我在活動中使用的代碼：
private fun addFragmentToActivity(fragment: Fragment?) {
if (fragment == null) return
val ft = supportFragmentManager.beginTransaction()
ft.replace(R.id.container, fragment)
ft.addToBackStack(null)
ft.commit()
checkForBackStack()
}
private fun checkForBackStack() {
val fm = supportFragmentManager
if (fm.backStackEntryCount > 0) {
binding.backIV.visible()
} else {
binding.backIV.gone()
}
}
我想根據 設定后退按鈕的可見性backStackEntryCount，但它總是回傳 0。我做錯了什么嗎？
uj5u.com熱心網友回復：
fm.executePendingTransactions()在條目計數檢查之前添加：
private fun addFragmentToActivity(fragment: Fragment?) {
if (fragment == null) return
val ft = supportFragmentManager.beginTransaction()
ft.replace(R.id.container, fragment)
ft.addToBackStack(null)
ft.commit()
fm.executePendingTransactions()
checkForBackStack()
}
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