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Ethernets
Asked:2022-08-22 21:38:37 +0800 CST2022-08-22 21:38:37 +0800 CST

如何正确地将 ArrayList 传递给另一个活动

  • 772

我有以下数据类：

data class LegendWrapper(
    val data: List<PlayerPerformance>? = emptyList()

)
data class PlayerPerformance(val name: String, val value: Int, val key: String)

data class TestList(val name: String, val data: LegendWrapper)

然后我完成了三月的清单

for((key, value ) in data.legends.all){
recList.add(TestList(key, value))
}

然后，当单击 RecyclerView 中的名称时，我想在另一个活动中获取数据。我尝试按照下面的示例执行此操作，但结果我以字符串的形式获取数据，使用它根本无法正常工作，我尝试通过putParcelableArrayListExtra我偶然发现类型不匹配异常，如何正确传输 ArrayList到另一个活动？

 heroesAdapt = HeroesRecyclerAdapter(this, recList){
   testList -> val heroesStatsActivity = Intent(this,HeroesStatsActivity::class.java)
   heroesStatsActivity.putExtra("nicknameHeroes", testList.name)
   heroesStatsActivity.putExtra("data", testList.data.toString())
   startActivity(heroesStatsActivity)
}

我用谷歌搜索了一下，找到了这样一个选项，但它也不起作用，heroesStatsActivity.putExtra("data", testList) 所以我把它传递了。并得到它这样val test = intent.extras?.getSerializable("data") as TestList尽管数据类本身继承自Serializable data class TestList(val name: String, val data: LegendWrapper) : Serializable从列表中选择名称时，这是错误

2021-08-22 17:33:12.426 4950-4950/com.example.studyactivitylifecyl
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.studyactivitylifecyl, PID: 4950
    java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name =
com.example.studyactivitylifecyl.Model.TestList)
        at android.os.Parcel.writeSerializable(Parcel.java:2113)
        at android.os.Parcel.writeValue(Parcel.java:1883)
        at android.os.Parcel.writeArrayMapInternal(Parcel.java:975)
        at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1620)
        at android.os.Bundle.writeToParcel(Bundle.java:1303)
        at android.os.Parcel.writeBundle(Parcel.java:1044)
        at android.content.Intent.writeToParcel(Intent.java:10855)
        at android.app.IActivityTaskManager$Stub$Proxy.startActivity(IActivityTaskManager.java:3668)
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1723)
        at android.app.Activity.startActivityForResult(Activity.java:5314)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:597)
        at android.app.Activity.startActivityForResult(Activity.java:5272)
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:583)
        at android.app.Activity.startActivity(Activity.java:5658)
        at android.app.Activity.startActivity(Activity.java:5611)
        at com.example.studyactivitylifecyl.HeroesActivity$onCreate$1.invoke(HeroesActivity.kt:45)
        at com.example.studyactivitylifecyl.HeroesActivity$onCreate$1.invoke(HeroesActivity.kt:40)
        at com.example.studyactivitylifecyl.Adapters.HeroesRecyclerAdapter$Holder.bindHeroes$lambda-0(HeroesRecyclerAdapter.kt:25)
        at com.example.studyactivitylifecyl.Adapters.HeroesRecyclerAdapter$Holder.lambda$m9Ppe9nWqwgcbjiXqOm_6-7XHbo(Unknown
Source:0)
        at com.example.studyactivitylifecyl.Adapters.-$$Lambda$HeroesRecyclerAdapter$Holder$m9Ppe9nWqwgcbjiXqOm_6-7XHbo.onClick(Unknown
Source:4)
        at android.view.View.performClick(View.java:7448)
        at android.view.View.performClickInternal(View.java:7425)
        at android.view.View.access$3600(View.java:810)
        at android.view.View$PerformClick.run(View.java:28305)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:223)
        at android.app.ActivityThread.main(ActivityThread.java:7656)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
     Caused by: java.io.NotSerializableException: com.example.studyactivitylifecyl.Model.LegendWrapper
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1240)
        at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1604)
        at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1565)
        at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1488)
        at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1234)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:354)
        at android.os.Parcel.writeSerializable(Parcel.java:2108)
        at android.os.Parcel.writeValue(Parcel.java:1883) 
        at android.os.Parcel.writeArrayMapInternal(Parcel.java:975) 
        at android.os.BaseBundle.writeToParcelInner(BaseBundle.java:1620) 
        at android.os.Bundle.writeToParcel(Bundle.java:1303) 
        at android.os.Parcel.writeBundle(Parcel.java:1044) 
        at android.content.Intent.writeToParcel(Intent.java:10855) 
        at android.app.IActivityTaskManager$Stub$Proxy.startActivity(IActivityTaskManager.java:3668) 
        at android.app.Instrumentation.execStartActivity(Instrumentation.java:1723) 
        at android.app.Activity.startActivityForResult(Activity.java:5314) 
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:597) 
        at android.app.Activity.startActivityForResult(Activity.java:5272) 
        at androidx.activity.ComponentActivity.startActivityForResult(ComponentActivity.java:583) 
        at android.app.Activity.startActivity(Activity.java:5658) 
        at android.app.Activity.startActivity(Activity.java:5611) 
        at com.example.studyactivitylifecyl.HeroesActivity$onCreate$1.invoke(HeroesActivity.kt:45) 
        at com.example.studyactivitylifecyl.HeroesActivity$onCreate$1.invoke(HeroesActivity.kt:40) 
        at com.example.studyactivitylifecyl.Adapters.HeroesRecyclerAdapter$Holder.bindHeroes$lambda-0(HeroesRecyclerAdapter.kt:25) 
        at com.example.studyactivitylifecyl.Adapters.HeroesRecyclerAdapter$Holder.lambda$m9Ppe9nWqwgcbjiXqOm_6-7XHbo(Unknown
Source:0) 
        at com.example.studyactivitylifecyl.Adapters.-$$Lambda$HeroesRecyclerAdapter$Holder$m9Ppe9nWqwgcbjiXqOm_6-7XHbo.onClick(Unknown
Source:4) 
        at android.view.View.performClick(View.java:7448) 
        at android.view.View.performClickInternal(View.java:7425) 
        at android.view.View.access$3600(View.java:810) 
        at android.view.View$PerformClick.run(View.java:28305) 
        at android.os.Handler.handleCallback(Handler.java:938) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:223) 
        at android.app.ActivityThread.main(ActivityThread.java:7656) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)

