如何使用 Kotlin 從 Android 中的片段訪問另一個片段？

Question

  val dialog = AlertDialog.Builder(activity as Context)
    dialog.setTitle("Confirmation")
    dialog.setMessage("Are you sure you want to log out?")
    dialog.setPositiveButton("YES"){ text, listener ->
        sharedPreferences.edit().clear().apply()
        println("Shared preferences cleared")
        println("Logged out")
        val intent =  Intent(activity as Context, LoginActivity::class.java)
        startActivity(intent)
    }
    dialog.setNegativeButton("NO"){text,listener ->
        
        val homeFragment = HomeFragment()
        val beginTransaction = activity!!.supportFragmentManager.beginTransaction()

        beginTransaction.replace(R.id.frameLayout, homeFragment)
        beginTransaction.commit()
        activity!!.navigationView.setCheckedItem(R.id.home_screen)
        println("Home title set")
        activity!!.actionBar!!.title = "Home"
        
    }
    dialog.create()
    dialog.show()

當用戶單擊“否”按鈕時，我想 go 主頁片段。 我被定向到 Home Fragment，但對話框沒有消失，當我再次單擊“否”時，應用程序崩潰，並在行上給出 Null 指針異常：

val beginTransaction = activity!!.supportFragmentManager.beginTransaction()

到達主頁片段時如何刪除對話框？ 請幫忙。

Answer 1

調用dialog.dismiss(); 在提交事務之前
並且在轉移到另一項活動之前

val builder = AlertDialog.Builder(activity as Context)
.setTitle("Confirmation")
.setMessage("Are you sure you want to log out?") 
.setPositiveButton("YES"){ dialog, _ -> 
    sharedPreferences.edit().clear().apply() 
    println("Shared preferences cleared")
    println("Logged out")
    dialog.dismiss()
    val intent = Intent(activity as Context, LoginActivity::class.java)
    startActivity(intent) 
} 
.setNegativeButton("NO"){dialog,_ ->
    val homeFragment = HomeFragment()  
    val beginTransaction = activity!!.supportFragmentManager.beginTransaction()
    beginTransaction.replace(R.id.frameLayout, homeFragment)
    dialog.dismiss()
    beginTransaction.commit()
    activity!!.navigationView.setCheckedItem(R.id.home_screen) 
    println("Home title set")     
    activity!!.actionBar!!.title = "Home"
 }
.show()

Answer 2

問題是，作為 clicklisteners 的參數，您會得到一個DialogInterface object。 object 有一個dismiss()方法。 您需要調用那個來關閉對話框。

 val dialog = AlertDialog.Builder(activity as Context)
    dialog.setTitle("Confirmation")
    dialog.setMessage("Are you sure you want to log out?")
    dialog.setPositiveButton("YES"){ text, listener ->
        sharedPreferences.edit().clear().apply()
        println("Shared preferences cleared")
        println("Logged out")
        val intent =  Intent(activity as Context, LoginActivity::class.java)
        startActivity(intent)
    }
    dialog.setNegativeButton("NO"){dlgInterface: DialogInterface,listener ->
        

        val homeFragment = HomeFragment()
        val beginTransaction = activity?.supportFragmentManager.beginTransaction()

        beginTransaction.replace(R.id.frameLayout, homeFragment)
        beginTransaction.commit()
        activity?.navigationView.setCheckedItem(R.id.home_screen)
        println("Home title set")
        activity?.actionBar?.title = "Home"

        dlgInterface.dismiss()
        
    }
    dialog.create()
    dialog.show()

也請停止使用強制解包!! . Kotlin 有這種安全展開的魔力? 它可以挽救生命。 用它;）