Question

绑定后，name和onClick的绑定都不起作用。该按钮没有文字，点击后没有任何反应。

是因为lateinit吗？我做到了，因为否则我必须让它可以为空，以使Kotlin高兴。因为我必须在声明它时初始化属性。我在这里缺少什么？

这是xml文件：

<?xml version="1.0" encoding="utf-8"?>

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <variable
            name="authViewModel"
            type="nz.salect.handset.viewmodels.AuthViewModel" />
    </data>

    <android.support.constraint.ConstraintLayout
        ...
        tools:context="nz.salect.handset.view.AuthActivity">

        ......

            <Button
                ...
                android:onClick="@{ () -> authViewModel.lookAroundHandler() }"
                android:text="@{authViewModel.name}"
                ... />

这是相应的观点：

class AuthActivity : AppCompatActivity() {
    private lateinit var authViewModel:AuthViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_auth)
        authViewModel = ViewModelProviders.of(this).get(AuthViewModel::class.java)
    }
}

这是视图模型

class AuthViewModel:ViewModel() {
    val name = "albert"

    fun lookAroundHandler() {
        println("I am here in view model")
    }
}

已将数据绑定添加到build.gradle：

dataBinding {
    enabled = true
}

Answer 1

您缺少的绑定代码

val mViewDataBinding = DataBindingUtil.setContentView(this,R.layout.activity_auth);

你不需要添加这一行

setContentView(R.layout.activity_auth)

https://developer.android.com/topic/libraries/data-binding/index.html

Answer 2

试试这段代码：

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)

binding = DataBindingUtil.setContentView(this, R.layout.activity_person)
(application as PeopleApplication).applicationComponent.inject(this)

val viewModelFactory: PersonViewModel.Factory = PersonViewModel.Factory(
personDataManager, this)
viewModel = ViewModelProviders.of(this, viewModelFactory).get(PersonViewModel::class.java)

binding.friendsList.adapter = PersonFriendListAdapter(viewModel)
viewModel.personData.observe(this, Observer<Person> { person ->
    binding.person = person
    person?.friends?.let {
        (binding.friendsList.adapter as PersonFriendListAdapter).setItems(person.friends)
    }
})
 }

检查您的代码

使用ViewModelProviders

2 个答案: