(科特林)碎片后堆栈句柄

Question

当我使用backStackEntryCount>1.popbackpack((它没有导航到我底部导航的任何片段

我需要知道的是，如何只堆叠一次片段，这样我就可以按一次后退按钮，导航到"活动"。

private fun navBottomClick() {
bottomNavigationView?.setOnItemSelectedListener {
when (it.itemId) {
R.id.workout -> {
var fragmentTransaction: FragmentTransaction =
supportFragmentManager.beginTransaction()
fragmentTransaction.replace(R.id.container, WorkoutFragment(), "WORKOUT")
fragmentTransaction.addToBackStack("WORKOUT")
fragmentTransaction.commit()
}
R.id.health -> {
var fragmentTransaction: FragmentTransaction =
supportFragmentManager.beginTransaction()
fragmentTransaction.replace(R.id.container, HealthyFoodFragment(), "HealthFood")
fragmentTransaction.addToBackStack("HealthFood")
fragmentTransaction.commit()
}
}
true
}
}

Answer 1

如果没有backStack，您可以尝试此

override fun onBackPressed() {
if (binding.bottomNavigation.selectedItemId == R.id.home) {
moveTaskToBack(true)
} else {
binding.bottomNavigation.selectedItemId = R.id.home
val homeFragment = HomeFragment.newInstance()
openFragment(homeFragment)
}
}

Answer 2

尝试打印日志supportFragmentManager.backStackEntryCount。

我认为条件是supportFragmentManager.backStackEntryCount > 0。