老师好，我按您的代码写了，只是使用了kotlin语言，程序运行没问题，但我使用FixFragmentNavigator界面不显示，onCreateView方法也执行了，不使用就可以。点几下菜单也不显示，按回退键界面显示了，但都重叠在一起了。请问这是什么问题，如果解决。感觉就是Fragment起始给hide了，可代码里明明是show了，搞不懂问题出在哪里
代码如下：请帮忙看看问题在哪里。
package pjy.caiflyy.food.navigator

import android.content.Context
import android.os.Bundle
import android.util.Log
import androidx.annotation.IdRes
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentManager
import androidx.navigation.NavDestination
import androidx.navigation.NavOptions
import androidx.navigation.Navigator
import androidx.navigation.fragment.FragmentNavigator
import java.lang.reflect.Field
import java.util.*

/**

• 自定义Fragment导航器
  */
  @Navigator.Name(“fixfragment”)
  class FixFragmentNavigator(
  val context: Context,
  val fragmentManager: FragmentManager,
  val containerId: Int
  ) : FragmentNavigator(
  context,
  fragmentManager,
  containerId
  ) {
  override fun navigate(
  destination: Destination,
  args: Bundle?,
  navOptions: NavOptions?,
  navigatorExtras: Navigator.Extras?
  ): NavDestination? {
  if (fragmentManager.isStateSaved) {
  Log.i(
  “MyLog”, “Ignoring navigate() call: FragmentManager has already”
  + " saved its state"
  )
  return null
  }
  var className = destination.className
  if (className[0] == ‘.’) {
  className = context.packageName + className
  }
  val tag = className.substring(className.lastIndexOf(".") + 1)
  val frag = instantiateFragment(
  context, fragmentManager,
  className, args
  )
  frag.arguments = args
  val ft = fragmentManager.beginTransaction()

   var enterAnim = navOptions?.enterAnim ?: -1
   var exitAnim = navOptions?.exitAnim ?: -1
   var popEnterAnim = navOptions?.popEnterAnim ?: -1
   var popExitAnim = navOptions?.popExitAnim ?: -1
   if (enterAnim != -1 || exitAnim != -1 || popEnterAnim != -1 || popExitAnim != -1) {
       enterAnim = if (enterAnim != -1) enterAnim else 0
       exitAnim = if (exitAnim != -1) exitAnim else 0
       popEnterAnim = if (popEnterAnim != -1) popEnterAnim else 0
       popExitAnim = if (popExitAnim != -1) popExitAnim else 0
       ft.setCustomAnimations(enterAnim, exitAnim, popEnterAnim, popExitAnim)
   }
  
   val fragments: List<Fragment> = fragmentManager.fragments
   for (fragment in fragments) {
       ft.hide(fragment)
   }
   if (!frag.isAdded) {
       ft.add(containerId, frag, tag)
   }
   ft.show(frag)
   ft.setPrimaryNavigationFragment(frag)
  
   val field: Field = FragmentNavigator::class.java.getDeclaredField("mBackStack")
   field.setAccessible(true)
   val mBackStack = field.get(this) as ArrayDeque<Int?>
  
   @IdRes val destId = destination.id
   val initialNavigation = mBackStack.isEmpty()
   val isSingleTopReplacement = (navOptions != null && !initialNavigation
           && navOptions.shouldLaunchSingleTop()
           && mBackStack.peekLast() == destId)
  
   val isAdded: Boolean
   isAdded = when {
       initialNavigation -> {
           true
       }
       isSingleTopReplacement -> {
           // Single Top means we only want one instance on the back stack
           if (mBackStack.size > 1) {
               // If the Fragment to be replaced is on the FragmentManager's
               // back stack, a simple replace() isn't enough so we
               // remove it from the back stack and put our replacement
               // on the back stack in its place
               fragmentManager.popBackStack(
                   generateBackStackName(mBackStack.size, mBackStack.peekLast()!!),
                   FragmentManager.POP_BACK_STACK_INCLUSIVE
               )
               ft.addToBackStack(generateBackStackName(mBackStack.size, destId))
           }
           false
       }
       else -> {
           ft.addToBackStack(generateBackStackName(mBackStack.size + 1, destId))
           true
       }
   }
   if (navigatorExtras is Extras) {
       for ((key, value) in navigatorExtras.sharedElements) {
           ft.addSharedElement(key!!, value!!)
       }
   }
   ft.setReorderingAllowed(true)
   ft.commit()
   return if (isAdded) {
       mBackStack.add(destId)
       destination
   } else {
       null
   }
  

  }

  private fun generateBackStackName(backStackIndex: Int, destid: Int): String? {
  return “$backStackIndex-$destid”
  }
  }