Cannot find symbol class Data binding impl

Question

Sorry I cannot post image directly to the post, because it said that I must have at least 10 reputation to post it.

I created an xml in android studio like this Xml

and created 2 variable inside view model like this

private val _loadingText = MutableLiveData<String>()
val loadingText: LiveData<String> = _loadingText

then implement the data binding like this into my dialog view

val dialogView = layoutInflater.inflate(R.layout.dialog_custom_loading, dialog_root)
    val binding = DialogCustomLoadingBinding.inflate(layoutInflater, dialogView as ViewGroup, false)
    binding.viewModel = viewModel
    loading = Dialog(this)
    loading.setContentView(binding.root)

but when i run the code, it shown an error like this

Error

and i dont know, how to solve it.. help me please..

UPDATE : when i run with --stacktrace i still dont know what error is this..

The expression 'viewModelLoadingText.getValue()' cannot be inverted, so it cannot be used in a two-way binding

Details: There is no inverse for method getValue, you must add an @InverseMethod annotation to the method to indicate which method should be used when using it in two-way binding expressions

@MohammadMoeinGolchin i already do that.. but still get that error — Garalax, Apr 25 '20 at 10:44
Hello Garalax, welcome to stackoverflow. Can you please edit your post and paste thea actual code here instead of image? It helps us to easily copy it and diagnose the error. — Dharmaraj, Apr 25 '20 at 11:01

score 4 · Accepted Answer · answered Apr 25 '20 at 12:19

4

You are using two-way databinding which is not correct in this place.

Change android:text="@={viewModel.loadingText}" to android:text="@{viewModel.loadingText}"

More information about the issue: Two-way databinding is used when you also want your data to be updated from UI. A case may be an EditText which posts its text to a MutableLiveData and sets its text from it. Check out the official documentation for more details.

answered Apr 25 '20 at 12:19

momvart

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Wogh.. idk why, previously I used LiveData and then use this at my xml `android:text="@={viewModel.loadingText}"` But then i change the loading text data type to Mutable Live data, but stil use the "@=". And it works.. but why? – Garalax Apr 26 '20 at 06:13
Because when you use two-way data binding the UI must be able to mutate the data which is not possible with `LiveData`. So if you use `MutableLiveData` instead you give access to outerworld (UI) to change your data and errors disappear. @Garalax – momvart Apr 26 '20 at 07:08
1

so when i want to use `LiveData` it must be a one way data binding? so i must use `"@{}"`?. Or, when i want to bind my data to view, it must be a two way data binding? – Garalax Apr 26 '20 at 07:13
1

yeah, it must be a one way data binding. as I mentioned, you use a two-way data binding when you want your data to be updated by user. for example, we can use a two-way data binding for an `EditText` text attribute, but when it is a `TextView` and we want to only show data one-way data binding is used. @Garalax – momvart Apr 26 '20 at 07:20

score 0 · Answer 2 · answered Apr 25 '20 at 12:49

Please try this code to implement databinding with custom dialog. It is working fine for me

    private fun showAddContactDialog() {
    dialog= Dialog(this)

    dialog.setCancelable(true)
    dialog.setCanceledOnTouchOutside(true)
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE)
    Objects.requireNonNull(dialog.window)!!.setBackgroundDrawable(
        ColorDrawable(Color.TRANSPARENT)
    )
    dialog.window!!.setGravity(Gravity.CENTER)

    val dialogAddNotesBinding:DialogAddNotesBinding =DataBindingUtil.inflate(LayoutInflater.from(this),R.layout.dialog_add_notes,null,false)
    homeViewModel= ViewModelProviders.of(this).get(HomeViewModel::class.java)
    dialogAddNotesBinding.homeModel=homeViewModel
    homeViewModel.addNewContactListener=this
    dialog.setContentView(dialogAddNotesBinding.root)
    val window = dialog.window
    window!!.setLayout(
        LinearLayout.LayoutParams.MATCH_PARENT,
        LinearLayout.LayoutParams.MATCH_PARENT
    )
    dialog.show()
}

Cannot find symbol class Data binding impl

2 Answers2