稍微改了一下代码。

@Parcelize
data class LegendWrapper(
    val data: List<PlayerPerformance>? = emptyList()

): Parcelable

@Parcelize
data class PlayerPerformance(val name: String, val value: Int, val key: String): Parcelable

@Parcelize
data class TestList(val name: String, val data: LegendWrapper) : Parcelable

接下来，我尝试发送

heroesStatsActivity.putParcelableArrayListExtra("data", testList)

但我得到一个错误

类型不匹配。必需：ArrayList<out Parcelable!>? 找到：测试列表

如果你只写 putExtra

heroesStatsActivity.putExtra("data", testList)

然后第二个活动出错了

val test = intent?.extras?.getParcelable("data")

没有足够的信息来推断类型变量 T

android

1 个回答

  1. Best Answer

    在 Android 中，不同活动之间的所有数据都在一个特殊的Parcel容器中传输。此容器中只能存储某些类型的数据。其中一种类型是Parcelable.

    你在使用putParcelableArrayListExtra，没错，它只需要实现ParcelableTestList接口。为了不手动编写 Parcelable 的实现，可以使用kotlin-parcelize 插件。

    我将举例说明如何使用 kotlin-parcelize 执行此操作：

    1. 我们用注解标记@Parcelize所有将被传输并实现接口的类Parcelable：

      @Parcelize
class MyExtra(...) : Parcelable

    2. 在活动“A”中，我们将对象myExtra放入意图中并启动活动“B”：

      val myExtra: MyExtra = ...
startActivity(
    Intent(this, ActivityБ::class.java)
        .putExtra("com.example.my_extra", myExtra)
)

    3. 在活动“B”中，我们从意图中拉出这个对象：

      val myExtra = intent.getParcelableExtra<MyExtra>("com.example.my_extra")
    • 4

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