Fragment 的 onCreateView() 没有被调用

Question

我正在创建我的片段的一个实例，然后尝试调用它的方法之一，但需要在 onCreateView() 中实例化一个变量，然后才能调用该方法而不抛出 NullPointerException。

这是我的片段的一部分：

class UpdatesFragment : androidx.fragment.app.Fragment(){

var progressBar: ProgressBar? = null
private var instance: UpdatesFragment? = null
private var application: CustomApplication? = null
var bluetoothManager2: BluetoothManager? = null
private lateinit var li: LayoutInflater
private var deviceContainer: ViewFlipper? = null
private var devicePrep: View? = null
private var progressLayout: View? = null
private var progressText: TextView? = null
var progressBarText: TextView? = null
var progressChunk: TextView? = null
private var scroll: ScrollView? = null
private var logWindow: TextView? = null
private var currentView = 0
private var disconnected = false

override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
View? {

instance = this
application = activity?.application as CustomApplication
if (bluetoothManager2 == null) {
bluetoothManager2 = SuotaManager() // THIS LINE NEEDS TO BE CALLED BEFORE MY METHOD IS CALLED. 
>         }
bluetoothManager2!!.setContext(this)
bluetoothManager2!!.setDevice(application!!.device)

progressText = progressLayout!!.findViewById(R.id.progress_text)
progressChunk = progressLayout!!.findViewById(R.id.progress_chunk)
progressBar = progressLayout!!.findViewById(R.id.progress_bar)
progressBarText = progressLayout!!.findViewById(R.id.progress_bar_text)
scroll = progressLayout!!.findViewById<View>(R.id.logScroll) as ScrollView
logWindow = progressLayout!!.findViewById<View>(R.id.logWindow) as TextView
logWindow!!.setText(null, TextView.BufferType.EDITABLE)
progressBar!!.progress = 0
progressBar!!.max = 100

initDevicePrepScreen()
val fragmentView = inflater.inflate(R.layout.activity_fragment, container, false)

li = LayoutInflater.from(activity)
deviceContainer = fragmentView.findViewById(R.id.deviceLayoutContainer) as ViewFlipper
devicePrep = inflater.inflate(R.layout.device_prep, deviceContainer, true)
progressLayout = inflater.inflate(R.layout.progress, deviceContainer, true)

return fragmentView
>     }

这是我从活动中调用它的位置：

bluetoothGattReceiver =
            object : BluetoothGattReceiver() {
                override fun onReceive(context: Context, intent: Intent) {
                    super.onReceive(context, intent)

                    if (updatesFragment == null) {
                        updatesFragment = UpdatesFragment()
                    }
                    updatesFragment!!.processStep(intent)

如何在运行 updatesFragment!!.processStep(intent) 之前调用 onCreateView()？

这是堆栈跟踪：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.unobatteries.unobmsapp, PID: 31486
    java.lang.NullPointerException
        at com.unobatteries.unobmsapp.fragments.UpdatesFragment.processStep(UpdatesFragment.kt:85)
        at com.unobatteries.unobmsapp.activities.UpdatesActivity$onResume$2.onReceive(UpdatesActivity.kt:144)
        at androidx.localbroadcastmanager.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:313)
        at androidx.localbroadcastmanager.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:121)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:246)
        at android.app.ActivityThread.main(ActivityThread.java:8653)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)

fun processStep(intent: Intent?) {
        bluetoothManager2!!.processStep(intent) // Line 85
    }

Answer 1

更新：我意识到我需要调用此函数而不显示片段，同时仍然访问它引用的 bluetoothManager 类。有人向我指出，我不需要片段的实例来访问 bluetoothManager 中的函数，因为片段主要用于使用 ui 组件。

由于BluetoothManager类是抽象的，在我的活动中，我声明了一个SuotaManager类的实例，它扩展了BluetoothManager并在该实例上调用了processStep()，这解决了问题！