片段，在接收时抛出异常。还原片段的状态时发生此错误

调用createFromParcel时，Intrinsics.CheckParametersNotNull中发生错误。模型中所有不可为空的字段都会出现这种情况

Caused by java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.b.h.b, parameter realtorImageUrl
   at com.android.app.ui.common.model.Property.(Unknown Source:16)
   at com.android.app.ui.common.model.Property$Creator.createFromParcel(Unknown Source:637)
   at android.os.Parcel.readParcelable(Parcel.java:2797)
   at android.os.Parcel.readValue(Parcel.java:2691)
   at android.os.Parcel.readArrayMapInternal(Parcel.java:3058)
   at android.os.BaseBundle.unparcel(BaseBundle.java:257)
   at android.os.BaseBundle.getInt(BaseBundle.java:961)
   at me.yokeyword.fragmentation.SupportFragmentDelegate.onCreate(SourceFile:93)
   at me.yokeyword.fragmentation.SupportFragment.onCreate(SourceFile:48)
   at android.support.v4.app.Fragment.performCreate(SourceFile:2331)
   at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1386)
   at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(SourceFile:1759)
   at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1827)
   at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(SourceFile:3244)
   at android.support.v4.app.FragmentManagerImpl.dispatchCreate(SourceFile:3194)
   at android.support.v4.app.Fragment.restoreChildFragmentState(SourceFile:1444)
   at android.support.v4.app.Fragment.onCreate(SourceFile:1415)
   at me.yokeyword.fragmentation.SupportFragment.onCreate(SourceFile:47)
   at android.support.v4.app.Fragment.performCreate(SourceFile:2331)
   at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1386)
   at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(SourceFile:1759)
   at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1827)
   at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(SourceFile:3244)
   at android.support.v4.app.FragmentManagerImpl.dispatchCreate(SourceFile:3194)
   at android.support.v4.app.FragmentController.dispatchCreate(SourceFile:184)
   at android.support.v4.app.FragmentActivity.onCreate(SourceFile:355)
   at android.support.v7.app.AppCompatActivity.onCreate(SourceFile:84)
   at me.yokeyword.fragmentation.SupportActivity.onCreate(SourceFile:38)
   at com.android.app.ui.home.HomeActivity.onCreate(SourceFile:47)
   at android.app.Activity.performCreate(Activity.java:7174)
   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1220)
   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2908)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3030)
   at android.app.ActivityThread.-wrap11(Unknown Source)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1696)
   at android.os.Handler.dispatchMessage(Handler.java:105)
   at android.os.Looper.loop(Looper.java:164)
   at android.app.ActivityThread.main(ActivityThread.java:6938)
   at java.lang.reflect.Method.invoke(Method.java)
   at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)

Property.kt

@Parcelize
data class Property(
    ...
    @Json(name = "RealtorImageUrl")
    val realtorImageUrl: String
    ...
) : Parcelable

@Parcelize
data class Property(
    ...
    @Json(name = "RealtorImageUrl")
    val realtorImageUrl: String
    ...
) : Parcelable

Kotlin 1.1.4，Android扩展插件提供了使用@Parcelize的Parcelable实现生成器

PropertyListFragment.kt

override fun showPropertyDetails(property: Property) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

class PropertyDetailsFragment{
    ...
    companion object {
        fun newInstance(property: Property) = PropertyDetailsFragment().withArgs {
            putParcelable(INT_EXTRA_PROPERTY, property)
        }
    }
    ...
}

override fun showPropertyDetails(property: Property?) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

PropertyDetailsFragment.kt

override fun showPropertyDetails(property: Property) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

class PropertyDetailsFragment{
    ...
    companion object {
        fun newInstance(property: Property) = PropertyDetailsFragment().withArgs {
            putParcelable(INT_EXTRA_PROPERTY, property)
        }
    }
    ...
}

override fun showPropertyDetails(property: Property?) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

---

我需要做什么来解决这个问题？

因为

realtorImageUrl

被定义为非空，所以kotlin不允许将其设置为空。因此，唯一可行的方法是通过反射设置空值。Json帮助程序库基于注释处理，并使用反射来设置字段的值，因此问题肯定来自它们

