小编m.k*_*man的帖子

我的应用程序只有两个基本活动和几个片段，我想在用户通过单击返回按到达特定基本片段时显示退出警报

override fun onBackPressed() {
        if (drawer_layout.isDrawerOpen(GravityCompat.START)) {
          drawer_layout.closeDrawer(GravityCompat.START)

        } else {
         // super.onBackPressed()
            AlertDialog.Builder(this)
                .setTitle("Exit Alert")
                .setMessage("Do You Want To Exit Petals App?")
                .setPositiveButton(android.R.string.ok) { dialog, whichButton ->
                    super.onBackPressed()
                }
                .setNegativeButton(android.R.string.cancel) { dialog, whichButton ->

                }
                .show()

        } 

我在每个片段上都使用了 addtosatck