使用幻灯片时Android中的空指针异常

Question

这是logcat输出

2022-06-20 13:19:27.605 20830-20830/com.example.moveapplication E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.moveapplication, PID: 20830
java.lang.NullPointerException: Argument must not be null
    at com.bumptech.glide.util.Preconditions.checkNotNull(Preconditions.java:29)
    at com.bumptech.glide.util.Preconditions.checkNotNull(Preconditions.java:23)
    at com.bumptech.glide.RequestBuilder.into(RequestBuilder.java:768)
    at com.example.moveapplication.activities.MainActivity.openBottomSheetDialog$lambda-2(MainActivity.kt:100)
    at com.example.moveapplication.activities.MainActivity.$r8$lambda$acEx44X-0qqDdGYpms4KzfGag5A(Unknown Source:0)
    at com.example.moveapplication.activities.MainActivity$$ExternalSyntheticLambda3.onSuccess(Unknown Source:15)
    at com.google.android.gms.tasks.zzm.run(com.google.android.gms:play-services-tasks@@18.0.1:1)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

在我的logcat中，当使用幻灯片加载图像时会出现异常。100号线是.into(uImage)

 private fun openBottomSheetDialog(position: Int) {
    val uImage = findViewById<ImageView>(R.id.sheetIvProfileImage)
    val uNumber = findViewById<TextView>(R.id.sheetTvOwnerNumber)
    val uEmail = findViewById<TextView>(R.id.tvOwnerEmail)
    val uAbout = findViewById<TextView>(R.id.tvOwnerAbout)
    val uTitle = findViewById<TextView>(R.id.sheetTvOwnerTitle)
    val publisher = posts[position].publisher

    val ownersRef = FirebaseFirestore.getInstance().collection("owners").document(publisher)
    ownersRef.get().addOnSuccessListener { document ->
        val ownerModel = document.toObject(Owner::class.java)
        if (ownerModel != null) {
            Glide.with(this)
                .load(ownerModel.profileImage)
                .into(uImage)
        }
        uTitle.text = ownerModel?.username
        uNumber.text = ownerModel?.phoneNumber
        uEmail.text = ownerModel?.email
        uAbout.text = ownerModel?.about
    }

    val bottomSheetDialog = BottomSheetDialog(this, R.style.BottomSheetDialogTheme)
    val bottomSheetView = LayoutInflater.from(applicationContext).inflate(
            R.layout.bottom_sheet_dialog,
            findViewById(R.id.bottomSheet)
    )
    bottomSheetDialog.apply {
        setContentView(bottomSheetView)
        setCancelable(true)
    }

}

Answer 1

据我所知，您正在错误地初始化BottomSheet的BottomSheets。如果我没有错，您正试图在一个BottomSheet中显示这个Activity，如果是，请尝试以下代码：

    private fun openBottomSheetDialog(position: Int) {
        // Initialize the View of the BottomSheet
        val bottomSheetView = LayoutInflater.from(this).inflate(R.layout.bottom_sheet_dialog, findViewById(R.id.bottomSheet), false)
        // Initialize the BottomSheetDialog
        val bottomSheetDialog = BottomSheetDialog(this, R.style.BottomSheetDialogTheme).apply {
            setCancelable(true)
            // Set the View
            setContentView(bottomSheetView)
        }
        /*
        * To initialize the Views of BottomSheet,
        * use parent view of the BottomSheet, i.e., bottomSheetView
        * */
        val uImage = bottomSheetView.findViewById<ImageView>(R.id.sheetIvProfileImage)
        val uNumber = bottomSheetView.findViewById<TextView>(R.id.sheetTvOwnerNumber)
        val uEmail = bottomSheetView.findViewById<TextView>(R.id.tvOwnerEmail)
        val uAbout = bottomSheetView.findViewById<TextView>(R.id.tvOwnerAbout)
        val uTitle = bottomSheetView.findViewById<TextView>(R.id.sheetTvOwnerTitle)
        val publisher = posts[position].publisher

        val ownersRef = FirebaseFirestore.getInstance().collection("owners").document(publisher)
        ownersRef.get().addOnSuccessListener { document ->
            val ownerModel = document.toObject(Owner::class.java)
            if (ownerModel != null) {
                Glide.with(this)
                    .load(ownerModel.profileImage)
                    .into(uImage)
                // These Views should be inside
                uTitle.text = ownerModel?.username
                uNumber.text = ownerModel?.phoneNumber
                uEmail.text = ownerModel?.email
                uAbout.text = ownerModel?.about
            }
        }
        
        // Add this line to show the BottomSheet
        bottomSheetDialog.show()
    }

Answer 2

this in Glide.with(this)它代表什么？您应该在那里传递一个视图或上下文。

Glide.with(requireContext())  //for example
.load(ownerModel.profileImage)
.into(uImage)

Answer 3

很难知道null的确切位置，因为我们没有您的项目，但是您有，所以一个断点会为您和其他人澄清这一点。

ownersRef.get().addOnSuccessListener { document ->
        val ownerModel = document.toObject(Owner::class.java)
        if (ownerModel != null) {
            Glide.with(this)
                .load(ownerModel.profileImage)
                .into(uImage)
        }

在此代码中，可以有各种空值。

ownerRef您在firebase上执行get()，但您确定这不是null吗？

this (在Glide.with(...)中)--这里可能指的是lambda中addOnSuccessListener的匿名实例，而不是活动或片段。

ownerModel不是空的，因为您检查了

uImage可能是空的，但我不知道Glide是否关心。

放置一个断点，调试应用程序，注意您有一个NullPointerReference异常。