• 首先，我强烈建议你使用谷歌

  Gson

• 其次，确保配置更改后json字符串不为null或空
• 第三，确保在依赖项中使用

  moshi kotlin

  （不是简单的

  moshi

  ），并将

  KotlinJsonAdapterFactory

  的实例添加到

  moshi

  生成器中

build.gradle:

implementation 'com.squareup.moshi:moshi-kotlin:1.8.0'

val json = "{\"RealtorImageUrl\": \"http://www.gstatic.com/tv/thumb/persons/667736/667736_v9_ba.jpg\"}"

val moshi = Moshi.Builder()
        .add(KotlinJsonAdapterFactory()) // com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
        .build()

val jsonAdapter = moshi.adapter(Property::class.java) as JsonAdapter<Property>
val property = jsonAdapter.fromJson(json) as Property

supportFragmentManager.beginTransaction()
        .replace(R.id.container, PropertyDetailsFragment.newInstance(property))
        .commit()

class PropertyDetailsFragment : Fragment() {

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val property = arguments?.getParcelable(KEY_EXTRA_PROPERTY) as Property
        val realtorImageUrl = property.realtorImageUrl
    }

    companion object {
        private const val KEY_EXTRA_PROPERTY = "KEY_EXTRA_PROPERTY"

        fun newInstance(property: Property) = PropertyDetailsFragment().withArguments(
                KEY_EXTRA_PROPERTY to property
        )
    }
}

测试：

implementation 'com.squareup.moshi:moshi-kotlin:1.8.0'

val json = "{\"RealtorImageUrl\": \"http://www.gstatic.com/tv/thumb/persons/667736/667736_v9_ba.jpg\"}"

val moshi = Moshi.Builder()
        .add(KotlinJsonAdapterFactory()) // com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
        .build()

val jsonAdapter = moshi.adapter(Property::class.java) as JsonAdapter<Property>
val property = jsonAdapter.fromJson(json) as Property

supportFragmentManager.beginTransaction()
        .replace(R.id.container, PropertyDetailsFragment.newInstance(property))
        .commit()

class PropertyDetailsFragment : Fragment() {

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val property = arguments?.getParcelable(KEY_EXTRA_PROPERTY) as Property
        val realtorImageUrl = property.realtorImageUrl
    }

    companion object {
        private const val KEY_EXTRA_PROPERTY = "KEY_EXTRA_PROPERTY"

        fun newInstance(property: Property) = PropertyDetailsFragment().withArguments(
                KEY_EXTRA_PROPERTY to property
        )
    }
}

---

嗯，这可能不是一个完美的解决方案，但它可以解决你的问题。您可以使您的属性为null，并且只要在访问它们时添加null检查即可

只需像这样初始化变量

Property.kt

@Parcelize
data class Property(
    ...
    @Json(name = "RealtorImageUrl")
    val realtorImageUrl: String
    ...
) : Parcelable

@Parcelize
data class Property(
    ...
    @Json(name = "RealtorImageUrl")
    val realtorImageUrl: String
    ...
) : Parcelable

PropertyListFragment.kt

override fun showPropertyDetails(property: Property) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

class PropertyDetailsFragment{
    ...
    companion object {
        fun newInstance(property: Property) = PropertyDetailsFragment().withArgs {
            putParcelable(INT_EXTRA_PROPERTY, property)
        }
    }
    ...
}

override fun showPropertyDetails(property: Property?) {
    (parentFragment as PropertySearchResultFragment).start(
        PropertyDetailsFragment.newInstance(property)
    )
}

在PropertyDetailsFragment.kt中

class PropertyDetailsFragment{
    ...
    companion object {
        fun newInstance(property: Property?) = PropertyDetailsFragment().withArgs {
            property?.let{
                putParcelable(INT_EXTRA_PROPERTY, property)
            }
        }
    }
    ...
}

---

你可以尝试使用@field:Json（name=“RealtorImageUrl”）并检查它是否有效吗

此外，请检查是否添加了正确的factory KotlinJsonAdapterFactory（）

---

不，你不能肯定。错误是您指定为非空的

realtorimagerurl

由于某种原因而变为空。您可能将其视为lateinit变量，在访问时该变量尚未初始化。@NileStrathod您提供的链接是另一个问题。在kotlin中访问java类时，所有变量都为null，因此在访问任何java变量时需要使用“？”。我不知道模型中的参数是如何变为null的。@EpicPandaForce我的意思是说数据在显示时不是null的。我想知道为什么它是空的。问题可能是用JSON解析，每当JsonResponse没有RealTrimeIdl时，它就会认为它是null@Rajesh：什么是带有

@Json

注释的库？我已经用google

Gson

对它进行了测试，在恢复像手机旋转这样的片段状态时没有出现任何问题。我使用的是Moshi库。使用安科图书馆有什么不同吗？我想问题出在莫西图书馆。我已经更新了答案。您能解释一下moshi library出现问题的原因吗？好的，您已经定义了

realtorImageUrl

非空，kotlin不允许将其设置为空。唯一可能的方法是通过反射设置空值。由于注释处理器json库使用反射为字段设置值，因此问题肯定来自它们。问题不在于

属性的空值，
realtorImageUrl
造成了问题。