非法状态异常：活动已被销毁（API 级别＜21）

Question

我有一个带有底部导航栏的单个活动应用。每个底部导航栏选项卡都是一个片段，它作为一个容器并呈现多个子片段。 仅在Android版本 <21上，该应用程序会崩溃，并出现以下堆栈跟踪：

Process: de.name.dev, PID: 5262                                                                       
java.lang.IllegalStateException: Activity has been destroyed                                                                           
    at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1345)               
    at android.app.BackStackRecord.commitInternal(BackStackRecord.java:597)           
    at android.app.BackStackRecord.commit(BackStackRecord.java:575)        
    at de.xxxxxx.more.MoreFragment.onViewCreated(MoreFragment.kt:30)                
    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:904)               
    at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)       
    at android.app.BackStackRecord.run(BackStackRecord.java:684)      
    at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)           
    at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)      
    at android.os.Handler.handleCallback(Handler.java:733)             
    at android.os.Handler.dispatchMessage(Handler.java:95)                         
    at android.os.Looper.loop(Looper.java:136)                         
    at android.app.ActivityThread.main(ActivityThread.java:5017)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
    at dalvik.system.NativeStart.main(Native Method)

我们的ContainerFragment看起来像这样：

class MoreFragment : KodeinFragment(), MoreOpenWebViewListener {

private val settingsFragment by lazy {
    SettingsFragment(this)
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
}

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup, savedInstanceState: Bundle?): View {
    return inflater.inflate(R.layout.fragment_more, container, false)
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    childFragmentManager.beginTransaction()
        .add(R.id.more_container, settingsFragment)
        .commit()
}

...

onViewCreated方法中，容器将要展示的fragment添加到其childFragmentManager中。 如果在不同标签之间切换，则该fragment将被销毁并重新创建。 当你第二次使用.commit()方法时，会导致崩溃并出现上述堆栈跟踪。

MoreFragment实例化是在另一个容器fragment中，即TabBarFragment中进行的：

class TabBarFragment : KodeinFragment() {

private val sessionStore: SessionStore by instance()

private val fragment1 by lazy { Fragment1() }
private val moreFragment by lazy { MoreFragment() }

private val fragment2 by lazy { fragment2.newFragment2(sessionStore.data) }

var currentTabFragment: Fragment? = null
    private set

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    childFragmentManager
        .beginTransaction()
        .add(R.id.fragment_container, contractsFragment)
        .commit()
    bottomBar.selectTabAtPosition(0)
    bottomBar.setOnTabSelectListener { tabId ->
        when (tabId) {
            R.id.tab1 -> replaceFragment(fragment1)
            R.id.tab2 -> replaceFragment(fragment2)
            R.id.tab_settings -> replaceFragment(moreFragment)
        }
    }
    ViewCompat.setElevation(bottomBar, 8.0f * resources.displayMetrics.density)
}

private fun replaceFragment(fragment: Fragment) {
    childFragmentManager.beginTransaction().replace(R.id.fragment_container, fragment).commit()
    currentTabFragment = fragment
}
}

有什么想法发生了吗？

- Ziiiimon

---

可能是重复的问题：在使用ViewPager和选项卡时出现“Java.lang.IllegalStateException Activity has been destroyed”错误。 - tynn

Answer 1

在这里找到了解决方案： 使用ViewPager和选项卡时出现“Java.lang.IllegalStateException Activity has been destroyed”错误 这是Android中已知的一个错误。

您需要在使用childFragmentManager的片段中覆盖onDetach()并将其引用设置为null。

override fun onDetach() {
    super.onDetach()

    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        try {
            val childFragmentManager = Fragment::class.java!!.getDeclaredField("mChildFragmentManager")
            childFragmentManager.setAccessible(true)
            childFragmentManager.set(this, null)

        } catch (e: NoSuchFieldException) {
            throw RuntimeException(e)
        } catch (e: IllegalAccessException) {
            throw RuntimeException(e)
        }
    }
}

- Ziiiimon