我知道这个问题似乎已经被提出并回答了,但这不是事实。因为我还没有找到解决方案。
我的活动有很多片段。并且我存储了所有转换历史记录(可以按后退按LIFO顺序返回每个片段-因为每个片段都会添加到后退堆栈中)
我想使用下一个功能: 当我按返回时-不能重新创建底部片段的视图。
我下一步
1)使用android导航组件和类似的转换
fun navigate(@IdRes resId: Int, bundle: Bundle? = null, navOptions: NavOptions? = null, sharedElements: List<View>? = null) {
navController.navigate(resId, bundle, navOptions, sharedElements?.let {
if (it.isEmpty()) null else
FragmentNavigatorExtras(
*it.map { view -> Pair(view, view.transitionNameCompat.safe) }
.filter { pair -> pair.second.isNotEmpty() }
.toTypedArray()
)
})
}
其中idRes是目的地ID(不是过渡ID)
2)将内容视图保持为片段,并通过onCreateView视图方法将其与父视图分离。因为getView()
返回null,所以即使从堆栈中也出现了碎片。
private var contentView: View? = null
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
prepareView(contentView) ?: createView(inflater, container)
private fun prepareView(view: View?): View? {
val parent = view?.parent
val viewGroup = parent as? ViewGroup
viewGroup?.removeView(view)
return view
}
protected open fun createView(inflater: LayoutInflater, container: ViewGroup?): View? {
val layout = layout()
if (layout == -1)
throw IllegalArgumentException("You need to override \"layout()\" fun or override \"createView\" fun")
return inflater.inflate(layout(), container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
if (contentView == null) {
onFirstInitialization(view, savedInstanceState)
} else {
onNextInitialization(view, savedInstanceState)
}
onEachInitialization(view, savedInstanceState)
contentView = view
}
只有当我过渡到下一个片段并快速按“返回”时,我才有例外!在正常模式下,一切正常。
例外:
java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
at android.view.ViewGroup.addViewInner(ViewGroup.java:5050)
at android.view.ViewGroup.addView(ViewGroup.java:4881)
at android.view.ViewGroup.addView(ViewGroup.java:4821)
at android.view.ViewGroup.addView(ViewGroup.java:4794)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:890)
at androidx.fragment.app.FragmentManagerImpl.addAddedFragments(FragmentManagerImpl.java:2092)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1866)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1822)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1723)
at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2624)
at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2580)
at androidx.fragment.app.Fragment.performActivityCreated(Fragment.java:2571)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:907)
at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1235)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1301)
at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2620)
at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2580)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:541)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1470)
at android.app.Activity.performStart(Activity.java:7176)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3086)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1926)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6923)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
我可以通过将prepareView
放置到onDestroyView
生命周期方法中来解决此问题,并且一切正常,但是会产生内存泄漏:我发现了-当视图在{{1}之后没有父级时},然后onDestroyView
再也不会被调用,即使在按回键之后,片段也会保留在内存中。
您可以说“嘿,伙计,不要着急,慢慢使用您的应用程序,就像您说的那样,永远不会抛出异常。但是在生产中,我遇到了这个bug导致崩溃的错误” :(我如何处理情况?
更新: 我研究了一下,发现了一些东西。仅当视图未从窗口分离时抛出异常。并且只有在打开新片段后300-400毫秒后,视图才会与窗口分离
答案 0 :(得分:1)
是的!这是真的。您无法再次创建其对象,因为它有一个父对象。您可能没有注意到的主要问题是,每当您再次调用片段时,就会调用onCreateView()
。
因此,在排序中,我建议您将代码从片段的onCreateView()
移至onCreate()
方法。
我也为这类问题而苦恼。因此,请以onCreate()
方法扩大视图并以onCreateView()
方法返回主视图。